topics per lesson
TRANSCRIPT
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
1 Characteristics of
metals and non ndash
metals
Physical properties of
metals
Chemical properties
of metals
2 Chemical properties
of metals
Chemical properties
of metals
Reactions of metal
compounds
3 Reactions of metal
compounds
Reactions of metal
compounds
Action of heat on
metal compounds
4 Action of heat on
metal compounds
Action of heat on
metal compounds
Reactivity of metals ndash
The Reactivity Series
5 Reactivity of metals Reactivity of metals Reactivity of metals
6 Extraction of metals Extraction of metals Alloys
7 Corrosion Importance of metals
and their compounds
on living systems and
environment
Chemical properties
of non ndash metals
8 Laboratory
preparation of gases
Laboratory
preparation of gases
Laboratory
preparation of gases
2
WEEK
LESSON
1 2 3
9 Uses of gases Uses of non ndash metals
and their compounds
Harmful effects of
non ndash metals and
their compounds on
living systems and
the environment
10 Green Chemistry Qualitative Analysis
ndash Identification of
cations
Qualitative Analysis
ndash Identification of
cations
11 Qualitative Analysis
ndash Test for gases
Qualitative Analysis
ndash Identification of
anions
Qualitative Analysis
ndash Identification of
anions
12 Problem solving of
Past CSEC Chemistry Paper 2
on topics completed in the term
13
14
15
3
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
WEEK 1 LESSON 1
TOPIC Characteristics of metals and non ndash metals
The elements of the periodic table may be classified as metals and non ndash metals The division is
The non ndash metals with the exception of hydrogen are found on the right hand side of the
periodic table These elements have atoms with completed filled or nearly filled outermost shells
The figure below shows an outline of the periodic table with the metals and non-metals
I II III IV V VI VII 0
B C N O F He
Si P S Cl Ne
METALS
As Se Br Ar
Te I Kr
At Xe
Rn
Periodic Table showing Metals and Non ndash metals
4
Differences between metals and non ndash metals
Metals Non ndash metals
Good conductor of electricity Do not conduct electricity
except graphite (carbon)
Good conductor of heat Do not conduct heat except graphite (carbon)
Lustrous solids at room temperature
(except mercury)
Solid liquid or gas at room temperature
eg iodine (solid) bromine (liquid) and
chlorine (gas) at room temperature
Malleable (can be beaten into different
shapes)
Not malleable
Ductile (can be drawn into wires) Not ductile
Sonorous (ring when hit with a hard object) Not sonorous
High melting and boiling points Low melting and boiling points compared to
metals
High density Much lower density at rtp compared to metals
5
WEEK 1 LESSON 1 WORKSHEET
Shade the letter next to the answer you choose for questions 1 to 4
1 Which of the following are metals
I Bromine
II Sodium
III Neon
IV Iron
(A) I and III (B) II and IV (C) I and IV (D) II and III
2 Which of the following are non ndash metals
I Chromium
II Carbon
III Iodine
IV Potassium
(A) I and III (B) II and IV (C) I and IV (D) II and III
3 A metal that is a liquid at room temperature is
(A) mercury (B) tin (C) magnesium (D) sodium
6
4 Consider the following information about four substances
Substance Melting point
0C
Electrical conductivity Water
solubility in solid in liquid
I 1050 Low High High
II 75 Low Low Low
III 1234 High High Low
IV 1913 Low Low Low
The substance which is MOST likely to be a metal is
(A) I (B) II (C) III (D) IV
5 Read the following and answer the question that follows
A new element was discovered to have the following properties
Lustrous solid
Can be beaten into shapes
High density
(a) Based only on the facts stated above is the element a metal or non metal
_______________________
(b) State 3 other properties that you expect this element to exhibit
______________________________________________________________________________
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7
WEEK 1 LESSON 2
TOPIC Physical properties of metals
Physical properties of some metals
Metals Melting point 0C
Boiling point
0C
Density
g cm-3
Other characteristics
Sodium 90 900 097 Very soft grey metal
Calcium 850 1487 153 Grey metal
Magnesium 650 1103 174 Soft grey metal
Aluminium 660 2350 270 Grey metal
Zinc 419 907 719 White metal
Iron 1535 2760 797 Dark grey metal
Copper 1083 2580 894 Gold coloured metal
conductivity second only to
silver
Sodium Calcium Magnesium Aluminium
Zinc Iron Copper
8
WEEK 1 LESSON 2 WORKSHEET
A group of students carried out an experiment to find the density of three different metals
aluminium calcium and an unknown metal X They measured the mass of each metal sample
using a balance The volumes of the metals were determined by displacement of oil The results
of their experiment are as follows
Aluminium Calcium Metal X
Mass (g) 100 100 100
Final volume (cm3) 335 365 310
Initial volume (cm3 300 300 300
Volume of metal (cm3)
Density (gcm-3)
Complete the table using the following formulae
Volume of metal = Final volume ndash Initial volume
Density = 119872119886119904119904
119881119900119897119906119898119890
Arrange the metals in order of increasing density _____________________________________
9
WEEK 1 LESSON 3
TOPIC Chemical properties of metals
Action of oxygen
Most metals react with oxygen or air to form the corresponding oxide These oxides are basic
oxides with the exception of aluminium zinc and lead which form amphoteric oxides Metals
lower in the electrochemical series do not react
Metal Reaction with air or oxygen
Potassium K
Burn very easily forming oxide
eg 4 Na (s) + O2 (g) 2 Na2O (s)
Sodium Na
Calcium Ca
Magnesium Mg
Aluminium Al
Burn especially if powered forming oxide
eg 4 Al (s) + 3 O2 (g) 2 Al2O3 (s)
Zinc Zn
Iron Fe
Lead Pb Do not burn form oxide when heated strongly
Copper Cu
Silver Ag No reaction
10
WEEK 1 LESSON 3 WORKSHEET
Write balanced chemical equations for the reaction of the named metals and air or oxygen
State the nature of the oxide formed (basic or amphoteric)
Potassium + Oxygen
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Sodium + Oxygen
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Calcium + Oxygen
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Magnesium + Oxygen
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Aluminium + Oxygen
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Zinc + Oxygen
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11
Iron + Oxygen
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Lead + Oxygen
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Copper + Oxygen
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Silver + Oxygen
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12
WEEK 2 LESSON 1
TOPIC Chemical properties of metals
Action of water
Metals high in the electrochemical series react with cold water to produce the metal hydroxide
and hydrogen
Reactive metals slightly lower in the electrochemical series react very slowly or not at all with
water However they may react with hot water or steam to produce the corresponding metal
oxide and hydrogen
Metals lower than hydrogen in the electrochemical series do not react with water
Metal Reaction with water or steam
Potassium K React with cold water forming metal hydroxide and hydrogen
eg Ca (s) + 2 H2O (l) Ca(OH))2 (aq) + H2 (g) Sodium Na
Calcium Ca
Magnesium Mg React with steam forming metal oxide and hydrogen
eg Zn (s) + H2O (g) ZnO (s) + H2 (g) Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
13
WEEK 2 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with water (or
steam if reaction does not occur with water)
Potassium + WaterSteam
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Sodium + WaterSteam
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Calcium + WaterSteam
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Magnesium + WaterSteam
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Aluminium + WaterSteam
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Zinc + WaterSteam
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14
Iron + WaterSteam
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Copper + WaterSteam
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Silver + WaterSteam
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15
WEEK 2 LESSON 2
TOPIC Chemical properties of metals
Action of dilute acids
Metals above hydrogen in the electrochemical series react with dilute acids to form a salt and
hydrogen gas They react with hydrochloric acid to form the metal chloride (a salt) and hydrogen
gas They also react with dilute suphuric acid to form the metal sulphate (a salt) and hydrogen
gas
Metal Reaction dilute hydrochloric or sulphuric acid
Potassium K Violent reaction forming a salt and hydrogen gas
eg 2 Na (s) + 2 HCl (aq) 2 NaCl (aq) + H2 (g) Sodium Na
Calcium Ca Vigorous reaction forming a salt and hydrogen gas
eg Mg (s) + 2 HCl (aq) MgCl2 (aq) + H2 (g) Magnesium Mg
Aluminium Al React forming a salt and hydrogen gas
eg Fe (s) + 2 HCl (aq) FeCl2 (aq) + H2 (g) Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
16
WEEK 2 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with
hydrochloric acid
Metal Balanced equation for reaction with hydrochloric acid
Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Copper
Silver
17
WEEK 2 LESSON 3
TOPIC Reactions of metal compounds
Reactions of metallic oxides with dilute acid
Metal oxides react with dilute hydrochloric acid or sulphuric acid to produce a salt and water
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
Some of these reactions may be slow and can be speeded up by adding heat
For example
zinc oxide + hydrochloric acid zinc chloride + water
ZnO (s) + 2 HCl (aq) ZnCl2 (aq) + H2O (l)
magnesium oxide + hydrochloric acid magnesium chloride + water
MgO (s) + 2 HCl (aq) MgCl2 (aq) + H2O (l)
aluminium oxide + sulphuric acid aluminium sulphate + water
Al2O3 3 H2SO4 (aq) Al2(SO4)3 (aq) + 3 H2O (l)
calcium oxide + sulphuric acid calcium sulphate + water
CaO H2SO4 (aq) CaSO4 (aq) + H2O (l)
18
WEEK 2 LESSON 3 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal oxides with the
corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium oxide Hydrochloric acid
Sodium oxide Sulphuric acid
Calcium oxide Hydrochloric acid
Magnesium oxide Sulphuric acid
Aluminium oxide Hydrochloric acid
Zinc oxide Sulphuric acid
19
WEEK 3 LESSON 1
TOPIC Reactions of metal compounds
Reactions of metallic hydroxides with dilute acid
Metal hydroxides react with dilute acids to form a salt and water in a neutralisation reaction
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
For example
magnesium hydroxide + hydrochloric acid magnesium chloride + water
Mg(OH)2 (aq) + 2 HCl (aq) MgCl2 (aq) + 2 H2O (l)
sodium hydroxide + hydrochloric acid sodium chloride + water
NaOH (aq) + HCl (aq) NaCl (aq) + H2O (l)
potassium hydroxide + sulphuric acid potassium sulphate + water
2 KOH + H2SO4 (aq) K2SO4 (aq) + 2 H2O (l)
calcium hydroxide + sulphuric acid calcium sulphate + water
Ca(OH)2 (aq) + H2SO4 (aq) CaSO4 (aq) + 2 H2O (l)
20
WEEK 3 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal hydroxides with
the corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium hydroxide Hydrochloric acid
Sodium hydroxide Sulphuric acid
Calcium hydroxide Hydrochloric acid
Magnesium hydroxide Sulphuric acid
Aluminium hydroxide Hydrochloric acid
Zinc hydroxide Sulphuric acid
21
WEEK 3 LESSON 2
TOPIC Reactions of metal compounds
Reactions of metallic carbonates with dilute acid
Metal carbonates react with dilute acid to form a salt carbon dioxide and water When
hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric acid is
used the corresponding sulphate salt is formed
For example
sodium carbonate + hydrochloric acid sodium chloride + carbon dioxide + water
Na2CO3 (s) + 2 HCl (aq) 2 NaCl (aq) + CO2 (g) + H2O (aq)
calcium carbonate + hydrochloric acid calcium chloride + carbon dioxide + water
CaCO3 (s) + 2 HCl (aq) CaCl2 (aq) + CO2 (g) + H2O (aq)
zinc carbonate + sulphuric acid zinc sulphate + carbon dioxide + water
ZnCO3 (s) + H2SO4 (aq) ZnSO4 (aq) CO2 (g) + H2O (aq)
potassium carbonate + sulphuric acid potassium sulphate + carbon dioxide + water
K2CO3 (s) H2SO4 (aq) K2SO4 (aq) CO2 (g) + 2 H2O (aq)
22
WEEK 3 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal carbonates with
the corresponding acid
Metallic
carbonate
Acid Balanced chemical equation
Potassium
carbonate
Hydrochloric
acid
Sodium
carbonate
Sulphuric acid
Zinc
carbonate
Hydrochloric
acid
Magnesium
carbonate
Sulphuric acid
Aluminium
carbonate
Hydrochloric
acid
Calcium
carbonate
Sulphuric acid
23
WEEK 3 LESSON 3
TOPIC Action of heat on metal compounds
Action of heat on nitrates
All nitrates decompose when heated The reactivity of the metal in the metal nitrate influences
the products of the decomposition
The nitrates of the alkali metals (Group I) with the exception of lithium nitrate decompose to
form the metal nitrite and oxygen
The nitrates of most other metals decompose to form the metal oxide nitrogen dioxide and
oxygen
The nitrates of the very unreactive metals decompose to form the meal nitrogen dioxide and
oxygen
Metal Nitrate Decomposition
Potassium K Products metal nitrite + oxygen
eg 2 NaNO3 (s) Heatrarr 2 NaNO2 (s) + O2 (g)
Sodium Na
Calcium Ca
Products metal oxide + nitrogen dioxide + oxygen
eg 2 Pb(NO3)2 (s)
Heatrarr 2 PbO (s) + 4 NO2 (g) + O2 (g)
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Products metal + nitrogen dioxide + oxygen
eg 2 AgNO3 (s) Heatrarr 2 Ag (s) + 2 NO2 (g) + O2 (g)
24
WEEK 3 LESSON 3 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
nitrates
Metal Balanced chemical equation
Potassium nitrate
Sodium nitrate
Calcium nitrate
Magnesium nitrate
Aluminium nitrate
Zinc nitrate
Lead nitrate
Copper nitrate
Silver nitrate
25
WEEK 4 LESSON 1
TOPIC Action of heat on metal compounds
Action of heat on carbonates
Upon application of heat many carbonates decompose to form the metal oxide and carbon
dioxide
Group I carbonates do not decompose on heating with the exception of lithium carbonate
Metal Carbonate decomposition
Potassium K
Stable not decomposed by heat Sodium Na
Calcium Ca
Decompose forming metal oxide and carbon dioxide
eg CaCO3 (s) Heatrarr CaO (s) + CO2 (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Unstable
26
WEEK 4 LESSON 1 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
carbonates
Metal Balanced chemical equation
Potassium carbonate
Sodium carbonate
Calcium carbonate
Magnesium carbonate
Aluminium carbonate
Zinc carbonate
Iron carbonate
Lead carbonate
Copper carbonate
27
WEEK 4 LESSON 2
TOPIC Action of heat on metal compounds
Action of heat on the metal hydroxides
Most metal hydroxides decompose on heating A metal oxide and water are formed
Group I hydroxides do not decompose on heating with the exception of lithium hydroxide
Metal Hydroxide decomposition
Potassium K Stable not decomposed by heat
Sodium Na
Calcium Ca Decompose forming metal oxide and water (as steam)
eg Zn(OH)2 (s) Heatrarr ZnO (s) + H2O (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag No hydroxide exist
28
WEEK 4 LESSON 2 WORKSHEET
Write the balanced chemical equations for the thermal decomposition of the following
metal hydroxides
Metal hydroxide Balanced chemical equation
Potassium hydroxide
Sodium hydroxide
Calcium hydroxide
Magnesium hydroxide
Aluminium hydroxide
Zinc hydroxide
Lead hydroxide
Copper hydroxide
29
WEEK 4 LESSON 3
TOPIC Reactivity of metals ndash The Reactivity Series
The reactivity series of metals is a list of metals arranged in order of their reactivity based on
Displacement reactions
Reactions with oxygen dilute acids and water
Relative ease of decomposition of their compounds
Metals at the top of the series are the most electropositive They lose electrons very easily and
readily form cations These ions are very stable and are not easily discharged to form atoms Due
to this fact they are the most reactive metals
Metals at the bottom of the series are the least electropositive They do not lose electrons easily
and do not readily form ions Their ions are very unstable and are easily discharged to form
atoms They are the least reactive metals
The reactivity series of metals
Mnemonic Metal Symbol Reactivity
People Potassium K Most reactive
Least reactive
Sometimes Sodium Na
Collect Calcium Ca
Magazines Magnesium Mg
About Aluminium Al
Zoos Zinc Zn
In Iron Fe
London Lead Pb
Having (Hydrogen) H
Cute Copper Cu
Monkeys and Mercury Hg
Small Silver Ag
Gorillas Gold Au
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
5 Reactivity of metals Reactivity of metals Reactivity of metals
6 Extraction of metals Extraction of metals Alloys
7 Corrosion Importance of metals
and their compounds
on living systems and
environment
Chemical properties
of non ndash metals
8 Laboratory
preparation of gases
Laboratory
preparation of gases
Laboratory
preparation of gases
9 Uses of gases Uses of non ndash metals
and their compounds
Harmful effects of
non ndash metals and
their compounds on
living systems and
the environment
10 Green Chemistry Qualitative Analysis
ndash Identification of
cations
Qualitative Analysis
ndash Identification of
cations
2
WEEK 5 LESSON 1
TOPIC Reactivity of metals
Reactivity based on displacement reactions between metals and metal ions
A metal will displace a metal which is lower than itself in the reactivity series from a solution of
the metal salt
Reaction of zinc and copper (II) sulphate
Expected observations
Explanation
The size of the zinc metal decreases
The zinc metal is reacting and forming the
salt zinc sulphate
The solution becomes lighter eventually
colourless
The Cu2+ (aq) ions (responsible for the blue
colour) is reduced to Cu (s)
A brown solid is deposited at the bottom of
the container
Copper metal is formed
Equation Zn (s) + CuSO4 (aq) ZnSO4 (aq) + Cu (s)
Ionic equation
Zn (s) + Cu2+ (aq) Zn2+ (aq) + Cu (s)
Zinc is higher in the reactivity series than copper Therefore it will displace the copper ions in
the reaction above
3
Examples of other displacement reactions
Magnesium will displace Zn2+ ions in zinc sulphate since it is higher in the series than zinc
Mg (s) + Zn2+(aq) Mg2+ (aq) + Zn (s)
Silver will not displace Cu2+ ions in copper (II) sulphate [Cu is higher in the series than Ag]
Using the information above we can arrange the metals in order of their reactivity with
magnesium being the most reactive and silver the least reactive metal among the four metals
Mg gt Zn gt Cu gt Ag
Reactivity based on reaction with oxygen
The reactivity of metals can also be deduced from their reaction with oxygen
The table below gives the observations for the reaction with oxygen with the selected metals
Reaction of metal with oxygen
Metal Observation
Copper The surface turns black upon heating
Magnesium Ribbon burns very rapidly
Sodium Burns vigorously
Gold No reaction
Based on the observations for the 4 metals the metal with highest reactivity is sodium and the
metal with the least reactivity is gold
The 4 metals can be arranged in terms of reactivity as follows
Na gt Mg gt Cu gt Au
4
WEEK 5 LESSON 1 WORKSHEET
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
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5
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
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6
WEEK 5 LESSON 2
TOPIC Reactivity of metals
Reactivity based on reactivity with acids
The metals that are higher than hydrogen in the electrochemical series react with non ndash oxidizing
acids to produce a salt and hydrogen gas
By using the same concentration of acid and same mass and size of the metals the order of
reactivity of the metals can be deduced
The table below shows the results for an experiment with the reaction of the named metals and
1 mol dm-3 hydrochloric acid
Reaction of metals with acid
Metal Observations
Silver No reaction
Magnesium Bubbles produced steadily
Calcium Bubbles produced very rapidly
Iron Bubbles produced slowly
Based on the above data the most reactive metal will be calcium with the least reactive being
silver The order of reactivity will be Ca gt Mg gt Fe gt Ag
By comparing this to the electrochemical series it can be seen that the reactivity of the metals
decrease as we go down the series
7
WEEK 5 LESSON 2 WORKSHEET
1 Place a next to the metals that will react with dilute acid and an X next to the metals
that will not react with dilute acid
Metal Reactivity with acid
Copper
Magnesium
Aluminium
Silver
Zinc
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
8
WEEK 5 LESSON 3
TOPIC Reactivity of metals
Reactivity based on ease of decomposition of the metal nitrates carbonates oxides and
hydroxides
The more reactive a metal the more difficult it is to decompose its nitrate carbonate oxide or
hydroxide on heating
For example Decomposition of carbonates
Procedure
1 Put a large spatula measure of the carbonate to be tested in a test tube
2 Fit a delivery tube and then clamp the test tube so that the delivery tube dips into a second test
tube containing 2ndash3 cm3 limewater
3 Heat the solid gently at first then more strongly
4 Lift the delivery tube from the limewater before or as soon as the heating is stopped This is to
avoid suck-back
5 Write down all observations Notice what happens to the limewater and how long it takes to turn
milky (if at all) Notice whether any melting occurs in the heated test tube and any colour
changes taking place Write your results in tabular form
6 Repeat the experiment with the other metal carbonates supplied and in each case write down
your observations
7 Wash your hands thoroughly at the end of these experiments since some of the metal carbonates
are toxic
9
Results
Metal Formula Gas evolved Ease of decomposition
Zinc ZnCO3 Carbon dioxide Fairly easy
Copper CuCO3 Carbon dioxide Easy
Sodium Na2CO3 None Very difficult
Using the results of the above activity the reactivity of the metals can be determined
Ease of decomposition Copper gt Zinc gt Sodium
The order of reactivity is the opposite for the ease of decomposition
Order of reactivity Sodium (most reactive) gt Zinc gt Copper (least reactive)
10
WEEK 5 LESSON 3 WORKSHEET
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
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11
WEEK 6 LESSON 1
TOPIC Extraction of metals
Elements exist all over the earth Some are found as free elements eg copper silver and gold
Others are found combined with other elements in compounds To get the elements the
compounds have to be broken up These compounds are generally called ores the most
convenient sources of which are rocks sea and air
The extraction of a metal from its ore is a reduction process where the metals ions gain electrons
to form atoms
The general equation is Mn+ + n e- M
The choice of the extraction method depends on the position of the metal in the reactivity series
As we go down the series the metals become more stable and the metal ions (in the ores)
become less stable
The very reactive metals that are high in the series K Na Ca Mg Al have very stable ores
Therefore they require a powerful method of reduction namely electrolysis During the process
the cathode provides the electrons and acts as the reducing agent
The metals in the middle of the series (Zn Fe Pb) do not have stable ores and can be extracted
by reduction with carbon in the case of zinc and with carbon monoxide in the case of iron and
lead
Metals low in the reactivity series if present as ores can be extracted simply by heating the ores
in air at high temperatures
12
Extraction of Aluminium from purified bauxite
Pure bauxite is pure alumina (Al2O3) Aluminium is obtained from bauxite by electrolysis
Aluminium oxide has a very high melting point approximately 2050 0C so it is first dissolved in
molten cryolite (Na2AlF6) The addition of cryolite lowers the melting point to approximately
900 0C
The electrolyte is a molten mixture of alumina and molten cryolite The cathode is the graphite
lining of the cell The anodes are blocks of graphite or titanium alloys
Reaction at the cathode
Al3+ (l) + 3 e- Al (l)
Reaction at the anode
2 O2- (l) ndash 4 e- O2 (g)
Aluminium (melting point 660 0C) is a liquid at the temperature at which electrolysis is carried
out and is collected at the bottom of the cell and tapped off Oxygen gas which is given off in the
main cathode reaction together with the heat causes the anodes to burn away The anodes have
to be replaced from time to time The use of anodes from titanium alloys reduce the number of
times that the anodes have to be replaced
13
WEEK 6 LESSON 1 Worksheet
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
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14
WEEK 6 LESSON 2
TOPIC Extraction of metals
Extraction of Iron
The traditional method of production of iron is by reduction of haematite by carbon monoxide in
a blast furnace
Ores Haematite ndash Fe2O3 Magnetite ndash Fe3O4 Siderite ndash FeCO3 Magnetite and Siderite are
converted to Haematite
A mixture of haematite limestone (CaCO3) and coke (C) called the charge is placed into the top
of the furnace
Hot air is blown into the bottom of the furnace
Coke burns in air forming carbon dioxide
C (s) + O2(g) CO2 (g) ΔH -ve
The heat produced keeps the temperature at about 1900 0C
The carbon dioxide is reduced to carbon monoxide by the hot coke
CO2 (g) + C (s) 2 CO(g) Δ +ve
Heat absorbed reduces the temperature to about 1100 0C
The carbon monoxide reduces the hot iron ore to molten iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + 3 CO2(g)
The temperature at this part of the furnace is about 700 0C The iron runs to the bottom of the
furnace
The impurities are removed by the addition of limestone (CaCO3) The limestone at the
temperature of the furnace breaks down
CaCO3 (s) CaO (s) + CO2 (g)
15
The calcium oxide formed combines with silicon dioxide (sand) the main impurity in the iron
ore to form molten slag
CaO (s) + SiO2 (s) CaSiO3 (l)
The slag does not mix with the molten iron but floats on it The molten iron and slag are run off
separately
The iron formed in a blast furnace is an impure form of the metal Because the molten metal is
allowed to solidify in shallow trays known as casts the iron is called lsquocast ironrsquo or lsquopigrsquo iron
Cast iron is quite brittle and contains 2 - 4 carbon and other impurities Most of the cast iron is
converted to steel
A blast furnace used for extracting iron
16
WEEK 6 LESSON 2 Worksheet
(a) What are the three raw materials that are added through the top of the blast furnace
during the extraction process for iron
______________________________________________________________________________
______________________________________________________________________________
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
17
WEEK 6 LESSON 3
TOPIC Alloys
An alloy is a mixture of two or more metals Alloys are made by melting the individual metals
mixing them and allowing the molten mixture to solidify
In general alloys are harder stronger and more resistant to corrosion than the actual metals they
are made up from
Alloy Use Properties
ALUMINIUM
-Duralumin
(AlMgCu)
-Magnalium (AlMg)
Alloys used in the
construction of
aircraft and ships
buses
Aluminium is used in
making cooking
utensils electrical
cables paint for fuel
storage tanks bottle
caps foil and utensils
for handling nitric
acid
The alloys have a low
density They are as
light as aluminium
and more resistant to
corrosion than
aluminium
LEAD
-Solder (PbSn)
Alloy is used in
joining metals
(soldering)
Lead is used in
underground cables
plates in
The alloy has a lower
melting point than
lead and is harder
than lead
18
Alloy Use Properties
accumulators shield
against x ndash rays
IRON
- Stainless Steel
(FeCONiC)
-Tungsten steel
(FeWC)
-Invar steel (FeNi)
Manganese steel
(FeMnC)
Iron is the main metal
of a variety of
constructions
Steel is used in
cutlery rock drills
electromagnets
vehicle body and
engine parts fences
pipes etc
Steel resists
corrosion is usually
harder than iron and
may be tough though
malleable and ductile
19
WEEK 6 LESSON 3 Worksheet
(a) Define the term alloy
______________________________________________________________________________
(b) State 3 general advantages that alloys have over the individual metals they are made
from
______________________________________________________________________________
______________________________________________________________________________
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
______________________________________________________________________________
______________________________________________________________________________
Uses
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 7 LESSON 1
TOPIC Corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
Familiar examples of corrosion are
- the formation of a green powder on copper sheeting
- the eating away of iron (rusting)
- the development by aluminum of a thin compact layer of oxide which protects the
underlying metal from further corrosion
When corrosion occurs in water ndash free environment it is called dry oxidation When it occurs in
aerated aqueous environments it is called wet corrosion Wet corrosion is the most common and
troublesome form of corrosion
The most familiar corrosion is the rusting of iron and steel On exposure to the atmosphere iron
and steel corrode to form rust which is hydrated iron (III) oxide Fe2O3xH2O Iron and steel
corrode easily and the rust formed flakes off easily thus exposing fresh surface for attack
When iron rust it loses electrons
Fe (s) ndash 2e- Fe 2+ (aq)
The iron (II) ions pass into solution and then combine with the hydroxyl (OH-) ions in the
aerated aqueous environment to form iron (II) hydroxide The oxygen present oxidises the iron
(II) hydroxide to hydrated iron (III) oxide or rust
Fe(OH)2 + O2 Fe2O3xH2O
21
Methods of preventing rusting
1 Coating the object with paint grease plastic or rubber which prevent contact with air or
water
2 Galvanising ndash coating the object with zinc The zinc forms an adherent oxide layer which
protects against further corrosion If damaged the zinc is oxidized in preference to the
iron since it is higher in the electrochemical series
3 Coating with tin lsquoTinrsquo cans are made of steel plated with tin However if scratched
rusting occurs since iron is more reactive than tin
4 Attaching a sacrificial anode to the object A piece of metal higher in the electrochemical
series such as magnesium is attached The magnesium will be oxidized in preference
since it is higher in the electrochemical series than iron
22
WEEK 7 LESSON 1 WORKSHEET
(a) Define the term corrosion
______________________________________________________________________________
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
23
WEEK 7 LESSON 2
TOPIC Importance of metals and their compounds on living systems and environment
Some metals are an integral part of different structures of living things
Metal Presence and Function
Potassium Main cation in fluid or animal cells essential for healthy plant growth
Calcium Necessary for strong bones teeth and shells needed by some enzymes Present
in dairy produce eggs nuts and cereals
Magnesium Central atom of chlorophyll needed for some enzyme action Involved in energy
and calcium metabolism
Zinc Present in many enzymes Needed for protein metabolism Essential for growth
of animals
Iron Present in haemoglobin Needed for protein metabolism Essential for growth of
animals
Chromium Needed for glucose uptake by cells and thus linked to the action of insulin
Manganese Needed for bone development and amino acid metabolism Present in several
enzymes Needed for plant growth
Cobalt Present in Vitamin B12 Needed for plant growth
Copper Involved in formation of haemoglobin and melanin Present in enzymes
controlling oxidation Needed for plant growth
24
Harmful effects of metals and their compounds to living systems and the environment
There are some metals and metal compounds which may cause harm to living systems and the
environment
Lead
Lead is a heavy metal poison that is widely encountered It may occur in food beverages paint
water formed from ndash sealed pipes in air polluted by combustion by fuels containing lead
compounds Lead is also used in some car batteries If these are paints or batteries are not
disposed of correctly lead may get into groundwater or air Lead and lead compounds harm the
nervous system including the brain especially young children
Arsenic
Arsenic compounds are poisonous They can get into the groundwater from mining waste and
from disposal of some electrical components
Cadmium
Cadmium compounds are poisonous They can get into the ground by improper disposal of
nickel ndash cadmium batteries Persons can get cadmium poisoning if they eat food grown in
contaminated soil
Mercury
Mercury can be spilled from broken thermometers in hospitals and laboratories Mercury and its
compounds are particularly poisonous to fish and it can accumulate in the food chain and
eventually poison humans
Problems of disposal of solid waste
Metals may react with water andor air and corrode to form soluble compounds that are
poisonous These toxic compounds diffuse into the soil and eventually enter rivers
Rust from iron may form unsightly pools of waste that reduce plant growth
Waste from aluminium extraction may react with water and form flammable gases
25
WEEK 7 LESSON 2 WORKSHEET
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Lead
______________________________________________________________________________
Mercury
______________________________________________________________________________
26
WEEK 7 LESSON 3
TOPIC Chemical properties of non ndash metals
Reaction with oxygen
Many non ndash metals burn in excess oxygen or air to form oxides For example
S (s) + O2 (g) SO2 (g)
C (s) + O2 (g) CO2 (g)
Reactions with metals
Some non ndash metals react with metals high in the electrochemical series when heated
For example
Sodium burns in chlorine to form sodium chloride
Na (s) + Cl2 (g) NaCl (s)
Magnesium burns in oxygen to form magnesium oxide
Mg (s) + O2 (g) MgO (s)
When heated iron combines with molten sulphur to form iron (II) sulphide
Fe (s) + S (l) FeS (s)
When heated reactive metals such as sodium and aluminium react with hydrogen to form metal
hydrides
2 Na (s) + H2 (g) 2 NaH (s)
Oxidising and Reducing properties
Hydrogen and Carbon are very good reducing agents
At high temperatures hydrogen reduces metal oxides below zinc in the electrochemical series to
form the metal For example PbO (s) + H2 (g) Pb (s) + H2O (g)
Under suitable conditions hydrogen reduces nitrogen to ammonia
N2(g) + 3 H2 (g) 2 NH3 (g)
27
At high temperatures carbon reduces metal oxides below aluminium in the reactivity series to
the metal For example
ZnO (s) + C (s) Zn (s) + CO (g)
Oxygen and Chlorine are very good oxidizing agents
Oxygen oxidized most metals to form metal oxides and some non ndash metals to non ndash metal oxides
For example
2 Mg (s) + O2(g) 2 MgO (s)
4 P (s) + 5 O2 (g) P4O10 (s)
Chlorine acts as an oxidizing agent either as a gas or as an aqueous solution For example
H2 (g) + Cl2 (g) 2 HCl (g)
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
28
WEEK 7 LESSON 3 WORKSHEET
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
______________________________________________________________________________
(b) Write the ionic equation for the above reaction
______________________________________________________________________________
(c) Identify the oxidising agent in the reaction
______________________________________________________________________________
(d) Justify your answer in part (c) in terms of oxidation number
______________________________________________________________________________
29
WEEK 8 LESSON 1
TOPIC Laboratory preparation of gases
Preparation of oxygen
Oxygen can be prepared by the decomposition of hydrogen peroxide potassium chlorate (V) or
potassium nitrate The safest method is the decomposition of hydrogen peroxide
Manganese (IV) oxide catalyses the decomposition of hydrogen peroxide
Silica gel anhydrous calcium chloride or concentrated sulphuric acid can be used as a drying
agent
The gas is collected by downward delivery since it is slightly denser than air
Equation
2 H2O2 (aq) 2 H2O (l) + O2 (g)
Apparatus used for laboratory preparation of oxygen
30
WEEK 8 LESSON 1 WORKSHEET
Describe the laboratory preparation of oxygen gas
In your answer include
The starting material
A suitable catalyst
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
31
WEEK 8 LESSON 2
TOPIC Laboratory preparation of gases
Preparation of carbon dioxide
Carbon dioxide can be prepared by the action of dilute acid on carbonates Marble chips (calcium
carbonate) and dilute hydrochloric acid are the common reagents The gas is collected by
downward delivery since it is denser than air
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
Apparatus used for laboratory preparation of carbon dioxide
32
WEEK 8 LESSON 2 WORKSHEET
Describe the laboratory preparation of carbon dioxide gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
33
WEEK 8 LESSON 3
TOPIC Laboratory preparation of gases
Preparation of ammonia
Ammonia may be prepared by heating a mixture of ammonium salt and a hydroxide The
ammonia gas is collected by upward delivery since it is less dense than air
For example
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
Calcium oxide is the only suitable drying agent since ammonia reacts with conc H2SO4 and
CaCl2
Apparatus used for laboratory preparation of dry ammonia
34
11
WEEK 8 LESSON 3 WORKSHEET
Describe the laboratory preparation of ammonia gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
35
WEEK 9 LESSON 1
TOPIC Uses of gases
Carbon dioxide
Used in fire extinguishers to put out fires Carbon dioxide is denser than air and lsquoblanketsrsquo the
fire preventing oxygen from reaching it Carbon dioxide extinguishers are especially useful for
dealing with fires involving flammable liquids and electrical equipment
Carbonation in soda is created when carbon dioxide is pumped into the soda can or bottle then
held under pressure As long as the can or bottle is sealed the carbon dioxide remains mostly
stable However if the drink gets shaken up or the top is opened the tiny carbon dioxide bubbles
react by bursting
Oxygen
Oxygen is needed for aerobic respiration We need a constant supply of oxygen for this process
Oxygen is used in hospitals to improve the respiration of patients with poor blood flow blood
poisoning and heart disease
Oxygen in used in welding (joining) metals In an oxyacetylene welding torch acetylene or
ethyne (C2H2) burns in oxygen and produces a very hot flame This flame is capable of melting
most metals
Oxygen is used in steel production A blast of oxygen is blown through the molten iron The
oxygen oxidises many of the impurities of the iron and the impurities are then removed
36
WEEK 9 LESSON 1 WORKSHEET
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Put out fires
Welding metals
Create lsquofizzrsquo in drinks
Used in steel production
Aerobic respiration
37
WEEK 9 LESSON 2
TOPIC Uses of non ndash metals and their compounds
Carbon (allotrophes carbon dioxide)
Carbon is used as a reducing agent in extraction of some metals
Carbon as graphite is used as electrodes lubricants and lsquoleadrsquo for pencils
Carbon in the form of diamond is used for jewellery (because of its lustre) and in drill tips for
high ndash speed drills (because of its hardness)
Carbon dioxide is used as refrigerant (as dry ice) for carbonated beverages
Sodium hydrogen carbonate and sodium carbonate are used for water softening and raising
agent
Sulphur
Sulphur is used in the manufacture of sulphuric acid Sulphur is also used in the manufacture of
tyres to make the rubber harder (vulcanisation)
Sulphur powder is used as fungicide on plant materials
Phosphorus
Phosphorus is used in the manufacture of fertilizers
Phosphorus is used to make phosphor bronze alloys
Phosphorus sulphide is used to make the heads of lsquostrike anywherersquo matches
38
Chlorine
Chlorine is used to make sodium hypochlorite which is present in bleach It is also used in
sterilizing swimming pools and in water treatment
Chlorine is used to make the monomer vinyl chloride which is used to make the plastic PVC
Nitrogen
Nitrogen is used to make fertilisers ammonia dyes and nitric acid
Nitrogen is used as an inert atmosphere to prevent substances being oxidised and as a coolant
Silicon
Silicon is used for making silicon chips for computers
Silicon (V) oxide is present in sand Glass is made by heating sand with lime (calcium oxide) and
sodium carbonate
Silicon in the form of silicates is used in jewellery
Silica gel is used as a drying agent
39
WEEK 9 LESSON 2 WORKSHEET
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Used to make sodium hypochlorite
Used as a fungicide on plant materials
Used for lsquoleadrsquo in pencils
Used in the manufacture of bronze alloys
Used in the manufacture of nitric acid
Used in the manufacture of computer chips
Used to make fertilisers
40
WEEK 9 LESSON 3
TOPIC Harmful effects of non ndash metals and their compounds on living systems and the
environment
Sulphur dioxide
Sulphur dioxide can cause a disease of the lungs Sulphur dioxide also poisons plants in two
main ways It may enter the stomata of leaves and react with the tissue fluids to form sulphites
with the on ndash going water loss the concentration of sulphites could build up killing the cells
The second adverse effect on plants occurs when sulphur dioxide dissolves in rain thereby
increasing soil acidity A prolonged acid soil situation may lead to plasmolysis and the death of
vegetation in an area
Carbon monoxide
Carbon monoxide combines much more readily than oxygen with haemoglobin When carbon
monoxide is inhaled it prevents the haemoglobin from taking oxygen to the bodyrsquos cells
Continued breathing of air containing carbon monoxide eventually causes death
Hydrogen sulphide
Hydrogen sulphide reacts readily with many cations forming insoluble sulphides Many cations
contribute to good health by contributing to enzyme activity and to the formation of bone
pigment and haemoglobin Although these cations are required in extremely small
concentrations they are removed by being precipitated as sulphides and thus not available for
regular function Careless dumping of refuse contributes to atmospheric pollution by hydrogen
sulphide
Oxides of nitrogen
In the presence of hydrocarbons from car exhausts ozone and sunlight nitrogen oxides react to
form photochemical smog which contains many harmful chemicals
Nitrogen dioxide can harm the lungs and irritate the nose throat and eyes The other compounds
present in photochemical smog are even more harmful irritants and can cause asthma
41
Carbon dioxide
Carbon dioxide water vapour and ozone referred to as ldquogreenhouse gasesrdquo acting as a blanket
readily absorb some of the radiated heat energy and in turn warms the earthrsquos atmosphere This is
called the ldquogreenhouse effectrdquo Scientists have found direct correlation between carbon dioxide
concentration and global warming An increase in carbon dioxide concentration resulted in an
increase global temperatures Global warming is a major potential problem that the world faces
Chloroflourocarbons (CFCs)
It is believed that CFCs might be responsible for destroying the ozone layer which prevents
harmful ultraviolet (UV) radiation from reaching the earth The carbon ndash chlorine bond in CFC
molecule is easily broken by a UV photon producing an active chlorine atom This atom
combines with an ozone molecule forming a chlorine oxide radical and oxygen The radicle
reacts with more ozone producing the chlorine atom again This kind of reaction is repeated
thousands of times This type of reaction is thought to account for about eighty percent of the
loss of ozone observed
Nitrates and phospates
Nitrates and phosphates cause eutrophication The process leading to eutrophication are
Nitrates and phosphates from fertilisers spread on fields may dissolve in groundwater and
get into lakes and rivers
Nitrates and phosphates cause excessive growth of algae so that they cover the surface of
the water
Water plants including algae die because of lack of sunlight Aerobic bacteria feed on
the plant remains The bacteria multiply
The aerobic bacteria use up the oxygen in the water so aquatic animals die
42
Solid waste
The main sources of pollution from non ndash metals is from glass paper and plastics
Broken glass can cause injury to animals It can also cause fires by acting as lens focusing the
sunrsquos rays on flammable materials
Printing inks from paper dumped in the ground may contain toxic elements such as arsenic and
cadmium Bleaches and chlorine compounds from paper are also harmful
43
WEEK 9 LESSON 3 WORKSHEET
Describe ONE harmful effect of the following non ndash metals andor their compounds on
living systems and the environment
Sulphur dioxide
______________________________________________________________________________
______________________________________________________________________________
Carbon monoxide
______________________________________________________________________________
______________________________________________________________________________
Carbon dioxide
______________________________________________________________________________
______________________________________________________________________________
Oxides of nitrogen
______________________________________________________________________________
______________________________________________________________________________
Hydrogen sulphide
______________________________________________________________________________
______________________________________________________________________________
44
Chloroflourocarbons (CFCs)
______________________________________________________________________________
______________________________________________________________________________
Nitrates and phospates
______________________________________________________________________________
______________________________________________________________________________
45
WEEK 10 LESSON 1
TOPIC Green Chemistry
Green Chemistry is defined as the utilisation of a set of principles that reduces or eliminates the
use and generation of hazardous substances
There are twelve principles of green chemistry as proposed by Paul T Anastas and John C
Warner These twelve principles are
1 Prevention ndash It is better to prevent waste than to treat or clean up waste after it has been
created
2 Atom economy - Synthetic methods should be designed to maximize the incorporation of
all materials used in the process into the final product
3 Less hazardous chemical synthesis - Wherever practicable synthetic methods should be
designed to use and generate substances that possess little or no toxicity to human health
and the environment
4 Safer chemical products - Chemical products should be designed to affect their desired
function while minimizing their toxicity
5 Safer solvents and other agents - The use of auxiliary substances (eg solvents
separation agents etc) should be made unnecessary wherever possible and harmless
when used
6 Minimum energy requirements - Energy requirements of chemical processes should be
recognized for their environmental and economic impacts and should be minimized If
possible synthetic methods should be conducted at ambient temperature and pressure
7 Use of renewable raw materials - A raw material or feedstock should be renewable rather
than depleting whenever technically and economically practicable
8 Reduce use of additional chemicals or additional steps - Unnecessary derivatization (use
of blocking groups protection deprotection temporary modification of
physicalchemical processes) should be minimized or avoided if possible because such
steps require additional reagents and can generate waste
46
9 Use of catalysts ndash The use of catalysts reduce energy costs because the reactions take
place at lower temperatures The more specific the catalyst for a particular reaction is the
less it the likelihood of getting additional unwanted products
10 Nature of breakdown of products - Chemical products should be designed so that at the
end of their function they break down into innocuous degradation products and do not
persist in the environment
11 Monitoring to prevent pollution - Analytical methodologies need to be further developed
to allow for real-time in-process monitoring and control prior to the formation of
hazardous substances
12 Minimise chemical accidents - Substances and the form of a substance used in a chemical
process should be chosen to minimize the potential for chemical accidents including
releases explosions and fires
47
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
48
WEEK 10 LESSON 2
TOPIC Qualitative Analysis ndash Identification of cations
Qualitative Analysis involves identifying the constituents of single substances or mixture of
substances
Appearance
An examination of the appearance of a substance can indicate which ion it contains
Appearances of substances
Observation Indication
Blue or blue ndash green Cu2+ salt
Pale green Fe2+ salt
Yellow ndash brown Fe3+ salt
Ammonia smell NH4+ salt
49
Test for cation using sodium hydroxide
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
(d) If no precipitate forms in step b warm gently and test for ammonia
Effect of dilute sodium hydroxide solution
Effect of dilute sodium hydroxide solution Cation
Dropwise Excess
White precipitate Precipitate soluble Ca2+
White precipitate Precipitate insoluble Al3+ Pb2+ Zn2+
Blue precipitate Precipitate insoluble Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
No precipitate ndash ammonia gas
evolved on heating
ndash NH4+
The metal cations all form insoluble hydroxides with sodium hydroxide solution
For example Ca2+ (aq) + 2 OH- (aq) Ca(OH)2 (s)
Ca(OH)2 Cu(OH)2 Fe(OH)2 and Fe(OH)3 are basic and therefore do not react with excess
sodium hydroxide solution Therefore the precipitate does not dissolve in excess sodium
hydroxide solution
Al(OH)3 Pb(OH)2 and Zn(OH)2 are amphoteric Therefore the precipitates react with the excess
sodium hydroxide solution forming soluble salts and the precipitate disappears in excess sodium
hydroxide solution
The NH4+ ion forms a soluble hydroxide However on heating it reacts with the hydroxide ion to
form ammonia and water
NH4+ (aq) + OH- (aq) NH3 (g) + H2O (l)
50
WEEK 10 LESSON 2 WORKSHEET
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P _____________ Q ___________________
R _____________ S ___________________
R + NaOH
______________________________________________________________________________
51
WEEK 10 LESSON 3
TOPIC Qualitative Analysis ndash Identification of cations
Test for cation using ammonia solution (ammonium hydroxide solution)
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
Effect of dilute ammonia (ammonium hydroxide) solution
Effect of dilute ammonia solution Cation
Dropwise Excess
No precipitate ndash Ca2+
White precipitate Precipitate soluble
(forming colourless solution)
Zn2+
White precipitate Precipitate insoluble Al3+ Pb2+
Blue precipitate Precipitate soluble
(forming deep blue solution)
Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
52
Ammonia solution is a weak alkali Metal cations except Ca2+ form insoluble hydroxides with
ammonia solution as with the sodium hydroxide solution
The amphoteric hydroxides Al(OH)3 and Pb(OH)2 and the basic hydroxides Fe(OH)2 and
Fe(OH)3 do not react with excess ammonia solution Therefore the precipitates remain
However Zn(OH)2 and Cu(OH)2 do react with excess ammonia solution to form complex
soluble hydroxides each Hence their precipitates disappear on the addition of excess ammonia
solution
Confirmatory test
After carrying out test for cations using sodium hydroxide solution and ammonia solution the
only cations which cannot be distinguished are Al3+ and Pb2+ A confirmatory test is carried out
to distinguish between the two cations
Confirmatory test
Test Observation Cation Ionic equation
Add potassium
or sodium
iodide solution
Bright yellow precipitate
No precipitate
Pb2+
Al3+
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
53
WEEK 10 LESSON 3 WORKSHEET
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A __________ B ________________ C ________________________
(b) State the inference after Test 2
C _______________________
(c) Write an ionic equation to support your answer in (b) above
___________________________________________________________________________
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
54
ANSWERS TO WORKSHEETS
55
WEEK 5 LESSON 1 WORKSHEET ANSWERS
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
Answer
Zinc + Iron (II) sulphate Zinc is higher in the electrochemical series and therefore displace
iron ions in iron (II) sulphate
Equation Zn (s) + FeSO4 (aq) ZnSO4 (aq) + Fe (s)
Ionic equation Zn (s) + Fe2+ (aq) Zn2+ (aq) + Fe (s)
Iron + Zinc sulphate No reaction iron is lower in the electrochemical series and cannot
displace the zinc ions in zinc sulphate
56
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
Answer
X displaces lead from an aqueous solution of its salts
X (s) + Pb2+ (aq) Xn+ (aq) + Pb (s)
rarr X is more reactive than Pb
X did not react with iron salts
rarr X is less reactive than Fe
Y burns very easily
Y is more reactive than Fe and Pb (both forming their corresponding oxide at a slower rate)
From electrochemical series Fe is higher and therefore more reactive than Pb
Order of reactivity
Y (most reactive) gt Fe gt X gt Pb (least reactive)
57
WEEK 5 LESSON 2 WORKSHEET ANSWERS
1
Metal Reactivity with acid
Copper X
Magnesium
Aluminium
Silver X
Zinc
58
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
Answer
Y and Z are the most reactive since they can react with dilute acid
Z is more reactive than Y since a reaction occurs with Z is added to an aqueous solution of Y
X is less reactive than W since it does not occur in nature as compounds
Order of reactivity Z (most reactive) gt Y gt W gt X
59
WEEK 5 LESSON 3 WORKSHEET ANSWERS
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
Answer
Ease of decomposition (from easiest to decompose to most difficult to decompose)
B rarrD rarrArarr C
Reactivity (most reactive to least reactive)
C (most reactive) gt A gt D gt B (least reactive)
60
WEEK 6 LESSON 1 Worksheet Answers
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
Potassium Zinc Copper
Calcium Lead Gold
Magnesium Iron
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
Aluminium is extracted from its ore bauxite through the process of electrolysis
Cryolite is added to bauxite to lower the melting point to about 900 0C The melting point of
bauxite is very high (about 2040 0C) It is difficult and expensive to keep the molten aluminium
oxide at this temperature
Reaction at the cathode Al3+ (l) + 3 e- Al (l)
61
WEEK 6 LESSON 2 Worksheet Answers
(a) What are the three raw materials that are added through the top of the blast
furnace during the extraction process for iron
Coke (carbon)
iron ore (haematitie mainly iron (II) oxide)
limestone (calcium carbonate)
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
Coke ndash coke burns to produce carbon dioxide The carbon dioxide further reacts with coke to
form carbon monoxide (reducing agent in the process)
C (s) + O2 (g) CO2 (g)
C (s) + CO2 (g) 2 CO
Haematite ndash iron ore provides the iron which is reduced by the carbon monoxide to produce
iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + CO2 (g)
Limestone ndash decomposes to form calcium oxide The calcium oxide reacts with the impurity
silicon dioxide to form slag (calcium silicate)
CaCO3 (s) CaO (s) + CO2 (g)
CaO (s) + SiO2 (l) CaSiO3(l)
62
WEEK 6 LESSON 3 Worksheet Answers
(a) Define the term alloy
An alloy is a material made from a mixture of two or more metals
(b) State 3 general advantages that alloys have over the individual metals they are made
from
They are harder stronger and more resistant to corrosion
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
1 High strength
2 Low density
Uses
1 Used to make aircraft bodies
2 Used to make space satellites
63
WEEK 7 LESSON 1 WORKSHEET ANSWERS
(a) Define the term corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
The paint forms a barrier which stops contact with air or water and the iron Hence rusting
will not take place
However when the paint is scratched that part of the iron nail is exposed to air or water and
rusting will take place
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
Magnesium is higher in the electrochemical series and will be oxidised in preference to iron
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
Aluminium is partly protected from corrosion by its coat of aluminium oxide However as the
iron rust it flakes and fall off and the rusting process continues
64
WEEK 7 LESSON 2 WORKSHEET ANSWERS
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
Magnesium is the ion found in chlorophyll Chlorophyll plays a vital part in the process of
photosynthesis A deficiency in magnesium will lead to low chlorophyll level in the tomato
plants and hence reduce the process of photosynthesis There will be less food storage and
hence will lead to smaller yield of tomatoes
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Any correct harmful effect of lead on health or environment
Any correct harmful effect of mercury on health or environment
65
WEEK 7 LESSON 3 WORKSHEET ANSWERS
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
(b) Write the ionic equation for the above reaction
2 Br- (aq) + Cl2 (aq) 2 Cl- (aq) + Br2 (aq)
(c) Identify the oxidising agent in the reaction
Cl2 (aq)
(d) Justify your answer in part (c) in terms of oxidation number
There is a reduction of the oxidation number for chlorine from 0 to ndash1
hence it has been reduced Therefore chlorine is the oxidising agent
66
WEEK 8 LESSON 1 WORKSHEET ANSWERS
Describe the laboratory preparation of oxygen gas
Oxygen is prepared in the laboratory by the decomposition of hydrogen peroxide
A suitable catalyst is manganese (IV) oxide
Drying agent silica gel OR anhydrous calcium chloride OR conc sulphuric acid
The gas is collected by downward delivery since oxygen is slightly denser than air
Balanced chemical equation 2 H2O2 (aq) 2 H2O (l) + O2 (g)
67
WEEK 8 LESSON 2 WORKSHEET ANSWERS
Describe the laboratory preparation of carbon dioxide gas
Carbon dioxide is commonly prepared in the laboratory by the reacting hydrochloric acid and
marble chips (calcium carbonate)
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
The carbon dioxide gas is collected by downward delivery since it is denser than air
Balanced chemical equation
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
68
WEEK 8 LESSON 3 WORKSHEET ANSWERS
Describe the laboratory preparation of ammonia gas
An ammonium salt (ammonium chloride) and a base (sodium hydroxide) are mixed together and
heated
Calcium oxide is used as the drying agent Calcium chloride and concentrated sulphuric acid
cannot be used since ammonia can react with them
The gas is collected by upward delivery since ammonia is less dense than air
Balanced chemical equation
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
69
WEEK 9 LESSON 1 WORKSHEET ANSWERS
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Carbon dioxide Put out fires
Oxygen Welding metals
Carbon dioxide Create lsquofizzrsquo in drinks
Oxygen Used in steel production
Oxygen Aerobic respiration
70
WEEK 9 LESSON 2 WORKSHEET ANSWERS
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Chlorine Used to make sodium hypochlorite
Sulphur Used as a fungicide on plant materials
Carbon (graphite) Used for lsquoleadrsquo in pencils
Phosphorus Used in the manufacture of bronze alloys
Nitrogen Used in the manufacture of nitric acid
Silicon Used in the manufacture of computer chips
Nitrogen Phosphorus Used to make fertilisers
71
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
Green Chemistry is using principles that reduceeliminate the use of hazardous materials in
the design manufacture and application of chemical products
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
Makes the environment safer
Reduces waste
Creates new jobs
Reduces respiratory illnesses
Atom economy
72
WEEK 10 LESSON 2 WORKSHEET ANSWERS
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P Cu2+ Q Fe2+
R Fe3+ S Ca2+
Ionic equation for R + NaOH
Fe3+ (aq) + 3 OH- (aq) Fe(OH)3 (s)
73
WEEK 10 LESSON 3 WORKSHEET ANSWERS
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A Fe3+ B Ca2+ C Al3+ Pb2+
(b) State the inference after Test 2
C Pb2+
(c) Write an ionic equation to support your answer in (b) above
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
11 Qualitative Analysis
ndash Test for gases
Qualitative Analysis
ndash Identification of
anions
Qualitative Analysis
ndash Identification of
anions
12 Problem solving of
Past CSEC Chemistry Paper 2
on topics completed in the term
13
14
15
2
WEEK 11 LESSON 1
TOPIC Qualitative Analysis ndash Test for gases
Identification of gases
Gas Colour Odour Effect on moist
litmus
Method of identification
Oxygen
O2
Colourless Odourless Neutral ndash no
effect
Relights a glowing splint
Hydrogen
H2
Colourless Odourless Neutral ndash no
effect
Lighted splint lsquopopsrsquo if air is also
present
Carbon
dioxide
CO2
Colourless Odourless Weakly acidic ndash
blue to slightly
red
A white precipitate forms in
limewater
Ca(OH)2 (aq) + CO2
CaCO3 (s) + H2O (l)
Precipitate redissolves on
continued bubbling
CaCO3 (s) + H2O (l) + CO2 (g)
Ca(HCO3)2 (aq)
Ammonia
NH3
Colourless Pungent Alkaline ndash red
to blue (only
common
alkaline gas)
Turns moist red litmus blue forms
dense white fumes with hydrogen
chloride gas
NH3 (g) + HCl (g) NH4Cl (s)
Gas Colour Odour Effect on moist
litmus
Method of identification
3
Sulphur
dioxide
SO2
Colourless Choking
smell
Acidic ndash blue to
red
Turns acidified potassium
manganate (VII) solution from
purple to colourless
Turns acidified potassium
dichromate (VI) solution from
orange to green
Chlorine
Cl2
Yellow ndash
green
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Bromine
Br2
Red ndash
brown
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Nitrogen
dioxide
NO2
Red ndash
brown
Irritating
smell
Acidic blue to
red
Turns moist blue litmus red but
does not bleach it
Water
vapour
H2O
Colourless Odourless Neutral ndash no
effect
Turns anhydrous cobalt (II)
chloride from blue to pink
Turns anhydrous copper (II)
sulphate from white to blue
4
WEEK 11 LESSON 1 WORKSHEET
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless
Yellow ndash green
Red ndash brown
Gases according to their odour
Odour of gas Identity of gas
Odourless
Pungent smell
Choking smell
Irritating smell
5
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect
Red to blue
Blue to red
Blue to red then bleaches it
6
WEEK 11 LESSON 2
TOPIC Qualitative Analysis ndash Identification of anions
Effect of heating
Method Heat a sample of the solid in a dry test tube
Effect of heating
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) not
of K or Na
CO32- (s) O2- (s) + CO2 (g)
Oxygen evolved NO3- of K or Na 2 NO3
- (s) 2 NO2- (s) + O2
(g)
Oxygen and nitrogen
dioxide evolved
NO3- of Ca and below
in reactivity series
4 NO3- (s) 2 O2- (s) + 4 NO2
(g) + O2
(g)
Sulphur dioxide evolved SO32- SO3
2- O2- (s) + SO2 (g)
Effect of dilute acid
Add dilute hydrochloric acid or nitric acid to a sample of the solid Warm if no reaction occurs
when cold
Effect of dilute acid
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) CO32- (s) + 2 H+ (aq) H2O (l) + CO2 (g)
Sulphur dioxide evolved SO32- SO3
2- (s) + 2 H+ (aq) H2O (l) + SO2 (g)
7
Effect of concentrated acid
Add concentrated sulphuric acid to a sample of the solid Warm if not reaction occurs when cold
Effect of concentrated sulphuric acid
Observation Anion
Carbon dioxide evolved CO32- or HCO3
-
Sulphur dioxide evolved SO3-
Hydrogen chloride evolved Cl-
Hydrogen bromide (colourless) and bromine
vapour (brown) evolved
Br-
Black iodine present and purple iodine vapour
evolved
I-
8
WEEK 11 LESSON 2 WORKSHEET
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater
Produces a gas which relights a glowing splint as the only gas
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green
Produces a gas forms a precipitate in limewater
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia
Black iodine present and purple iodine vapour evolved
9
WEEK 11 LESSON 3
TOPIC Qualitative Analysis ndash Identification of anions
Test for the halides ndash using silver nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous silver nitrate and
observe the precipitate Add ammonia solution and observe the solubility of the precipitate
Test for halides using silver nitrate solution
Effect of silver
nitrate solution
Anion Explanation Effect of aqueous
ammonia
White precipitate ndash
turns white in
sunlight
Cl- Ag+ (aq) + Cl- AgCl (s) Precipitate soluble
Cream precipitate ndash
turns yellow ndash green
in sunlight
Br- Ag+ (aq) + Br- AgBr (s) Precipitate slightly
soluble
Pale yellow
precipitate
I- Ag+ (aq) + I- AgI (s) Precipitate insoluble
Test for the halides ndash using lead nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous lead nitrate and
observe the precipitate
Test for halides using lead nitrate solution
Effect of lead nitrate solution Anion Explanation
White precipitate Cl- Pb2+ (aq) + 2 Cl- PbCl2 (s)
Pale yellow Br- Pb2+ (aq) + 2 Br- PbBr2 (s)
Deep yellow I- Pb2+ (aq) + 2 I- PbI2 (s)
10
Effect of barium nitrate or chloride solution followed by dilute acid
Make a solution of the solid Add barium nitrate or chloride solution and observe the precipitate
Add dilute hydrochloric or nitric acid warn if necessary and observe the solubility of the
precipitate
Effect of barium nitrate or chloride solution followed by dilute acid
Effect of
Ba(NO3)2 (aq)
or BaCl2 (aq)
Effect of HCl (aq)
or HNO3 (aq)
Anion Explanation
White precipitate Precipitate insoluble SO42- Ba2+ (aq) + SO4
2- (aq) BaSO4 (s)
BaSO4 does not react with dilute acids
White precipitate Precipitate soluble ndash
CO2 evolved
CO32- Ba2+ (aq) + CO3
2- (aq) BaCO3 (s)
BaCO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + CO2 (g)
White precipitate Precipitate soluble ndash
SO2 evolved on
warming
SO32- Ba2+ (aq) + SO3
2- (aq) BaSO3 (s)
BaSO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + SO2 (g)
11
WEEK 11 LESSON 3 WORKSHEET
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
(Ionic equation required)
12
WEEK 12 LESSON 1 WORKSHEET
(a) The Caribbean islands are known for their many resources For example the ore of
aluminium is found in Jamaica and Guyana
(i) Briefly describe the extraction of aluminium from its named ore Include in your
description one ionic equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Although aluminium ore is mined in the Caribbean the extraction of aluminium usually
takes place in other countries Suggest ONE reason why it may be difficult to extract
aluminium in the Caribbean
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) An alloy can be described as a lsquomixed metal solutionrsquo Aluminium forms an alloy with
magnesium that is used to make an aircraft
13
Identify this alloy and suggest why it is better to use it rather than the pure metal in the
manufacture of aircraft
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) ldquoSome metals can be useful to man yet harmful to the environmentrdquo Comment on this
statement with reference to mercury
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 12 LESSON 2 Worksheet
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate formed
Soluble in excess
15
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate formed
Insoluble in excess
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate formed
(Ionic equation required)
16
WEEK 12 LESSON 3 Worksheet
Dry ammonia gas can be produced in a school laboratory
(a) Identify TWO reagents that are necessary for the laboratory production of ammonia
______________________________________________________________________________
______________________________________________________________________________
(b) Two common drying agents used in the laboratory are calcium oxide and concentrated
sulphuric acid However calcium oxide is the preferred choice for drying ammonia gas
Explain why concentrated sulphuric acid is now used Include in your answer a balanced
chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) When gases are prepared in the laboratory there are three main ways in which they can
be collected
- Upward delivery
- Downward delivery
- Displacement of water
(i) What TWO other factors should be considered when choosing an appropriate method for
the collection of gases in the laboratory
______________________________________________________________________________
______________________________________________________________________________
(ii) Identify ONE of the three methods that is best suited for the collection of ammonia gas in
the laboratory Explain why EACH of the other two methods would NOT have been
appropriate
______________________________________________________________________________
17
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(d) Hence draw a labelled diagram of the apparatus which could be used for the preparation
of dry ammonia in the laboratory
Be sure to identify in your diagram
- where the reagents are placed
- where the ammonia is dried and
- where the ammonia is collected
18
WEEK 13 LESSON 1 Worksheet
(a) In solution two metals A and B form A+ and B2+ ions respectively Metal A displaces Fe
from a solution containing Fe2+ ions but metal B does NOT
(i) Arrange the metals A B and Fe in order of reactivity from LEAST reactive to MOST
reactive Write a balanced chemical equation to show the reaction between metal A and
Fe2+ ions
______________________________________________________________________________
______________________________________________________________________________
(ii) Metal A is placed in a solution of copper (II) sulphate CuSO4 (aq) Write an equation for
the reaction State ONE observable change that will occur and explain why this reaction
takes place
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) For EACH metal A and B state ONE method that can be used to extract it from its
respective oxide Give a reason for EACH answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
19
______________________________________________________________________________
(b) Metal alloys are often used for making objects found in our daily lives Name an alloy of
iron and state ONE of its uses
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 13 LESSON 2 Worksheet
(a) Many important biological processes in plants and animals depend on the specific roles
of certain metal ions
(i) Farmer Jones reaped a crop of tomatoes and reported that the yield was far below what
was expected Analysis of the soil revealed that there was a deficiency of magnesium
Discuss the importance of magnesium in plant health and explain how a magnesium
deficiency can result in the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE other metal ion which is important to plant health and state the result of its
deficiency
______________________________________________________________________________
______________________________________________________________________________
21
(b) Many years ago car exhaust fumes were known to contain compounds of metals and
non ndash metals which could negatively impact both humans and the environment Identify
ONE metal and ONE non ndash metal whose compounds were present in car exhaust fumes
Discuss the effect of these compounds on human health and the environment
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) Define lsquogreen chemistryrsquo and discuss the measures that have been taken to produce a
lsquogreenerrsquo automotive fuel
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
22
WEEK 13 LESSON 3 Worksheet
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
Zn2+ ions are present
23
WEEK 14 LESSON 1 Worksheet
(a) Metal alloys are often used in place of metals because of their enhanced properties
(i) Define the term lsquoalloyrsquo
______________________________________________________________________________
______________________________________________________________________________
(ii) Name ONE alloy of aluminium and state its use based on one of its enhanced properties
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) A student conducted an experiment to investigate the reactivity of each of the following
metals (copper iron zinc and lead) by using solutionPs of their sulphate salts
The data presented in the table below shows whether a visible chemical reaction took
place when each metal was added to the four sulphate solutions
Key Visible chemical reaction took place
X No visible chemical reaction
CHEMICAL REACTION OF METALS IN SULPHATE SOLUTIONS
Sulphate solution Cu Fe Zn Pb
CuSO4 X
FeSO4 X X X
ZnSO4 X X X X
PbSO4 X X
24
(i) State which of the TWO metals is more reaction Fe or Zn Give a reason for our answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Using the data in the previous Table deduce the order of reactivity of the four metals Cu
Fe Zn and Pb from the most reactive to the least reactive metal
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The student recorded the following observations from the reaction between the iron and
copper (II) sulphate solution
Observations Reddish ndash brown solid coating formed on the iron strip
Blue colour of the solution changed to dirty green
Account for the observations made from the reaction between the iron and copper (II)
sulphate solution
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iv) Write an ionic equation including state symbols for the reaction between the iron and
copper (II) sulphate solution
______________________________________________________________________________
25
(c) Some metal compounds are health and environmental hazards
(i) Identify which of the metals used in the experiment in (b) is MOST hazardous to the
environment
______________________________________________________________________________
______________________________________________________________________________
(ii) State TWO harmful effects of continuous exposure to the metal identified in (c) (i) on
human beings
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
26
WEEK 14 LESSON 2 Worksheet
(a) Carbon is found in the form of diamond and graphite and is a main component in many
naturally occurring compounds such as organic matter and carbon dioxide gas
(i) State ONE way in which diamond differs physically from graphite
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE similarity between diamond and graphite other than they both contain carbon
______________________________________________________________________________
______________________________________________________________________________
(b) Carbon can react with a limited supply of oxygen to form carbon monoxide which can
negatively affect human health
(i) Write a balanced chemical equation including state symbols to show the formation of
carbon monoxide
______________________________________________________________________________
(ii) State TWO effects of carbon monoxide inhalation on the human body
______________________________________________________________________________
______________________________________________________________________________
(c) Jamal wants to prepare and collect a sample of carbon dioxide gas in the laboratory using
calcium carbonate
(i) Write a balanced chemical equation including state symbols for the laboratory
preparation of carbon dioxide gas from calcium carbonate
______________________________________________________________________________
______________________________________________________________________________
(ii) Draw a clearly labelled diagram to show the arrangement of the apparatus and materials
that could be used in the laboratory to prepare and collect the carbon dioxide gas
(iii) State ONE use of carbon dioxide as it relates to the beverage industry
______________________________________________________________________________
27
WEEK 14 LESSON 3 Worksheet
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
(Ionic equation required)
Suggest a possible identity of the solid R __________________________
28
WEEK 15 LESSON 1 Worksheet
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a small
portion of solid Y gently at
first and then strongly
Colourless gas evolved
with a choking odour
Turns acidified potassium
dichromate solution from
orange to green
(ii) To the remaining portion
of solid Y add 20 cm3 of
distilled water stir to dissolve
and filter Collect the filtrate
and divide into 3 equal
portions
Filtrate is pale green in
colour
(iii) To the first portion of the
filtrate from (ii) add aqueous
sodium hydroxide slowly
until in excess
A green precipitate
Insoluble in excess sodium
hydroxide
Ionic equation required
29
TEST OBSERVATIONS INFERENCES
(iv) To the second portion of
the filtrate from (ii) add
aqueous silver nitrate
followed by aqueous
ammonia
White precipitate
Soluble in aqueous
ammonia
(v) To the third portion of the
filtrate from (ii) add aqueous
barium nitrate followed by
aqueous hydrochloric acid
White precipitate formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with the
evolution of a colourless
gas with a choking smell
30
WEEK 15 LESSON 2 Worksheet
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
31
WEEK 15 LESSON 3 Worksheet
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in excess
aqueous NH3
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change
32
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
warm filter and then divide
the filtrate into two portions
Vigorous effervescence
observed upon addition of
dilute HNO3
Gas evolved turns lime water
cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Cu2+ ions present
33
ANSWERS TO WORKSHEETS
34
WEEK 11 LESSON 1 WORKSHEET ANSWERS
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless O2 H2 CO2 NH3 SO2 H2O
Yellow ndash green Cl2
Red ndash brown Br2 NO2
Gases according to their odour
Odour of gas Identity of gas
Odourless O2 H2 CO2 H2O
Pungent smell NH3
Choking smell SO2 Cl2 Br2
Irritating smell NO2
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect Neutral O2 H2 H2O
Red to blue Alkaline NH3
Blue to red Acidic CO2 SO2 NO2
Blue to red then bleaches it Acidic Cl2 Br2
35
WEEK 11 LESSON 2 WORKSHEET ANSWERS
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-) not
of K or Na
Produces a gas which relights a glowing splint as the only gas NO3- of K or Na
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green SO32-
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-)
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia Cl-
Black iodine present and purple iodine vapour evolved I-
36
WEEK 11 LESSON 3 WORKSHEET ANSWERS
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Br-
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
Cl-
Ag+ (aq) + Cl- AgCl (s)
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow Br-
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
SO42-
Ba2+ (aq) + SO42- (aq)
BaSO4 (s)
(Ionic equation required)
37
WEEK 12 LESSON 1 Worksheet Answers
(a) (i)
The ore bauxite is purified
The purified bauxite is dissolved in molten cryolite
The aluminium oxidecryolite solution is then eletrolysed
Equation at the cathode Al3+ (l) + 3 e- Al (l)
Equation at the anode 2 O2- (l) ndash 4 e- O2 (g)
(ii) The process is too expensive mainly because too much electricity or energy is needed
(b) The alloy of Al and Mg is magnalium It is less dense than the pure metals and hence allow
aircraft to be lighter It is also stronger than the pure metals and hence allows aircraft to last
longer since it is not easily destroyed
(c) Your answer should cater for the following aspects
Benefits of mercury to humans for example in thermometers barometers in dentistry
and gold mining
Entry of mercury to the environment For example this could have been through broken
thermometers barometers or lightbulbs or improper disposal of them or batteries and
indiscriminate use in gold mining in Guyana
The identification of a negative impact on the environment such as poisoned fish and the
persons who eat the fish death mood swings and psychosis
38
WEEK 12 LESSON 2 Worksheet Answers
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas
evolved
NO2 evolved OR nitrates
present OR
Br2 gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate
formed
Soluble in excess
Pb2+ Zn2+ Al3+ or Ca2+
present
Pb2+ Zn2+ Al3+ or present
39
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate
formed
Insoluble in excess
Pb2+ Zn2+ Al3+ or present
Pb2+ or Al3+ present
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate
formed
Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
40
WEEK 12 LESSON 3 Worksheet Answers
(a) an ammonium salt and a strong alkali
(b) Ammonia is basic and it will react with H2SO4
Equation 2 NH3 (aq) + H2SO4 (aq) (NH4)2SO4 (aq)
(c) (i) ndash Density of the gas relative to air ndash The solubility of the gas in water
(ii) Ammonia is collected by upward delivery
It cannot be collected by downward delivery since ammonia is less dense than air
It cannot be collected by displacement of water since it is soluble in water
(d)
41
WEEK 13 LESSON 1 Worksheet Answer
a) i) B ˂ Fe ˂ A
2A (s) + Fe 2+ (aq) rarr 2A+ (aq) + Fe (s)
ii) 2A (s) + CuSO4 (aq) rarr A2SO4 (aq) + Cu (s)
Observation blue colour fades gets lighter OR brown solid forms is deposited OR metal A
decreases in size dissolves
Explanation Metal A is higher (than Fe which is higher) than Cu in the reactivity series OR
Metal A is more reactive (than Fe which is more reactive) than Cu so Metal A can displace Cu
iii) Metal A can be extracted by electrolysis (of its molten oxide) because Metal A is a very
reactive metal is high in the reactivity series forms stable oxides needs a lot of energy to be
extracted and very reactive metals are extracted by electrolysis
Metal B can be extracted by heating with carbon carbon monoxide OR by chemical reduction
of the oxide because Metal B is less reactive than Fe is low in the reactivity series forms less
stable oxides does not need a lot of energy to be extracted and oxides of less reactive metals are
easily reduced
b) Alloy of iron steel
Use of alloy making buildings bridges ships motor vehicles furniture utensils
42
WEEK 13 LESSON 2 Worksheet Answer
(a) (i)
Magensium is the metal ion found in chlorophyll
Chlorophyll is essential for photosynthesis
A deficiency in magnesium will result in low chlorophyll yellow leaves and a reduction in
photosynthesis
Hence there will be low carbohydrates or energy production
Hence small fruits stunted growth and lower yield will result
(ii)
Metal ion Results of deficiency
Potassium Stunted growth premature loss of leaves yellowing of leaves curling of leaf tips
Calcium Growth abnormalities in tips of roots and shoots curling of leaves
Iron Yellowing of leaves
Zinc Low chlorophyll content yellowing of leaves
Manganese Yellowing of leaves poor flavors in some crops for example potato
(b)
Metal Lead is present in some types of gasoline Upon combustion lead compounds escape into
the atmosphere It accumulates in body tissues and slowly poisons the person It causes mental
illness
Non ndash metal SulphurSulphur dioxide or NitrogenNitrogen dioxide
Dissolves in rain water to form acid rain or cause respiratory illnessproblems Acid rain can
cause corrosion damage in buildings
(c)
Green chemistry is the utilisation of a set of principles that reduces or eliminates the use or
generation of hazardous substances
43
Automotive fuels are now produced without lead so as to eliminate the release of lead
compounds into the atmosphere
Low sulphur fuel is being produced with much reduced sulphur content which causes a reduction
of sulphur dioxide release into the atmosphere
44
WEEK 13 LESSON 3 Worksheet Answer
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
gas turns litmus blue
red
brown gas
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
white precipitate
precipitate soluble in
excess
Zn2+ ions are present
45
WEEK 14 LESSON 1 Worksheet Answers
(a)(i) An alloy is a material made from a mixture of two or more metals
(ii) Any suitable answer chosen from below
Alloy Enhance Property Use
Duralumin High strength
Low density
Light
Hard
Used to make aircraft bodies
space satellites
Magnalium Light
Hard
Easier to weld
Corrosion resistant
Strong
High ductability
Used in pyrotechnics
(fireworks)
Mirrors
Aircraft parts
To make scientific
instruments
Used to make marine castings
Alchlad Strong
Corrosion resistant
Cladding for buildings
(b) (i) Zinc is more reactive than iron
Zinc displaces iron from iron (II) sulphate
Zinc is higher in the reactivity series than iron
Iron does not displace zinc from zinc sulphate
(ii) Order of reactivity Zn gt Fe gt Pb gt Cu
(iii) Reddish brown solid ndash copper metal formed
46
Dirty green solution ndash presence of Fe2+ ion
(iv) Fe (s) + Cu2+ (aq) Fe2+ (aq) + Cu (s)
(c) (i) Lead
(ii) Any two correct harmful effects of lead on the body
Impedes brain development (in young children)
Affectimpede development of the immune system in humans
Affecthamper development of nervous system in humans
Long term exposure can result in kidney and liver damage
Mental retardation
Anaemia
Death
47
WEEK 14 LESSON 2 Worksheet Answers
a) i) Diamond is transparent clear Graphite is opaque black
OR hard OR brittle
OR does not conduct electricity OR conducts electricity
a) ii) Both have a macromolecular giant molecular giant covalent structure (lattice)
OR Both have high melting point boiling point
OR Both are insoluble in water organic solvent
b) i) 2C (s) + O2 (g) rarr 2CO (g)
ii) CO reduction in amount of oxygen carried by (the haemoglobin in the red blood
cells of) the blood
Headache OR dizziness OR nausea OR fatigue OR loss of consciousness OR
death
c) i) CaCO3 (s) + 2HCl (aq) rarr CaCl2 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) + H2SO4 (aq) rarr CaSO4 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) rarr CaO (s) + CO2 (g)
48
ii)
OR
OR
Entirely closed system thistle funnel below the level of the liquid OR tap that could be
closed
Two reagents labelled CaCO3marble chips and HCl H2SO4 or heat source
collection of CO2 upward displacement of air OR over watersulphuric acid OR in gas
syringe
iii) CO2 use put in aerated drinks carbonated beverages
OR put in carbon dioxide fire extinguishers
49
WEEK 14 LESSON 3 Worksheet Answers
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
NH4+
NH4+ confirmed OR
NH3 (g) produced
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
Cl- ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation required)
Suggest a possible identity of the solid R NH4Cl (ammonium chloride)
50
WEEK 15 LESSON 1 Worksheet Answers
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a
small portion of solid Y
gently at first and then
strongly
Colourless gas
evolved with a
choking odour
Turns acidified
potassium dichromate
solution from orange
to green
SO2 evolved
Presence of a sulphite
(ii) To the remaining
portion of solid Y add 20
cm3 of distilled water stir
to dissolve and filter
Collect the filtrate and
divide into 3 equal portions
Filtrate is pale green
in colour
Fe2+ ions present
(iii) To the first portion of
the filtrate from (ii) add
aqueous sodium hydroxide
slowly until in excess
A green precipitate
Insoluble in excess
sodium hydroxide
Fe2+ ions present
Fe2+ (aq) + 2 OH- (aq) Fe(OH)2 (s)
Ionic equation required
TEST OBSERVATIONS INFERENCES
(iv) To the second portion
of the filtrate from (ii) add
aqueous silver nitrate
White precipitate
Soluble in aqueous
ammonia
Cl- ions present
51
followed by aqueous
ammonia
(v) To the third portion of
the filtrate from (ii) add
aqueous barium nitrate
followed by aqueous
hydrochloric acid
White precipitate
formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with
the evolution of a
colourless gas with a
choking smell
SO32- CO3
2- SO42- ions present
SO32- ions present
52
WEEK 15 LESSON 2 Worksheet Answers
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
Chloride ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
Cu2+ ions present
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
X contains a reducing agent
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
SO32- SO4
2- or CO32- ions are
present
SO32- ions are present
53
WEEK 15 LESSON 3 Worksheet Answers
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
White ppt
Ppt soluble in excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in
excess aqueous NH3
Al3+ Pb2+ Zn2+ present
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change Cl- Br- I- absent
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
Vigorous effervescence
observed upon addition of
dilute HNO3
CO2 evolved OR
Carbonate present
54
warm filter and then divide
the filtrate into two portions
Gas evolved turns lime
water cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
Cu2+ (aq) + OH- (aq)
Cu(OH)2 (s)
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Blue ppt
ppt dissolves in excess
NH3 to give a deep blue
solution
Cu2+ ions present
55
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
REFERENCES
Hunte-King J Maragh P Nagir F amp Norris R (2013) Chemistry for CSEC United
Kingdom Nelson Thornes Ltd
Remy C Mason L Lambert N amp Mohammed M (2007) Chemistry for CSEC England and
Wales Pearson Education Limited
Taylor M amp Chung-Harris T (2010) CXC Chemistry England Macmillan Publishers
Limited
Tindale A (2016) Chemistry A Concise Revision for CXC London HarperCollins Publishers
Limited
2
WEEK
LESSON
1 2 3
9 Uses of gases Uses of non ndash metals
and their compounds
Harmful effects of
non ndash metals and
their compounds on
living systems and
the environment
10 Green Chemistry Qualitative Analysis
ndash Identification of
cations
Qualitative Analysis
ndash Identification of
cations
11 Qualitative Analysis
ndash Test for gases
Qualitative Analysis
ndash Identification of
anions
Qualitative Analysis
ndash Identification of
anions
12 Problem solving of
Past CSEC Chemistry Paper 2
on topics completed in the term
13
14
15
3
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
WEEK 1 LESSON 1
TOPIC Characteristics of metals and non ndash metals
The elements of the periodic table may be classified as metals and non ndash metals The division is
The non ndash metals with the exception of hydrogen are found on the right hand side of the
periodic table These elements have atoms with completed filled or nearly filled outermost shells
The figure below shows an outline of the periodic table with the metals and non-metals
I II III IV V VI VII 0
B C N O F He
Si P S Cl Ne
METALS
As Se Br Ar
Te I Kr
At Xe
Rn
Periodic Table showing Metals and Non ndash metals
4
Differences between metals and non ndash metals
Metals Non ndash metals
Good conductor of electricity Do not conduct electricity
except graphite (carbon)
Good conductor of heat Do not conduct heat except graphite (carbon)
Lustrous solids at room temperature
(except mercury)
Solid liquid or gas at room temperature
eg iodine (solid) bromine (liquid) and
chlorine (gas) at room temperature
Malleable (can be beaten into different
shapes)
Not malleable
Ductile (can be drawn into wires) Not ductile
Sonorous (ring when hit with a hard object) Not sonorous
High melting and boiling points Low melting and boiling points compared to
metals
High density Much lower density at rtp compared to metals
5
WEEK 1 LESSON 1 WORKSHEET
Shade the letter next to the answer you choose for questions 1 to 4
1 Which of the following are metals
I Bromine
II Sodium
III Neon
IV Iron
(A) I and III (B) II and IV (C) I and IV (D) II and III
2 Which of the following are non ndash metals
I Chromium
II Carbon
III Iodine
IV Potassium
(A) I and III (B) II and IV (C) I and IV (D) II and III
3 A metal that is a liquid at room temperature is
(A) mercury (B) tin (C) magnesium (D) sodium
6
4 Consider the following information about four substances
Substance Melting point
0C
Electrical conductivity Water
solubility in solid in liquid
I 1050 Low High High
II 75 Low Low Low
III 1234 High High Low
IV 1913 Low Low Low
The substance which is MOST likely to be a metal is
(A) I (B) II (C) III (D) IV
5 Read the following and answer the question that follows
A new element was discovered to have the following properties
Lustrous solid
Can be beaten into shapes
High density
(a) Based only on the facts stated above is the element a metal or non metal
_______________________
(b) State 3 other properties that you expect this element to exhibit
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
7
WEEK 1 LESSON 2
TOPIC Physical properties of metals
Physical properties of some metals
Metals Melting point 0C
Boiling point
0C
Density
g cm-3
Other characteristics
Sodium 90 900 097 Very soft grey metal
Calcium 850 1487 153 Grey metal
Magnesium 650 1103 174 Soft grey metal
Aluminium 660 2350 270 Grey metal
Zinc 419 907 719 White metal
Iron 1535 2760 797 Dark grey metal
Copper 1083 2580 894 Gold coloured metal
conductivity second only to
silver
Sodium Calcium Magnesium Aluminium
Zinc Iron Copper
8
WEEK 1 LESSON 2 WORKSHEET
A group of students carried out an experiment to find the density of three different metals
aluminium calcium and an unknown metal X They measured the mass of each metal sample
using a balance The volumes of the metals were determined by displacement of oil The results
of their experiment are as follows
Aluminium Calcium Metal X
Mass (g) 100 100 100
Final volume (cm3) 335 365 310
Initial volume (cm3 300 300 300
Volume of metal (cm3)
Density (gcm-3)
Complete the table using the following formulae
Volume of metal = Final volume ndash Initial volume
Density = 119872119886119904119904
119881119900119897119906119898119890
Arrange the metals in order of increasing density _____________________________________
9
WEEK 1 LESSON 3
TOPIC Chemical properties of metals
Action of oxygen
Most metals react with oxygen or air to form the corresponding oxide These oxides are basic
oxides with the exception of aluminium zinc and lead which form amphoteric oxides Metals
lower in the electrochemical series do not react
Metal Reaction with air or oxygen
Potassium K
Burn very easily forming oxide
eg 4 Na (s) + O2 (g) 2 Na2O (s)
Sodium Na
Calcium Ca
Magnesium Mg
Aluminium Al
Burn especially if powered forming oxide
eg 4 Al (s) + 3 O2 (g) 2 Al2O3 (s)
Zinc Zn
Iron Fe
Lead Pb Do not burn form oxide when heated strongly
Copper Cu
Silver Ag No reaction
10
WEEK 1 LESSON 3 WORKSHEET
Write balanced chemical equations for the reaction of the named metals and air or oxygen
State the nature of the oxide formed (basic or amphoteric)
Potassium + Oxygen
______________________________________________________________________________
Sodium + Oxygen
______________________________________________________________________________
Calcium + Oxygen
______________________________________________________________________________
Magnesium + Oxygen
______________________________________________________________________________
Aluminium + Oxygen
______________________________________________________________________________
Zinc + Oxygen
______________________________________________________________________________
11
Iron + Oxygen
______________________________________________________________________________
Lead + Oxygen
______________________________________________________________________________
Copper + Oxygen
______________________________________________________________________________
Silver + Oxygen
______________________________________________________________________________
12
WEEK 2 LESSON 1
TOPIC Chemical properties of metals
Action of water
Metals high in the electrochemical series react with cold water to produce the metal hydroxide
and hydrogen
Reactive metals slightly lower in the electrochemical series react very slowly or not at all with
water However they may react with hot water or steam to produce the corresponding metal
oxide and hydrogen
Metals lower than hydrogen in the electrochemical series do not react with water
Metal Reaction with water or steam
Potassium K React with cold water forming metal hydroxide and hydrogen
eg Ca (s) + 2 H2O (l) Ca(OH))2 (aq) + H2 (g) Sodium Na
Calcium Ca
Magnesium Mg React with steam forming metal oxide and hydrogen
eg Zn (s) + H2O (g) ZnO (s) + H2 (g) Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
13
WEEK 2 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with water (or
steam if reaction does not occur with water)
Potassium + WaterSteam
______________________________________________________________________________
Sodium + WaterSteam
______________________________________________________________________________
Calcium + WaterSteam
______________________________________________________________________________
Magnesium + WaterSteam
______________________________________________________________________________
Aluminium + WaterSteam
______________________________________________________________________________
Zinc + WaterSteam
______________________________________________________________________________
14
Iron + WaterSteam
______________________________________________________________________________
Copper + WaterSteam
______________________________________________________________________________
Silver + WaterSteam
______________________________________________________________________________
15
WEEK 2 LESSON 2
TOPIC Chemical properties of metals
Action of dilute acids
Metals above hydrogen in the electrochemical series react with dilute acids to form a salt and
hydrogen gas They react with hydrochloric acid to form the metal chloride (a salt) and hydrogen
gas They also react with dilute suphuric acid to form the metal sulphate (a salt) and hydrogen
gas
Metal Reaction dilute hydrochloric or sulphuric acid
Potassium K Violent reaction forming a salt and hydrogen gas
eg 2 Na (s) + 2 HCl (aq) 2 NaCl (aq) + H2 (g) Sodium Na
Calcium Ca Vigorous reaction forming a salt and hydrogen gas
eg Mg (s) + 2 HCl (aq) MgCl2 (aq) + H2 (g) Magnesium Mg
Aluminium Al React forming a salt and hydrogen gas
eg Fe (s) + 2 HCl (aq) FeCl2 (aq) + H2 (g) Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
16
WEEK 2 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with
hydrochloric acid
Metal Balanced equation for reaction with hydrochloric acid
Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Copper
Silver
17
WEEK 2 LESSON 3
TOPIC Reactions of metal compounds
Reactions of metallic oxides with dilute acid
Metal oxides react with dilute hydrochloric acid or sulphuric acid to produce a salt and water
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
Some of these reactions may be slow and can be speeded up by adding heat
For example
zinc oxide + hydrochloric acid zinc chloride + water
ZnO (s) + 2 HCl (aq) ZnCl2 (aq) + H2O (l)
magnesium oxide + hydrochloric acid magnesium chloride + water
MgO (s) + 2 HCl (aq) MgCl2 (aq) + H2O (l)
aluminium oxide + sulphuric acid aluminium sulphate + water
Al2O3 3 H2SO4 (aq) Al2(SO4)3 (aq) + 3 H2O (l)
calcium oxide + sulphuric acid calcium sulphate + water
CaO H2SO4 (aq) CaSO4 (aq) + H2O (l)
18
WEEK 2 LESSON 3 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal oxides with the
corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium oxide Hydrochloric acid
Sodium oxide Sulphuric acid
Calcium oxide Hydrochloric acid
Magnesium oxide Sulphuric acid
Aluminium oxide Hydrochloric acid
Zinc oxide Sulphuric acid
19
WEEK 3 LESSON 1
TOPIC Reactions of metal compounds
Reactions of metallic hydroxides with dilute acid
Metal hydroxides react with dilute acids to form a salt and water in a neutralisation reaction
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
For example
magnesium hydroxide + hydrochloric acid magnesium chloride + water
Mg(OH)2 (aq) + 2 HCl (aq) MgCl2 (aq) + 2 H2O (l)
sodium hydroxide + hydrochloric acid sodium chloride + water
NaOH (aq) + HCl (aq) NaCl (aq) + H2O (l)
potassium hydroxide + sulphuric acid potassium sulphate + water
2 KOH + H2SO4 (aq) K2SO4 (aq) + 2 H2O (l)
calcium hydroxide + sulphuric acid calcium sulphate + water
Ca(OH)2 (aq) + H2SO4 (aq) CaSO4 (aq) + 2 H2O (l)
20
WEEK 3 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal hydroxides with
the corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium hydroxide Hydrochloric acid
Sodium hydroxide Sulphuric acid
Calcium hydroxide Hydrochloric acid
Magnesium hydroxide Sulphuric acid
Aluminium hydroxide Hydrochloric acid
Zinc hydroxide Sulphuric acid
21
WEEK 3 LESSON 2
TOPIC Reactions of metal compounds
Reactions of metallic carbonates with dilute acid
Metal carbonates react with dilute acid to form a salt carbon dioxide and water When
hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric acid is
used the corresponding sulphate salt is formed
For example
sodium carbonate + hydrochloric acid sodium chloride + carbon dioxide + water
Na2CO3 (s) + 2 HCl (aq) 2 NaCl (aq) + CO2 (g) + H2O (aq)
calcium carbonate + hydrochloric acid calcium chloride + carbon dioxide + water
CaCO3 (s) + 2 HCl (aq) CaCl2 (aq) + CO2 (g) + H2O (aq)
zinc carbonate + sulphuric acid zinc sulphate + carbon dioxide + water
ZnCO3 (s) + H2SO4 (aq) ZnSO4 (aq) CO2 (g) + H2O (aq)
potassium carbonate + sulphuric acid potassium sulphate + carbon dioxide + water
K2CO3 (s) H2SO4 (aq) K2SO4 (aq) CO2 (g) + 2 H2O (aq)
22
WEEK 3 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal carbonates with
the corresponding acid
Metallic
carbonate
Acid Balanced chemical equation
Potassium
carbonate
Hydrochloric
acid
Sodium
carbonate
Sulphuric acid
Zinc
carbonate
Hydrochloric
acid
Magnesium
carbonate
Sulphuric acid
Aluminium
carbonate
Hydrochloric
acid
Calcium
carbonate
Sulphuric acid
23
WEEK 3 LESSON 3
TOPIC Action of heat on metal compounds
Action of heat on nitrates
All nitrates decompose when heated The reactivity of the metal in the metal nitrate influences
the products of the decomposition
The nitrates of the alkali metals (Group I) with the exception of lithium nitrate decompose to
form the metal nitrite and oxygen
The nitrates of most other metals decompose to form the metal oxide nitrogen dioxide and
oxygen
The nitrates of the very unreactive metals decompose to form the meal nitrogen dioxide and
oxygen
Metal Nitrate Decomposition
Potassium K Products metal nitrite + oxygen
eg 2 NaNO3 (s) Heatrarr 2 NaNO2 (s) + O2 (g)
Sodium Na
Calcium Ca
Products metal oxide + nitrogen dioxide + oxygen
eg 2 Pb(NO3)2 (s)
Heatrarr 2 PbO (s) + 4 NO2 (g) + O2 (g)
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Products metal + nitrogen dioxide + oxygen
eg 2 AgNO3 (s) Heatrarr 2 Ag (s) + 2 NO2 (g) + O2 (g)
24
WEEK 3 LESSON 3 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
nitrates
Metal Balanced chemical equation
Potassium nitrate
Sodium nitrate
Calcium nitrate
Magnesium nitrate
Aluminium nitrate
Zinc nitrate
Lead nitrate
Copper nitrate
Silver nitrate
25
WEEK 4 LESSON 1
TOPIC Action of heat on metal compounds
Action of heat on carbonates
Upon application of heat many carbonates decompose to form the metal oxide and carbon
dioxide
Group I carbonates do not decompose on heating with the exception of lithium carbonate
Metal Carbonate decomposition
Potassium K
Stable not decomposed by heat Sodium Na
Calcium Ca
Decompose forming metal oxide and carbon dioxide
eg CaCO3 (s) Heatrarr CaO (s) + CO2 (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Unstable
26
WEEK 4 LESSON 1 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
carbonates
Metal Balanced chemical equation
Potassium carbonate
Sodium carbonate
Calcium carbonate
Magnesium carbonate
Aluminium carbonate
Zinc carbonate
Iron carbonate
Lead carbonate
Copper carbonate
27
WEEK 4 LESSON 2
TOPIC Action of heat on metal compounds
Action of heat on the metal hydroxides
Most metal hydroxides decompose on heating A metal oxide and water are formed
Group I hydroxides do not decompose on heating with the exception of lithium hydroxide
Metal Hydroxide decomposition
Potassium K Stable not decomposed by heat
Sodium Na
Calcium Ca Decompose forming metal oxide and water (as steam)
eg Zn(OH)2 (s) Heatrarr ZnO (s) + H2O (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag No hydroxide exist
28
WEEK 4 LESSON 2 WORKSHEET
Write the balanced chemical equations for the thermal decomposition of the following
metal hydroxides
Metal hydroxide Balanced chemical equation
Potassium hydroxide
Sodium hydroxide
Calcium hydroxide
Magnesium hydroxide
Aluminium hydroxide
Zinc hydroxide
Lead hydroxide
Copper hydroxide
29
WEEK 4 LESSON 3
TOPIC Reactivity of metals ndash The Reactivity Series
The reactivity series of metals is a list of metals arranged in order of their reactivity based on
Displacement reactions
Reactions with oxygen dilute acids and water
Relative ease of decomposition of their compounds
Metals at the top of the series are the most electropositive They lose electrons very easily and
readily form cations These ions are very stable and are not easily discharged to form atoms Due
to this fact they are the most reactive metals
Metals at the bottom of the series are the least electropositive They do not lose electrons easily
and do not readily form ions Their ions are very unstable and are easily discharged to form
atoms They are the least reactive metals
The reactivity series of metals
Mnemonic Metal Symbol Reactivity
People Potassium K Most reactive
Least reactive
Sometimes Sodium Na
Collect Calcium Ca
Magazines Magnesium Mg
About Aluminium Al
Zoos Zinc Zn
In Iron Fe
London Lead Pb
Having (Hydrogen) H
Cute Copper Cu
Monkeys and Mercury Hg
Small Silver Ag
Gorillas Gold Au
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
5 Reactivity of metals Reactivity of metals Reactivity of metals
6 Extraction of metals Extraction of metals Alloys
7 Corrosion Importance of metals
and their compounds
on living systems and
environment
Chemical properties
of non ndash metals
8 Laboratory
preparation of gases
Laboratory
preparation of gases
Laboratory
preparation of gases
9 Uses of gases Uses of non ndash metals
and their compounds
Harmful effects of
non ndash metals and
their compounds on
living systems and
the environment
10 Green Chemistry Qualitative Analysis
ndash Identification of
cations
Qualitative Analysis
ndash Identification of
cations
2
WEEK 5 LESSON 1
TOPIC Reactivity of metals
Reactivity based on displacement reactions between metals and metal ions
A metal will displace a metal which is lower than itself in the reactivity series from a solution of
the metal salt
Reaction of zinc and copper (II) sulphate
Expected observations
Explanation
The size of the zinc metal decreases
The zinc metal is reacting and forming the
salt zinc sulphate
The solution becomes lighter eventually
colourless
The Cu2+ (aq) ions (responsible for the blue
colour) is reduced to Cu (s)
A brown solid is deposited at the bottom of
the container
Copper metal is formed
Equation Zn (s) + CuSO4 (aq) ZnSO4 (aq) + Cu (s)
Ionic equation
Zn (s) + Cu2+ (aq) Zn2+ (aq) + Cu (s)
Zinc is higher in the reactivity series than copper Therefore it will displace the copper ions in
the reaction above
3
Examples of other displacement reactions
Magnesium will displace Zn2+ ions in zinc sulphate since it is higher in the series than zinc
Mg (s) + Zn2+(aq) Mg2+ (aq) + Zn (s)
Silver will not displace Cu2+ ions in copper (II) sulphate [Cu is higher in the series than Ag]
Using the information above we can arrange the metals in order of their reactivity with
magnesium being the most reactive and silver the least reactive metal among the four metals
Mg gt Zn gt Cu gt Ag
Reactivity based on reaction with oxygen
The reactivity of metals can also be deduced from their reaction with oxygen
The table below gives the observations for the reaction with oxygen with the selected metals
Reaction of metal with oxygen
Metal Observation
Copper The surface turns black upon heating
Magnesium Ribbon burns very rapidly
Sodium Burns vigorously
Gold No reaction
Based on the observations for the 4 metals the metal with highest reactivity is sodium and the
metal with the least reactivity is gold
The 4 metals can be arranged in terms of reactivity as follows
Na gt Mg gt Cu gt Au
4
WEEK 5 LESSON 1 WORKSHEET
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
5
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
6
WEEK 5 LESSON 2
TOPIC Reactivity of metals
Reactivity based on reactivity with acids
The metals that are higher than hydrogen in the electrochemical series react with non ndash oxidizing
acids to produce a salt and hydrogen gas
By using the same concentration of acid and same mass and size of the metals the order of
reactivity of the metals can be deduced
The table below shows the results for an experiment with the reaction of the named metals and
1 mol dm-3 hydrochloric acid
Reaction of metals with acid
Metal Observations
Silver No reaction
Magnesium Bubbles produced steadily
Calcium Bubbles produced very rapidly
Iron Bubbles produced slowly
Based on the above data the most reactive metal will be calcium with the least reactive being
silver The order of reactivity will be Ca gt Mg gt Fe gt Ag
By comparing this to the electrochemical series it can be seen that the reactivity of the metals
decrease as we go down the series
7
WEEK 5 LESSON 2 WORKSHEET
1 Place a next to the metals that will react with dilute acid and an X next to the metals
that will not react with dilute acid
Metal Reactivity with acid
Copper
Magnesium
Aluminium
Silver
Zinc
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
8
WEEK 5 LESSON 3
TOPIC Reactivity of metals
Reactivity based on ease of decomposition of the metal nitrates carbonates oxides and
hydroxides
The more reactive a metal the more difficult it is to decompose its nitrate carbonate oxide or
hydroxide on heating
For example Decomposition of carbonates
Procedure
1 Put a large spatula measure of the carbonate to be tested in a test tube
2 Fit a delivery tube and then clamp the test tube so that the delivery tube dips into a second test
tube containing 2ndash3 cm3 limewater
3 Heat the solid gently at first then more strongly
4 Lift the delivery tube from the limewater before or as soon as the heating is stopped This is to
avoid suck-back
5 Write down all observations Notice what happens to the limewater and how long it takes to turn
milky (if at all) Notice whether any melting occurs in the heated test tube and any colour
changes taking place Write your results in tabular form
6 Repeat the experiment with the other metal carbonates supplied and in each case write down
your observations
7 Wash your hands thoroughly at the end of these experiments since some of the metal carbonates
are toxic
9
Results
Metal Formula Gas evolved Ease of decomposition
Zinc ZnCO3 Carbon dioxide Fairly easy
Copper CuCO3 Carbon dioxide Easy
Sodium Na2CO3 None Very difficult
Using the results of the above activity the reactivity of the metals can be determined
Ease of decomposition Copper gt Zinc gt Sodium
The order of reactivity is the opposite for the ease of decomposition
Order of reactivity Sodium (most reactive) gt Zinc gt Copper (least reactive)
10
WEEK 5 LESSON 3 WORKSHEET
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
11
WEEK 6 LESSON 1
TOPIC Extraction of metals
Elements exist all over the earth Some are found as free elements eg copper silver and gold
Others are found combined with other elements in compounds To get the elements the
compounds have to be broken up These compounds are generally called ores the most
convenient sources of which are rocks sea and air
The extraction of a metal from its ore is a reduction process where the metals ions gain electrons
to form atoms
The general equation is Mn+ + n e- M
The choice of the extraction method depends on the position of the metal in the reactivity series
As we go down the series the metals become more stable and the metal ions (in the ores)
become less stable
The very reactive metals that are high in the series K Na Ca Mg Al have very stable ores
Therefore they require a powerful method of reduction namely electrolysis During the process
the cathode provides the electrons and acts as the reducing agent
The metals in the middle of the series (Zn Fe Pb) do not have stable ores and can be extracted
by reduction with carbon in the case of zinc and with carbon monoxide in the case of iron and
lead
Metals low in the reactivity series if present as ores can be extracted simply by heating the ores
in air at high temperatures
12
Extraction of Aluminium from purified bauxite
Pure bauxite is pure alumina (Al2O3) Aluminium is obtained from bauxite by electrolysis
Aluminium oxide has a very high melting point approximately 2050 0C so it is first dissolved in
molten cryolite (Na2AlF6) The addition of cryolite lowers the melting point to approximately
900 0C
The electrolyte is a molten mixture of alumina and molten cryolite The cathode is the graphite
lining of the cell The anodes are blocks of graphite or titanium alloys
Reaction at the cathode
Al3+ (l) + 3 e- Al (l)
Reaction at the anode
2 O2- (l) ndash 4 e- O2 (g)
Aluminium (melting point 660 0C) is a liquid at the temperature at which electrolysis is carried
out and is collected at the bottom of the cell and tapped off Oxygen gas which is given off in the
main cathode reaction together with the heat causes the anodes to burn away The anodes have
to be replaced from time to time The use of anodes from titanium alloys reduce the number of
times that the anodes have to be replaced
13
WEEK 6 LESSON 1 Worksheet
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 6 LESSON 2
TOPIC Extraction of metals
Extraction of Iron
The traditional method of production of iron is by reduction of haematite by carbon monoxide in
a blast furnace
Ores Haematite ndash Fe2O3 Magnetite ndash Fe3O4 Siderite ndash FeCO3 Magnetite and Siderite are
converted to Haematite
A mixture of haematite limestone (CaCO3) and coke (C) called the charge is placed into the top
of the furnace
Hot air is blown into the bottom of the furnace
Coke burns in air forming carbon dioxide
C (s) + O2(g) CO2 (g) ΔH -ve
The heat produced keeps the temperature at about 1900 0C
The carbon dioxide is reduced to carbon monoxide by the hot coke
CO2 (g) + C (s) 2 CO(g) Δ +ve
Heat absorbed reduces the temperature to about 1100 0C
The carbon monoxide reduces the hot iron ore to molten iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + 3 CO2(g)
The temperature at this part of the furnace is about 700 0C The iron runs to the bottom of the
furnace
The impurities are removed by the addition of limestone (CaCO3) The limestone at the
temperature of the furnace breaks down
CaCO3 (s) CaO (s) + CO2 (g)
15
The calcium oxide formed combines with silicon dioxide (sand) the main impurity in the iron
ore to form molten slag
CaO (s) + SiO2 (s) CaSiO3 (l)
The slag does not mix with the molten iron but floats on it The molten iron and slag are run off
separately
The iron formed in a blast furnace is an impure form of the metal Because the molten metal is
allowed to solidify in shallow trays known as casts the iron is called lsquocast ironrsquo or lsquopigrsquo iron
Cast iron is quite brittle and contains 2 - 4 carbon and other impurities Most of the cast iron is
converted to steel
A blast furnace used for extracting iron
16
WEEK 6 LESSON 2 Worksheet
(a) What are the three raw materials that are added through the top of the blast furnace
during the extraction process for iron
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______________________________________________________________________________
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
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17
WEEK 6 LESSON 3
TOPIC Alloys
An alloy is a mixture of two or more metals Alloys are made by melting the individual metals
mixing them and allowing the molten mixture to solidify
In general alloys are harder stronger and more resistant to corrosion than the actual metals they
are made up from
Alloy Use Properties
ALUMINIUM
-Duralumin
(AlMgCu)
-Magnalium (AlMg)
Alloys used in the
construction of
aircraft and ships
buses
Aluminium is used in
making cooking
utensils electrical
cables paint for fuel
storage tanks bottle
caps foil and utensils
for handling nitric
acid
The alloys have a low
density They are as
light as aluminium
and more resistant to
corrosion than
aluminium
LEAD
-Solder (PbSn)
Alloy is used in
joining metals
(soldering)
Lead is used in
underground cables
plates in
The alloy has a lower
melting point than
lead and is harder
than lead
18
Alloy Use Properties
accumulators shield
against x ndash rays
IRON
- Stainless Steel
(FeCONiC)
-Tungsten steel
(FeWC)
-Invar steel (FeNi)
Manganese steel
(FeMnC)
Iron is the main metal
of a variety of
constructions
Steel is used in
cutlery rock drills
electromagnets
vehicle body and
engine parts fences
pipes etc
Steel resists
corrosion is usually
harder than iron and
may be tough though
malleable and ductile
19
WEEK 6 LESSON 3 Worksheet
(a) Define the term alloy
______________________________________________________________________________
(b) State 3 general advantages that alloys have over the individual metals they are made
from
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______________________________________________________________________________
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
______________________________________________________________________________
______________________________________________________________________________
Uses
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 7 LESSON 1
TOPIC Corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
Familiar examples of corrosion are
- the formation of a green powder on copper sheeting
- the eating away of iron (rusting)
- the development by aluminum of a thin compact layer of oxide which protects the
underlying metal from further corrosion
When corrosion occurs in water ndash free environment it is called dry oxidation When it occurs in
aerated aqueous environments it is called wet corrosion Wet corrosion is the most common and
troublesome form of corrosion
The most familiar corrosion is the rusting of iron and steel On exposure to the atmosphere iron
and steel corrode to form rust which is hydrated iron (III) oxide Fe2O3xH2O Iron and steel
corrode easily and the rust formed flakes off easily thus exposing fresh surface for attack
When iron rust it loses electrons
Fe (s) ndash 2e- Fe 2+ (aq)
The iron (II) ions pass into solution and then combine with the hydroxyl (OH-) ions in the
aerated aqueous environment to form iron (II) hydroxide The oxygen present oxidises the iron
(II) hydroxide to hydrated iron (III) oxide or rust
Fe(OH)2 + O2 Fe2O3xH2O
21
Methods of preventing rusting
1 Coating the object with paint grease plastic or rubber which prevent contact with air or
water
2 Galvanising ndash coating the object with zinc The zinc forms an adherent oxide layer which
protects against further corrosion If damaged the zinc is oxidized in preference to the
iron since it is higher in the electrochemical series
3 Coating with tin lsquoTinrsquo cans are made of steel plated with tin However if scratched
rusting occurs since iron is more reactive than tin
4 Attaching a sacrificial anode to the object A piece of metal higher in the electrochemical
series such as magnesium is attached The magnesium will be oxidized in preference
since it is higher in the electrochemical series than iron
22
WEEK 7 LESSON 1 WORKSHEET
(a) Define the term corrosion
______________________________________________________________________________
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
______________________________________________________________________________
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______________________________________________________________________________
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
23
WEEK 7 LESSON 2
TOPIC Importance of metals and their compounds on living systems and environment
Some metals are an integral part of different structures of living things
Metal Presence and Function
Potassium Main cation in fluid or animal cells essential for healthy plant growth
Calcium Necessary for strong bones teeth and shells needed by some enzymes Present
in dairy produce eggs nuts and cereals
Magnesium Central atom of chlorophyll needed for some enzyme action Involved in energy
and calcium metabolism
Zinc Present in many enzymes Needed for protein metabolism Essential for growth
of animals
Iron Present in haemoglobin Needed for protein metabolism Essential for growth of
animals
Chromium Needed for glucose uptake by cells and thus linked to the action of insulin
Manganese Needed for bone development and amino acid metabolism Present in several
enzymes Needed for plant growth
Cobalt Present in Vitamin B12 Needed for plant growth
Copper Involved in formation of haemoglobin and melanin Present in enzymes
controlling oxidation Needed for plant growth
24
Harmful effects of metals and their compounds to living systems and the environment
There are some metals and metal compounds which may cause harm to living systems and the
environment
Lead
Lead is a heavy metal poison that is widely encountered It may occur in food beverages paint
water formed from ndash sealed pipes in air polluted by combustion by fuels containing lead
compounds Lead is also used in some car batteries If these are paints or batteries are not
disposed of correctly lead may get into groundwater or air Lead and lead compounds harm the
nervous system including the brain especially young children
Arsenic
Arsenic compounds are poisonous They can get into the groundwater from mining waste and
from disposal of some electrical components
Cadmium
Cadmium compounds are poisonous They can get into the ground by improper disposal of
nickel ndash cadmium batteries Persons can get cadmium poisoning if they eat food grown in
contaminated soil
Mercury
Mercury can be spilled from broken thermometers in hospitals and laboratories Mercury and its
compounds are particularly poisonous to fish and it can accumulate in the food chain and
eventually poison humans
Problems of disposal of solid waste
Metals may react with water andor air and corrode to form soluble compounds that are
poisonous These toxic compounds diffuse into the soil and eventually enter rivers
Rust from iron may form unsightly pools of waste that reduce plant growth
Waste from aluminium extraction may react with water and form flammable gases
25
WEEK 7 LESSON 2 WORKSHEET
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Lead
______________________________________________________________________________
Mercury
______________________________________________________________________________
26
WEEK 7 LESSON 3
TOPIC Chemical properties of non ndash metals
Reaction with oxygen
Many non ndash metals burn in excess oxygen or air to form oxides For example
S (s) + O2 (g) SO2 (g)
C (s) + O2 (g) CO2 (g)
Reactions with metals
Some non ndash metals react with metals high in the electrochemical series when heated
For example
Sodium burns in chlorine to form sodium chloride
Na (s) + Cl2 (g) NaCl (s)
Magnesium burns in oxygen to form magnesium oxide
Mg (s) + O2 (g) MgO (s)
When heated iron combines with molten sulphur to form iron (II) sulphide
Fe (s) + S (l) FeS (s)
When heated reactive metals such as sodium and aluminium react with hydrogen to form metal
hydrides
2 Na (s) + H2 (g) 2 NaH (s)
Oxidising and Reducing properties
Hydrogen and Carbon are very good reducing agents
At high temperatures hydrogen reduces metal oxides below zinc in the electrochemical series to
form the metal For example PbO (s) + H2 (g) Pb (s) + H2O (g)
Under suitable conditions hydrogen reduces nitrogen to ammonia
N2(g) + 3 H2 (g) 2 NH3 (g)
27
At high temperatures carbon reduces metal oxides below aluminium in the reactivity series to
the metal For example
ZnO (s) + C (s) Zn (s) + CO (g)
Oxygen and Chlorine are very good oxidizing agents
Oxygen oxidized most metals to form metal oxides and some non ndash metals to non ndash metal oxides
For example
2 Mg (s) + O2(g) 2 MgO (s)
4 P (s) + 5 O2 (g) P4O10 (s)
Chlorine acts as an oxidizing agent either as a gas or as an aqueous solution For example
H2 (g) + Cl2 (g) 2 HCl (g)
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
28
WEEK 7 LESSON 3 WORKSHEET
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
______________________________________________________________________________
(b) Write the ionic equation for the above reaction
______________________________________________________________________________
(c) Identify the oxidising agent in the reaction
______________________________________________________________________________
(d) Justify your answer in part (c) in terms of oxidation number
______________________________________________________________________________
29
WEEK 8 LESSON 1
TOPIC Laboratory preparation of gases
Preparation of oxygen
Oxygen can be prepared by the decomposition of hydrogen peroxide potassium chlorate (V) or
potassium nitrate The safest method is the decomposition of hydrogen peroxide
Manganese (IV) oxide catalyses the decomposition of hydrogen peroxide
Silica gel anhydrous calcium chloride or concentrated sulphuric acid can be used as a drying
agent
The gas is collected by downward delivery since it is slightly denser than air
Equation
2 H2O2 (aq) 2 H2O (l) + O2 (g)
Apparatus used for laboratory preparation of oxygen
30
WEEK 8 LESSON 1 WORKSHEET
Describe the laboratory preparation of oxygen gas
In your answer include
The starting material
A suitable catalyst
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
31
WEEK 8 LESSON 2
TOPIC Laboratory preparation of gases
Preparation of carbon dioxide
Carbon dioxide can be prepared by the action of dilute acid on carbonates Marble chips (calcium
carbonate) and dilute hydrochloric acid are the common reagents The gas is collected by
downward delivery since it is denser than air
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
Apparatus used for laboratory preparation of carbon dioxide
32
WEEK 8 LESSON 2 WORKSHEET
Describe the laboratory preparation of carbon dioxide gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
33
WEEK 8 LESSON 3
TOPIC Laboratory preparation of gases
Preparation of ammonia
Ammonia may be prepared by heating a mixture of ammonium salt and a hydroxide The
ammonia gas is collected by upward delivery since it is less dense than air
For example
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
Calcium oxide is the only suitable drying agent since ammonia reacts with conc H2SO4 and
CaCl2
Apparatus used for laboratory preparation of dry ammonia
34
11
WEEK 8 LESSON 3 WORKSHEET
Describe the laboratory preparation of ammonia gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
35
WEEK 9 LESSON 1
TOPIC Uses of gases
Carbon dioxide
Used in fire extinguishers to put out fires Carbon dioxide is denser than air and lsquoblanketsrsquo the
fire preventing oxygen from reaching it Carbon dioxide extinguishers are especially useful for
dealing with fires involving flammable liquids and electrical equipment
Carbonation in soda is created when carbon dioxide is pumped into the soda can or bottle then
held under pressure As long as the can or bottle is sealed the carbon dioxide remains mostly
stable However if the drink gets shaken up or the top is opened the tiny carbon dioxide bubbles
react by bursting
Oxygen
Oxygen is needed for aerobic respiration We need a constant supply of oxygen for this process
Oxygen is used in hospitals to improve the respiration of patients with poor blood flow blood
poisoning and heart disease
Oxygen in used in welding (joining) metals In an oxyacetylene welding torch acetylene or
ethyne (C2H2) burns in oxygen and produces a very hot flame This flame is capable of melting
most metals
Oxygen is used in steel production A blast of oxygen is blown through the molten iron The
oxygen oxidises many of the impurities of the iron and the impurities are then removed
36
WEEK 9 LESSON 1 WORKSHEET
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Put out fires
Welding metals
Create lsquofizzrsquo in drinks
Used in steel production
Aerobic respiration
37
WEEK 9 LESSON 2
TOPIC Uses of non ndash metals and their compounds
Carbon (allotrophes carbon dioxide)
Carbon is used as a reducing agent in extraction of some metals
Carbon as graphite is used as electrodes lubricants and lsquoleadrsquo for pencils
Carbon in the form of diamond is used for jewellery (because of its lustre) and in drill tips for
high ndash speed drills (because of its hardness)
Carbon dioxide is used as refrigerant (as dry ice) for carbonated beverages
Sodium hydrogen carbonate and sodium carbonate are used for water softening and raising
agent
Sulphur
Sulphur is used in the manufacture of sulphuric acid Sulphur is also used in the manufacture of
tyres to make the rubber harder (vulcanisation)
Sulphur powder is used as fungicide on plant materials
Phosphorus
Phosphorus is used in the manufacture of fertilizers
Phosphorus is used to make phosphor bronze alloys
Phosphorus sulphide is used to make the heads of lsquostrike anywherersquo matches
38
Chlorine
Chlorine is used to make sodium hypochlorite which is present in bleach It is also used in
sterilizing swimming pools and in water treatment
Chlorine is used to make the monomer vinyl chloride which is used to make the plastic PVC
Nitrogen
Nitrogen is used to make fertilisers ammonia dyes and nitric acid
Nitrogen is used as an inert atmosphere to prevent substances being oxidised and as a coolant
Silicon
Silicon is used for making silicon chips for computers
Silicon (V) oxide is present in sand Glass is made by heating sand with lime (calcium oxide) and
sodium carbonate
Silicon in the form of silicates is used in jewellery
Silica gel is used as a drying agent
39
WEEK 9 LESSON 2 WORKSHEET
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Used to make sodium hypochlorite
Used as a fungicide on plant materials
Used for lsquoleadrsquo in pencils
Used in the manufacture of bronze alloys
Used in the manufacture of nitric acid
Used in the manufacture of computer chips
Used to make fertilisers
40
WEEK 9 LESSON 3
TOPIC Harmful effects of non ndash metals and their compounds on living systems and the
environment
Sulphur dioxide
Sulphur dioxide can cause a disease of the lungs Sulphur dioxide also poisons plants in two
main ways It may enter the stomata of leaves and react with the tissue fluids to form sulphites
with the on ndash going water loss the concentration of sulphites could build up killing the cells
The second adverse effect on plants occurs when sulphur dioxide dissolves in rain thereby
increasing soil acidity A prolonged acid soil situation may lead to plasmolysis and the death of
vegetation in an area
Carbon monoxide
Carbon monoxide combines much more readily than oxygen with haemoglobin When carbon
monoxide is inhaled it prevents the haemoglobin from taking oxygen to the bodyrsquos cells
Continued breathing of air containing carbon monoxide eventually causes death
Hydrogen sulphide
Hydrogen sulphide reacts readily with many cations forming insoluble sulphides Many cations
contribute to good health by contributing to enzyme activity and to the formation of bone
pigment and haemoglobin Although these cations are required in extremely small
concentrations they are removed by being precipitated as sulphides and thus not available for
regular function Careless dumping of refuse contributes to atmospheric pollution by hydrogen
sulphide
Oxides of nitrogen
In the presence of hydrocarbons from car exhausts ozone and sunlight nitrogen oxides react to
form photochemical smog which contains many harmful chemicals
Nitrogen dioxide can harm the lungs and irritate the nose throat and eyes The other compounds
present in photochemical smog are even more harmful irritants and can cause asthma
41
Carbon dioxide
Carbon dioxide water vapour and ozone referred to as ldquogreenhouse gasesrdquo acting as a blanket
readily absorb some of the radiated heat energy and in turn warms the earthrsquos atmosphere This is
called the ldquogreenhouse effectrdquo Scientists have found direct correlation between carbon dioxide
concentration and global warming An increase in carbon dioxide concentration resulted in an
increase global temperatures Global warming is a major potential problem that the world faces
Chloroflourocarbons (CFCs)
It is believed that CFCs might be responsible for destroying the ozone layer which prevents
harmful ultraviolet (UV) radiation from reaching the earth The carbon ndash chlorine bond in CFC
molecule is easily broken by a UV photon producing an active chlorine atom This atom
combines with an ozone molecule forming a chlorine oxide radical and oxygen The radicle
reacts with more ozone producing the chlorine atom again This kind of reaction is repeated
thousands of times This type of reaction is thought to account for about eighty percent of the
loss of ozone observed
Nitrates and phospates
Nitrates and phosphates cause eutrophication The process leading to eutrophication are
Nitrates and phosphates from fertilisers spread on fields may dissolve in groundwater and
get into lakes and rivers
Nitrates and phosphates cause excessive growth of algae so that they cover the surface of
the water
Water plants including algae die because of lack of sunlight Aerobic bacteria feed on
the plant remains The bacteria multiply
The aerobic bacteria use up the oxygen in the water so aquatic animals die
42
Solid waste
The main sources of pollution from non ndash metals is from glass paper and plastics
Broken glass can cause injury to animals It can also cause fires by acting as lens focusing the
sunrsquos rays on flammable materials
Printing inks from paper dumped in the ground may contain toxic elements such as arsenic and
cadmium Bleaches and chlorine compounds from paper are also harmful
43
WEEK 9 LESSON 3 WORKSHEET
Describe ONE harmful effect of the following non ndash metals andor their compounds on
living systems and the environment
Sulphur dioxide
______________________________________________________________________________
______________________________________________________________________________
Carbon monoxide
______________________________________________________________________________
______________________________________________________________________________
Carbon dioxide
______________________________________________________________________________
______________________________________________________________________________
Oxides of nitrogen
______________________________________________________________________________
______________________________________________________________________________
Hydrogen sulphide
______________________________________________________________________________
______________________________________________________________________________
44
Chloroflourocarbons (CFCs)
______________________________________________________________________________
______________________________________________________________________________
Nitrates and phospates
______________________________________________________________________________
______________________________________________________________________________
45
WEEK 10 LESSON 1
TOPIC Green Chemistry
Green Chemistry is defined as the utilisation of a set of principles that reduces or eliminates the
use and generation of hazardous substances
There are twelve principles of green chemistry as proposed by Paul T Anastas and John C
Warner These twelve principles are
1 Prevention ndash It is better to prevent waste than to treat or clean up waste after it has been
created
2 Atom economy - Synthetic methods should be designed to maximize the incorporation of
all materials used in the process into the final product
3 Less hazardous chemical synthesis - Wherever practicable synthetic methods should be
designed to use and generate substances that possess little or no toxicity to human health
and the environment
4 Safer chemical products - Chemical products should be designed to affect their desired
function while minimizing their toxicity
5 Safer solvents and other agents - The use of auxiliary substances (eg solvents
separation agents etc) should be made unnecessary wherever possible and harmless
when used
6 Minimum energy requirements - Energy requirements of chemical processes should be
recognized for their environmental and economic impacts and should be minimized If
possible synthetic methods should be conducted at ambient temperature and pressure
7 Use of renewable raw materials - A raw material or feedstock should be renewable rather
than depleting whenever technically and economically practicable
8 Reduce use of additional chemicals or additional steps - Unnecessary derivatization (use
of blocking groups protection deprotection temporary modification of
physicalchemical processes) should be minimized or avoided if possible because such
steps require additional reagents and can generate waste
46
9 Use of catalysts ndash The use of catalysts reduce energy costs because the reactions take
place at lower temperatures The more specific the catalyst for a particular reaction is the
less it the likelihood of getting additional unwanted products
10 Nature of breakdown of products - Chemical products should be designed so that at the
end of their function they break down into innocuous degradation products and do not
persist in the environment
11 Monitoring to prevent pollution - Analytical methodologies need to be further developed
to allow for real-time in-process monitoring and control prior to the formation of
hazardous substances
12 Minimise chemical accidents - Substances and the form of a substance used in a chemical
process should be chosen to minimize the potential for chemical accidents including
releases explosions and fires
47
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
48
WEEK 10 LESSON 2
TOPIC Qualitative Analysis ndash Identification of cations
Qualitative Analysis involves identifying the constituents of single substances or mixture of
substances
Appearance
An examination of the appearance of a substance can indicate which ion it contains
Appearances of substances
Observation Indication
Blue or blue ndash green Cu2+ salt
Pale green Fe2+ salt
Yellow ndash brown Fe3+ salt
Ammonia smell NH4+ salt
49
Test for cation using sodium hydroxide
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
(d) If no precipitate forms in step b warm gently and test for ammonia
Effect of dilute sodium hydroxide solution
Effect of dilute sodium hydroxide solution Cation
Dropwise Excess
White precipitate Precipitate soluble Ca2+
White precipitate Precipitate insoluble Al3+ Pb2+ Zn2+
Blue precipitate Precipitate insoluble Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
No precipitate ndash ammonia gas
evolved on heating
ndash NH4+
The metal cations all form insoluble hydroxides with sodium hydroxide solution
For example Ca2+ (aq) + 2 OH- (aq) Ca(OH)2 (s)
Ca(OH)2 Cu(OH)2 Fe(OH)2 and Fe(OH)3 are basic and therefore do not react with excess
sodium hydroxide solution Therefore the precipitate does not dissolve in excess sodium
hydroxide solution
Al(OH)3 Pb(OH)2 and Zn(OH)2 are amphoteric Therefore the precipitates react with the excess
sodium hydroxide solution forming soluble salts and the precipitate disappears in excess sodium
hydroxide solution
The NH4+ ion forms a soluble hydroxide However on heating it reacts with the hydroxide ion to
form ammonia and water
NH4+ (aq) + OH- (aq) NH3 (g) + H2O (l)
50
WEEK 10 LESSON 2 WORKSHEET
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P _____________ Q ___________________
R _____________ S ___________________
R + NaOH
______________________________________________________________________________
51
WEEK 10 LESSON 3
TOPIC Qualitative Analysis ndash Identification of cations
Test for cation using ammonia solution (ammonium hydroxide solution)
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
Effect of dilute ammonia (ammonium hydroxide) solution
Effect of dilute ammonia solution Cation
Dropwise Excess
No precipitate ndash Ca2+
White precipitate Precipitate soluble
(forming colourless solution)
Zn2+
White precipitate Precipitate insoluble Al3+ Pb2+
Blue precipitate Precipitate soluble
(forming deep blue solution)
Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
52
Ammonia solution is a weak alkali Metal cations except Ca2+ form insoluble hydroxides with
ammonia solution as with the sodium hydroxide solution
The amphoteric hydroxides Al(OH)3 and Pb(OH)2 and the basic hydroxides Fe(OH)2 and
Fe(OH)3 do not react with excess ammonia solution Therefore the precipitates remain
However Zn(OH)2 and Cu(OH)2 do react with excess ammonia solution to form complex
soluble hydroxides each Hence their precipitates disappear on the addition of excess ammonia
solution
Confirmatory test
After carrying out test for cations using sodium hydroxide solution and ammonia solution the
only cations which cannot be distinguished are Al3+ and Pb2+ A confirmatory test is carried out
to distinguish between the two cations
Confirmatory test
Test Observation Cation Ionic equation
Add potassium
or sodium
iodide solution
Bright yellow precipitate
No precipitate
Pb2+
Al3+
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
53
WEEK 10 LESSON 3 WORKSHEET
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A __________ B ________________ C ________________________
(b) State the inference after Test 2
C _______________________
(c) Write an ionic equation to support your answer in (b) above
___________________________________________________________________________
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
54
ANSWERS TO WORKSHEETS
55
WEEK 5 LESSON 1 WORKSHEET ANSWERS
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
Answer
Zinc + Iron (II) sulphate Zinc is higher in the electrochemical series and therefore displace
iron ions in iron (II) sulphate
Equation Zn (s) + FeSO4 (aq) ZnSO4 (aq) + Fe (s)
Ionic equation Zn (s) + Fe2+ (aq) Zn2+ (aq) + Fe (s)
Iron + Zinc sulphate No reaction iron is lower in the electrochemical series and cannot
displace the zinc ions in zinc sulphate
56
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
Answer
X displaces lead from an aqueous solution of its salts
X (s) + Pb2+ (aq) Xn+ (aq) + Pb (s)
rarr X is more reactive than Pb
X did not react with iron salts
rarr X is less reactive than Fe
Y burns very easily
Y is more reactive than Fe and Pb (both forming their corresponding oxide at a slower rate)
From electrochemical series Fe is higher and therefore more reactive than Pb
Order of reactivity
Y (most reactive) gt Fe gt X gt Pb (least reactive)
57
WEEK 5 LESSON 2 WORKSHEET ANSWERS
1
Metal Reactivity with acid
Copper X
Magnesium
Aluminium
Silver X
Zinc
58
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
Answer
Y and Z are the most reactive since they can react with dilute acid
Z is more reactive than Y since a reaction occurs with Z is added to an aqueous solution of Y
X is less reactive than W since it does not occur in nature as compounds
Order of reactivity Z (most reactive) gt Y gt W gt X
59
WEEK 5 LESSON 3 WORKSHEET ANSWERS
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
Answer
Ease of decomposition (from easiest to decompose to most difficult to decompose)
B rarrD rarrArarr C
Reactivity (most reactive to least reactive)
C (most reactive) gt A gt D gt B (least reactive)
60
WEEK 6 LESSON 1 Worksheet Answers
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
Potassium Zinc Copper
Calcium Lead Gold
Magnesium Iron
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
Aluminium is extracted from its ore bauxite through the process of electrolysis
Cryolite is added to bauxite to lower the melting point to about 900 0C The melting point of
bauxite is very high (about 2040 0C) It is difficult and expensive to keep the molten aluminium
oxide at this temperature
Reaction at the cathode Al3+ (l) + 3 e- Al (l)
61
WEEK 6 LESSON 2 Worksheet Answers
(a) What are the three raw materials that are added through the top of the blast
furnace during the extraction process for iron
Coke (carbon)
iron ore (haematitie mainly iron (II) oxide)
limestone (calcium carbonate)
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
Coke ndash coke burns to produce carbon dioxide The carbon dioxide further reacts with coke to
form carbon monoxide (reducing agent in the process)
C (s) + O2 (g) CO2 (g)
C (s) + CO2 (g) 2 CO
Haematite ndash iron ore provides the iron which is reduced by the carbon monoxide to produce
iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + CO2 (g)
Limestone ndash decomposes to form calcium oxide The calcium oxide reacts with the impurity
silicon dioxide to form slag (calcium silicate)
CaCO3 (s) CaO (s) + CO2 (g)
CaO (s) + SiO2 (l) CaSiO3(l)
62
WEEK 6 LESSON 3 Worksheet Answers
(a) Define the term alloy
An alloy is a material made from a mixture of two or more metals
(b) State 3 general advantages that alloys have over the individual metals they are made
from
They are harder stronger and more resistant to corrosion
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
1 High strength
2 Low density
Uses
1 Used to make aircraft bodies
2 Used to make space satellites
63
WEEK 7 LESSON 1 WORKSHEET ANSWERS
(a) Define the term corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
The paint forms a barrier which stops contact with air or water and the iron Hence rusting
will not take place
However when the paint is scratched that part of the iron nail is exposed to air or water and
rusting will take place
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
Magnesium is higher in the electrochemical series and will be oxidised in preference to iron
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
Aluminium is partly protected from corrosion by its coat of aluminium oxide However as the
iron rust it flakes and fall off and the rusting process continues
64
WEEK 7 LESSON 2 WORKSHEET ANSWERS
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
Magnesium is the ion found in chlorophyll Chlorophyll plays a vital part in the process of
photosynthesis A deficiency in magnesium will lead to low chlorophyll level in the tomato
plants and hence reduce the process of photosynthesis There will be less food storage and
hence will lead to smaller yield of tomatoes
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Any correct harmful effect of lead on health or environment
Any correct harmful effect of mercury on health or environment
65
WEEK 7 LESSON 3 WORKSHEET ANSWERS
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
(b) Write the ionic equation for the above reaction
2 Br- (aq) + Cl2 (aq) 2 Cl- (aq) + Br2 (aq)
(c) Identify the oxidising agent in the reaction
Cl2 (aq)
(d) Justify your answer in part (c) in terms of oxidation number
There is a reduction of the oxidation number for chlorine from 0 to ndash1
hence it has been reduced Therefore chlorine is the oxidising agent
66
WEEK 8 LESSON 1 WORKSHEET ANSWERS
Describe the laboratory preparation of oxygen gas
Oxygen is prepared in the laboratory by the decomposition of hydrogen peroxide
A suitable catalyst is manganese (IV) oxide
Drying agent silica gel OR anhydrous calcium chloride OR conc sulphuric acid
The gas is collected by downward delivery since oxygen is slightly denser than air
Balanced chemical equation 2 H2O2 (aq) 2 H2O (l) + O2 (g)
67
WEEK 8 LESSON 2 WORKSHEET ANSWERS
Describe the laboratory preparation of carbon dioxide gas
Carbon dioxide is commonly prepared in the laboratory by the reacting hydrochloric acid and
marble chips (calcium carbonate)
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
The carbon dioxide gas is collected by downward delivery since it is denser than air
Balanced chemical equation
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
68
WEEK 8 LESSON 3 WORKSHEET ANSWERS
Describe the laboratory preparation of ammonia gas
An ammonium salt (ammonium chloride) and a base (sodium hydroxide) are mixed together and
heated
Calcium oxide is used as the drying agent Calcium chloride and concentrated sulphuric acid
cannot be used since ammonia can react with them
The gas is collected by upward delivery since ammonia is less dense than air
Balanced chemical equation
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
69
WEEK 9 LESSON 1 WORKSHEET ANSWERS
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Carbon dioxide Put out fires
Oxygen Welding metals
Carbon dioxide Create lsquofizzrsquo in drinks
Oxygen Used in steel production
Oxygen Aerobic respiration
70
WEEK 9 LESSON 2 WORKSHEET ANSWERS
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Chlorine Used to make sodium hypochlorite
Sulphur Used as a fungicide on plant materials
Carbon (graphite) Used for lsquoleadrsquo in pencils
Phosphorus Used in the manufacture of bronze alloys
Nitrogen Used in the manufacture of nitric acid
Silicon Used in the manufacture of computer chips
Nitrogen Phosphorus Used to make fertilisers
71
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
Green Chemistry is using principles that reduceeliminate the use of hazardous materials in
the design manufacture and application of chemical products
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
Makes the environment safer
Reduces waste
Creates new jobs
Reduces respiratory illnesses
Atom economy
72
WEEK 10 LESSON 2 WORKSHEET ANSWERS
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P Cu2+ Q Fe2+
R Fe3+ S Ca2+
Ionic equation for R + NaOH
Fe3+ (aq) + 3 OH- (aq) Fe(OH)3 (s)
73
WEEK 10 LESSON 3 WORKSHEET ANSWERS
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A Fe3+ B Ca2+ C Al3+ Pb2+
(b) State the inference after Test 2
C Pb2+
(c) Write an ionic equation to support your answer in (b) above
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
11 Qualitative Analysis
ndash Test for gases
Qualitative Analysis
ndash Identification of
anions
Qualitative Analysis
ndash Identification of
anions
12 Problem solving of
Past CSEC Chemistry Paper 2
on topics completed in the term
13
14
15
2
WEEK 11 LESSON 1
TOPIC Qualitative Analysis ndash Test for gases
Identification of gases
Gas Colour Odour Effect on moist
litmus
Method of identification
Oxygen
O2
Colourless Odourless Neutral ndash no
effect
Relights a glowing splint
Hydrogen
H2
Colourless Odourless Neutral ndash no
effect
Lighted splint lsquopopsrsquo if air is also
present
Carbon
dioxide
CO2
Colourless Odourless Weakly acidic ndash
blue to slightly
red
A white precipitate forms in
limewater
Ca(OH)2 (aq) + CO2
CaCO3 (s) + H2O (l)
Precipitate redissolves on
continued bubbling
CaCO3 (s) + H2O (l) + CO2 (g)
Ca(HCO3)2 (aq)
Ammonia
NH3
Colourless Pungent Alkaline ndash red
to blue (only
common
alkaline gas)
Turns moist red litmus blue forms
dense white fumes with hydrogen
chloride gas
NH3 (g) + HCl (g) NH4Cl (s)
Gas Colour Odour Effect on moist
litmus
Method of identification
3
Sulphur
dioxide
SO2
Colourless Choking
smell
Acidic ndash blue to
red
Turns acidified potassium
manganate (VII) solution from
purple to colourless
Turns acidified potassium
dichromate (VI) solution from
orange to green
Chlorine
Cl2
Yellow ndash
green
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Bromine
Br2
Red ndash
brown
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Nitrogen
dioxide
NO2
Red ndash
brown
Irritating
smell
Acidic blue to
red
Turns moist blue litmus red but
does not bleach it
Water
vapour
H2O
Colourless Odourless Neutral ndash no
effect
Turns anhydrous cobalt (II)
chloride from blue to pink
Turns anhydrous copper (II)
sulphate from white to blue
4
WEEK 11 LESSON 1 WORKSHEET
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless
Yellow ndash green
Red ndash brown
Gases according to their odour
Odour of gas Identity of gas
Odourless
Pungent smell
Choking smell
Irritating smell
5
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect
Red to blue
Blue to red
Blue to red then bleaches it
6
WEEK 11 LESSON 2
TOPIC Qualitative Analysis ndash Identification of anions
Effect of heating
Method Heat a sample of the solid in a dry test tube
Effect of heating
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) not
of K or Na
CO32- (s) O2- (s) + CO2 (g)
Oxygen evolved NO3- of K or Na 2 NO3
- (s) 2 NO2- (s) + O2
(g)
Oxygen and nitrogen
dioxide evolved
NO3- of Ca and below
in reactivity series
4 NO3- (s) 2 O2- (s) + 4 NO2
(g) + O2
(g)
Sulphur dioxide evolved SO32- SO3
2- O2- (s) + SO2 (g)
Effect of dilute acid
Add dilute hydrochloric acid or nitric acid to a sample of the solid Warm if no reaction occurs
when cold
Effect of dilute acid
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) CO32- (s) + 2 H+ (aq) H2O (l) + CO2 (g)
Sulphur dioxide evolved SO32- SO3
2- (s) + 2 H+ (aq) H2O (l) + SO2 (g)
7
Effect of concentrated acid
Add concentrated sulphuric acid to a sample of the solid Warm if not reaction occurs when cold
Effect of concentrated sulphuric acid
Observation Anion
Carbon dioxide evolved CO32- or HCO3
-
Sulphur dioxide evolved SO3-
Hydrogen chloride evolved Cl-
Hydrogen bromide (colourless) and bromine
vapour (brown) evolved
Br-
Black iodine present and purple iodine vapour
evolved
I-
8
WEEK 11 LESSON 2 WORKSHEET
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater
Produces a gas which relights a glowing splint as the only gas
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green
Produces a gas forms a precipitate in limewater
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia
Black iodine present and purple iodine vapour evolved
9
WEEK 11 LESSON 3
TOPIC Qualitative Analysis ndash Identification of anions
Test for the halides ndash using silver nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous silver nitrate and
observe the precipitate Add ammonia solution and observe the solubility of the precipitate
Test for halides using silver nitrate solution
Effect of silver
nitrate solution
Anion Explanation Effect of aqueous
ammonia
White precipitate ndash
turns white in
sunlight
Cl- Ag+ (aq) + Cl- AgCl (s) Precipitate soluble
Cream precipitate ndash
turns yellow ndash green
in sunlight
Br- Ag+ (aq) + Br- AgBr (s) Precipitate slightly
soluble
Pale yellow
precipitate
I- Ag+ (aq) + I- AgI (s) Precipitate insoluble
Test for the halides ndash using lead nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous lead nitrate and
observe the precipitate
Test for halides using lead nitrate solution
Effect of lead nitrate solution Anion Explanation
White precipitate Cl- Pb2+ (aq) + 2 Cl- PbCl2 (s)
Pale yellow Br- Pb2+ (aq) + 2 Br- PbBr2 (s)
Deep yellow I- Pb2+ (aq) + 2 I- PbI2 (s)
10
Effect of barium nitrate or chloride solution followed by dilute acid
Make a solution of the solid Add barium nitrate or chloride solution and observe the precipitate
Add dilute hydrochloric or nitric acid warn if necessary and observe the solubility of the
precipitate
Effect of barium nitrate or chloride solution followed by dilute acid
Effect of
Ba(NO3)2 (aq)
or BaCl2 (aq)
Effect of HCl (aq)
or HNO3 (aq)
Anion Explanation
White precipitate Precipitate insoluble SO42- Ba2+ (aq) + SO4
2- (aq) BaSO4 (s)
BaSO4 does not react with dilute acids
White precipitate Precipitate soluble ndash
CO2 evolved
CO32- Ba2+ (aq) + CO3
2- (aq) BaCO3 (s)
BaCO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + CO2 (g)
White precipitate Precipitate soluble ndash
SO2 evolved on
warming
SO32- Ba2+ (aq) + SO3
2- (aq) BaSO3 (s)
BaSO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + SO2 (g)
11
WEEK 11 LESSON 3 WORKSHEET
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
(Ionic equation required)
12
WEEK 12 LESSON 1 WORKSHEET
(a) The Caribbean islands are known for their many resources For example the ore of
aluminium is found in Jamaica and Guyana
(i) Briefly describe the extraction of aluminium from its named ore Include in your
description one ionic equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Although aluminium ore is mined in the Caribbean the extraction of aluminium usually
takes place in other countries Suggest ONE reason why it may be difficult to extract
aluminium in the Caribbean
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) An alloy can be described as a lsquomixed metal solutionrsquo Aluminium forms an alloy with
magnesium that is used to make an aircraft
13
Identify this alloy and suggest why it is better to use it rather than the pure metal in the
manufacture of aircraft
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) ldquoSome metals can be useful to man yet harmful to the environmentrdquo Comment on this
statement with reference to mercury
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 12 LESSON 2 Worksheet
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate formed
Soluble in excess
15
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate formed
Insoluble in excess
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate formed
(Ionic equation required)
16
WEEK 12 LESSON 3 Worksheet
Dry ammonia gas can be produced in a school laboratory
(a) Identify TWO reagents that are necessary for the laboratory production of ammonia
______________________________________________________________________________
______________________________________________________________________________
(b) Two common drying agents used in the laboratory are calcium oxide and concentrated
sulphuric acid However calcium oxide is the preferred choice for drying ammonia gas
Explain why concentrated sulphuric acid is now used Include in your answer a balanced
chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) When gases are prepared in the laboratory there are three main ways in which they can
be collected
- Upward delivery
- Downward delivery
- Displacement of water
(i) What TWO other factors should be considered when choosing an appropriate method for
the collection of gases in the laboratory
______________________________________________________________________________
______________________________________________________________________________
(ii) Identify ONE of the three methods that is best suited for the collection of ammonia gas in
the laboratory Explain why EACH of the other two methods would NOT have been
appropriate
______________________________________________________________________________
17
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(d) Hence draw a labelled diagram of the apparatus which could be used for the preparation
of dry ammonia in the laboratory
Be sure to identify in your diagram
- where the reagents are placed
- where the ammonia is dried and
- where the ammonia is collected
18
WEEK 13 LESSON 1 Worksheet
(a) In solution two metals A and B form A+ and B2+ ions respectively Metal A displaces Fe
from a solution containing Fe2+ ions but metal B does NOT
(i) Arrange the metals A B and Fe in order of reactivity from LEAST reactive to MOST
reactive Write a balanced chemical equation to show the reaction between metal A and
Fe2+ ions
______________________________________________________________________________
______________________________________________________________________________
(ii) Metal A is placed in a solution of copper (II) sulphate CuSO4 (aq) Write an equation for
the reaction State ONE observable change that will occur and explain why this reaction
takes place
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) For EACH metal A and B state ONE method that can be used to extract it from its
respective oxide Give a reason for EACH answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
19
______________________________________________________________________________
(b) Metal alloys are often used for making objects found in our daily lives Name an alloy of
iron and state ONE of its uses
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 13 LESSON 2 Worksheet
(a) Many important biological processes in plants and animals depend on the specific roles
of certain metal ions
(i) Farmer Jones reaped a crop of tomatoes and reported that the yield was far below what
was expected Analysis of the soil revealed that there was a deficiency of magnesium
Discuss the importance of magnesium in plant health and explain how a magnesium
deficiency can result in the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE other metal ion which is important to plant health and state the result of its
deficiency
______________________________________________________________________________
______________________________________________________________________________
21
(b) Many years ago car exhaust fumes were known to contain compounds of metals and
non ndash metals which could negatively impact both humans and the environment Identify
ONE metal and ONE non ndash metal whose compounds were present in car exhaust fumes
Discuss the effect of these compounds on human health and the environment
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) Define lsquogreen chemistryrsquo and discuss the measures that have been taken to produce a
lsquogreenerrsquo automotive fuel
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
22
WEEK 13 LESSON 3 Worksheet
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
Zn2+ ions are present
23
WEEK 14 LESSON 1 Worksheet
(a) Metal alloys are often used in place of metals because of their enhanced properties
(i) Define the term lsquoalloyrsquo
______________________________________________________________________________
______________________________________________________________________________
(ii) Name ONE alloy of aluminium and state its use based on one of its enhanced properties
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) A student conducted an experiment to investigate the reactivity of each of the following
metals (copper iron zinc and lead) by using solutionPs of their sulphate salts
The data presented in the table below shows whether a visible chemical reaction took
place when each metal was added to the four sulphate solutions
Key Visible chemical reaction took place
X No visible chemical reaction
CHEMICAL REACTION OF METALS IN SULPHATE SOLUTIONS
Sulphate solution Cu Fe Zn Pb
CuSO4 X
FeSO4 X X X
ZnSO4 X X X X
PbSO4 X X
24
(i) State which of the TWO metals is more reaction Fe or Zn Give a reason for our answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Using the data in the previous Table deduce the order of reactivity of the four metals Cu
Fe Zn and Pb from the most reactive to the least reactive metal
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The student recorded the following observations from the reaction between the iron and
copper (II) sulphate solution
Observations Reddish ndash brown solid coating formed on the iron strip
Blue colour of the solution changed to dirty green
Account for the observations made from the reaction between the iron and copper (II)
sulphate solution
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iv) Write an ionic equation including state symbols for the reaction between the iron and
copper (II) sulphate solution
______________________________________________________________________________
25
(c) Some metal compounds are health and environmental hazards
(i) Identify which of the metals used in the experiment in (b) is MOST hazardous to the
environment
______________________________________________________________________________
______________________________________________________________________________
(ii) State TWO harmful effects of continuous exposure to the metal identified in (c) (i) on
human beings
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
26
WEEK 14 LESSON 2 Worksheet
(a) Carbon is found in the form of diamond and graphite and is a main component in many
naturally occurring compounds such as organic matter and carbon dioxide gas
(i) State ONE way in which diamond differs physically from graphite
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE similarity between diamond and graphite other than they both contain carbon
______________________________________________________________________________
______________________________________________________________________________
(b) Carbon can react with a limited supply of oxygen to form carbon monoxide which can
negatively affect human health
(i) Write a balanced chemical equation including state symbols to show the formation of
carbon monoxide
______________________________________________________________________________
(ii) State TWO effects of carbon monoxide inhalation on the human body
______________________________________________________________________________
______________________________________________________________________________
(c) Jamal wants to prepare and collect a sample of carbon dioxide gas in the laboratory using
calcium carbonate
(i) Write a balanced chemical equation including state symbols for the laboratory
preparation of carbon dioxide gas from calcium carbonate
______________________________________________________________________________
______________________________________________________________________________
(ii) Draw a clearly labelled diagram to show the arrangement of the apparatus and materials
that could be used in the laboratory to prepare and collect the carbon dioxide gas
(iii) State ONE use of carbon dioxide as it relates to the beverage industry
______________________________________________________________________________
27
WEEK 14 LESSON 3 Worksheet
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
(Ionic equation required)
Suggest a possible identity of the solid R __________________________
28
WEEK 15 LESSON 1 Worksheet
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a small
portion of solid Y gently at
first and then strongly
Colourless gas evolved
with a choking odour
Turns acidified potassium
dichromate solution from
orange to green
(ii) To the remaining portion
of solid Y add 20 cm3 of
distilled water stir to dissolve
and filter Collect the filtrate
and divide into 3 equal
portions
Filtrate is pale green in
colour
(iii) To the first portion of the
filtrate from (ii) add aqueous
sodium hydroxide slowly
until in excess
A green precipitate
Insoluble in excess sodium
hydroxide
Ionic equation required
29
TEST OBSERVATIONS INFERENCES
(iv) To the second portion of
the filtrate from (ii) add
aqueous silver nitrate
followed by aqueous
ammonia
White precipitate
Soluble in aqueous
ammonia
(v) To the third portion of the
filtrate from (ii) add aqueous
barium nitrate followed by
aqueous hydrochloric acid
White precipitate formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with the
evolution of a colourless
gas with a choking smell
30
WEEK 15 LESSON 2 Worksheet
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
31
WEEK 15 LESSON 3 Worksheet
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in excess
aqueous NH3
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change
32
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
warm filter and then divide
the filtrate into two portions
Vigorous effervescence
observed upon addition of
dilute HNO3
Gas evolved turns lime water
cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Cu2+ ions present
33
ANSWERS TO WORKSHEETS
34
WEEK 11 LESSON 1 WORKSHEET ANSWERS
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless O2 H2 CO2 NH3 SO2 H2O
Yellow ndash green Cl2
Red ndash brown Br2 NO2
Gases according to their odour
Odour of gas Identity of gas
Odourless O2 H2 CO2 H2O
Pungent smell NH3
Choking smell SO2 Cl2 Br2
Irritating smell NO2
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect Neutral O2 H2 H2O
Red to blue Alkaline NH3
Blue to red Acidic CO2 SO2 NO2
Blue to red then bleaches it Acidic Cl2 Br2
35
WEEK 11 LESSON 2 WORKSHEET ANSWERS
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-) not
of K or Na
Produces a gas which relights a glowing splint as the only gas NO3- of K or Na
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green SO32-
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-)
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia Cl-
Black iodine present and purple iodine vapour evolved I-
36
WEEK 11 LESSON 3 WORKSHEET ANSWERS
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Br-
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
Cl-
Ag+ (aq) + Cl- AgCl (s)
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow Br-
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
SO42-
Ba2+ (aq) + SO42- (aq)
BaSO4 (s)
(Ionic equation required)
37
WEEK 12 LESSON 1 Worksheet Answers
(a) (i)
The ore bauxite is purified
The purified bauxite is dissolved in molten cryolite
The aluminium oxidecryolite solution is then eletrolysed
Equation at the cathode Al3+ (l) + 3 e- Al (l)
Equation at the anode 2 O2- (l) ndash 4 e- O2 (g)
(ii) The process is too expensive mainly because too much electricity or energy is needed
(b) The alloy of Al and Mg is magnalium It is less dense than the pure metals and hence allow
aircraft to be lighter It is also stronger than the pure metals and hence allows aircraft to last
longer since it is not easily destroyed
(c) Your answer should cater for the following aspects
Benefits of mercury to humans for example in thermometers barometers in dentistry
and gold mining
Entry of mercury to the environment For example this could have been through broken
thermometers barometers or lightbulbs or improper disposal of them or batteries and
indiscriminate use in gold mining in Guyana
The identification of a negative impact on the environment such as poisoned fish and the
persons who eat the fish death mood swings and psychosis
38
WEEK 12 LESSON 2 Worksheet Answers
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas
evolved
NO2 evolved OR nitrates
present OR
Br2 gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate
formed
Soluble in excess
Pb2+ Zn2+ Al3+ or Ca2+
present
Pb2+ Zn2+ Al3+ or present
39
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate
formed
Insoluble in excess
Pb2+ Zn2+ Al3+ or present
Pb2+ or Al3+ present
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate
formed
Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
40
WEEK 12 LESSON 3 Worksheet Answers
(a) an ammonium salt and a strong alkali
(b) Ammonia is basic and it will react with H2SO4
Equation 2 NH3 (aq) + H2SO4 (aq) (NH4)2SO4 (aq)
(c) (i) ndash Density of the gas relative to air ndash The solubility of the gas in water
(ii) Ammonia is collected by upward delivery
It cannot be collected by downward delivery since ammonia is less dense than air
It cannot be collected by displacement of water since it is soluble in water
(d)
41
WEEK 13 LESSON 1 Worksheet Answer
a) i) B ˂ Fe ˂ A
2A (s) + Fe 2+ (aq) rarr 2A+ (aq) + Fe (s)
ii) 2A (s) + CuSO4 (aq) rarr A2SO4 (aq) + Cu (s)
Observation blue colour fades gets lighter OR brown solid forms is deposited OR metal A
decreases in size dissolves
Explanation Metal A is higher (than Fe which is higher) than Cu in the reactivity series OR
Metal A is more reactive (than Fe which is more reactive) than Cu so Metal A can displace Cu
iii) Metal A can be extracted by electrolysis (of its molten oxide) because Metal A is a very
reactive metal is high in the reactivity series forms stable oxides needs a lot of energy to be
extracted and very reactive metals are extracted by electrolysis
Metal B can be extracted by heating with carbon carbon monoxide OR by chemical reduction
of the oxide because Metal B is less reactive than Fe is low in the reactivity series forms less
stable oxides does not need a lot of energy to be extracted and oxides of less reactive metals are
easily reduced
b) Alloy of iron steel
Use of alloy making buildings bridges ships motor vehicles furniture utensils
42
WEEK 13 LESSON 2 Worksheet Answer
(a) (i)
Magensium is the metal ion found in chlorophyll
Chlorophyll is essential for photosynthesis
A deficiency in magnesium will result in low chlorophyll yellow leaves and a reduction in
photosynthesis
Hence there will be low carbohydrates or energy production
Hence small fruits stunted growth and lower yield will result
(ii)
Metal ion Results of deficiency
Potassium Stunted growth premature loss of leaves yellowing of leaves curling of leaf tips
Calcium Growth abnormalities in tips of roots and shoots curling of leaves
Iron Yellowing of leaves
Zinc Low chlorophyll content yellowing of leaves
Manganese Yellowing of leaves poor flavors in some crops for example potato
(b)
Metal Lead is present in some types of gasoline Upon combustion lead compounds escape into
the atmosphere It accumulates in body tissues and slowly poisons the person It causes mental
illness
Non ndash metal SulphurSulphur dioxide or NitrogenNitrogen dioxide
Dissolves in rain water to form acid rain or cause respiratory illnessproblems Acid rain can
cause corrosion damage in buildings
(c)
Green chemistry is the utilisation of a set of principles that reduces or eliminates the use or
generation of hazardous substances
43
Automotive fuels are now produced without lead so as to eliminate the release of lead
compounds into the atmosphere
Low sulphur fuel is being produced with much reduced sulphur content which causes a reduction
of sulphur dioxide release into the atmosphere
44
WEEK 13 LESSON 3 Worksheet Answer
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
gas turns litmus blue
red
brown gas
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
white precipitate
precipitate soluble in
excess
Zn2+ ions are present
45
WEEK 14 LESSON 1 Worksheet Answers
(a)(i) An alloy is a material made from a mixture of two or more metals
(ii) Any suitable answer chosen from below
Alloy Enhance Property Use
Duralumin High strength
Low density
Light
Hard
Used to make aircraft bodies
space satellites
Magnalium Light
Hard
Easier to weld
Corrosion resistant
Strong
High ductability
Used in pyrotechnics
(fireworks)
Mirrors
Aircraft parts
To make scientific
instruments
Used to make marine castings
Alchlad Strong
Corrosion resistant
Cladding for buildings
(b) (i) Zinc is more reactive than iron
Zinc displaces iron from iron (II) sulphate
Zinc is higher in the reactivity series than iron
Iron does not displace zinc from zinc sulphate
(ii) Order of reactivity Zn gt Fe gt Pb gt Cu
(iii) Reddish brown solid ndash copper metal formed
46
Dirty green solution ndash presence of Fe2+ ion
(iv) Fe (s) + Cu2+ (aq) Fe2+ (aq) + Cu (s)
(c) (i) Lead
(ii) Any two correct harmful effects of lead on the body
Impedes brain development (in young children)
Affectimpede development of the immune system in humans
Affecthamper development of nervous system in humans
Long term exposure can result in kidney and liver damage
Mental retardation
Anaemia
Death
47
WEEK 14 LESSON 2 Worksheet Answers
a) i) Diamond is transparent clear Graphite is opaque black
OR hard OR brittle
OR does not conduct electricity OR conducts electricity
a) ii) Both have a macromolecular giant molecular giant covalent structure (lattice)
OR Both have high melting point boiling point
OR Both are insoluble in water organic solvent
b) i) 2C (s) + O2 (g) rarr 2CO (g)
ii) CO reduction in amount of oxygen carried by (the haemoglobin in the red blood
cells of) the blood
Headache OR dizziness OR nausea OR fatigue OR loss of consciousness OR
death
c) i) CaCO3 (s) + 2HCl (aq) rarr CaCl2 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) + H2SO4 (aq) rarr CaSO4 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) rarr CaO (s) + CO2 (g)
48
ii)
OR
OR
Entirely closed system thistle funnel below the level of the liquid OR tap that could be
closed
Two reagents labelled CaCO3marble chips and HCl H2SO4 or heat source
collection of CO2 upward displacement of air OR over watersulphuric acid OR in gas
syringe
iii) CO2 use put in aerated drinks carbonated beverages
OR put in carbon dioxide fire extinguishers
49
WEEK 14 LESSON 3 Worksheet Answers
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
NH4+
NH4+ confirmed OR
NH3 (g) produced
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
Cl- ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation required)
Suggest a possible identity of the solid R NH4Cl (ammonium chloride)
50
WEEK 15 LESSON 1 Worksheet Answers
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a
small portion of solid Y
gently at first and then
strongly
Colourless gas
evolved with a
choking odour
Turns acidified
potassium dichromate
solution from orange
to green
SO2 evolved
Presence of a sulphite
(ii) To the remaining
portion of solid Y add 20
cm3 of distilled water stir
to dissolve and filter
Collect the filtrate and
divide into 3 equal portions
Filtrate is pale green
in colour
Fe2+ ions present
(iii) To the first portion of
the filtrate from (ii) add
aqueous sodium hydroxide
slowly until in excess
A green precipitate
Insoluble in excess
sodium hydroxide
Fe2+ ions present
Fe2+ (aq) + 2 OH- (aq) Fe(OH)2 (s)
Ionic equation required
TEST OBSERVATIONS INFERENCES
(iv) To the second portion
of the filtrate from (ii) add
aqueous silver nitrate
White precipitate
Soluble in aqueous
ammonia
Cl- ions present
51
followed by aqueous
ammonia
(v) To the third portion of
the filtrate from (ii) add
aqueous barium nitrate
followed by aqueous
hydrochloric acid
White precipitate
formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with
the evolution of a
colourless gas with a
choking smell
SO32- CO3
2- SO42- ions present
SO32- ions present
52
WEEK 15 LESSON 2 Worksheet Answers
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
Chloride ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
Cu2+ ions present
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
X contains a reducing agent
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
SO32- SO4
2- or CO32- ions are
present
SO32- ions are present
53
WEEK 15 LESSON 3 Worksheet Answers
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
White ppt
Ppt soluble in excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in
excess aqueous NH3
Al3+ Pb2+ Zn2+ present
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change Cl- Br- I- absent
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
Vigorous effervescence
observed upon addition of
dilute HNO3
CO2 evolved OR
Carbonate present
54
warm filter and then divide
the filtrate into two portions
Gas evolved turns lime
water cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
Cu2+ (aq) + OH- (aq)
Cu(OH)2 (s)
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Blue ppt
ppt dissolves in excess
NH3 to give a deep blue
solution
Cu2+ ions present
55
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
REFERENCES
Hunte-King J Maragh P Nagir F amp Norris R (2013) Chemistry for CSEC United
Kingdom Nelson Thornes Ltd
Remy C Mason L Lambert N amp Mohammed M (2007) Chemistry for CSEC England and
Wales Pearson Education Limited
Taylor M amp Chung-Harris T (2010) CXC Chemistry England Macmillan Publishers
Limited
Tindale A (2016) Chemistry A Concise Revision for CXC London HarperCollins Publishers
Limited
3
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
WEEK 1 LESSON 1
TOPIC Characteristics of metals and non ndash metals
The elements of the periodic table may be classified as metals and non ndash metals The division is
The non ndash metals with the exception of hydrogen are found on the right hand side of the
periodic table These elements have atoms with completed filled or nearly filled outermost shells
The figure below shows an outline of the periodic table with the metals and non-metals
I II III IV V VI VII 0
B C N O F He
Si P S Cl Ne
METALS
As Se Br Ar
Te I Kr
At Xe
Rn
Periodic Table showing Metals and Non ndash metals
4
Differences between metals and non ndash metals
Metals Non ndash metals
Good conductor of electricity Do not conduct electricity
except graphite (carbon)
Good conductor of heat Do not conduct heat except graphite (carbon)
Lustrous solids at room temperature
(except mercury)
Solid liquid or gas at room temperature
eg iodine (solid) bromine (liquid) and
chlorine (gas) at room temperature
Malleable (can be beaten into different
shapes)
Not malleable
Ductile (can be drawn into wires) Not ductile
Sonorous (ring when hit with a hard object) Not sonorous
High melting and boiling points Low melting and boiling points compared to
metals
High density Much lower density at rtp compared to metals
5
WEEK 1 LESSON 1 WORKSHEET
Shade the letter next to the answer you choose for questions 1 to 4
1 Which of the following are metals
I Bromine
II Sodium
III Neon
IV Iron
(A) I and III (B) II and IV (C) I and IV (D) II and III
2 Which of the following are non ndash metals
I Chromium
II Carbon
III Iodine
IV Potassium
(A) I and III (B) II and IV (C) I and IV (D) II and III
3 A metal that is a liquid at room temperature is
(A) mercury (B) tin (C) magnesium (D) sodium
6
4 Consider the following information about four substances
Substance Melting point
0C
Electrical conductivity Water
solubility in solid in liquid
I 1050 Low High High
II 75 Low Low Low
III 1234 High High Low
IV 1913 Low Low Low
The substance which is MOST likely to be a metal is
(A) I (B) II (C) III (D) IV
5 Read the following and answer the question that follows
A new element was discovered to have the following properties
Lustrous solid
Can be beaten into shapes
High density
(a) Based only on the facts stated above is the element a metal or non metal
_______________________
(b) State 3 other properties that you expect this element to exhibit
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
7
WEEK 1 LESSON 2
TOPIC Physical properties of metals
Physical properties of some metals
Metals Melting point 0C
Boiling point
0C
Density
g cm-3
Other characteristics
Sodium 90 900 097 Very soft grey metal
Calcium 850 1487 153 Grey metal
Magnesium 650 1103 174 Soft grey metal
Aluminium 660 2350 270 Grey metal
Zinc 419 907 719 White metal
Iron 1535 2760 797 Dark grey metal
Copper 1083 2580 894 Gold coloured metal
conductivity second only to
silver
Sodium Calcium Magnesium Aluminium
Zinc Iron Copper
8
WEEK 1 LESSON 2 WORKSHEET
A group of students carried out an experiment to find the density of three different metals
aluminium calcium and an unknown metal X They measured the mass of each metal sample
using a balance The volumes of the metals were determined by displacement of oil The results
of their experiment are as follows
Aluminium Calcium Metal X
Mass (g) 100 100 100
Final volume (cm3) 335 365 310
Initial volume (cm3 300 300 300
Volume of metal (cm3)
Density (gcm-3)
Complete the table using the following formulae
Volume of metal = Final volume ndash Initial volume
Density = 119872119886119904119904
119881119900119897119906119898119890
Arrange the metals in order of increasing density _____________________________________
9
WEEK 1 LESSON 3
TOPIC Chemical properties of metals
Action of oxygen
Most metals react with oxygen or air to form the corresponding oxide These oxides are basic
oxides with the exception of aluminium zinc and lead which form amphoteric oxides Metals
lower in the electrochemical series do not react
Metal Reaction with air or oxygen
Potassium K
Burn very easily forming oxide
eg 4 Na (s) + O2 (g) 2 Na2O (s)
Sodium Na
Calcium Ca
Magnesium Mg
Aluminium Al
Burn especially if powered forming oxide
eg 4 Al (s) + 3 O2 (g) 2 Al2O3 (s)
Zinc Zn
Iron Fe
Lead Pb Do not burn form oxide when heated strongly
Copper Cu
Silver Ag No reaction
10
WEEK 1 LESSON 3 WORKSHEET
Write balanced chemical equations for the reaction of the named metals and air or oxygen
State the nature of the oxide formed (basic or amphoteric)
Potassium + Oxygen
______________________________________________________________________________
Sodium + Oxygen
______________________________________________________________________________
Calcium + Oxygen
______________________________________________________________________________
Magnesium + Oxygen
______________________________________________________________________________
Aluminium + Oxygen
______________________________________________________________________________
Zinc + Oxygen
______________________________________________________________________________
11
Iron + Oxygen
______________________________________________________________________________
Lead + Oxygen
______________________________________________________________________________
Copper + Oxygen
______________________________________________________________________________
Silver + Oxygen
______________________________________________________________________________
12
WEEK 2 LESSON 1
TOPIC Chemical properties of metals
Action of water
Metals high in the electrochemical series react with cold water to produce the metal hydroxide
and hydrogen
Reactive metals slightly lower in the electrochemical series react very slowly or not at all with
water However they may react with hot water or steam to produce the corresponding metal
oxide and hydrogen
Metals lower than hydrogen in the electrochemical series do not react with water
Metal Reaction with water or steam
Potassium K React with cold water forming metal hydroxide and hydrogen
eg Ca (s) + 2 H2O (l) Ca(OH))2 (aq) + H2 (g) Sodium Na
Calcium Ca
Magnesium Mg React with steam forming metal oxide and hydrogen
eg Zn (s) + H2O (g) ZnO (s) + H2 (g) Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
13
WEEK 2 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with water (or
steam if reaction does not occur with water)
Potassium + WaterSteam
______________________________________________________________________________
Sodium + WaterSteam
______________________________________________________________________________
Calcium + WaterSteam
______________________________________________________________________________
Magnesium + WaterSteam
______________________________________________________________________________
Aluminium + WaterSteam
______________________________________________________________________________
Zinc + WaterSteam
______________________________________________________________________________
14
Iron + WaterSteam
______________________________________________________________________________
Copper + WaterSteam
______________________________________________________________________________
Silver + WaterSteam
______________________________________________________________________________
15
WEEK 2 LESSON 2
TOPIC Chemical properties of metals
Action of dilute acids
Metals above hydrogen in the electrochemical series react with dilute acids to form a salt and
hydrogen gas They react with hydrochloric acid to form the metal chloride (a salt) and hydrogen
gas They also react with dilute suphuric acid to form the metal sulphate (a salt) and hydrogen
gas
Metal Reaction dilute hydrochloric or sulphuric acid
Potassium K Violent reaction forming a salt and hydrogen gas
eg 2 Na (s) + 2 HCl (aq) 2 NaCl (aq) + H2 (g) Sodium Na
Calcium Ca Vigorous reaction forming a salt and hydrogen gas
eg Mg (s) + 2 HCl (aq) MgCl2 (aq) + H2 (g) Magnesium Mg
Aluminium Al React forming a salt and hydrogen gas
eg Fe (s) + 2 HCl (aq) FeCl2 (aq) + H2 (g) Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
16
WEEK 2 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with
hydrochloric acid
Metal Balanced equation for reaction with hydrochloric acid
Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Copper
Silver
17
WEEK 2 LESSON 3
TOPIC Reactions of metal compounds
Reactions of metallic oxides with dilute acid
Metal oxides react with dilute hydrochloric acid or sulphuric acid to produce a salt and water
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
Some of these reactions may be slow and can be speeded up by adding heat
For example
zinc oxide + hydrochloric acid zinc chloride + water
ZnO (s) + 2 HCl (aq) ZnCl2 (aq) + H2O (l)
magnesium oxide + hydrochloric acid magnesium chloride + water
MgO (s) + 2 HCl (aq) MgCl2 (aq) + H2O (l)
aluminium oxide + sulphuric acid aluminium sulphate + water
Al2O3 3 H2SO4 (aq) Al2(SO4)3 (aq) + 3 H2O (l)
calcium oxide + sulphuric acid calcium sulphate + water
CaO H2SO4 (aq) CaSO4 (aq) + H2O (l)
18
WEEK 2 LESSON 3 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal oxides with the
corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium oxide Hydrochloric acid
Sodium oxide Sulphuric acid
Calcium oxide Hydrochloric acid
Magnesium oxide Sulphuric acid
Aluminium oxide Hydrochloric acid
Zinc oxide Sulphuric acid
19
WEEK 3 LESSON 1
TOPIC Reactions of metal compounds
Reactions of metallic hydroxides with dilute acid
Metal hydroxides react with dilute acids to form a salt and water in a neutralisation reaction
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
For example
magnesium hydroxide + hydrochloric acid magnesium chloride + water
Mg(OH)2 (aq) + 2 HCl (aq) MgCl2 (aq) + 2 H2O (l)
sodium hydroxide + hydrochloric acid sodium chloride + water
NaOH (aq) + HCl (aq) NaCl (aq) + H2O (l)
potassium hydroxide + sulphuric acid potassium sulphate + water
2 KOH + H2SO4 (aq) K2SO4 (aq) + 2 H2O (l)
calcium hydroxide + sulphuric acid calcium sulphate + water
Ca(OH)2 (aq) + H2SO4 (aq) CaSO4 (aq) + 2 H2O (l)
20
WEEK 3 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal hydroxides with
the corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium hydroxide Hydrochloric acid
Sodium hydroxide Sulphuric acid
Calcium hydroxide Hydrochloric acid
Magnesium hydroxide Sulphuric acid
Aluminium hydroxide Hydrochloric acid
Zinc hydroxide Sulphuric acid
21
WEEK 3 LESSON 2
TOPIC Reactions of metal compounds
Reactions of metallic carbonates with dilute acid
Metal carbonates react with dilute acid to form a salt carbon dioxide and water When
hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric acid is
used the corresponding sulphate salt is formed
For example
sodium carbonate + hydrochloric acid sodium chloride + carbon dioxide + water
Na2CO3 (s) + 2 HCl (aq) 2 NaCl (aq) + CO2 (g) + H2O (aq)
calcium carbonate + hydrochloric acid calcium chloride + carbon dioxide + water
CaCO3 (s) + 2 HCl (aq) CaCl2 (aq) + CO2 (g) + H2O (aq)
zinc carbonate + sulphuric acid zinc sulphate + carbon dioxide + water
ZnCO3 (s) + H2SO4 (aq) ZnSO4 (aq) CO2 (g) + H2O (aq)
potassium carbonate + sulphuric acid potassium sulphate + carbon dioxide + water
K2CO3 (s) H2SO4 (aq) K2SO4 (aq) CO2 (g) + 2 H2O (aq)
22
WEEK 3 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal carbonates with
the corresponding acid
Metallic
carbonate
Acid Balanced chemical equation
Potassium
carbonate
Hydrochloric
acid
Sodium
carbonate
Sulphuric acid
Zinc
carbonate
Hydrochloric
acid
Magnesium
carbonate
Sulphuric acid
Aluminium
carbonate
Hydrochloric
acid
Calcium
carbonate
Sulphuric acid
23
WEEK 3 LESSON 3
TOPIC Action of heat on metal compounds
Action of heat on nitrates
All nitrates decompose when heated The reactivity of the metal in the metal nitrate influences
the products of the decomposition
The nitrates of the alkali metals (Group I) with the exception of lithium nitrate decompose to
form the metal nitrite and oxygen
The nitrates of most other metals decompose to form the metal oxide nitrogen dioxide and
oxygen
The nitrates of the very unreactive metals decompose to form the meal nitrogen dioxide and
oxygen
Metal Nitrate Decomposition
Potassium K Products metal nitrite + oxygen
eg 2 NaNO3 (s) Heatrarr 2 NaNO2 (s) + O2 (g)
Sodium Na
Calcium Ca
Products metal oxide + nitrogen dioxide + oxygen
eg 2 Pb(NO3)2 (s)
Heatrarr 2 PbO (s) + 4 NO2 (g) + O2 (g)
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Products metal + nitrogen dioxide + oxygen
eg 2 AgNO3 (s) Heatrarr 2 Ag (s) + 2 NO2 (g) + O2 (g)
24
WEEK 3 LESSON 3 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
nitrates
Metal Balanced chemical equation
Potassium nitrate
Sodium nitrate
Calcium nitrate
Magnesium nitrate
Aluminium nitrate
Zinc nitrate
Lead nitrate
Copper nitrate
Silver nitrate
25
WEEK 4 LESSON 1
TOPIC Action of heat on metal compounds
Action of heat on carbonates
Upon application of heat many carbonates decompose to form the metal oxide and carbon
dioxide
Group I carbonates do not decompose on heating with the exception of lithium carbonate
Metal Carbonate decomposition
Potassium K
Stable not decomposed by heat Sodium Na
Calcium Ca
Decompose forming metal oxide and carbon dioxide
eg CaCO3 (s) Heatrarr CaO (s) + CO2 (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Unstable
26
WEEK 4 LESSON 1 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
carbonates
Metal Balanced chemical equation
Potassium carbonate
Sodium carbonate
Calcium carbonate
Magnesium carbonate
Aluminium carbonate
Zinc carbonate
Iron carbonate
Lead carbonate
Copper carbonate
27
WEEK 4 LESSON 2
TOPIC Action of heat on metal compounds
Action of heat on the metal hydroxides
Most metal hydroxides decompose on heating A metal oxide and water are formed
Group I hydroxides do not decompose on heating with the exception of lithium hydroxide
Metal Hydroxide decomposition
Potassium K Stable not decomposed by heat
Sodium Na
Calcium Ca Decompose forming metal oxide and water (as steam)
eg Zn(OH)2 (s) Heatrarr ZnO (s) + H2O (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag No hydroxide exist
28
WEEK 4 LESSON 2 WORKSHEET
Write the balanced chemical equations for the thermal decomposition of the following
metal hydroxides
Metal hydroxide Balanced chemical equation
Potassium hydroxide
Sodium hydroxide
Calcium hydroxide
Magnesium hydroxide
Aluminium hydroxide
Zinc hydroxide
Lead hydroxide
Copper hydroxide
29
WEEK 4 LESSON 3
TOPIC Reactivity of metals ndash The Reactivity Series
The reactivity series of metals is a list of metals arranged in order of their reactivity based on
Displacement reactions
Reactions with oxygen dilute acids and water
Relative ease of decomposition of their compounds
Metals at the top of the series are the most electropositive They lose electrons very easily and
readily form cations These ions are very stable and are not easily discharged to form atoms Due
to this fact they are the most reactive metals
Metals at the bottom of the series are the least electropositive They do not lose electrons easily
and do not readily form ions Their ions are very unstable and are easily discharged to form
atoms They are the least reactive metals
The reactivity series of metals
Mnemonic Metal Symbol Reactivity
People Potassium K Most reactive
Least reactive
Sometimes Sodium Na
Collect Calcium Ca
Magazines Magnesium Mg
About Aluminium Al
Zoos Zinc Zn
In Iron Fe
London Lead Pb
Having (Hydrogen) H
Cute Copper Cu
Monkeys and Mercury Hg
Small Silver Ag
Gorillas Gold Au
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
5 Reactivity of metals Reactivity of metals Reactivity of metals
6 Extraction of metals Extraction of metals Alloys
7 Corrosion Importance of metals
and their compounds
on living systems and
environment
Chemical properties
of non ndash metals
8 Laboratory
preparation of gases
Laboratory
preparation of gases
Laboratory
preparation of gases
9 Uses of gases Uses of non ndash metals
and their compounds
Harmful effects of
non ndash metals and
their compounds on
living systems and
the environment
10 Green Chemistry Qualitative Analysis
ndash Identification of
cations
Qualitative Analysis
ndash Identification of
cations
2
WEEK 5 LESSON 1
TOPIC Reactivity of metals
Reactivity based on displacement reactions between metals and metal ions
A metal will displace a metal which is lower than itself in the reactivity series from a solution of
the metal salt
Reaction of zinc and copper (II) sulphate
Expected observations
Explanation
The size of the zinc metal decreases
The zinc metal is reacting and forming the
salt zinc sulphate
The solution becomes lighter eventually
colourless
The Cu2+ (aq) ions (responsible for the blue
colour) is reduced to Cu (s)
A brown solid is deposited at the bottom of
the container
Copper metal is formed
Equation Zn (s) + CuSO4 (aq) ZnSO4 (aq) + Cu (s)
Ionic equation
Zn (s) + Cu2+ (aq) Zn2+ (aq) + Cu (s)
Zinc is higher in the reactivity series than copper Therefore it will displace the copper ions in
the reaction above
3
Examples of other displacement reactions
Magnesium will displace Zn2+ ions in zinc sulphate since it is higher in the series than zinc
Mg (s) + Zn2+(aq) Mg2+ (aq) + Zn (s)
Silver will not displace Cu2+ ions in copper (II) sulphate [Cu is higher in the series than Ag]
Using the information above we can arrange the metals in order of their reactivity with
magnesium being the most reactive and silver the least reactive metal among the four metals
Mg gt Zn gt Cu gt Ag
Reactivity based on reaction with oxygen
The reactivity of metals can also be deduced from their reaction with oxygen
The table below gives the observations for the reaction with oxygen with the selected metals
Reaction of metal with oxygen
Metal Observation
Copper The surface turns black upon heating
Magnesium Ribbon burns very rapidly
Sodium Burns vigorously
Gold No reaction
Based on the observations for the 4 metals the metal with highest reactivity is sodium and the
metal with the least reactivity is gold
The 4 metals can be arranged in terms of reactivity as follows
Na gt Mg gt Cu gt Au
4
WEEK 5 LESSON 1 WORKSHEET
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
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5
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
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6
WEEK 5 LESSON 2
TOPIC Reactivity of metals
Reactivity based on reactivity with acids
The metals that are higher than hydrogen in the electrochemical series react with non ndash oxidizing
acids to produce a salt and hydrogen gas
By using the same concentration of acid and same mass and size of the metals the order of
reactivity of the metals can be deduced
The table below shows the results for an experiment with the reaction of the named metals and
1 mol dm-3 hydrochloric acid
Reaction of metals with acid
Metal Observations
Silver No reaction
Magnesium Bubbles produced steadily
Calcium Bubbles produced very rapidly
Iron Bubbles produced slowly
Based on the above data the most reactive metal will be calcium with the least reactive being
silver The order of reactivity will be Ca gt Mg gt Fe gt Ag
By comparing this to the electrochemical series it can be seen that the reactivity of the metals
decrease as we go down the series
7
WEEK 5 LESSON 2 WORKSHEET
1 Place a next to the metals that will react with dilute acid and an X next to the metals
that will not react with dilute acid
Metal Reactivity with acid
Copper
Magnesium
Aluminium
Silver
Zinc
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
8
WEEK 5 LESSON 3
TOPIC Reactivity of metals
Reactivity based on ease of decomposition of the metal nitrates carbonates oxides and
hydroxides
The more reactive a metal the more difficult it is to decompose its nitrate carbonate oxide or
hydroxide on heating
For example Decomposition of carbonates
Procedure
1 Put a large spatula measure of the carbonate to be tested in a test tube
2 Fit a delivery tube and then clamp the test tube so that the delivery tube dips into a second test
tube containing 2ndash3 cm3 limewater
3 Heat the solid gently at first then more strongly
4 Lift the delivery tube from the limewater before or as soon as the heating is stopped This is to
avoid suck-back
5 Write down all observations Notice what happens to the limewater and how long it takes to turn
milky (if at all) Notice whether any melting occurs in the heated test tube and any colour
changes taking place Write your results in tabular form
6 Repeat the experiment with the other metal carbonates supplied and in each case write down
your observations
7 Wash your hands thoroughly at the end of these experiments since some of the metal carbonates
are toxic
9
Results
Metal Formula Gas evolved Ease of decomposition
Zinc ZnCO3 Carbon dioxide Fairly easy
Copper CuCO3 Carbon dioxide Easy
Sodium Na2CO3 None Very difficult
Using the results of the above activity the reactivity of the metals can be determined
Ease of decomposition Copper gt Zinc gt Sodium
The order of reactivity is the opposite for the ease of decomposition
Order of reactivity Sodium (most reactive) gt Zinc gt Copper (least reactive)
10
WEEK 5 LESSON 3 WORKSHEET
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
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11
WEEK 6 LESSON 1
TOPIC Extraction of metals
Elements exist all over the earth Some are found as free elements eg copper silver and gold
Others are found combined with other elements in compounds To get the elements the
compounds have to be broken up These compounds are generally called ores the most
convenient sources of which are rocks sea and air
The extraction of a metal from its ore is a reduction process where the metals ions gain electrons
to form atoms
The general equation is Mn+ + n e- M
The choice of the extraction method depends on the position of the metal in the reactivity series
As we go down the series the metals become more stable and the metal ions (in the ores)
become less stable
The very reactive metals that are high in the series K Na Ca Mg Al have very stable ores
Therefore they require a powerful method of reduction namely electrolysis During the process
the cathode provides the electrons and acts as the reducing agent
The metals in the middle of the series (Zn Fe Pb) do not have stable ores and can be extracted
by reduction with carbon in the case of zinc and with carbon monoxide in the case of iron and
lead
Metals low in the reactivity series if present as ores can be extracted simply by heating the ores
in air at high temperatures
12
Extraction of Aluminium from purified bauxite
Pure bauxite is pure alumina (Al2O3) Aluminium is obtained from bauxite by electrolysis
Aluminium oxide has a very high melting point approximately 2050 0C so it is first dissolved in
molten cryolite (Na2AlF6) The addition of cryolite lowers the melting point to approximately
900 0C
The electrolyte is a molten mixture of alumina and molten cryolite The cathode is the graphite
lining of the cell The anodes are blocks of graphite or titanium alloys
Reaction at the cathode
Al3+ (l) + 3 e- Al (l)
Reaction at the anode
2 O2- (l) ndash 4 e- O2 (g)
Aluminium (melting point 660 0C) is a liquid at the temperature at which electrolysis is carried
out and is collected at the bottom of the cell and tapped off Oxygen gas which is given off in the
main cathode reaction together with the heat causes the anodes to burn away The anodes have
to be replaced from time to time The use of anodes from titanium alloys reduce the number of
times that the anodes have to be replaced
13
WEEK 6 LESSON 1 Worksheet
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
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14
WEEK 6 LESSON 2
TOPIC Extraction of metals
Extraction of Iron
The traditional method of production of iron is by reduction of haematite by carbon monoxide in
a blast furnace
Ores Haematite ndash Fe2O3 Magnetite ndash Fe3O4 Siderite ndash FeCO3 Magnetite and Siderite are
converted to Haematite
A mixture of haematite limestone (CaCO3) and coke (C) called the charge is placed into the top
of the furnace
Hot air is blown into the bottom of the furnace
Coke burns in air forming carbon dioxide
C (s) + O2(g) CO2 (g) ΔH -ve
The heat produced keeps the temperature at about 1900 0C
The carbon dioxide is reduced to carbon monoxide by the hot coke
CO2 (g) + C (s) 2 CO(g) Δ +ve
Heat absorbed reduces the temperature to about 1100 0C
The carbon monoxide reduces the hot iron ore to molten iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + 3 CO2(g)
The temperature at this part of the furnace is about 700 0C The iron runs to the bottom of the
furnace
The impurities are removed by the addition of limestone (CaCO3) The limestone at the
temperature of the furnace breaks down
CaCO3 (s) CaO (s) + CO2 (g)
15
The calcium oxide formed combines with silicon dioxide (sand) the main impurity in the iron
ore to form molten slag
CaO (s) + SiO2 (s) CaSiO3 (l)
The slag does not mix with the molten iron but floats on it The molten iron and slag are run off
separately
The iron formed in a blast furnace is an impure form of the metal Because the molten metal is
allowed to solidify in shallow trays known as casts the iron is called lsquocast ironrsquo or lsquopigrsquo iron
Cast iron is quite brittle and contains 2 - 4 carbon and other impurities Most of the cast iron is
converted to steel
A blast furnace used for extracting iron
16
WEEK 6 LESSON 2 Worksheet
(a) What are the three raw materials that are added through the top of the blast furnace
during the extraction process for iron
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(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
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17
WEEK 6 LESSON 3
TOPIC Alloys
An alloy is a mixture of two or more metals Alloys are made by melting the individual metals
mixing them and allowing the molten mixture to solidify
In general alloys are harder stronger and more resistant to corrosion than the actual metals they
are made up from
Alloy Use Properties
ALUMINIUM
-Duralumin
(AlMgCu)
-Magnalium (AlMg)
Alloys used in the
construction of
aircraft and ships
buses
Aluminium is used in
making cooking
utensils electrical
cables paint for fuel
storage tanks bottle
caps foil and utensils
for handling nitric
acid
The alloys have a low
density They are as
light as aluminium
and more resistant to
corrosion than
aluminium
LEAD
-Solder (PbSn)
Alloy is used in
joining metals
(soldering)
Lead is used in
underground cables
plates in
The alloy has a lower
melting point than
lead and is harder
than lead
18
Alloy Use Properties
accumulators shield
against x ndash rays
IRON
- Stainless Steel
(FeCONiC)
-Tungsten steel
(FeWC)
-Invar steel (FeNi)
Manganese steel
(FeMnC)
Iron is the main metal
of a variety of
constructions
Steel is used in
cutlery rock drills
electromagnets
vehicle body and
engine parts fences
pipes etc
Steel resists
corrosion is usually
harder than iron and
may be tough though
malleable and ductile
19
WEEK 6 LESSON 3 Worksheet
(a) Define the term alloy
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(b) State 3 general advantages that alloys have over the individual metals they are made
from
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(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
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Uses
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20
WEEK 7 LESSON 1
TOPIC Corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
Familiar examples of corrosion are
- the formation of a green powder on copper sheeting
- the eating away of iron (rusting)
- the development by aluminum of a thin compact layer of oxide which protects the
underlying metal from further corrosion
When corrosion occurs in water ndash free environment it is called dry oxidation When it occurs in
aerated aqueous environments it is called wet corrosion Wet corrosion is the most common and
troublesome form of corrosion
The most familiar corrosion is the rusting of iron and steel On exposure to the atmosphere iron
and steel corrode to form rust which is hydrated iron (III) oxide Fe2O3xH2O Iron and steel
corrode easily and the rust formed flakes off easily thus exposing fresh surface for attack
When iron rust it loses electrons
Fe (s) ndash 2e- Fe 2+ (aq)
The iron (II) ions pass into solution and then combine with the hydroxyl (OH-) ions in the
aerated aqueous environment to form iron (II) hydroxide The oxygen present oxidises the iron
(II) hydroxide to hydrated iron (III) oxide or rust
Fe(OH)2 + O2 Fe2O3xH2O
21
Methods of preventing rusting
1 Coating the object with paint grease plastic or rubber which prevent contact with air or
water
2 Galvanising ndash coating the object with zinc The zinc forms an adherent oxide layer which
protects against further corrosion If damaged the zinc is oxidized in preference to the
iron since it is higher in the electrochemical series
3 Coating with tin lsquoTinrsquo cans are made of steel plated with tin However if scratched
rusting occurs since iron is more reactive than tin
4 Attaching a sacrificial anode to the object A piece of metal higher in the electrochemical
series such as magnesium is attached The magnesium will be oxidized in preference
since it is higher in the electrochemical series than iron
22
WEEK 7 LESSON 1 WORKSHEET
(a) Define the term corrosion
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(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
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(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
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(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
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23
WEEK 7 LESSON 2
TOPIC Importance of metals and their compounds on living systems and environment
Some metals are an integral part of different structures of living things
Metal Presence and Function
Potassium Main cation in fluid or animal cells essential for healthy plant growth
Calcium Necessary for strong bones teeth and shells needed by some enzymes Present
in dairy produce eggs nuts and cereals
Magnesium Central atom of chlorophyll needed for some enzyme action Involved in energy
and calcium metabolism
Zinc Present in many enzymes Needed for protein metabolism Essential for growth
of animals
Iron Present in haemoglobin Needed for protein metabolism Essential for growth of
animals
Chromium Needed for glucose uptake by cells and thus linked to the action of insulin
Manganese Needed for bone development and amino acid metabolism Present in several
enzymes Needed for plant growth
Cobalt Present in Vitamin B12 Needed for plant growth
Copper Involved in formation of haemoglobin and melanin Present in enzymes
controlling oxidation Needed for plant growth
24
Harmful effects of metals and their compounds to living systems and the environment
There are some metals and metal compounds which may cause harm to living systems and the
environment
Lead
Lead is a heavy metal poison that is widely encountered It may occur in food beverages paint
water formed from ndash sealed pipes in air polluted by combustion by fuels containing lead
compounds Lead is also used in some car batteries If these are paints or batteries are not
disposed of correctly lead may get into groundwater or air Lead and lead compounds harm the
nervous system including the brain especially young children
Arsenic
Arsenic compounds are poisonous They can get into the groundwater from mining waste and
from disposal of some electrical components
Cadmium
Cadmium compounds are poisonous They can get into the ground by improper disposal of
nickel ndash cadmium batteries Persons can get cadmium poisoning if they eat food grown in
contaminated soil
Mercury
Mercury can be spilled from broken thermometers in hospitals and laboratories Mercury and its
compounds are particularly poisonous to fish and it can accumulate in the food chain and
eventually poison humans
Problems of disposal of solid waste
Metals may react with water andor air and corrode to form soluble compounds that are
poisonous These toxic compounds diffuse into the soil and eventually enter rivers
Rust from iron may form unsightly pools of waste that reduce plant growth
Waste from aluminium extraction may react with water and form flammable gases
25
WEEK 7 LESSON 2 WORKSHEET
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
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(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Lead
______________________________________________________________________________
Mercury
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26
WEEK 7 LESSON 3
TOPIC Chemical properties of non ndash metals
Reaction with oxygen
Many non ndash metals burn in excess oxygen or air to form oxides For example
S (s) + O2 (g) SO2 (g)
C (s) + O2 (g) CO2 (g)
Reactions with metals
Some non ndash metals react with metals high in the electrochemical series when heated
For example
Sodium burns in chlorine to form sodium chloride
Na (s) + Cl2 (g) NaCl (s)
Magnesium burns in oxygen to form magnesium oxide
Mg (s) + O2 (g) MgO (s)
When heated iron combines with molten sulphur to form iron (II) sulphide
Fe (s) + S (l) FeS (s)
When heated reactive metals such as sodium and aluminium react with hydrogen to form metal
hydrides
2 Na (s) + H2 (g) 2 NaH (s)
Oxidising and Reducing properties
Hydrogen and Carbon are very good reducing agents
At high temperatures hydrogen reduces metal oxides below zinc in the electrochemical series to
form the metal For example PbO (s) + H2 (g) Pb (s) + H2O (g)
Under suitable conditions hydrogen reduces nitrogen to ammonia
N2(g) + 3 H2 (g) 2 NH3 (g)
27
At high temperatures carbon reduces metal oxides below aluminium in the reactivity series to
the metal For example
ZnO (s) + C (s) Zn (s) + CO (g)
Oxygen and Chlorine are very good oxidizing agents
Oxygen oxidized most metals to form metal oxides and some non ndash metals to non ndash metal oxides
For example
2 Mg (s) + O2(g) 2 MgO (s)
4 P (s) + 5 O2 (g) P4O10 (s)
Chlorine acts as an oxidizing agent either as a gas or as an aqueous solution For example
H2 (g) + Cl2 (g) 2 HCl (g)
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
28
WEEK 7 LESSON 3 WORKSHEET
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
______________________________________________________________________________
(b) Write the ionic equation for the above reaction
______________________________________________________________________________
(c) Identify the oxidising agent in the reaction
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(d) Justify your answer in part (c) in terms of oxidation number
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29
WEEK 8 LESSON 1
TOPIC Laboratory preparation of gases
Preparation of oxygen
Oxygen can be prepared by the decomposition of hydrogen peroxide potassium chlorate (V) or
potassium nitrate The safest method is the decomposition of hydrogen peroxide
Manganese (IV) oxide catalyses the decomposition of hydrogen peroxide
Silica gel anhydrous calcium chloride or concentrated sulphuric acid can be used as a drying
agent
The gas is collected by downward delivery since it is slightly denser than air
Equation
2 H2O2 (aq) 2 H2O (l) + O2 (g)
Apparatus used for laboratory preparation of oxygen
30
WEEK 8 LESSON 1 WORKSHEET
Describe the laboratory preparation of oxygen gas
In your answer include
The starting material
A suitable catalyst
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
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31
WEEK 8 LESSON 2
TOPIC Laboratory preparation of gases
Preparation of carbon dioxide
Carbon dioxide can be prepared by the action of dilute acid on carbonates Marble chips (calcium
carbonate) and dilute hydrochloric acid are the common reagents The gas is collected by
downward delivery since it is denser than air
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
Apparatus used for laboratory preparation of carbon dioxide
32
WEEK 8 LESSON 2 WORKSHEET
Describe the laboratory preparation of carbon dioxide gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
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33
WEEK 8 LESSON 3
TOPIC Laboratory preparation of gases
Preparation of ammonia
Ammonia may be prepared by heating a mixture of ammonium salt and a hydroxide The
ammonia gas is collected by upward delivery since it is less dense than air
For example
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
Calcium oxide is the only suitable drying agent since ammonia reacts with conc H2SO4 and
CaCl2
Apparatus used for laboratory preparation of dry ammonia
34
11
WEEK 8 LESSON 3 WORKSHEET
Describe the laboratory preparation of ammonia gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
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35
WEEK 9 LESSON 1
TOPIC Uses of gases
Carbon dioxide
Used in fire extinguishers to put out fires Carbon dioxide is denser than air and lsquoblanketsrsquo the
fire preventing oxygen from reaching it Carbon dioxide extinguishers are especially useful for
dealing with fires involving flammable liquids and electrical equipment
Carbonation in soda is created when carbon dioxide is pumped into the soda can or bottle then
held under pressure As long as the can or bottle is sealed the carbon dioxide remains mostly
stable However if the drink gets shaken up or the top is opened the tiny carbon dioxide bubbles
react by bursting
Oxygen
Oxygen is needed for aerobic respiration We need a constant supply of oxygen for this process
Oxygen is used in hospitals to improve the respiration of patients with poor blood flow blood
poisoning and heart disease
Oxygen in used in welding (joining) metals In an oxyacetylene welding torch acetylene or
ethyne (C2H2) burns in oxygen and produces a very hot flame This flame is capable of melting
most metals
Oxygen is used in steel production A blast of oxygen is blown through the molten iron The
oxygen oxidises many of the impurities of the iron and the impurities are then removed
36
WEEK 9 LESSON 1 WORKSHEET
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Put out fires
Welding metals
Create lsquofizzrsquo in drinks
Used in steel production
Aerobic respiration
37
WEEK 9 LESSON 2
TOPIC Uses of non ndash metals and their compounds
Carbon (allotrophes carbon dioxide)
Carbon is used as a reducing agent in extraction of some metals
Carbon as graphite is used as electrodes lubricants and lsquoleadrsquo for pencils
Carbon in the form of diamond is used for jewellery (because of its lustre) and in drill tips for
high ndash speed drills (because of its hardness)
Carbon dioxide is used as refrigerant (as dry ice) for carbonated beverages
Sodium hydrogen carbonate and sodium carbonate are used for water softening and raising
agent
Sulphur
Sulphur is used in the manufacture of sulphuric acid Sulphur is also used in the manufacture of
tyres to make the rubber harder (vulcanisation)
Sulphur powder is used as fungicide on plant materials
Phosphorus
Phosphorus is used in the manufacture of fertilizers
Phosphorus is used to make phosphor bronze alloys
Phosphorus sulphide is used to make the heads of lsquostrike anywherersquo matches
38
Chlorine
Chlorine is used to make sodium hypochlorite which is present in bleach It is also used in
sterilizing swimming pools and in water treatment
Chlorine is used to make the monomer vinyl chloride which is used to make the plastic PVC
Nitrogen
Nitrogen is used to make fertilisers ammonia dyes and nitric acid
Nitrogen is used as an inert atmosphere to prevent substances being oxidised and as a coolant
Silicon
Silicon is used for making silicon chips for computers
Silicon (V) oxide is present in sand Glass is made by heating sand with lime (calcium oxide) and
sodium carbonate
Silicon in the form of silicates is used in jewellery
Silica gel is used as a drying agent
39
WEEK 9 LESSON 2 WORKSHEET
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Used to make sodium hypochlorite
Used as a fungicide on plant materials
Used for lsquoleadrsquo in pencils
Used in the manufacture of bronze alloys
Used in the manufacture of nitric acid
Used in the manufacture of computer chips
Used to make fertilisers
40
WEEK 9 LESSON 3
TOPIC Harmful effects of non ndash metals and their compounds on living systems and the
environment
Sulphur dioxide
Sulphur dioxide can cause a disease of the lungs Sulphur dioxide also poisons plants in two
main ways It may enter the stomata of leaves and react with the tissue fluids to form sulphites
with the on ndash going water loss the concentration of sulphites could build up killing the cells
The second adverse effect on plants occurs when sulphur dioxide dissolves in rain thereby
increasing soil acidity A prolonged acid soil situation may lead to plasmolysis and the death of
vegetation in an area
Carbon monoxide
Carbon monoxide combines much more readily than oxygen with haemoglobin When carbon
monoxide is inhaled it prevents the haemoglobin from taking oxygen to the bodyrsquos cells
Continued breathing of air containing carbon monoxide eventually causes death
Hydrogen sulphide
Hydrogen sulphide reacts readily with many cations forming insoluble sulphides Many cations
contribute to good health by contributing to enzyme activity and to the formation of bone
pigment and haemoglobin Although these cations are required in extremely small
concentrations they are removed by being precipitated as sulphides and thus not available for
regular function Careless dumping of refuse contributes to atmospheric pollution by hydrogen
sulphide
Oxides of nitrogen
In the presence of hydrocarbons from car exhausts ozone and sunlight nitrogen oxides react to
form photochemical smog which contains many harmful chemicals
Nitrogen dioxide can harm the lungs and irritate the nose throat and eyes The other compounds
present in photochemical smog are even more harmful irritants and can cause asthma
41
Carbon dioxide
Carbon dioxide water vapour and ozone referred to as ldquogreenhouse gasesrdquo acting as a blanket
readily absorb some of the radiated heat energy and in turn warms the earthrsquos atmosphere This is
called the ldquogreenhouse effectrdquo Scientists have found direct correlation between carbon dioxide
concentration and global warming An increase in carbon dioxide concentration resulted in an
increase global temperatures Global warming is a major potential problem that the world faces
Chloroflourocarbons (CFCs)
It is believed that CFCs might be responsible for destroying the ozone layer which prevents
harmful ultraviolet (UV) radiation from reaching the earth The carbon ndash chlorine bond in CFC
molecule is easily broken by a UV photon producing an active chlorine atom This atom
combines with an ozone molecule forming a chlorine oxide radical and oxygen The radicle
reacts with more ozone producing the chlorine atom again This kind of reaction is repeated
thousands of times This type of reaction is thought to account for about eighty percent of the
loss of ozone observed
Nitrates and phospates
Nitrates and phosphates cause eutrophication The process leading to eutrophication are
Nitrates and phosphates from fertilisers spread on fields may dissolve in groundwater and
get into lakes and rivers
Nitrates and phosphates cause excessive growth of algae so that they cover the surface of
the water
Water plants including algae die because of lack of sunlight Aerobic bacteria feed on
the plant remains The bacteria multiply
The aerobic bacteria use up the oxygen in the water so aquatic animals die
42
Solid waste
The main sources of pollution from non ndash metals is from glass paper and plastics
Broken glass can cause injury to animals It can also cause fires by acting as lens focusing the
sunrsquos rays on flammable materials
Printing inks from paper dumped in the ground may contain toxic elements such as arsenic and
cadmium Bleaches and chlorine compounds from paper are also harmful
43
WEEK 9 LESSON 3 WORKSHEET
Describe ONE harmful effect of the following non ndash metals andor their compounds on
living systems and the environment
Sulphur dioxide
______________________________________________________________________________
______________________________________________________________________________
Carbon monoxide
______________________________________________________________________________
______________________________________________________________________________
Carbon dioxide
______________________________________________________________________________
______________________________________________________________________________
Oxides of nitrogen
______________________________________________________________________________
______________________________________________________________________________
Hydrogen sulphide
______________________________________________________________________________
______________________________________________________________________________
44
Chloroflourocarbons (CFCs)
______________________________________________________________________________
______________________________________________________________________________
Nitrates and phospates
______________________________________________________________________________
______________________________________________________________________________
45
WEEK 10 LESSON 1
TOPIC Green Chemistry
Green Chemistry is defined as the utilisation of a set of principles that reduces or eliminates the
use and generation of hazardous substances
There are twelve principles of green chemistry as proposed by Paul T Anastas and John C
Warner These twelve principles are
1 Prevention ndash It is better to prevent waste than to treat or clean up waste after it has been
created
2 Atom economy - Synthetic methods should be designed to maximize the incorporation of
all materials used in the process into the final product
3 Less hazardous chemical synthesis - Wherever practicable synthetic methods should be
designed to use and generate substances that possess little or no toxicity to human health
and the environment
4 Safer chemical products - Chemical products should be designed to affect their desired
function while minimizing their toxicity
5 Safer solvents and other agents - The use of auxiliary substances (eg solvents
separation agents etc) should be made unnecessary wherever possible and harmless
when used
6 Minimum energy requirements - Energy requirements of chemical processes should be
recognized for their environmental and economic impacts and should be minimized If
possible synthetic methods should be conducted at ambient temperature and pressure
7 Use of renewable raw materials - A raw material or feedstock should be renewable rather
than depleting whenever technically and economically practicable
8 Reduce use of additional chemicals or additional steps - Unnecessary derivatization (use
of blocking groups protection deprotection temporary modification of
physicalchemical processes) should be minimized or avoided if possible because such
steps require additional reagents and can generate waste
46
9 Use of catalysts ndash The use of catalysts reduce energy costs because the reactions take
place at lower temperatures The more specific the catalyst for a particular reaction is the
less it the likelihood of getting additional unwanted products
10 Nature of breakdown of products - Chemical products should be designed so that at the
end of their function they break down into innocuous degradation products and do not
persist in the environment
11 Monitoring to prevent pollution - Analytical methodologies need to be further developed
to allow for real-time in-process monitoring and control prior to the formation of
hazardous substances
12 Minimise chemical accidents - Substances and the form of a substance used in a chemical
process should be chosen to minimize the potential for chemical accidents including
releases explosions and fires
47
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
48
WEEK 10 LESSON 2
TOPIC Qualitative Analysis ndash Identification of cations
Qualitative Analysis involves identifying the constituents of single substances or mixture of
substances
Appearance
An examination of the appearance of a substance can indicate which ion it contains
Appearances of substances
Observation Indication
Blue or blue ndash green Cu2+ salt
Pale green Fe2+ salt
Yellow ndash brown Fe3+ salt
Ammonia smell NH4+ salt
49
Test for cation using sodium hydroxide
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
(d) If no precipitate forms in step b warm gently and test for ammonia
Effect of dilute sodium hydroxide solution
Effect of dilute sodium hydroxide solution Cation
Dropwise Excess
White precipitate Precipitate soluble Ca2+
White precipitate Precipitate insoluble Al3+ Pb2+ Zn2+
Blue precipitate Precipitate insoluble Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
No precipitate ndash ammonia gas
evolved on heating
ndash NH4+
The metal cations all form insoluble hydroxides with sodium hydroxide solution
For example Ca2+ (aq) + 2 OH- (aq) Ca(OH)2 (s)
Ca(OH)2 Cu(OH)2 Fe(OH)2 and Fe(OH)3 are basic and therefore do not react with excess
sodium hydroxide solution Therefore the precipitate does not dissolve in excess sodium
hydroxide solution
Al(OH)3 Pb(OH)2 and Zn(OH)2 are amphoteric Therefore the precipitates react with the excess
sodium hydroxide solution forming soluble salts and the precipitate disappears in excess sodium
hydroxide solution
The NH4+ ion forms a soluble hydroxide However on heating it reacts with the hydroxide ion to
form ammonia and water
NH4+ (aq) + OH- (aq) NH3 (g) + H2O (l)
50
WEEK 10 LESSON 2 WORKSHEET
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P _____________ Q ___________________
R _____________ S ___________________
R + NaOH
______________________________________________________________________________
51
WEEK 10 LESSON 3
TOPIC Qualitative Analysis ndash Identification of cations
Test for cation using ammonia solution (ammonium hydroxide solution)
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
Effect of dilute ammonia (ammonium hydroxide) solution
Effect of dilute ammonia solution Cation
Dropwise Excess
No precipitate ndash Ca2+
White precipitate Precipitate soluble
(forming colourless solution)
Zn2+
White precipitate Precipitate insoluble Al3+ Pb2+
Blue precipitate Precipitate soluble
(forming deep blue solution)
Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
52
Ammonia solution is a weak alkali Metal cations except Ca2+ form insoluble hydroxides with
ammonia solution as with the sodium hydroxide solution
The amphoteric hydroxides Al(OH)3 and Pb(OH)2 and the basic hydroxides Fe(OH)2 and
Fe(OH)3 do not react with excess ammonia solution Therefore the precipitates remain
However Zn(OH)2 and Cu(OH)2 do react with excess ammonia solution to form complex
soluble hydroxides each Hence their precipitates disappear on the addition of excess ammonia
solution
Confirmatory test
After carrying out test for cations using sodium hydroxide solution and ammonia solution the
only cations which cannot be distinguished are Al3+ and Pb2+ A confirmatory test is carried out
to distinguish between the two cations
Confirmatory test
Test Observation Cation Ionic equation
Add potassium
or sodium
iodide solution
Bright yellow precipitate
No precipitate
Pb2+
Al3+
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
53
WEEK 10 LESSON 3 WORKSHEET
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A __________ B ________________ C ________________________
(b) State the inference after Test 2
C _______________________
(c) Write an ionic equation to support your answer in (b) above
___________________________________________________________________________
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
54
ANSWERS TO WORKSHEETS
55
WEEK 5 LESSON 1 WORKSHEET ANSWERS
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
Answer
Zinc + Iron (II) sulphate Zinc is higher in the electrochemical series and therefore displace
iron ions in iron (II) sulphate
Equation Zn (s) + FeSO4 (aq) ZnSO4 (aq) + Fe (s)
Ionic equation Zn (s) + Fe2+ (aq) Zn2+ (aq) + Fe (s)
Iron + Zinc sulphate No reaction iron is lower in the electrochemical series and cannot
displace the zinc ions in zinc sulphate
56
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
Answer
X displaces lead from an aqueous solution of its salts
X (s) + Pb2+ (aq) Xn+ (aq) + Pb (s)
rarr X is more reactive than Pb
X did not react with iron salts
rarr X is less reactive than Fe
Y burns very easily
Y is more reactive than Fe and Pb (both forming their corresponding oxide at a slower rate)
From electrochemical series Fe is higher and therefore more reactive than Pb
Order of reactivity
Y (most reactive) gt Fe gt X gt Pb (least reactive)
57
WEEK 5 LESSON 2 WORKSHEET ANSWERS
1
Metal Reactivity with acid
Copper X
Magnesium
Aluminium
Silver X
Zinc
58
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
Answer
Y and Z are the most reactive since they can react with dilute acid
Z is more reactive than Y since a reaction occurs with Z is added to an aqueous solution of Y
X is less reactive than W since it does not occur in nature as compounds
Order of reactivity Z (most reactive) gt Y gt W gt X
59
WEEK 5 LESSON 3 WORKSHEET ANSWERS
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
Answer
Ease of decomposition (from easiest to decompose to most difficult to decompose)
B rarrD rarrArarr C
Reactivity (most reactive to least reactive)
C (most reactive) gt A gt D gt B (least reactive)
60
WEEK 6 LESSON 1 Worksheet Answers
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
Potassium Zinc Copper
Calcium Lead Gold
Magnesium Iron
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
Aluminium is extracted from its ore bauxite through the process of electrolysis
Cryolite is added to bauxite to lower the melting point to about 900 0C The melting point of
bauxite is very high (about 2040 0C) It is difficult and expensive to keep the molten aluminium
oxide at this temperature
Reaction at the cathode Al3+ (l) + 3 e- Al (l)
61
WEEK 6 LESSON 2 Worksheet Answers
(a) What are the three raw materials that are added through the top of the blast
furnace during the extraction process for iron
Coke (carbon)
iron ore (haematitie mainly iron (II) oxide)
limestone (calcium carbonate)
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
Coke ndash coke burns to produce carbon dioxide The carbon dioxide further reacts with coke to
form carbon monoxide (reducing agent in the process)
C (s) + O2 (g) CO2 (g)
C (s) + CO2 (g) 2 CO
Haematite ndash iron ore provides the iron which is reduced by the carbon monoxide to produce
iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + CO2 (g)
Limestone ndash decomposes to form calcium oxide The calcium oxide reacts with the impurity
silicon dioxide to form slag (calcium silicate)
CaCO3 (s) CaO (s) + CO2 (g)
CaO (s) + SiO2 (l) CaSiO3(l)
62
WEEK 6 LESSON 3 Worksheet Answers
(a) Define the term alloy
An alloy is a material made from a mixture of two or more metals
(b) State 3 general advantages that alloys have over the individual metals they are made
from
They are harder stronger and more resistant to corrosion
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
1 High strength
2 Low density
Uses
1 Used to make aircraft bodies
2 Used to make space satellites
63
WEEK 7 LESSON 1 WORKSHEET ANSWERS
(a) Define the term corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
The paint forms a barrier which stops contact with air or water and the iron Hence rusting
will not take place
However when the paint is scratched that part of the iron nail is exposed to air or water and
rusting will take place
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
Magnesium is higher in the electrochemical series and will be oxidised in preference to iron
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
Aluminium is partly protected from corrosion by its coat of aluminium oxide However as the
iron rust it flakes and fall off and the rusting process continues
64
WEEK 7 LESSON 2 WORKSHEET ANSWERS
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
Magnesium is the ion found in chlorophyll Chlorophyll plays a vital part in the process of
photosynthesis A deficiency in magnesium will lead to low chlorophyll level in the tomato
plants and hence reduce the process of photosynthesis There will be less food storage and
hence will lead to smaller yield of tomatoes
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Any correct harmful effect of lead on health or environment
Any correct harmful effect of mercury on health or environment
65
WEEK 7 LESSON 3 WORKSHEET ANSWERS
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
(b) Write the ionic equation for the above reaction
2 Br- (aq) + Cl2 (aq) 2 Cl- (aq) + Br2 (aq)
(c) Identify the oxidising agent in the reaction
Cl2 (aq)
(d) Justify your answer in part (c) in terms of oxidation number
There is a reduction of the oxidation number for chlorine from 0 to ndash1
hence it has been reduced Therefore chlorine is the oxidising agent
66
WEEK 8 LESSON 1 WORKSHEET ANSWERS
Describe the laboratory preparation of oxygen gas
Oxygen is prepared in the laboratory by the decomposition of hydrogen peroxide
A suitable catalyst is manganese (IV) oxide
Drying agent silica gel OR anhydrous calcium chloride OR conc sulphuric acid
The gas is collected by downward delivery since oxygen is slightly denser than air
Balanced chemical equation 2 H2O2 (aq) 2 H2O (l) + O2 (g)
67
WEEK 8 LESSON 2 WORKSHEET ANSWERS
Describe the laboratory preparation of carbon dioxide gas
Carbon dioxide is commonly prepared in the laboratory by the reacting hydrochloric acid and
marble chips (calcium carbonate)
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
The carbon dioxide gas is collected by downward delivery since it is denser than air
Balanced chemical equation
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
68
WEEK 8 LESSON 3 WORKSHEET ANSWERS
Describe the laboratory preparation of ammonia gas
An ammonium salt (ammonium chloride) and a base (sodium hydroxide) are mixed together and
heated
Calcium oxide is used as the drying agent Calcium chloride and concentrated sulphuric acid
cannot be used since ammonia can react with them
The gas is collected by upward delivery since ammonia is less dense than air
Balanced chemical equation
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
69
WEEK 9 LESSON 1 WORKSHEET ANSWERS
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Carbon dioxide Put out fires
Oxygen Welding metals
Carbon dioxide Create lsquofizzrsquo in drinks
Oxygen Used in steel production
Oxygen Aerobic respiration
70
WEEK 9 LESSON 2 WORKSHEET ANSWERS
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Chlorine Used to make sodium hypochlorite
Sulphur Used as a fungicide on plant materials
Carbon (graphite) Used for lsquoleadrsquo in pencils
Phosphorus Used in the manufacture of bronze alloys
Nitrogen Used in the manufacture of nitric acid
Silicon Used in the manufacture of computer chips
Nitrogen Phosphorus Used to make fertilisers
71
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
Green Chemistry is using principles that reduceeliminate the use of hazardous materials in
the design manufacture and application of chemical products
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
Makes the environment safer
Reduces waste
Creates new jobs
Reduces respiratory illnesses
Atom economy
72
WEEK 10 LESSON 2 WORKSHEET ANSWERS
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P Cu2+ Q Fe2+
R Fe3+ S Ca2+
Ionic equation for R + NaOH
Fe3+ (aq) + 3 OH- (aq) Fe(OH)3 (s)
73
WEEK 10 LESSON 3 WORKSHEET ANSWERS
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A Fe3+ B Ca2+ C Al3+ Pb2+
(b) State the inference after Test 2
C Pb2+
(c) Write an ionic equation to support your answer in (b) above
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
11 Qualitative Analysis
ndash Test for gases
Qualitative Analysis
ndash Identification of
anions
Qualitative Analysis
ndash Identification of
anions
12 Problem solving of
Past CSEC Chemistry Paper 2
on topics completed in the term
13
14
15
2
WEEK 11 LESSON 1
TOPIC Qualitative Analysis ndash Test for gases
Identification of gases
Gas Colour Odour Effect on moist
litmus
Method of identification
Oxygen
O2
Colourless Odourless Neutral ndash no
effect
Relights a glowing splint
Hydrogen
H2
Colourless Odourless Neutral ndash no
effect
Lighted splint lsquopopsrsquo if air is also
present
Carbon
dioxide
CO2
Colourless Odourless Weakly acidic ndash
blue to slightly
red
A white precipitate forms in
limewater
Ca(OH)2 (aq) + CO2
CaCO3 (s) + H2O (l)
Precipitate redissolves on
continued bubbling
CaCO3 (s) + H2O (l) + CO2 (g)
Ca(HCO3)2 (aq)
Ammonia
NH3
Colourless Pungent Alkaline ndash red
to blue (only
common
alkaline gas)
Turns moist red litmus blue forms
dense white fumes with hydrogen
chloride gas
NH3 (g) + HCl (g) NH4Cl (s)
Gas Colour Odour Effect on moist
litmus
Method of identification
3
Sulphur
dioxide
SO2
Colourless Choking
smell
Acidic ndash blue to
red
Turns acidified potassium
manganate (VII) solution from
purple to colourless
Turns acidified potassium
dichromate (VI) solution from
orange to green
Chlorine
Cl2
Yellow ndash
green
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Bromine
Br2
Red ndash
brown
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Nitrogen
dioxide
NO2
Red ndash
brown
Irritating
smell
Acidic blue to
red
Turns moist blue litmus red but
does not bleach it
Water
vapour
H2O
Colourless Odourless Neutral ndash no
effect
Turns anhydrous cobalt (II)
chloride from blue to pink
Turns anhydrous copper (II)
sulphate from white to blue
4
WEEK 11 LESSON 1 WORKSHEET
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless
Yellow ndash green
Red ndash brown
Gases according to their odour
Odour of gas Identity of gas
Odourless
Pungent smell
Choking smell
Irritating smell
5
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect
Red to blue
Blue to red
Blue to red then bleaches it
6
WEEK 11 LESSON 2
TOPIC Qualitative Analysis ndash Identification of anions
Effect of heating
Method Heat a sample of the solid in a dry test tube
Effect of heating
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) not
of K or Na
CO32- (s) O2- (s) + CO2 (g)
Oxygen evolved NO3- of K or Na 2 NO3
- (s) 2 NO2- (s) + O2
(g)
Oxygen and nitrogen
dioxide evolved
NO3- of Ca and below
in reactivity series
4 NO3- (s) 2 O2- (s) + 4 NO2
(g) + O2
(g)
Sulphur dioxide evolved SO32- SO3
2- O2- (s) + SO2 (g)
Effect of dilute acid
Add dilute hydrochloric acid or nitric acid to a sample of the solid Warm if no reaction occurs
when cold
Effect of dilute acid
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) CO32- (s) + 2 H+ (aq) H2O (l) + CO2 (g)
Sulphur dioxide evolved SO32- SO3
2- (s) + 2 H+ (aq) H2O (l) + SO2 (g)
7
Effect of concentrated acid
Add concentrated sulphuric acid to a sample of the solid Warm if not reaction occurs when cold
Effect of concentrated sulphuric acid
Observation Anion
Carbon dioxide evolved CO32- or HCO3
-
Sulphur dioxide evolved SO3-
Hydrogen chloride evolved Cl-
Hydrogen bromide (colourless) and bromine
vapour (brown) evolved
Br-
Black iodine present and purple iodine vapour
evolved
I-
8
WEEK 11 LESSON 2 WORKSHEET
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater
Produces a gas which relights a glowing splint as the only gas
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green
Produces a gas forms a precipitate in limewater
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia
Black iodine present and purple iodine vapour evolved
9
WEEK 11 LESSON 3
TOPIC Qualitative Analysis ndash Identification of anions
Test for the halides ndash using silver nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous silver nitrate and
observe the precipitate Add ammonia solution and observe the solubility of the precipitate
Test for halides using silver nitrate solution
Effect of silver
nitrate solution
Anion Explanation Effect of aqueous
ammonia
White precipitate ndash
turns white in
sunlight
Cl- Ag+ (aq) + Cl- AgCl (s) Precipitate soluble
Cream precipitate ndash
turns yellow ndash green
in sunlight
Br- Ag+ (aq) + Br- AgBr (s) Precipitate slightly
soluble
Pale yellow
precipitate
I- Ag+ (aq) + I- AgI (s) Precipitate insoluble
Test for the halides ndash using lead nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous lead nitrate and
observe the precipitate
Test for halides using lead nitrate solution
Effect of lead nitrate solution Anion Explanation
White precipitate Cl- Pb2+ (aq) + 2 Cl- PbCl2 (s)
Pale yellow Br- Pb2+ (aq) + 2 Br- PbBr2 (s)
Deep yellow I- Pb2+ (aq) + 2 I- PbI2 (s)
10
Effect of barium nitrate or chloride solution followed by dilute acid
Make a solution of the solid Add barium nitrate or chloride solution and observe the precipitate
Add dilute hydrochloric or nitric acid warn if necessary and observe the solubility of the
precipitate
Effect of barium nitrate or chloride solution followed by dilute acid
Effect of
Ba(NO3)2 (aq)
or BaCl2 (aq)
Effect of HCl (aq)
or HNO3 (aq)
Anion Explanation
White precipitate Precipitate insoluble SO42- Ba2+ (aq) + SO4
2- (aq) BaSO4 (s)
BaSO4 does not react with dilute acids
White precipitate Precipitate soluble ndash
CO2 evolved
CO32- Ba2+ (aq) + CO3
2- (aq) BaCO3 (s)
BaCO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + CO2 (g)
White precipitate Precipitate soluble ndash
SO2 evolved on
warming
SO32- Ba2+ (aq) + SO3
2- (aq) BaSO3 (s)
BaSO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + SO2 (g)
11
WEEK 11 LESSON 3 WORKSHEET
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
(Ionic equation required)
12
WEEK 12 LESSON 1 WORKSHEET
(a) The Caribbean islands are known for their many resources For example the ore of
aluminium is found in Jamaica and Guyana
(i) Briefly describe the extraction of aluminium from its named ore Include in your
description one ionic equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Although aluminium ore is mined in the Caribbean the extraction of aluminium usually
takes place in other countries Suggest ONE reason why it may be difficult to extract
aluminium in the Caribbean
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) An alloy can be described as a lsquomixed metal solutionrsquo Aluminium forms an alloy with
magnesium that is used to make an aircraft
13
Identify this alloy and suggest why it is better to use it rather than the pure metal in the
manufacture of aircraft
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) ldquoSome metals can be useful to man yet harmful to the environmentrdquo Comment on this
statement with reference to mercury
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 12 LESSON 2 Worksheet
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate formed
Soluble in excess
15
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate formed
Insoluble in excess
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate formed
(Ionic equation required)
16
WEEK 12 LESSON 3 Worksheet
Dry ammonia gas can be produced in a school laboratory
(a) Identify TWO reagents that are necessary for the laboratory production of ammonia
______________________________________________________________________________
______________________________________________________________________________
(b) Two common drying agents used in the laboratory are calcium oxide and concentrated
sulphuric acid However calcium oxide is the preferred choice for drying ammonia gas
Explain why concentrated sulphuric acid is now used Include in your answer a balanced
chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) When gases are prepared in the laboratory there are three main ways in which they can
be collected
- Upward delivery
- Downward delivery
- Displacement of water
(i) What TWO other factors should be considered when choosing an appropriate method for
the collection of gases in the laboratory
______________________________________________________________________________
______________________________________________________________________________
(ii) Identify ONE of the three methods that is best suited for the collection of ammonia gas in
the laboratory Explain why EACH of the other two methods would NOT have been
appropriate
______________________________________________________________________________
17
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(d) Hence draw a labelled diagram of the apparatus which could be used for the preparation
of dry ammonia in the laboratory
Be sure to identify in your diagram
- where the reagents are placed
- where the ammonia is dried and
- where the ammonia is collected
18
WEEK 13 LESSON 1 Worksheet
(a) In solution two metals A and B form A+ and B2+ ions respectively Metal A displaces Fe
from a solution containing Fe2+ ions but metal B does NOT
(i) Arrange the metals A B and Fe in order of reactivity from LEAST reactive to MOST
reactive Write a balanced chemical equation to show the reaction between metal A and
Fe2+ ions
______________________________________________________________________________
______________________________________________________________________________
(ii) Metal A is placed in a solution of copper (II) sulphate CuSO4 (aq) Write an equation for
the reaction State ONE observable change that will occur and explain why this reaction
takes place
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) For EACH metal A and B state ONE method that can be used to extract it from its
respective oxide Give a reason for EACH answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
19
______________________________________________________________________________
(b) Metal alloys are often used for making objects found in our daily lives Name an alloy of
iron and state ONE of its uses
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 13 LESSON 2 Worksheet
(a) Many important biological processes in plants and animals depend on the specific roles
of certain metal ions
(i) Farmer Jones reaped a crop of tomatoes and reported that the yield was far below what
was expected Analysis of the soil revealed that there was a deficiency of magnesium
Discuss the importance of magnesium in plant health and explain how a magnesium
deficiency can result in the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE other metal ion which is important to plant health and state the result of its
deficiency
______________________________________________________________________________
______________________________________________________________________________
21
(b) Many years ago car exhaust fumes were known to contain compounds of metals and
non ndash metals which could negatively impact both humans and the environment Identify
ONE metal and ONE non ndash metal whose compounds were present in car exhaust fumes
Discuss the effect of these compounds on human health and the environment
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) Define lsquogreen chemistryrsquo and discuss the measures that have been taken to produce a
lsquogreenerrsquo automotive fuel
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
22
WEEK 13 LESSON 3 Worksheet
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
Zn2+ ions are present
23
WEEK 14 LESSON 1 Worksheet
(a) Metal alloys are often used in place of metals because of their enhanced properties
(i) Define the term lsquoalloyrsquo
______________________________________________________________________________
______________________________________________________________________________
(ii) Name ONE alloy of aluminium and state its use based on one of its enhanced properties
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) A student conducted an experiment to investigate the reactivity of each of the following
metals (copper iron zinc and lead) by using solutionPs of their sulphate salts
The data presented in the table below shows whether a visible chemical reaction took
place when each metal was added to the four sulphate solutions
Key Visible chemical reaction took place
X No visible chemical reaction
CHEMICAL REACTION OF METALS IN SULPHATE SOLUTIONS
Sulphate solution Cu Fe Zn Pb
CuSO4 X
FeSO4 X X X
ZnSO4 X X X X
PbSO4 X X
24
(i) State which of the TWO metals is more reaction Fe or Zn Give a reason for our answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Using the data in the previous Table deduce the order of reactivity of the four metals Cu
Fe Zn and Pb from the most reactive to the least reactive metal
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The student recorded the following observations from the reaction between the iron and
copper (II) sulphate solution
Observations Reddish ndash brown solid coating formed on the iron strip
Blue colour of the solution changed to dirty green
Account for the observations made from the reaction between the iron and copper (II)
sulphate solution
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iv) Write an ionic equation including state symbols for the reaction between the iron and
copper (II) sulphate solution
______________________________________________________________________________
25
(c) Some metal compounds are health and environmental hazards
(i) Identify which of the metals used in the experiment in (b) is MOST hazardous to the
environment
______________________________________________________________________________
______________________________________________________________________________
(ii) State TWO harmful effects of continuous exposure to the metal identified in (c) (i) on
human beings
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
26
WEEK 14 LESSON 2 Worksheet
(a) Carbon is found in the form of diamond and graphite and is a main component in many
naturally occurring compounds such as organic matter and carbon dioxide gas
(i) State ONE way in which diamond differs physically from graphite
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE similarity between diamond and graphite other than they both contain carbon
______________________________________________________________________________
______________________________________________________________________________
(b) Carbon can react with a limited supply of oxygen to form carbon monoxide which can
negatively affect human health
(i) Write a balanced chemical equation including state symbols to show the formation of
carbon monoxide
______________________________________________________________________________
(ii) State TWO effects of carbon monoxide inhalation on the human body
______________________________________________________________________________
______________________________________________________________________________
(c) Jamal wants to prepare and collect a sample of carbon dioxide gas in the laboratory using
calcium carbonate
(i) Write a balanced chemical equation including state symbols for the laboratory
preparation of carbon dioxide gas from calcium carbonate
______________________________________________________________________________
______________________________________________________________________________
(ii) Draw a clearly labelled diagram to show the arrangement of the apparatus and materials
that could be used in the laboratory to prepare and collect the carbon dioxide gas
(iii) State ONE use of carbon dioxide as it relates to the beverage industry
______________________________________________________________________________
27
WEEK 14 LESSON 3 Worksheet
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
(Ionic equation required)
Suggest a possible identity of the solid R __________________________
28
WEEK 15 LESSON 1 Worksheet
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a small
portion of solid Y gently at
first and then strongly
Colourless gas evolved
with a choking odour
Turns acidified potassium
dichromate solution from
orange to green
(ii) To the remaining portion
of solid Y add 20 cm3 of
distilled water stir to dissolve
and filter Collect the filtrate
and divide into 3 equal
portions
Filtrate is pale green in
colour
(iii) To the first portion of the
filtrate from (ii) add aqueous
sodium hydroxide slowly
until in excess
A green precipitate
Insoluble in excess sodium
hydroxide
Ionic equation required
29
TEST OBSERVATIONS INFERENCES
(iv) To the second portion of
the filtrate from (ii) add
aqueous silver nitrate
followed by aqueous
ammonia
White precipitate
Soluble in aqueous
ammonia
(v) To the third portion of the
filtrate from (ii) add aqueous
barium nitrate followed by
aqueous hydrochloric acid
White precipitate formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with the
evolution of a colourless
gas with a choking smell
30
WEEK 15 LESSON 2 Worksheet
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
31
WEEK 15 LESSON 3 Worksheet
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in excess
aqueous NH3
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change
32
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
warm filter and then divide
the filtrate into two portions
Vigorous effervescence
observed upon addition of
dilute HNO3
Gas evolved turns lime water
cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Cu2+ ions present
33
ANSWERS TO WORKSHEETS
34
WEEK 11 LESSON 1 WORKSHEET ANSWERS
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless O2 H2 CO2 NH3 SO2 H2O
Yellow ndash green Cl2
Red ndash brown Br2 NO2
Gases according to their odour
Odour of gas Identity of gas
Odourless O2 H2 CO2 H2O
Pungent smell NH3
Choking smell SO2 Cl2 Br2
Irritating smell NO2
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect Neutral O2 H2 H2O
Red to blue Alkaline NH3
Blue to red Acidic CO2 SO2 NO2
Blue to red then bleaches it Acidic Cl2 Br2
35
WEEK 11 LESSON 2 WORKSHEET ANSWERS
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-) not
of K or Na
Produces a gas which relights a glowing splint as the only gas NO3- of K or Na
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green SO32-
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-)
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia Cl-
Black iodine present and purple iodine vapour evolved I-
36
WEEK 11 LESSON 3 WORKSHEET ANSWERS
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Br-
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
Cl-
Ag+ (aq) + Cl- AgCl (s)
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow Br-
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
SO42-
Ba2+ (aq) + SO42- (aq)
BaSO4 (s)
(Ionic equation required)
37
WEEK 12 LESSON 1 Worksheet Answers
(a) (i)
The ore bauxite is purified
The purified bauxite is dissolved in molten cryolite
The aluminium oxidecryolite solution is then eletrolysed
Equation at the cathode Al3+ (l) + 3 e- Al (l)
Equation at the anode 2 O2- (l) ndash 4 e- O2 (g)
(ii) The process is too expensive mainly because too much electricity or energy is needed
(b) The alloy of Al and Mg is magnalium It is less dense than the pure metals and hence allow
aircraft to be lighter It is also stronger than the pure metals and hence allows aircraft to last
longer since it is not easily destroyed
(c) Your answer should cater for the following aspects
Benefits of mercury to humans for example in thermometers barometers in dentistry
and gold mining
Entry of mercury to the environment For example this could have been through broken
thermometers barometers or lightbulbs or improper disposal of them or batteries and
indiscriminate use in gold mining in Guyana
The identification of a negative impact on the environment such as poisoned fish and the
persons who eat the fish death mood swings and psychosis
38
WEEK 12 LESSON 2 Worksheet Answers
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas
evolved
NO2 evolved OR nitrates
present OR
Br2 gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate
formed
Soluble in excess
Pb2+ Zn2+ Al3+ or Ca2+
present
Pb2+ Zn2+ Al3+ or present
39
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate
formed
Insoluble in excess
Pb2+ Zn2+ Al3+ or present
Pb2+ or Al3+ present
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate
formed
Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
40
WEEK 12 LESSON 3 Worksheet Answers
(a) an ammonium salt and a strong alkali
(b) Ammonia is basic and it will react with H2SO4
Equation 2 NH3 (aq) + H2SO4 (aq) (NH4)2SO4 (aq)
(c) (i) ndash Density of the gas relative to air ndash The solubility of the gas in water
(ii) Ammonia is collected by upward delivery
It cannot be collected by downward delivery since ammonia is less dense than air
It cannot be collected by displacement of water since it is soluble in water
(d)
41
WEEK 13 LESSON 1 Worksheet Answer
a) i) B ˂ Fe ˂ A
2A (s) + Fe 2+ (aq) rarr 2A+ (aq) + Fe (s)
ii) 2A (s) + CuSO4 (aq) rarr A2SO4 (aq) + Cu (s)
Observation blue colour fades gets lighter OR brown solid forms is deposited OR metal A
decreases in size dissolves
Explanation Metal A is higher (than Fe which is higher) than Cu in the reactivity series OR
Metal A is more reactive (than Fe which is more reactive) than Cu so Metal A can displace Cu
iii) Metal A can be extracted by electrolysis (of its molten oxide) because Metal A is a very
reactive metal is high in the reactivity series forms stable oxides needs a lot of energy to be
extracted and very reactive metals are extracted by electrolysis
Metal B can be extracted by heating with carbon carbon monoxide OR by chemical reduction
of the oxide because Metal B is less reactive than Fe is low in the reactivity series forms less
stable oxides does not need a lot of energy to be extracted and oxides of less reactive metals are
easily reduced
b) Alloy of iron steel
Use of alloy making buildings bridges ships motor vehicles furniture utensils
42
WEEK 13 LESSON 2 Worksheet Answer
(a) (i)
Magensium is the metal ion found in chlorophyll
Chlorophyll is essential for photosynthesis
A deficiency in magnesium will result in low chlorophyll yellow leaves and a reduction in
photosynthesis
Hence there will be low carbohydrates or energy production
Hence small fruits stunted growth and lower yield will result
(ii)
Metal ion Results of deficiency
Potassium Stunted growth premature loss of leaves yellowing of leaves curling of leaf tips
Calcium Growth abnormalities in tips of roots and shoots curling of leaves
Iron Yellowing of leaves
Zinc Low chlorophyll content yellowing of leaves
Manganese Yellowing of leaves poor flavors in some crops for example potato
(b)
Metal Lead is present in some types of gasoline Upon combustion lead compounds escape into
the atmosphere It accumulates in body tissues and slowly poisons the person It causes mental
illness
Non ndash metal SulphurSulphur dioxide or NitrogenNitrogen dioxide
Dissolves in rain water to form acid rain or cause respiratory illnessproblems Acid rain can
cause corrosion damage in buildings
(c)
Green chemistry is the utilisation of a set of principles that reduces or eliminates the use or
generation of hazardous substances
43
Automotive fuels are now produced without lead so as to eliminate the release of lead
compounds into the atmosphere
Low sulphur fuel is being produced with much reduced sulphur content which causes a reduction
of sulphur dioxide release into the atmosphere
44
WEEK 13 LESSON 3 Worksheet Answer
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
gas turns litmus blue
red
brown gas
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
white precipitate
precipitate soluble in
excess
Zn2+ ions are present
45
WEEK 14 LESSON 1 Worksheet Answers
(a)(i) An alloy is a material made from a mixture of two or more metals
(ii) Any suitable answer chosen from below
Alloy Enhance Property Use
Duralumin High strength
Low density
Light
Hard
Used to make aircraft bodies
space satellites
Magnalium Light
Hard
Easier to weld
Corrosion resistant
Strong
High ductability
Used in pyrotechnics
(fireworks)
Mirrors
Aircraft parts
To make scientific
instruments
Used to make marine castings
Alchlad Strong
Corrosion resistant
Cladding for buildings
(b) (i) Zinc is more reactive than iron
Zinc displaces iron from iron (II) sulphate
Zinc is higher in the reactivity series than iron
Iron does not displace zinc from zinc sulphate
(ii) Order of reactivity Zn gt Fe gt Pb gt Cu
(iii) Reddish brown solid ndash copper metal formed
46
Dirty green solution ndash presence of Fe2+ ion
(iv) Fe (s) + Cu2+ (aq) Fe2+ (aq) + Cu (s)
(c) (i) Lead
(ii) Any two correct harmful effects of lead on the body
Impedes brain development (in young children)
Affectimpede development of the immune system in humans
Affecthamper development of nervous system in humans
Long term exposure can result in kidney and liver damage
Mental retardation
Anaemia
Death
47
WEEK 14 LESSON 2 Worksheet Answers
a) i) Diamond is transparent clear Graphite is opaque black
OR hard OR brittle
OR does not conduct electricity OR conducts electricity
a) ii) Both have a macromolecular giant molecular giant covalent structure (lattice)
OR Both have high melting point boiling point
OR Both are insoluble in water organic solvent
b) i) 2C (s) + O2 (g) rarr 2CO (g)
ii) CO reduction in amount of oxygen carried by (the haemoglobin in the red blood
cells of) the blood
Headache OR dizziness OR nausea OR fatigue OR loss of consciousness OR
death
c) i) CaCO3 (s) + 2HCl (aq) rarr CaCl2 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) + H2SO4 (aq) rarr CaSO4 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) rarr CaO (s) + CO2 (g)
48
ii)
OR
OR
Entirely closed system thistle funnel below the level of the liquid OR tap that could be
closed
Two reagents labelled CaCO3marble chips and HCl H2SO4 or heat source
collection of CO2 upward displacement of air OR over watersulphuric acid OR in gas
syringe
iii) CO2 use put in aerated drinks carbonated beverages
OR put in carbon dioxide fire extinguishers
49
WEEK 14 LESSON 3 Worksheet Answers
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
NH4+
NH4+ confirmed OR
NH3 (g) produced
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
Cl- ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation required)
Suggest a possible identity of the solid R NH4Cl (ammonium chloride)
50
WEEK 15 LESSON 1 Worksheet Answers
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a
small portion of solid Y
gently at first and then
strongly
Colourless gas
evolved with a
choking odour
Turns acidified
potassium dichromate
solution from orange
to green
SO2 evolved
Presence of a sulphite
(ii) To the remaining
portion of solid Y add 20
cm3 of distilled water stir
to dissolve and filter
Collect the filtrate and
divide into 3 equal portions
Filtrate is pale green
in colour
Fe2+ ions present
(iii) To the first portion of
the filtrate from (ii) add
aqueous sodium hydroxide
slowly until in excess
A green precipitate
Insoluble in excess
sodium hydroxide
Fe2+ ions present
Fe2+ (aq) + 2 OH- (aq) Fe(OH)2 (s)
Ionic equation required
TEST OBSERVATIONS INFERENCES
(iv) To the second portion
of the filtrate from (ii) add
aqueous silver nitrate
White precipitate
Soluble in aqueous
ammonia
Cl- ions present
51
followed by aqueous
ammonia
(v) To the third portion of
the filtrate from (ii) add
aqueous barium nitrate
followed by aqueous
hydrochloric acid
White precipitate
formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with
the evolution of a
colourless gas with a
choking smell
SO32- CO3
2- SO42- ions present
SO32- ions present
52
WEEK 15 LESSON 2 Worksheet Answers
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
Chloride ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
Cu2+ ions present
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
X contains a reducing agent
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
SO32- SO4
2- or CO32- ions are
present
SO32- ions are present
53
WEEK 15 LESSON 3 Worksheet Answers
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
White ppt
Ppt soluble in excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in
excess aqueous NH3
Al3+ Pb2+ Zn2+ present
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change Cl- Br- I- absent
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
Vigorous effervescence
observed upon addition of
dilute HNO3
CO2 evolved OR
Carbonate present
54
warm filter and then divide
the filtrate into two portions
Gas evolved turns lime
water cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
Cu2+ (aq) + OH- (aq)
Cu(OH)2 (s)
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Blue ppt
ppt dissolves in excess
NH3 to give a deep blue
solution
Cu2+ ions present
55
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
REFERENCES
Hunte-King J Maragh P Nagir F amp Norris R (2013) Chemistry for CSEC United
Kingdom Nelson Thornes Ltd
Remy C Mason L Lambert N amp Mohammed M (2007) Chemistry for CSEC England and
Wales Pearson Education Limited
Taylor M amp Chung-Harris T (2010) CXC Chemistry England Macmillan Publishers
Limited
Tindale A (2016) Chemistry A Concise Revision for CXC London HarperCollins Publishers
Limited
4
Differences between metals and non ndash metals
Metals Non ndash metals
Good conductor of electricity Do not conduct electricity
except graphite (carbon)
Good conductor of heat Do not conduct heat except graphite (carbon)
Lustrous solids at room temperature
(except mercury)
Solid liquid or gas at room temperature
eg iodine (solid) bromine (liquid) and
chlorine (gas) at room temperature
Malleable (can be beaten into different
shapes)
Not malleable
Ductile (can be drawn into wires) Not ductile
Sonorous (ring when hit with a hard object) Not sonorous
High melting and boiling points Low melting and boiling points compared to
metals
High density Much lower density at rtp compared to metals
5
WEEK 1 LESSON 1 WORKSHEET
Shade the letter next to the answer you choose for questions 1 to 4
1 Which of the following are metals
I Bromine
II Sodium
III Neon
IV Iron
(A) I and III (B) II and IV (C) I and IV (D) II and III
2 Which of the following are non ndash metals
I Chromium
II Carbon
III Iodine
IV Potassium
(A) I and III (B) II and IV (C) I and IV (D) II and III
3 A metal that is a liquid at room temperature is
(A) mercury (B) tin (C) magnesium (D) sodium
6
4 Consider the following information about four substances
Substance Melting point
0C
Electrical conductivity Water
solubility in solid in liquid
I 1050 Low High High
II 75 Low Low Low
III 1234 High High Low
IV 1913 Low Low Low
The substance which is MOST likely to be a metal is
(A) I (B) II (C) III (D) IV
5 Read the following and answer the question that follows
A new element was discovered to have the following properties
Lustrous solid
Can be beaten into shapes
High density
(a) Based only on the facts stated above is the element a metal or non metal
_______________________
(b) State 3 other properties that you expect this element to exhibit
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
7
WEEK 1 LESSON 2
TOPIC Physical properties of metals
Physical properties of some metals
Metals Melting point 0C
Boiling point
0C
Density
g cm-3
Other characteristics
Sodium 90 900 097 Very soft grey metal
Calcium 850 1487 153 Grey metal
Magnesium 650 1103 174 Soft grey metal
Aluminium 660 2350 270 Grey metal
Zinc 419 907 719 White metal
Iron 1535 2760 797 Dark grey metal
Copper 1083 2580 894 Gold coloured metal
conductivity second only to
silver
Sodium Calcium Magnesium Aluminium
Zinc Iron Copper
8
WEEK 1 LESSON 2 WORKSHEET
A group of students carried out an experiment to find the density of three different metals
aluminium calcium and an unknown metal X They measured the mass of each metal sample
using a balance The volumes of the metals were determined by displacement of oil The results
of their experiment are as follows
Aluminium Calcium Metal X
Mass (g) 100 100 100
Final volume (cm3) 335 365 310
Initial volume (cm3 300 300 300
Volume of metal (cm3)
Density (gcm-3)
Complete the table using the following formulae
Volume of metal = Final volume ndash Initial volume
Density = 119872119886119904119904
119881119900119897119906119898119890
Arrange the metals in order of increasing density _____________________________________
9
WEEK 1 LESSON 3
TOPIC Chemical properties of metals
Action of oxygen
Most metals react with oxygen or air to form the corresponding oxide These oxides are basic
oxides with the exception of aluminium zinc and lead which form amphoteric oxides Metals
lower in the electrochemical series do not react
Metal Reaction with air or oxygen
Potassium K
Burn very easily forming oxide
eg 4 Na (s) + O2 (g) 2 Na2O (s)
Sodium Na
Calcium Ca
Magnesium Mg
Aluminium Al
Burn especially if powered forming oxide
eg 4 Al (s) + 3 O2 (g) 2 Al2O3 (s)
Zinc Zn
Iron Fe
Lead Pb Do not burn form oxide when heated strongly
Copper Cu
Silver Ag No reaction
10
WEEK 1 LESSON 3 WORKSHEET
Write balanced chemical equations for the reaction of the named metals and air or oxygen
State the nature of the oxide formed (basic or amphoteric)
Potassium + Oxygen
______________________________________________________________________________
Sodium + Oxygen
______________________________________________________________________________
Calcium + Oxygen
______________________________________________________________________________
Magnesium + Oxygen
______________________________________________________________________________
Aluminium + Oxygen
______________________________________________________________________________
Zinc + Oxygen
______________________________________________________________________________
11
Iron + Oxygen
______________________________________________________________________________
Lead + Oxygen
______________________________________________________________________________
Copper + Oxygen
______________________________________________________________________________
Silver + Oxygen
______________________________________________________________________________
12
WEEK 2 LESSON 1
TOPIC Chemical properties of metals
Action of water
Metals high in the electrochemical series react with cold water to produce the metal hydroxide
and hydrogen
Reactive metals slightly lower in the electrochemical series react very slowly or not at all with
water However they may react with hot water or steam to produce the corresponding metal
oxide and hydrogen
Metals lower than hydrogen in the electrochemical series do not react with water
Metal Reaction with water or steam
Potassium K React with cold water forming metal hydroxide and hydrogen
eg Ca (s) + 2 H2O (l) Ca(OH))2 (aq) + H2 (g) Sodium Na
Calcium Ca
Magnesium Mg React with steam forming metal oxide and hydrogen
eg Zn (s) + H2O (g) ZnO (s) + H2 (g) Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
13
WEEK 2 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with water (or
steam if reaction does not occur with water)
Potassium + WaterSteam
______________________________________________________________________________
Sodium + WaterSteam
______________________________________________________________________________
Calcium + WaterSteam
______________________________________________________________________________
Magnesium + WaterSteam
______________________________________________________________________________
Aluminium + WaterSteam
______________________________________________________________________________
Zinc + WaterSteam
______________________________________________________________________________
14
Iron + WaterSteam
______________________________________________________________________________
Copper + WaterSteam
______________________________________________________________________________
Silver + WaterSteam
______________________________________________________________________________
15
WEEK 2 LESSON 2
TOPIC Chemical properties of metals
Action of dilute acids
Metals above hydrogen in the electrochemical series react with dilute acids to form a salt and
hydrogen gas They react with hydrochloric acid to form the metal chloride (a salt) and hydrogen
gas They also react with dilute suphuric acid to form the metal sulphate (a salt) and hydrogen
gas
Metal Reaction dilute hydrochloric or sulphuric acid
Potassium K Violent reaction forming a salt and hydrogen gas
eg 2 Na (s) + 2 HCl (aq) 2 NaCl (aq) + H2 (g) Sodium Na
Calcium Ca Vigorous reaction forming a salt and hydrogen gas
eg Mg (s) + 2 HCl (aq) MgCl2 (aq) + H2 (g) Magnesium Mg
Aluminium Al React forming a salt and hydrogen gas
eg Fe (s) + 2 HCl (aq) FeCl2 (aq) + H2 (g) Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
16
WEEK 2 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with
hydrochloric acid
Metal Balanced equation for reaction with hydrochloric acid
Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Copper
Silver
17
WEEK 2 LESSON 3
TOPIC Reactions of metal compounds
Reactions of metallic oxides with dilute acid
Metal oxides react with dilute hydrochloric acid or sulphuric acid to produce a salt and water
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
Some of these reactions may be slow and can be speeded up by adding heat
For example
zinc oxide + hydrochloric acid zinc chloride + water
ZnO (s) + 2 HCl (aq) ZnCl2 (aq) + H2O (l)
magnesium oxide + hydrochloric acid magnesium chloride + water
MgO (s) + 2 HCl (aq) MgCl2 (aq) + H2O (l)
aluminium oxide + sulphuric acid aluminium sulphate + water
Al2O3 3 H2SO4 (aq) Al2(SO4)3 (aq) + 3 H2O (l)
calcium oxide + sulphuric acid calcium sulphate + water
CaO H2SO4 (aq) CaSO4 (aq) + H2O (l)
18
WEEK 2 LESSON 3 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal oxides with the
corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium oxide Hydrochloric acid
Sodium oxide Sulphuric acid
Calcium oxide Hydrochloric acid
Magnesium oxide Sulphuric acid
Aluminium oxide Hydrochloric acid
Zinc oxide Sulphuric acid
19
WEEK 3 LESSON 1
TOPIC Reactions of metal compounds
Reactions of metallic hydroxides with dilute acid
Metal hydroxides react with dilute acids to form a salt and water in a neutralisation reaction
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
For example
magnesium hydroxide + hydrochloric acid magnesium chloride + water
Mg(OH)2 (aq) + 2 HCl (aq) MgCl2 (aq) + 2 H2O (l)
sodium hydroxide + hydrochloric acid sodium chloride + water
NaOH (aq) + HCl (aq) NaCl (aq) + H2O (l)
potassium hydroxide + sulphuric acid potassium sulphate + water
2 KOH + H2SO4 (aq) K2SO4 (aq) + 2 H2O (l)
calcium hydroxide + sulphuric acid calcium sulphate + water
Ca(OH)2 (aq) + H2SO4 (aq) CaSO4 (aq) + 2 H2O (l)
20
WEEK 3 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal hydroxides with
the corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium hydroxide Hydrochloric acid
Sodium hydroxide Sulphuric acid
Calcium hydroxide Hydrochloric acid
Magnesium hydroxide Sulphuric acid
Aluminium hydroxide Hydrochloric acid
Zinc hydroxide Sulphuric acid
21
WEEK 3 LESSON 2
TOPIC Reactions of metal compounds
Reactions of metallic carbonates with dilute acid
Metal carbonates react with dilute acid to form a salt carbon dioxide and water When
hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric acid is
used the corresponding sulphate salt is formed
For example
sodium carbonate + hydrochloric acid sodium chloride + carbon dioxide + water
Na2CO3 (s) + 2 HCl (aq) 2 NaCl (aq) + CO2 (g) + H2O (aq)
calcium carbonate + hydrochloric acid calcium chloride + carbon dioxide + water
CaCO3 (s) + 2 HCl (aq) CaCl2 (aq) + CO2 (g) + H2O (aq)
zinc carbonate + sulphuric acid zinc sulphate + carbon dioxide + water
ZnCO3 (s) + H2SO4 (aq) ZnSO4 (aq) CO2 (g) + H2O (aq)
potassium carbonate + sulphuric acid potassium sulphate + carbon dioxide + water
K2CO3 (s) H2SO4 (aq) K2SO4 (aq) CO2 (g) + 2 H2O (aq)
22
WEEK 3 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal carbonates with
the corresponding acid
Metallic
carbonate
Acid Balanced chemical equation
Potassium
carbonate
Hydrochloric
acid
Sodium
carbonate
Sulphuric acid
Zinc
carbonate
Hydrochloric
acid
Magnesium
carbonate
Sulphuric acid
Aluminium
carbonate
Hydrochloric
acid
Calcium
carbonate
Sulphuric acid
23
WEEK 3 LESSON 3
TOPIC Action of heat on metal compounds
Action of heat on nitrates
All nitrates decompose when heated The reactivity of the metal in the metal nitrate influences
the products of the decomposition
The nitrates of the alkali metals (Group I) with the exception of lithium nitrate decompose to
form the metal nitrite and oxygen
The nitrates of most other metals decompose to form the metal oxide nitrogen dioxide and
oxygen
The nitrates of the very unreactive metals decompose to form the meal nitrogen dioxide and
oxygen
Metal Nitrate Decomposition
Potassium K Products metal nitrite + oxygen
eg 2 NaNO3 (s) Heatrarr 2 NaNO2 (s) + O2 (g)
Sodium Na
Calcium Ca
Products metal oxide + nitrogen dioxide + oxygen
eg 2 Pb(NO3)2 (s)
Heatrarr 2 PbO (s) + 4 NO2 (g) + O2 (g)
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Products metal + nitrogen dioxide + oxygen
eg 2 AgNO3 (s) Heatrarr 2 Ag (s) + 2 NO2 (g) + O2 (g)
24
WEEK 3 LESSON 3 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
nitrates
Metal Balanced chemical equation
Potassium nitrate
Sodium nitrate
Calcium nitrate
Magnesium nitrate
Aluminium nitrate
Zinc nitrate
Lead nitrate
Copper nitrate
Silver nitrate
25
WEEK 4 LESSON 1
TOPIC Action of heat on metal compounds
Action of heat on carbonates
Upon application of heat many carbonates decompose to form the metal oxide and carbon
dioxide
Group I carbonates do not decompose on heating with the exception of lithium carbonate
Metal Carbonate decomposition
Potassium K
Stable not decomposed by heat Sodium Na
Calcium Ca
Decompose forming metal oxide and carbon dioxide
eg CaCO3 (s) Heatrarr CaO (s) + CO2 (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Unstable
26
WEEK 4 LESSON 1 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
carbonates
Metal Balanced chemical equation
Potassium carbonate
Sodium carbonate
Calcium carbonate
Magnesium carbonate
Aluminium carbonate
Zinc carbonate
Iron carbonate
Lead carbonate
Copper carbonate
27
WEEK 4 LESSON 2
TOPIC Action of heat on metal compounds
Action of heat on the metal hydroxides
Most metal hydroxides decompose on heating A metal oxide and water are formed
Group I hydroxides do not decompose on heating with the exception of lithium hydroxide
Metal Hydroxide decomposition
Potassium K Stable not decomposed by heat
Sodium Na
Calcium Ca Decompose forming metal oxide and water (as steam)
eg Zn(OH)2 (s) Heatrarr ZnO (s) + H2O (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag No hydroxide exist
28
WEEK 4 LESSON 2 WORKSHEET
Write the balanced chemical equations for the thermal decomposition of the following
metal hydroxides
Metal hydroxide Balanced chemical equation
Potassium hydroxide
Sodium hydroxide
Calcium hydroxide
Magnesium hydroxide
Aluminium hydroxide
Zinc hydroxide
Lead hydroxide
Copper hydroxide
29
WEEK 4 LESSON 3
TOPIC Reactivity of metals ndash The Reactivity Series
The reactivity series of metals is a list of metals arranged in order of their reactivity based on
Displacement reactions
Reactions with oxygen dilute acids and water
Relative ease of decomposition of their compounds
Metals at the top of the series are the most electropositive They lose electrons very easily and
readily form cations These ions are very stable and are not easily discharged to form atoms Due
to this fact they are the most reactive metals
Metals at the bottom of the series are the least electropositive They do not lose electrons easily
and do not readily form ions Their ions are very unstable and are easily discharged to form
atoms They are the least reactive metals
The reactivity series of metals
Mnemonic Metal Symbol Reactivity
People Potassium K Most reactive
Least reactive
Sometimes Sodium Na
Collect Calcium Ca
Magazines Magnesium Mg
About Aluminium Al
Zoos Zinc Zn
In Iron Fe
London Lead Pb
Having (Hydrogen) H
Cute Copper Cu
Monkeys and Mercury Hg
Small Silver Ag
Gorillas Gold Au
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
5 Reactivity of metals Reactivity of metals Reactivity of metals
6 Extraction of metals Extraction of metals Alloys
7 Corrosion Importance of metals
and their compounds
on living systems and
environment
Chemical properties
of non ndash metals
8 Laboratory
preparation of gases
Laboratory
preparation of gases
Laboratory
preparation of gases
9 Uses of gases Uses of non ndash metals
and their compounds
Harmful effects of
non ndash metals and
their compounds on
living systems and
the environment
10 Green Chemistry Qualitative Analysis
ndash Identification of
cations
Qualitative Analysis
ndash Identification of
cations
2
WEEK 5 LESSON 1
TOPIC Reactivity of metals
Reactivity based on displacement reactions between metals and metal ions
A metal will displace a metal which is lower than itself in the reactivity series from a solution of
the metal salt
Reaction of zinc and copper (II) sulphate
Expected observations
Explanation
The size of the zinc metal decreases
The zinc metal is reacting and forming the
salt zinc sulphate
The solution becomes lighter eventually
colourless
The Cu2+ (aq) ions (responsible for the blue
colour) is reduced to Cu (s)
A brown solid is deposited at the bottom of
the container
Copper metal is formed
Equation Zn (s) + CuSO4 (aq) ZnSO4 (aq) + Cu (s)
Ionic equation
Zn (s) + Cu2+ (aq) Zn2+ (aq) + Cu (s)
Zinc is higher in the reactivity series than copper Therefore it will displace the copper ions in
the reaction above
3
Examples of other displacement reactions
Magnesium will displace Zn2+ ions in zinc sulphate since it is higher in the series than zinc
Mg (s) + Zn2+(aq) Mg2+ (aq) + Zn (s)
Silver will not displace Cu2+ ions in copper (II) sulphate [Cu is higher in the series than Ag]
Using the information above we can arrange the metals in order of their reactivity with
magnesium being the most reactive and silver the least reactive metal among the four metals
Mg gt Zn gt Cu gt Ag
Reactivity based on reaction with oxygen
The reactivity of metals can also be deduced from their reaction with oxygen
The table below gives the observations for the reaction with oxygen with the selected metals
Reaction of metal with oxygen
Metal Observation
Copper The surface turns black upon heating
Magnesium Ribbon burns very rapidly
Sodium Burns vigorously
Gold No reaction
Based on the observations for the 4 metals the metal with highest reactivity is sodium and the
metal with the least reactivity is gold
The 4 metals can be arranged in terms of reactivity as follows
Na gt Mg gt Cu gt Au
4
WEEK 5 LESSON 1 WORKSHEET
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
5
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
6
WEEK 5 LESSON 2
TOPIC Reactivity of metals
Reactivity based on reactivity with acids
The metals that are higher than hydrogen in the electrochemical series react with non ndash oxidizing
acids to produce a salt and hydrogen gas
By using the same concentration of acid and same mass and size of the metals the order of
reactivity of the metals can be deduced
The table below shows the results for an experiment with the reaction of the named metals and
1 mol dm-3 hydrochloric acid
Reaction of metals with acid
Metal Observations
Silver No reaction
Magnesium Bubbles produced steadily
Calcium Bubbles produced very rapidly
Iron Bubbles produced slowly
Based on the above data the most reactive metal will be calcium with the least reactive being
silver The order of reactivity will be Ca gt Mg gt Fe gt Ag
By comparing this to the electrochemical series it can be seen that the reactivity of the metals
decrease as we go down the series
7
WEEK 5 LESSON 2 WORKSHEET
1 Place a next to the metals that will react with dilute acid and an X next to the metals
that will not react with dilute acid
Metal Reactivity with acid
Copper
Magnesium
Aluminium
Silver
Zinc
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
8
WEEK 5 LESSON 3
TOPIC Reactivity of metals
Reactivity based on ease of decomposition of the metal nitrates carbonates oxides and
hydroxides
The more reactive a metal the more difficult it is to decompose its nitrate carbonate oxide or
hydroxide on heating
For example Decomposition of carbonates
Procedure
1 Put a large spatula measure of the carbonate to be tested in a test tube
2 Fit a delivery tube and then clamp the test tube so that the delivery tube dips into a second test
tube containing 2ndash3 cm3 limewater
3 Heat the solid gently at first then more strongly
4 Lift the delivery tube from the limewater before or as soon as the heating is stopped This is to
avoid suck-back
5 Write down all observations Notice what happens to the limewater and how long it takes to turn
milky (if at all) Notice whether any melting occurs in the heated test tube and any colour
changes taking place Write your results in tabular form
6 Repeat the experiment with the other metal carbonates supplied and in each case write down
your observations
7 Wash your hands thoroughly at the end of these experiments since some of the metal carbonates
are toxic
9
Results
Metal Formula Gas evolved Ease of decomposition
Zinc ZnCO3 Carbon dioxide Fairly easy
Copper CuCO3 Carbon dioxide Easy
Sodium Na2CO3 None Very difficult
Using the results of the above activity the reactivity of the metals can be determined
Ease of decomposition Copper gt Zinc gt Sodium
The order of reactivity is the opposite for the ease of decomposition
Order of reactivity Sodium (most reactive) gt Zinc gt Copper (least reactive)
10
WEEK 5 LESSON 3 WORKSHEET
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
11
WEEK 6 LESSON 1
TOPIC Extraction of metals
Elements exist all over the earth Some are found as free elements eg copper silver and gold
Others are found combined with other elements in compounds To get the elements the
compounds have to be broken up These compounds are generally called ores the most
convenient sources of which are rocks sea and air
The extraction of a metal from its ore is a reduction process where the metals ions gain electrons
to form atoms
The general equation is Mn+ + n e- M
The choice of the extraction method depends on the position of the metal in the reactivity series
As we go down the series the metals become more stable and the metal ions (in the ores)
become less stable
The very reactive metals that are high in the series K Na Ca Mg Al have very stable ores
Therefore they require a powerful method of reduction namely electrolysis During the process
the cathode provides the electrons and acts as the reducing agent
The metals in the middle of the series (Zn Fe Pb) do not have stable ores and can be extracted
by reduction with carbon in the case of zinc and with carbon monoxide in the case of iron and
lead
Metals low in the reactivity series if present as ores can be extracted simply by heating the ores
in air at high temperatures
12
Extraction of Aluminium from purified bauxite
Pure bauxite is pure alumina (Al2O3) Aluminium is obtained from bauxite by electrolysis
Aluminium oxide has a very high melting point approximately 2050 0C so it is first dissolved in
molten cryolite (Na2AlF6) The addition of cryolite lowers the melting point to approximately
900 0C
The electrolyte is a molten mixture of alumina and molten cryolite The cathode is the graphite
lining of the cell The anodes are blocks of graphite or titanium alloys
Reaction at the cathode
Al3+ (l) + 3 e- Al (l)
Reaction at the anode
2 O2- (l) ndash 4 e- O2 (g)
Aluminium (melting point 660 0C) is a liquid at the temperature at which electrolysis is carried
out and is collected at the bottom of the cell and tapped off Oxygen gas which is given off in the
main cathode reaction together with the heat causes the anodes to burn away The anodes have
to be replaced from time to time The use of anodes from titanium alloys reduce the number of
times that the anodes have to be replaced
13
WEEK 6 LESSON 1 Worksheet
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 6 LESSON 2
TOPIC Extraction of metals
Extraction of Iron
The traditional method of production of iron is by reduction of haematite by carbon monoxide in
a blast furnace
Ores Haematite ndash Fe2O3 Magnetite ndash Fe3O4 Siderite ndash FeCO3 Magnetite and Siderite are
converted to Haematite
A mixture of haematite limestone (CaCO3) and coke (C) called the charge is placed into the top
of the furnace
Hot air is blown into the bottom of the furnace
Coke burns in air forming carbon dioxide
C (s) + O2(g) CO2 (g) ΔH -ve
The heat produced keeps the temperature at about 1900 0C
The carbon dioxide is reduced to carbon monoxide by the hot coke
CO2 (g) + C (s) 2 CO(g) Δ +ve
Heat absorbed reduces the temperature to about 1100 0C
The carbon monoxide reduces the hot iron ore to molten iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + 3 CO2(g)
The temperature at this part of the furnace is about 700 0C The iron runs to the bottom of the
furnace
The impurities are removed by the addition of limestone (CaCO3) The limestone at the
temperature of the furnace breaks down
CaCO3 (s) CaO (s) + CO2 (g)
15
The calcium oxide formed combines with silicon dioxide (sand) the main impurity in the iron
ore to form molten slag
CaO (s) + SiO2 (s) CaSiO3 (l)
The slag does not mix with the molten iron but floats on it The molten iron and slag are run off
separately
The iron formed in a blast furnace is an impure form of the metal Because the molten metal is
allowed to solidify in shallow trays known as casts the iron is called lsquocast ironrsquo or lsquopigrsquo iron
Cast iron is quite brittle and contains 2 - 4 carbon and other impurities Most of the cast iron is
converted to steel
A blast furnace used for extracting iron
16
WEEK 6 LESSON 2 Worksheet
(a) What are the three raw materials that are added through the top of the blast furnace
during the extraction process for iron
______________________________________________________________________________
______________________________________________________________________________
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
17
WEEK 6 LESSON 3
TOPIC Alloys
An alloy is a mixture of two or more metals Alloys are made by melting the individual metals
mixing them and allowing the molten mixture to solidify
In general alloys are harder stronger and more resistant to corrosion than the actual metals they
are made up from
Alloy Use Properties
ALUMINIUM
-Duralumin
(AlMgCu)
-Magnalium (AlMg)
Alloys used in the
construction of
aircraft and ships
buses
Aluminium is used in
making cooking
utensils electrical
cables paint for fuel
storage tanks bottle
caps foil and utensils
for handling nitric
acid
The alloys have a low
density They are as
light as aluminium
and more resistant to
corrosion than
aluminium
LEAD
-Solder (PbSn)
Alloy is used in
joining metals
(soldering)
Lead is used in
underground cables
plates in
The alloy has a lower
melting point than
lead and is harder
than lead
18
Alloy Use Properties
accumulators shield
against x ndash rays
IRON
- Stainless Steel
(FeCONiC)
-Tungsten steel
(FeWC)
-Invar steel (FeNi)
Manganese steel
(FeMnC)
Iron is the main metal
of a variety of
constructions
Steel is used in
cutlery rock drills
electromagnets
vehicle body and
engine parts fences
pipes etc
Steel resists
corrosion is usually
harder than iron and
may be tough though
malleable and ductile
19
WEEK 6 LESSON 3 Worksheet
(a) Define the term alloy
______________________________________________________________________________
(b) State 3 general advantages that alloys have over the individual metals they are made
from
______________________________________________________________________________
______________________________________________________________________________
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
______________________________________________________________________________
______________________________________________________________________________
Uses
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 7 LESSON 1
TOPIC Corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
Familiar examples of corrosion are
- the formation of a green powder on copper sheeting
- the eating away of iron (rusting)
- the development by aluminum of a thin compact layer of oxide which protects the
underlying metal from further corrosion
When corrosion occurs in water ndash free environment it is called dry oxidation When it occurs in
aerated aqueous environments it is called wet corrosion Wet corrosion is the most common and
troublesome form of corrosion
The most familiar corrosion is the rusting of iron and steel On exposure to the atmosphere iron
and steel corrode to form rust which is hydrated iron (III) oxide Fe2O3xH2O Iron and steel
corrode easily and the rust formed flakes off easily thus exposing fresh surface for attack
When iron rust it loses electrons
Fe (s) ndash 2e- Fe 2+ (aq)
The iron (II) ions pass into solution and then combine with the hydroxyl (OH-) ions in the
aerated aqueous environment to form iron (II) hydroxide The oxygen present oxidises the iron
(II) hydroxide to hydrated iron (III) oxide or rust
Fe(OH)2 + O2 Fe2O3xH2O
21
Methods of preventing rusting
1 Coating the object with paint grease plastic or rubber which prevent contact with air or
water
2 Galvanising ndash coating the object with zinc The zinc forms an adherent oxide layer which
protects against further corrosion If damaged the zinc is oxidized in preference to the
iron since it is higher in the electrochemical series
3 Coating with tin lsquoTinrsquo cans are made of steel plated with tin However if scratched
rusting occurs since iron is more reactive than tin
4 Attaching a sacrificial anode to the object A piece of metal higher in the electrochemical
series such as magnesium is attached The magnesium will be oxidized in preference
since it is higher in the electrochemical series than iron
22
WEEK 7 LESSON 1 WORKSHEET
(a) Define the term corrosion
______________________________________________________________________________
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
23
WEEK 7 LESSON 2
TOPIC Importance of metals and their compounds on living systems and environment
Some metals are an integral part of different structures of living things
Metal Presence and Function
Potassium Main cation in fluid or animal cells essential for healthy plant growth
Calcium Necessary for strong bones teeth and shells needed by some enzymes Present
in dairy produce eggs nuts and cereals
Magnesium Central atom of chlorophyll needed for some enzyme action Involved in energy
and calcium metabolism
Zinc Present in many enzymes Needed for protein metabolism Essential for growth
of animals
Iron Present in haemoglobin Needed for protein metabolism Essential for growth of
animals
Chromium Needed for glucose uptake by cells and thus linked to the action of insulin
Manganese Needed for bone development and amino acid metabolism Present in several
enzymes Needed for plant growth
Cobalt Present in Vitamin B12 Needed for plant growth
Copper Involved in formation of haemoglobin and melanin Present in enzymes
controlling oxidation Needed for plant growth
24
Harmful effects of metals and their compounds to living systems and the environment
There are some metals and metal compounds which may cause harm to living systems and the
environment
Lead
Lead is a heavy metal poison that is widely encountered It may occur in food beverages paint
water formed from ndash sealed pipes in air polluted by combustion by fuels containing lead
compounds Lead is also used in some car batteries If these are paints or batteries are not
disposed of correctly lead may get into groundwater or air Lead and lead compounds harm the
nervous system including the brain especially young children
Arsenic
Arsenic compounds are poisonous They can get into the groundwater from mining waste and
from disposal of some electrical components
Cadmium
Cadmium compounds are poisonous They can get into the ground by improper disposal of
nickel ndash cadmium batteries Persons can get cadmium poisoning if they eat food grown in
contaminated soil
Mercury
Mercury can be spilled from broken thermometers in hospitals and laboratories Mercury and its
compounds are particularly poisonous to fish and it can accumulate in the food chain and
eventually poison humans
Problems of disposal of solid waste
Metals may react with water andor air and corrode to form soluble compounds that are
poisonous These toxic compounds diffuse into the soil and eventually enter rivers
Rust from iron may form unsightly pools of waste that reduce plant growth
Waste from aluminium extraction may react with water and form flammable gases
25
WEEK 7 LESSON 2 WORKSHEET
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Lead
______________________________________________________________________________
Mercury
______________________________________________________________________________
26
WEEK 7 LESSON 3
TOPIC Chemical properties of non ndash metals
Reaction with oxygen
Many non ndash metals burn in excess oxygen or air to form oxides For example
S (s) + O2 (g) SO2 (g)
C (s) + O2 (g) CO2 (g)
Reactions with metals
Some non ndash metals react with metals high in the electrochemical series when heated
For example
Sodium burns in chlorine to form sodium chloride
Na (s) + Cl2 (g) NaCl (s)
Magnesium burns in oxygen to form magnesium oxide
Mg (s) + O2 (g) MgO (s)
When heated iron combines with molten sulphur to form iron (II) sulphide
Fe (s) + S (l) FeS (s)
When heated reactive metals such as sodium and aluminium react with hydrogen to form metal
hydrides
2 Na (s) + H2 (g) 2 NaH (s)
Oxidising and Reducing properties
Hydrogen and Carbon are very good reducing agents
At high temperatures hydrogen reduces metal oxides below zinc in the electrochemical series to
form the metal For example PbO (s) + H2 (g) Pb (s) + H2O (g)
Under suitable conditions hydrogen reduces nitrogen to ammonia
N2(g) + 3 H2 (g) 2 NH3 (g)
27
At high temperatures carbon reduces metal oxides below aluminium in the reactivity series to
the metal For example
ZnO (s) + C (s) Zn (s) + CO (g)
Oxygen and Chlorine are very good oxidizing agents
Oxygen oxidized most metals to form metal oxides and some non ndash metals to non ndash metal oxides
For example
2 Mg (s) + O2(g) 2 MgO (s)
4 P (s) + 5 O2 (g) P4O10 (s)
Chlorine acts as an oxidizing agent either as a gas or as an aqueous solution For example
H2 (g) + Cl2 (g) 2 HCl (g)
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
28
WEEK 7 LESSON 3 WORKSHEET
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
______________________________________________________________________________
(b) Write the ionic equation for the above reaction
______________________________________________________________________________
(c) Identify the oxidising agent in the reaction
______________________________________________________________________________
(d) Justify your answer in part (c) in terms of oxidation number
______________________________________________________________________________
29
WEEK 8 LESSON 1
TOPIC Laboratory preparation of gases
Preparation of oxygen
Oxygen can be prepared by the decomposition of hydrogen peroxide potassium chlorate (V) or
potassium nitrate The safest method is the decomposition of hydrogen peroxide
Manganese (IV) oxide catalyses the decomposition of hydrogen peroxide
Silica gel anhydrous calcium chloride or concentrated sulphuric acid can be used as a drying
agent
The gas is collected by downward delivery since it is slightly denser than air
Equation
2 H2O2 (aq) 2 H2O (l) + O2 (g)
Apparatus used for laboratory preparation of oxygen
30
WEEK 8 LESSON 1 WORKSHEET
Describe the laboratory preparation of oxygen gas
In your answer include
The starting material
A suitable catalyst
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
31
WEEK 8 LESSON 2
TOPIC Laboratory preparation of gases
Preparation of carbon dioxide
Carbon dioxide can be prepared by the action of dilute acid on carbonates Marble chips (calcium
carbonate) and dilute hydrochloric acid are the common reagents The gas is collected by
downward delivery since it is denser than air
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
Apparatus used for laboratory preparation of carbon dioxide
32
WEEK 8 LESSON 2 WORKSHEET
Describe the laboratory preparation of carbon dioxide gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
33
WEEK 8 LESSON 3
TOPIC Laboratory preparation of gases
Preparation of ammonia
Ammonia may be prepared by heating a mixture of ammonium salt and a hydroxide The
ammonia gas is collected by upward delivery since it is less dense than air
For example
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
Calcium oxide is the only suitable drying agent since ammonia reacts with conc H2SO4 and
CaCl2
Apparatus used for laboratory preparation of dry ammonia
34
11
WEEK 8 LESSON 3 WORKSHEET
Describe the laboratory preparation of ammonia gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
35
WEEK 9 LESSON 1
TOPIC Uses of gases
Carbon dioxide
Used in fire extinguishers to put out fires Carbon dioxide is denser than air and lsquoblanketsrsquo the
fire preventing oxygen from reaching it Carbon dioxide extinguishers are especially useful for
dealing with fires involving flammable liquids and electrical equipment
Carbonation in soda is created when carbon dioxide is pumped into the soda can or bottle then
held under pressure As long as the can or bottle is sealed the carbon dioxide remains mostly
stable However if the drink gets shaken up or the top is opened the tiny carbon dioxide bubbles
react by bursting
Oxygen
Oxygen is needed for aerobic respiration We need a constant supply of oxygen for this process
Oxygen is used in hospitals to improve the respiration of patients with poor blood flow blood
poisoning and heart disease
Oxygen in used in welding (joining) metals In an oxyacetylene welding torch acetylene or
ethyne (C2H2) burns in oxygen and produces a very hot flame This flame is capable of melting
most metals
Oxygen is used in steel production A blast of oxygen is blown through the molten iron The
oxygen oxidises many of the impurities of the iron and the impurities are then removed
36
WEEK 9 LESSON 1 WORKSHEET
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Put out fires
Welding metals
Create lsquofizzrsquo in drinks
Used in steel production
Aerobic respiration
37
WEEK 9 LESSON 2
TOPIC Uses of non ndash metals and their compounds
Carbon (allotrophes carbon dioxide)
Carbon is used as a reducing agent in extraction of some metals
Carbon as graphite is used as electrodes lubricants and lsquoleadrsquo for pencils
Carbon in the form of diamond is used for jewellery (because of its lustre) and in drill tips for
high ndash speed drills (because of its hardness)
Carbon dioxide is used as refrigerant (as dry ice) for carbonated beverages
Sodium hydrogen carbonate and sodium carbonate are used for water softening and raising
agent
Sulphur
Sulphur is used in the manufacture of sulphuric acid Sulphur is also used in the manufacture of
tyres to make the rubber harder (vulcanisation)
Sulphur powder is used as fungicide on plant materials
Phosphorus
Phosphorus is used in the manufacture of fertilizers
Phosphorus is used to make phosphor bronze alloys
Phosphorus sulphide is used to make the heads of lsquostrike anywherersquo matches
38
Chlorine
Chlorine is used to make sodium hypochlorite which is present in bleach It is also used in
sterilizing swimming pools and in water treatment
Chlorine is used to make the monomer vinyl chloride which is used to make the plastic PVC
Nitrogen
Nitrogen is used to make fertilisers ammonia dyes and nitric acid
Nitrogen is used as an inert atmosphere to prevent substances being oxidised and as a coolant
Silicon
Silicon is used for making silicon chips for computers
Silicon (V) oxide is present in sand Glass is made by heating sand with lime (calcium oxide) and
sodium carbonate
Silicon in the form of silicates is used in jewellery
Silica gel is used as a drying agent
39
WEEK 9 LESSON 2 WORKSHEET
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Used to make sodium hypochlorite
Used as a fungicide on plant materials
Used for lsquoleadrsquo in pencils
Used in the manufacture of bronze alloys
Used in the manufacture of nitric acid
Used in the manufacture of computer chips
Used to make fertilisers
40
WEEK 9 LESSON 3
TOPIC Harmful effects of non ndash metals and their compounds on living systems and the
environment
Sulphur dioxide
Sulphur dioxide can cause a disease of the lungs Sulphur dioxide also poisons plants in two
main ways It may enter the stomata of leaves and react with the tissue fluids to form sulphites
with the on ndash going water loss the concentration of sulphites could build up killing the cells
The second adverse effect on plants occurs when sulphur dioxide dissolves in rain thereby
increasing soil acidity A prolonged acid soil situation may lead to plasmolysis and the death of
vegetation in an area
Carbon monoxide
Carbon monoxide combines much more readily than oxygen with haemoglobin When carbon
monoxide is inhaled it prevents the haemoglobin from taking oxygen to the bodyrsquos cells
Continued breathing of air containing carbon monoxide eventually causes death
Hydrogen sulphide
Hydrogen sulphide reacts readily with many cations forming insoluble sulphides Many cations
contribute to good health by contributing to enzyme activity and to the formation of bone
pigment and haemoglobin Although these cations are required in extremely small
concentrations they are removed by being precipitated as sulphides and thus not available for
regular function Careless dumping of refuse contributes to atmospheric pollution by hydrogen
sulphide
Oxides of nitrogen
In the presence of hydrocarbons from car exhausts ozone and sunlight nitrogen oxides react to
form photochemical smog which contains many harmful chemicals
Nitrogen dioxide can harm the lungs and irritate the nose throat and eyes The other compounds
present in photochemical smog are even more harmful irritants and can cause asthma
41
Carbon dioxide
Carbon dioxide water vapour and ozone referred to as ldquogreenhouse gasesrdquo acting as a blanket
readily absorb some of the radiated heat energy and in turn warms the earthrsquos atmosphere This is
called the ldquogreenhouse effectrdquo Scientists have found direct correlation between carbon dioxide
concentration and global warming An increase in carbon dioxide concentration resulted in an
increase global temperatures Global warming is a major potential problem that the world faces
Chloroflourocarbons (CFCs)
It is believed that CFCs might be responsible for destroying the ozone layer which prevents
harmful ultraviolet (UV) radiation from reaching the earth The carbon ndash chlorine bond in CFC
molecule is easily broken by a UV photon producing an active chlorine atom This atom
combines with an ozone molecule forming a chlorine oxide radical and oxygen The radicle
reacts with more ozone producing the chlorine atom again This kind of reaction is repeated
thousands of times This type of reaction is thought to account for about eighty percent of the
loss of ozone observed
Nitrates and phospates
Nitrates and phosphates cause eutrophication The process leading to eutrophication are
Nitrates and phosphates from fertilisers spread on fields may dissolve in groundwater and
get into lakes and rivers
Nitrates and phosphates cause excessive growth of algae so that they cover the surface of
the water
Water plants including algae die because of lack of sunlight Aerobic bacteria feed on
the plant remains The bacteria multiply
The aerobic bacteria use up the oxygen in the water so aquatic animals die
42
Solid waste
The main sources of pollution from non ndash metals is from glass paper and plastics
Broken glass can cause injury to animals It can also cause fires by acting as lens focusing the
sunrsquos rays on flammable materials
Printing inks from paper dumped in the ground may contain toxic elements such as arsenic and
cadmium Bleaches and chlorine compounds from paper are also harmful
43
WEEK 9 LESSON 3 WORKSHEET
Describe ONE harmful effect of the following non ndash metals andor their compounds on
living systems and the environment
Sulphur dioxide
______________________________________________________________________________
______________________________________________________________________________
Carbon monoxide
______________________________________________________________________________
______________________________________________________________________________
Carbon dioxide
______________________________________________________________________________
______________________________________________________________________________
Oxides of nitrogen
______________________________________________________________________________
______________________________________________________________________________
Hydrogen sulphide
______________________________________________________________________________
______________________________________________________________________________
44
Chloroflourocarbons (CFCs)
______________________________________________________________________________
______________________________________________________________________________
Nitrates and phospates
______________________________________________________________________________
______________________________________________________________________________
45
WEEK 10 LESSON 1
TOPIC Green Chemistry
Green Chemistry is defined as the utilisation of a set of principles that reduces or eliminates the
use and generation of hazardous substances
There are twelve principles of green chemistry as proposed by Paul T Anastas and John C
Warner These twelve principles are
1 Prevention ndash It is better to prevent waste than to treat or clean up waste after it has been
created
2 Atom economy - Synthetic methods should be designed to maximize the incorporation of
all materials used in the process into the final product
3 Less hazardous chemical synthesis - Wherever practicable synthetic methods should be
designed to use and generate substances that possess little or no toxicity to human health
and the environment
4 Safer chemical products - Chemical products should be designed to affect their desired
function while minimizing their toxicity
5 Safer solvents and other agents - The use of auxiliary substances (eg solvents
separation agents etc) should be made unnecessary wherever possible and harmless
when used
6 Minimum energy requirements - Energy requirements of chemical processes should be
recognized for their environmental and economic impacts and should be minimized If
possible synthetic methods should be conducted at ambient temperature and pressure
7 Use of renewable raw materials - A raw material or feedstock should be renewable rather
than depleting whenever technically and economically practicable
8 Reduce use of additional chemicals or additional steps - Unnecessary derivatization (use
of blocking groups protection deprotection temporary modification of
physicalchemical processes) should be minimized or avoided if possible because such
steps require additional reagents and can generate waste
46
9 Use of catalysts ndash The use of catalysts reduce energy costs because the reactions take
place at lower temperatures The more specific the catalyst for a particular reaction is the
less it the likelihood of getting additional unwanted products
10 Nature of breakdown of products - Chemical products should be designed so that at the
end of their function they break down into innocuous degradation products and do not
persist in the environment
11 Monitoring to prevent pollution - Analytical methodologies need to be further developed
to allow for real-time in-process monitoring and control prior to the formation of
hazardous substances
12 Minimise chemical accidents - Substances and the form of a substance used in a chemical
process should be chosen to minimize the potential for chemical accidents including
releases explosions and fires
47
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
48
WEEK 10 LESSON 2
TOPIC Qualitative Analysis ndash Identification of cations
Qualitative Analysis involves identifying the constituents of single substances or mixture of
substances
Appearance
An examination of the appearance of a substance can indicate which ion it contains
Appearances of substances
Observation Indication
Blue or blue ndash green Cu2+ salt
Pale green Fe2+ salt
Yellow ndash brown Fe3+ salt
Ammonia smell NH4+ salt
49
Test for cation using sodium hydroxide
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
(d) If no precipitate forms in step b warm gently and test for ammonia
Effect of dilute sodium hydroxide solution
Effect of dilute sodium hydroxide solution Cation
Dropwise Excess
White precipitate Precipitate soluble Ca2+
White precipitate Precipitate insoluble Al3+ Pb2+ Zn2+
Blue precipitate Precipitate insoluble Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
No precipitate ndash ammonia gas
evolved on heating
ndash NH4+
The metal cations all form insoluble hydroxides with sodium hydroxide solution
For example Ca2+ (aq) + 2 OH- (aq) Ca(OH)2 (s)
Ca(OH)2 Cu(OH)2 Fe(OH)2 and Fe(OH)3 are basic and therefore do not react with excess
sodium hydroxide solution Therefore the precipitate does not dissolve in excess sodium
hydroxide solution
Al(OH)3 Pb(OH)2 and Zn(OH)2 are amphoteric Therefore the precipitates react with the excess
sodium hydroxide solution forming soluble salts and the precipitate disappears in excess sodium
hydroxide solution
The NH4+ ion forms a soluble hydroxide However on heating it reacts with the hydroxide ion to
form ammonia and water
NH4+ (aq) + OH- (aq) NH3 (g) + H2O (l)
50
WEEK 10 LESSON 2 WORKSHEET
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P _____________ Q ___________________
R _____________ S ___________________
R + NaOH
______________________________________________________________________________
51
WEEK 10 LESSON 3
TOPIC Qualitative Analysis ndash Identification of cations
Test for cation using ammonia solution (ammonium hydroxide solution)
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
Effect of dilute ammonia (ammonium hydroxide) solution
Effect of dilute ammonia solution Cation
Dropwise Excess
No precipitate ndash Ca2+
White precipitate Precipitate soluble
(forming colourless solution)
Zn2+
White precipitate Precipitate insoluble Al3+ Pb2+
Blue precipitate Precipitate soluble
(forming deep blue solution)
Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
52
Ammonia solution is a weak alkali Metal cations except Ca2+ form insoluble hydroxides with
ammonia solution as with the sodium hydroxide solution
The amphoteric hydroxides Al(OH)3 and Pb(OH)2 and the basic hydroxides Fe(OH)2 and
Fe(OH)3 do not react with excess ammonia solution Therefore the precipitates remain
However Zn(OH)2 and Cu(OH)2 do react with excess ammonia solution to form complex
soluble hydroxides each Hence their precipitates disappear on the addition of excess ammonia
solution
Confirmatory test
After carrying out test for cations using sodium hydroxide solution and ammonia solution the
only cations which cannot be distinguished are Al3+ and Pb2+ A confirmatory test is carried out
to distinguish between the two cations
Confirmatory test
Test Observation Cation Ionic equation
Add potassium
or sodium
iodide solution
Bright yellow precipitate
No precipitate
Pb2+
Al3+
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
53
WEEK 10 LESSON 3 WORKSHEET
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A __________ B ________________ C ________________________
(b) State the inference after Test 2
C _______________________
(c) Write an ionic equation to support your answer in (b) above
___________________________________________________________________________
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
54
ANSWERS TO WORKSHEETS
55
WEEK 5 LESSON 1 WORKSHEET ANSWERS
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
Answer
Zinc + Iron (II) sulphate Zinc is higher in the electrochemical series and therefore displace
iron ions in iron (II) sulphate
Equation Zn (s) + FeSO4 (aq) ZnSO4 (aq) + Fe (s)
Ionic equation Zn (s) + Fe2+ (aq) Zn2+ (aq) + Fe (s)
Iron + Zinc sulphate No reaction iron is lower in the electrochemical series and cannot
displace the zinc ions in zinc sulphate
56
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
Answer
X displaces lead from an aqueous solution of its salts
X (s) + Pb2+ (aq) Xn+ (aq) + Pb (s)
rarr X is more reactive than Pb
X did not react with iron salts
rarr X is less reactive than Fe
Y burns very easily
Y is more reactive than Fe and Pb (both forming their corresponding oxide at a slower rate)
From electrochemical series Fe is higher and therefore more reactive than Pb
Order of reactivity
Y (most reactive) gt Fe gt X gt Pb (least reactive)
57
WEEK 5 LESSON 2 WORKSHEET ANSWERS
1
Metal Reactivity with acid
Copper X
Magnesium
Aluminium
Silver X
Zinc
58
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
Answer
Y and Z are the most reactive since they can react with dilute acid
Z is more reactive than Y since a reaction occurs with Z is added to an aqueous solution of Y
X is less reactive than W since it does not occur in nature as compounds
Order of reactivity Z (most reactive) gt Y gt W gt X
59
WEEK 5 LESSON 3 WORKSHEET ANSWERS
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
Answer
Ease of decomposition (from easiest to decompose to most difficult to decompose)
B rarrD rarrArarr C
Reactivity (most reactive to least reactive)
C (most reactive) gt A gt D gt B (least reactive)
60
WEEK 6 LESSON 1 Worksheet Answers
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
Potassium Zinc Copper
Calcium Lead Gold
Magnesium Iron
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
Aluminium is extracted from its ore bauxite through the process of electrolysis
Cryolite is added to bauxite to lower the melting point to about 900 0C The melting point of
bauxite is very high (about 2040 0C) It is difficult and expensive to keep the molten aluminium
oxide at this temperature
Reaction at the cathode Al3+ (l) + 3 e- Al (l)
61
WEEK 6 LESSON 2 Worksheet Answers
(a) What are the three raw materials that are added through the top of the blast
furnace during the extraction process for iron
Coke (carbon)
iron ore (haematitie mainly iron (II) oxide)
limestone (calcium carbonate)
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
Coke ndash coke burns to produce carbon dioxide The carbon dioxide further reacts with coke to
form carbon monoxide (reducing agent in the process)
C (s) + O2 (g) CO2 (g)
C (s) + CO2 (g) 2 CO
Haematite ndash iron ore provides the iron which is reduced by the carbon monoxide to produce
iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + CO2 (g)
Limestone ndash decomposes to form calcium oxide The calcium oxide reacts with the impurity
silicon dioxide to form slag (calcium silicate)
CaCO3 (s) CaO (s) + CO2 (g)
CaO (s) + SiO2 (l) CaSiO3(l)
62
WEEK 6 LESSON 3 Worksheet Answers
(a) Define the term alloy
An alloy is a material made from a mixture of two or more metals
(b) State 3 general advantages that alloys have over the individual metals they are made
from
They are harder stronger and more resistant to corrosion
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
1 High strength
2 Low density
Uses
1 Used to make aircraft bodies
2 Used to make space satellites
63
WEEK 7 LESSON 1 WORKSHEET ANSWERS
(a) Define the term corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
The paint forms a barrier which stops contact with air or water and the iron Hence rusting
will not take place
However when the paint is scratched that part of the iron nail is exposed to air or water and
rusting will take place
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
Magnesium is higher in the electrochemical series and will be oxidised in preference to iron
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
Aluminium is partly protected from corrosion by its coat of aluminium oxide However as the
iron rust it flakes and fall off and the rusting process continues
64
WEEK 7 LESSON 2 WORKSHEET ANSWERS
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
Magnesium is the ion found in chlorophyll Chlorophyll plays a vital part in the process of
photosynthesis A deficiency in magnesium will lead to low chlorophyll level in the tomato
plants and hence reduce the process of photosynthesis There will be less food storage and
hence will lead to smaller yield of tomatoes
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Any correct harmful effect of lead on health or environment
Any correct harmful effect of mercury on health or environment
65
WEEK 7 LESSON 3 WORKSHEET ANSWERS
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
(b) Write the ionic equation for the above reaction
2 Br- (aq) + Cl2 (aq) 2 Cl- (aq) + Br2 (aq)
(c) Identify the oxidising agent in the reaction
Cl2 (aq)
(d) Justify your answer in part (c) in terms of oxidation number
There is a reduction of the oxidation number for chlorine from 0 to ndash1
hence it has been reduced Therefore chlorine is the oxidising agent
66
WEEK 8 LESSON 1 WORKSHEET ANSWERS
Describe the laboratory preparation of oxygen gas
Oxygen is prepared in the laboratory by the decomposition of hydrogen peroxide
A suitable catalyst is manganese (IV) oxide
Drying agent silica gel OR anhydrous calcium chloride OR conc sulphuric acid
The gas is collected by downward delivery since oxygen is slightly denser than air
Balanced chemical equation 2 H2O2 (aq) 2 H2O (l) + O2 (g)
67
WEEK 8 LESSON 2 WORKSHEET ANSWERS
Describe the laboratory preparation of carbon dioxide gas
Carbon dioxide is commonly prepared in the laboratory by the reacting hydrochloric acid and
marble chips (calcium carbonate)
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
The carbon dioxide gas is collected by downward delivery since it is denser than air
Balanced chemical equation
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
68
WEEK 8 LESSON 3 WORKSHEET ANSWERS
Describe the laboratory preparation of ammonia gas
An ammonium salt (ammonium chloride) and a base (sodium hydroxide) are mixed together and
heated
Calcium oxide is used as the drying agent Calcium chloride and concentrated sulphuric acid
cannot be used since ammonia can react with them
The gas is collected by upward delivery since ammonia is less dense than air
Balanced chemical equation
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
69
WEEK 9 LESSON 1 WORKSHEET ANSWERS
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Carbon dioxide Put out fires
Oxygen Welding metals
Carbon dioxide Create lsquofizzrsquo in drinks
Oxygen Used in steel production
Oxygen Aerobic respiration
70
WEEK 9 LESSON 2 WORKSHEET ANSWERS
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Chlorine Used to make sodium hypochlorite
Sulphur Used as a fungicide on plant materials
Carbon (graphite) Used for lsquoleadrsquo in pencils
Phosphorus Used in the manufacture of bronze alloys
Nitrogen Used in the manufacture of nitric acid
Silicon Used in the manufacture of computer chips
Nitrogen Phosphorus Used to make fertilisers
71
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
Green Chemistry is using principles that reduceeliminate the use of hazardous materials in
the design manufacture and application of chemical products
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
Makes the environment safer
Reduces waste
Creates new jobs
Reduces respiratory illnesses
Atom economy
72
WEEK 10 LESSON 2 WORKSHEET ANSWERS
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P Cu2+ Q Fe2+
R Fe3+ S Ca2+
Ionic equation for R + NaOH
Fe3+ (aq) + 3 OH- (aq) Fe(OH)3 (s)
73
WEEK 10 LESSON 3 WORKSHEET ANSWERS
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A Fe3+ B Ca2+ C Al3+ Pb2+
(b) State the inference after Test 2
C Pb2+
(c) Write an ionic equation to support your answer in (b) above
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
11 Qualitative Analysis
ndash Test for gases
Qualitative Analysis
ndash Identification of
anions
Qualitative Analysis
ndash Identification of
anions
12 Problem solving of
Past CSEC Chemistry Paper 2
on topics completed in the term
13
14
15
2
WEEK 11 LESSON 1
TOPIC Qualitative Analysis ndash Test for gases
Identification of gases
Gas Colour Odour Effect on moist
litmus
Method of identification
Oxygen
O2
Colourless Odourless Neutral ndash no
effect
Relights a glowing splint
Hydrogen
H2
Colourless Odourless Neutral ndash no
effect
Lighted splint lsquopopsrsquo if air is also
present
Carbon
dioxide
CO2
Colourless Odourless Weakly acidic ndash
blue to slightly
red
A white precipitate forms in
limewater
Ca(OH)2 (aq) + CO2
CaCO3 (s) + H2O (l)
Precipitate redissolves on
continued bubbling
CaCO3 (s) + H2O (l) + CO2 (g)
Ca(HCO3)2 (aq)
Ammonia
NH3
Colourless Pungent Alkaline ndash red
to blue (only
common
alkaline gas)
Turns moist red litmus blue forms
dense white fumes with hydrogen
chloride gas
NH3 (g) + HCl (g) NH4Cl (s)
Gas Colour Odour Effect on moist
litmus
Method of identification
3
Sulphur
dioxide
SO2
Colourless Choking
smell
Acidic ndash blue to
red
Turns acidified potassium
manganate (VII) solution from
purple to colourless
Turns acidified potassium
dichromate (VI) solution from
orange to green
Chlorine
Cl2
Yellow ndash
green
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Bromine
Br2
Red ndash
brown
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Nitrogen
dioxide
NO2
Red ndash
brown
Irritating
smell
Acidic blue to
red
Turns moist blue litmus red but
does not bleach it
Water
vapour
H2O
Colourless Odourless Neutral ndash no
effect
Turns anhydrous cobalt (II)
chloride from blue to pink
Turns anhydrous copper (II)
sulphate from white to blue
4
WEEK 11 LESSON 1 WORKSHEET
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless
Yellow ndash green
Red ndash brown
Gases according to their odour
Odour of gas Identity of gas
Odourless
Pungent smell
Choking smell
Irritating smell
5
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect
Red to blue
Blue to red
Blue to red then bleaches it
6
WEEK 11 LESSON 2
TOPIC Qualitative Analysis ndash Identification of anions
Effect of heating
Method Heat a sample of the solid in a dry test tube
Effect of heating
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) not
of K or Na
CO32- (s) O2- (s) + CO2 (g)
Oxygen evolved NO3- of K or Na 2 NO3
- (s) 2 NO2- (s) + O2
(g)
Oxygen and nitrogen
dioxide evolved
NO3- of Ca and below
in reactivity series
4 NO3- (s) 2 O2- (s) + 4 NO2
(g) + O2
(g)
Sulphur dioxide evolved SO32- SO3
2- O2- (s) + SO2 (g)
Effect of dilute acid
Add dilute hydrochloric acid or nitric acid to a sample of the solid Warm if no reaction occurs
when cold
Effect of dilute acid
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) CO32- (s) + 2 H+ (aq) H2O (l) + CO2 (g)
Sulphur dioxide evolved SO32- SO3
2- (s) + 2 H+ (aq) H2O (l) + SO2 (g)
7
Effect of concentrated acid
Add concentrated sulphuric acid to a sample of the solid Warm if not reaction occurs when cold
Effect of concentrated sulphuric acid
Observation Anion
Carbon dioxide evolved CO32- or HCO3
-
Sulphur dioxide evolved SO3-
Hydrogen chloride evolved Cl-
Hydrogen bromide (colourless) and bromine
vapour (brown) evolved
Br-
Black iodine present and purple iodine vapour
evolved
I-
8
WEEK 11 LESSON 2 WORKSHEET
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater
Produces a gas which relights a glowing splint as the only gas
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green
Produces a gas forms a precipitate in limewater
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia
Black iodine present and purple iodine vapour evolved
9
WEEK 11 LESSON 3
TOPIC Qualitative Analysis ndash Identification of anions
Test for the halides ndash using silver nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous silver nitrate and
observe the precipitate Add ammonia solution and observe the solubility of the precipitate
Test for halides using silver nitrate solution
Effect of silver
nitrate solution
Anion Explanation Effect of aqueous
ammonia
White precipitate ndash
turns white in
sunlight
Cl- Ag+ (aq) + Cl- AgCl (s) Precipitate soluble
Cream precipitate ndash
turns yellow ndash green
in sunlight
Br- Ag+ (aq) + Br- AgBr (s) Precipitate slightly
soluble
Pale yellow
precipitate
I- Ag+ (aq) + I- AgI (s) Precipitate insoluble
Test for the halides ndash using lead nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous lead nitrate and
observe the precipitate
Test for halides using lead nitrate solution
Effect of lead nitrate solution Anion Explanation
White precipitate Cl- Pb2+ (aq) + 2 Cl- PbCl2 (s)
Pale yellow Br- Pb2+ (aq) + 2 Br- PbBr2 (s)
Deep yellow I- Pb2+ (aq) + 2 I- PbI2 (s)
10
Effect of barium nitrate or chloride solution followed by dilute acid
Make a solution of the solid Add barium nitrate or chloride solution and observe the precipitate
Add dilute hydrochloric or nitric acid warn if necessary and observe the solubility of the
precipitate
Effect of barium nitrate or chloride solution followed by dilute acid
Effect of
Ba(NO3)2 (aq)
or BaCl2 (aq)
Effect of HCl (aq)
or HNO3 (aq)
Anion Explanation
White precipitate Precipitate insoluble SO42- Ba2+ (aq) + SO4
2- (aq) BaSO4 (s)
BaSO4 does not react with dilute acids
White precipitate Precipitate soluble ndash
CO2 evolved
CO32- Ba2+ (aq) + CO3
2- (aq) BaCO3 (s)
BaCO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + CO2 (g)
White precipitate Precipitate soluble ndash
SO2 evolved on
warming
SO32- Ba2+ (aq) + SO3
2- (aq) BaSO3 (s)
BaSO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + SO2 (g)
11
WEEK 11 LESSON 3 WORKSHEET
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
(Ionic equation required)
12
WEEK 12 LESSON 1 WORKSHEET
(a) The Caribbean islands are known for their many resources For example the ore of
aluminium is found in Jamaica and Guyana
(i) Briefly describe the extraction of aluminium from its named ore Include in your
description one ionic equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Although aluminium ore is mined in the Caribbean the extraction of aluminium usually
takes place in other countries Suggest ONE reason why it may be difficult to extract
aluminium in the Caribbean
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) An alloy can be described as a lsquomixed metal solutionrsquo Aluminium forms an alloy with
magnesium that is used to make an aircraft
13
Identify this alloy and suggest why it is better to use it rather than the pure metal in the
manufacture of aircraft
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) ldquoSome metals can be useful to man yet harmful to the environmentrdquo Comment on this
statement with reference to mercury
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 12 LESSON 2 Worksheet
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate formed
Soluble in excess
15
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate formed
Insoluble in excess
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate formed
(Ionic equation required)
16
WEEK 12 LESSON 3 Worksheet
Dry ammonia gas can be produced in a school laboratory
(a) Identify TWO reagents that are necessary for the laboratory production of ammonia
______________________________________________________________________________
______________________________________________________________________________
(b) Two common drying agents used in the laboratory are calcium oxide and concentrated
sulphuric acid However calcium oxide is the preferred choice for drying ammonia gas
Explain why concentrated sulphuric acid is now used Include in your answer a balanced
chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) When gases are prepared in the laboratory there are three main ways in which they can
be collected
- Upward delivery
- Downward delivery
- Displacement of water
(i) What TWO other factors should be considered when choosing an appropriate method for
the collection of gases in the laboratory
______________________________________________________________________________
______________________________________________________________________________
(ii) Identify ONE of the three methods that is best suited for the collection of ammonia gas in
the laboratory Explain why EACH of the other two methods would NOT have been
appropriate
______________________________________________________________________________
17
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(d) Hence draw a labelled diagram of the apparatus which could be used for the preparation
of dry ammonia in the laboratory
Be sure to identify in your diagram
- where the reagents are placed
- where the ammonia is dried and
- where the ammonia is collected
18
WEEK 13 LESSON 1 Worksheet
(a) In solution two metals A and B form A+ and B2+ ions respectively Metal A displaces Fe
from a solution containing Fe2+ ions but metal B does NOT
(i) Arrange the metals A B and Fe in order of reactivity from LEAST reactive to MOST
reactive Write a balanced chemical equation to show the reaction between metal A and
Fe2+ ions
______________________________________________________________________________
______________________________________________________________________________
(ii) Metal A is placed in a solution of copper (II) sulphate CuSO4 (aq) Write an equation for
the reaction State ONE observable change that will occur and explain why this reaction
takes place
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) For EACH metal A and B state ONE method that can be used to extract it from its
respective oxide Give a reason for EACH answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
19
______________________________________________________________________________
(b) Metal alloys are often used for making objects found in our daily lives Name an alloy of
iron and state ONE of its uses
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 13 LESSON 2 Worksheet
(a) Many important biological processes in plants and animals depend on the specific roles
of certain metal ions
(i) Farmer Jones reaped a crop of tomatoes and reported that the yield was far below what
was expected Analysis of the soil revealed that there was a deficiency of magnesium
Discuss the importance of magnesium in plant health and explain how a magnesium
deficiency can result in the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE other metal ion which is important to plant health and state the result of its
deficiency
______________________________________________________________________________
______________________________________________________________________________
21
(b) Many years ago car exhaust fumes were known to contain compounds of metals and
non ndash metals which could negatively impact both humans and the environment Identify
ONE metal and ONE non ndash metal whose compounds were present in car exhaust fumes
Discuss the effect of these compounds on human health and the environment
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) Define lsquogreen chemistryrsquo and discuss the measures that have been taken to produce a
lsquogreenerrsquo automotive fuel
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
22
WEEK 13 LESSON 3 Worksheet
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
Zn2+ ions are present
23
WEEK 14 LESSON 1 Worksheet
(a) Metal alloys are often used in place of metals because of their enhanced properties
(i) Define the term lsquoalloyrsquo
______________________________________________________________________________
______________________________________________________________________________
(ii) Name ONE alloy of aluminium and state its use based on one of its enhanced properties
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) A student conducted an experiment to investigate the reactivity of each of the following
metals (copper iron zinc and lead) by using solutionPs of their sulphate salts
The data presented in the table below shows whether a visible chemical reaction took
place when each metal was added to the four sulphate solutions
Key Visible chemical reaction took place
X No visible chemical reaction
CHEMICAL REACTION OF METALS IN SULPHATE SOLUTIONS
Sulphate solution Cu Fe Zn Pb
CuSO4 X
FeSO4 X X X
ZnSO4 X X X X
PbSO4 X X
24
(i) State which of the TWO metals is more reaction Fe or Zn Give a reason for our answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Using the data in the previous Table deduce the order of reactivity of the four metals Cu
Fe Zn and Pb from the most reactive to the least reactive metal
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The student recorded the following observations from the reaction between the iron and
copper (II) sulphate solution
Observations Reddish ndash brown solid coating formed on the iron strip
Blue colour of the solution changed to dirty green
Account for the observations made from the reaction between the iron and copper (II)
sulphate solution
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iv) Write an ionic equation including state symbols for the reaction between the iron and
copper (II) sulphate solution
______________________________________________________________________________
25
(c) Some metal compounds are health and environmental hazards
(i) Identify which of the metals used in the experiment in (b) is MOST hazardous to the
environment
______________________________________________________________________________
______________________________________________________________________________
(ii) State TWO harmful effects of continuous exposure to the metal identified in (c) (i) on
human beings
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
26
WEEK 14 LESSON 2 Worksheet
(a) Carbon is found in the form of diamond and graphite and is a main component in many
naturally occurring compounds such as organic matter and carbon dioxide gas
(i) State ONE way in which diamond differs physically from graphite
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE similarity between diamond and graphite other than they both contain carbon
______________________________________________________________________________
______________________________________________________________________________
(b) Carbon can react with a limited supply of oxygen to form carbon monoxide which can
negatively affect human health
(i) Write a balanced chemical equation including state symbols to show the formation of
carbon monoxide
______________________________________________________________________________
(ii) State TWO effects of carbon monoxide inhalation on the human body
______________________________________________________________________________
______________________________________________________________________________
(c) Jamal wants to prepare and collect a sample of carbon dioxide gas in the laboratory using
calcium carbonate
(i) Write a balanced chemical equation including state symbols for the laboratory
preparation of carbon dioxide gas from calcium carbonate
______________________________________________________________________________
______________________________________________________________________________
(ii) Draw a clearly labelled diagram to show the arrangement of the apparatus and materials
that could be used in the laboratory to prepare and collect the carbon dioxide gas
(iii) State ONE use of carbon dioxide as it relates to the beverage industry
______________________________________________________________________________
27
WEEK 14 LESSON 3 Worksheet
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
(Ionic equation required)
Suggest a possible identity of the solid R __________________________
28
WEEK 15 LESSON 1 Worksheet
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a small
portion of solid Y gently at
first and then strongly
Colourless gas evolved
with a choking odour
Turns acidified potassium
dichromate solution from
orange to green
(ii) To the remaining portion
of solid Y add 20 cm3 of
distilled water stir to dissolve
and filter Collect the filtrate
and divide into 3 equal
portions
Filtrate is pale green in
colour
(iii) To the first portion of the
filtrate from (ii) add aqueous
sodium hydroxide slowly
until in excess
A green precipitate
Insoluble in excess sodium
hydroxide
Ionic equation required
29
TEST OBSERVATIONS INFERENCES
(iv) To the second portion of
the filtrate from (ii) add
aqueous silver nitrate
followed by aqueous
ammonia
White precipitate
Soluble in aqueous
ammonia
(v) To the third portion of the
filtrate from (ii) add aqueous
barium nitrate followed by
aqueous hydrochloric acid
White precipitate formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with the
evolution of a colourless
gas with a choking smell
30
WEEK 15 LESSON 2 Worksheet
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
31
WEEK 15 LESSON 3 Worksheet
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in excess
aqueous NH3
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change
32
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
warm filter and then divide
the filtrate into two portions
Vigorous effervescence
observed upon addition of
dilute HNO3
Gas evolved turns lime water
cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Cu2+ ions present
33
ANSWERS TO WORKSHEETS
34
WEEK 11 LESSON 1 WORKSHEET ANSWERS
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless O2 H2 CO2 NH3 SO2 H2O
Yellow ndash green Cl2
Red ndash brown Br2 NO2
Gases according to their odour
Odour of gas Identity of gas
Odourless O2 H2 CO2 H2O
Pungent smell NH3
Choking smell SO2 Cl2 Br2
Irritating smell NO2
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect Neutral O2 H2 H2O
Red to blue Alkaline NH3
Blue to red Acidic CO2 SO2 NO2
Blue to red then bleaches it Acidic Cl2 Br2
35
WEEK 11 LESSON 2 WORKSHEET ANSWERS
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-) not
of K or Na
Produces a gas which relights a glowing splint as the only gas NO3- of K or Na
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green SO32-
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-)
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia Cl-
Black iodine present and purple iodine vapour evolved I-
36
WEEK 11 LESSON 3 WORKSHEET ANSWERS
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Br-
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
Cl-
Ag+ (aq) + Cl- AgCl (s)
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow Br-
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
SO42-
Ba2+ (aq) + SO42- (aq)
BaSO4 (s)
(Ionic equation required)
37
WEEK 12 LESSON 1 Worksheet Answers
(a) (i)
The ore bauxite is purified
The purified bauxite is dissolved in molten cryolite
The aluminium oxidecryolite solution is then eletrolysed
Equation at the cathode Al3+ (l) + 3 e- Al (l)
Equation at the anode 2 O2- (l) ndash 4 e- O2 (g)
(ii) The process is too expensive mainly because too much electricity or energy is needed
(b) The alloy of Al and Mg is magnalium It is less dense than the pure metals and hence allow
aircraft to be lighter It is also stronger than the pure metals and hence allows aircraft to last
longer since it is not easily destroyed
(c) Your answer should cater for the following aspects
Benefits of mercury to humans for example in thermometers barometers in dentistry
and gold mining
Entry of mercury to the environment For example this could have been through broken
thermometers barometers or lightbulbs or improper disposal of them or batteries and
indiscriminate use in gold mining in Guyana
The identification of a negative impact on the environment such as poisoned fish and the
persons who eat the fish death mood swings and psychosis
38
WEEK 12 LESSON 2 Worksheet Answers
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas
evolved
NO2 evolved OR nitrates
present OR
Br2 gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate
formed
Soluble in excess
Pb2+ Zn2+ Al3+ or Ca2+
present
Pb2+ Zn2+ Al3+ or present
39
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate
formed
Insoluble in excess
Pb2+ Zn2+ Al3+ or present
Pb2+ or Al3+ present
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate
formed
Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
40
WEEK 12 LESSON 3 Worksheet Answers
(a) an ammonium salt and a strong alkali
(b) Ammonia is basic and it will react with H2SO4
Equation 2 NH3 (aq) + H2SO4 (aq) (NH4)2SO4 (aq)
(c) (i) ndash Density of the gas relative to air ndash The solubility of the gas in water
(ii) Ammonia is collected by upward delivery
It cannot be collected by downward delivery since ammonia is less dense than air
It cannot be collected by displacement of water since it is soluble in water
(d)
41
WEEK 13 LESSON 1 Worksheet Answer
a) i) B ˂ Fe ˂ A
2A (s) + Fe 2+ (aq) rarr 2A+ (aq) + Fe (s)
ii) 2A (s) + CuSO4 (aq) rarr A2SO4 (aq) + Cu (s)
Observation blue colour fades gets lighter OR brown solid forms is deposited OR metal A
decreases in size dissolves
Explanation Metal A is higher (than Fe which is higher) than Cu in the reactivity series OR
Metal A is more reactive (than Fe which is more reactive) than Cu so Metal A can displace Cu
iii) Metal A can be extracted by electrolysis (of its molten oxide) because Metal A is a very
reactive metal is high in the reactivity series forms stable oxides needs a lot of energy to be
extracted and very reactive metals are extracted by electrolysis
Metal B can be extracted by heating with carbon carbon monoxide OR by chemical reduction
of the oxide because Metal B is less reactive than Fe is low in the reactivity series forms less
stable oxides does not need a lot of energy to be extracted and oxides of less reactive metals are
easily reduced
b) Alloy of iron steel
Use of alloy making buildings bridges ships motor vehicles furniture utensils
42
WEEK 13 LESSON 2 Worksheet Answer
(a) (i)
Magensium is the metal ion found in chlorophyll
Chlorophyll is essential for photosynthesis
A deficiency in magnesium will result in low chlorophyll yellow leaves and a reduction in
photosynthesis
Hence there will be low carbohydrates or energy production
Hence small fruits stunted growth and lower yield will result
(ii)
Metal ion Results of deficiency
Potassium Stunted growth premature loss of leaves yellowing of leaves curling of leaf tips
Calcium Growth abnormalities in tips of roots and shoots curling of leaves
Iron Yellowing of leaves
Zinc Low chlorophyll content yellowing of leaves
Manganese Yellowing of leaves poor flavors in some crops for example potato
(b)
Metal Lead is present in some types of gasoline Upon combustion lead compounds escape into
the atmosphere It accumulates in body tissues and slowly poisons the person It causes mental
illness
Non ndash metal SulphurSulphur dioxide or NitrogenNitrogen dioxide
Dissolves in rain water to form acid rain or cause respiratory illnessproblems Acid rain can
cause corrosion damage in buildings
(c)
Green chemistry is the utilisation of a set of principles that reduces or eliminates the use or
generation of hazardous substances
43
Automotive fuels are now produced without lead so as to eliminate the release of lead
compounds into the atmosphere
Low sulphur fuel is being produced with much reduced sulphur content which causes a reduction
of sulphur dioxide release into the atmosphere
44
WEEK 13 LESSON 3 Worksheet Answer
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
gas turns litmus blue
red
brown gas
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
white precipitate
precipitate soluble in
excess
Zn2+ ions are present
45
WEEK 14 LESSON 1 Worksheet Answers
(a)(i) An alloy is a material made from a mixture of two or more metals
(ii) Any suitable answer chosen from below
Alloy Enhance Property Use
Duralumin High strength
Low density
Light
Hard
Used to make aircraft bodies
space satellites
Magnalium Light
Hard
Easier to weld
Corrosion resistant
Strong
High ductability
Used in pyrotechnics
(fireworks)
Mirrors
Aircraft parts
To make scientific
instruments
Used to make marine castings
Alchlad Strong
Corrosion resistant
Cladding for buildings
(b) (i) Zinc is more reactive than iron
Zinc displaces iron from iron (II) sulphate
Zinc is higher in the reactivity series than iron
Iron does not displace zinc from zinc sulphate
(ii) Order of reactivity Zn gt Fe gt Pb gt Cu
(iii) Reddish brown solid ndash copper metal formed
46
Dirty green solution ndash presence of Fe2+ ion
(iv) Fe (s) + Cu2+ (aq) Fe2+ (aq) + Cu (s)
(c) (i) Lead
(ii) Any two correct harmful effects of lead on the body
Impedes brain development (in young children)
Affectimpede development of the immune system in humans
Affecthamper development of nervous system in humans
Long term exposure can result in kidney and liver damage
Mental retardation
Anaemia
Death
47
WEEK 14 LESSON 2 Worksheet Answers
a) i) Diamond is transparent clear Graphite is opaque black
OR hard OR brittle
OR does not conduct electricity OR conducts electricity
a) ii) Both have a macromolecular giant molecular giant covalent structure (lattice)
OR Both have high melting point boiling point
OR Both are insoluble in water organic solvent
b) i) 2C (s) + O2 (g) rarr 2CO (g)
ii) CO reduction in amount of oxygen carried by (the haemoglobin in the red blood
cells of) the blood
Headache OR dizziness OR nausea OR fatigue OR loss of consciousness OR
death
c) i) CaCO3 (s) + 2HCl (aq) rarr CaCl2 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) + H2SO4 (aq) rarr CaSO4 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) rarr CaO (s) + CO2 (g)
48
ii)
OR
OR
Entirely closed system thistle funnel below the level of the liquid OR tap that could be
closed
Two reagents labelled CaCO3marble chips and HCl H2SO4 or heat source
collection of CO2 upward displacement of air OR over watersulphuric acid OR in gas
syringe
iii) CO2 use put in aerated drinks carbonated beverages
OR put in carbon dioxide fire extinguishers
49
WEEK 14 LESSON 3 Worksheet Answers
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
NH4+
NH4+ confirmed OR
NH3 (g) produced
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
Cl- ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation required)
Suggest a possible identity of the solid R NH4Cl (ammonium chloride)
50
WEEK 15 LESSON 1 Worksheet Answers
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a
small portion of solid Y
gently at first and then
strongly
Colourless gas
evolved with a
choking odour
Turns acidified
potassium dichromate
solution from orange
to green
SO2 evolved
Presence of a sulphite
(ii) To the remaining
portion of solid Y add 20
cm3 of distilled water stir
to dissolve and filter
Collect the filtrate and
divide into 3 equal portions
Filtrate is pale green
in colour
Fe2+ ions present
(iii) To the first portion of
the filtrate from (ii) add
aqueous sodium hydroxide
slowly until in excess
A green precipitate
Insoluble in excess
sodium hydroxide
Fe2+ ions present
Fe2+ (aq) + 2 OH- (aq) Fe(OH)2 (s)
Ionic equation required
TEST OBSERVATIONS INFERENCES
(iv) To the second portion
of the filtrate from (ii) add
aqueous silver nitrate
White precipitate
Soluble in aqueous
ammonia
Cl- ions present
51
followed by aqueous
ammonia
(v) To the third portion of
the filtrate from (ii) add
aqueous barium nitrate
followed by aqueous
hydrochloric acid
White precipitate
formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with
the evolution of a
colourless gas with a
choking smell
SO32- CO3
2- SO42- ions present
SO32- ions present
52
WEEK 15 LESSON 2 Worksheet Answers
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
Chloride ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
Cu2+ ions present
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
X contains a reducing agent
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
SO32- SO4
2- or CO32- ions are
present
SO32- ions are present
53
WEEK 15 LESSON 3 Worksheet Answers
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
White ppt
Ppt soluble in excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in
excess aqueous NH3
Al3+ Pb2+ Zn2+ present
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change Cl- Br- I- absent
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
Vigorous effervescence
observed upon addition of
dilute HNO3
CO2 evolved OR
Carbonate present
54
warm filter and then divide
the filtrate into two portions
Gas evolved turns lime
water cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
Cu2+ (aq) + OH- (aq)
Cu(OH)2 (s)
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Blue ppt
ppt dissolves in excess
NH3 to give a deep blue
solution
Cu2+ ions present
55
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
REFERENCES
Hunte-King J Maragh P Nagir F amp Norris R (2013) Chemistry for CSEC United
Kingdom Nelson Thornes Ltd
Remy C Mason L Lambert N amp Mohammed M (2007) Chemistry for CSEC England and
Wales Pearson Education Limited
Taylor M amp Chung-Harris T (2010) CXC Chemistry England Macmillan Publishers
Limited
Tindale A (2016) Chemistry A Concise Revision for CXC London HarperCollins Publishers
Limited
5
WEEK 1 LESSON 1 WORKSHEET
Shade the letter next to the answer you choose for questions 1 to 4
1 Which of the following are metals
I Bromine
II Sodium
III Neon
IV Iron
(A) I and III (B) II and IV (C) I and IV (D) II and III
2 Which of the following are non ndash metals
I Chromium
II Carbon
III Iodine
IV Potassium
(A) I and III (B) II and IV (C) I and IV (D) II and III
3 A metal that is a liquid at room temperature is
(A) mercury (B) tin (C) magnesium (D) sodium
6
4 Consider the following information about four substances
Substance Melting point
0C
Electrical conductivity Water
solubility in solid in liquid
I 1050 Low High High
II 75 Low Low Low
III 1234 High High Low
IV 1913 Low Low Low
The substance which is MOST likely to be a metal is
(A) I (B) II (C) III (D) IV
5 Read the following and answer the question that follows
A new element was discovered to have the following properties
Lustrous solid
Can be beaten into shapes
High density
(a) Based only on the facts stated above is the element a metal or non metal
_______________________
(b) State 3 other properties that you expect this element to exhibit
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
7
WEEK 1 LESSON 2
TOPIC Physical properties of metals
Physical properties of some metals
Metals Melting point 0C
Boiling point
0C
Density
g cm-3
Other characteristics
Sodium 90 900 097 Very soft grey metal
Calcium 850 1487 153 Grey metal
Magnesium 650 1103 174 Soft grey metal
Aluminium 660 2350 270 Grey metal
Zinc 419 907 719 White metal
Iron 1535 2760 797 Dark grey metal
Copper 1083 2580 894 Gold coloured metal
conductivity second only to
silver
Sodium Calcium Magnesium Aluminium
Zinc Iron Copper
8
WEEK 1 LESSON 2 WORKSHEET
A group of students carried out an experiment to find the density of three different metals
aluminium calcium and an unknown metal X They measured the mass of each metal sample
using a balance The volumes of the metals were determined by displacement of oil The results
of their experiment are as follows
Aluminium Calcium Metal X
Mass (g) 100 100 100
Final volume (cm3) 335 365 310
Initial volume (cm3 300 300 300
Volume of metal (cm3)
Density (gcm-3)
Complete the table using the following formulae
Volume of metal = Final volume ndash Initial volume
Density = 119872119886119904119904
119881119900119897119906119898119890
Arrange the metals in order of increasing density _____________________________________
9
WEEK 1 LESSON 3
TOPIC Chemical properties of metals
Action of oxygen
Most metals react with oxygen or air to form the corresponding oxide These oxides are basic
oxides with the exception of aluminium zinc and lead which form amphoteric oxides Metals
lower in the electrochemical series do not react
Metal Reaction with air or oxygen
Potassium K
Burn very easily forming oxide
eg 4 Na (s) + O2 (g) 2 Na2O (s)
Sodium Na
Calcium Ca
Magnesium Mg
Aluminium Al
Burn especially if powered forming oxide
eg 4 Al (s) + 3 O2 (g) 2 Al2O3 (s)
Zinc Zn
Iron Fe
Lead Pb Do not burn form oxide when heated strongly
Copper Cu
Silver Ag No reaction
10
WEEK 1 LESSON 3 WORKSHEET
Write balanced chemical equations for the reaction of the named metals and air or oxygen
State the nature of the oxide formed (basic or amphoteric)
Potassium + Oxygen
______________________________________________________________________________
Sodium + Oxygen
______________________________________________________________________________
Calcium + Oxygen
______________________________________________________________________________
Magnesium + Oxygen
______________________________________________________________________________
Aluminium + Oxygen
______________________________________________________________________________
Zinc + Oxygen
______________________________________________________________________________
11
Iron + Oxygen
______________________________________________________________________________
Lead + Oxygen
______________________________________________________________________________
Copper + Oxygen
______________________________________________________________________________
Silver + Oxygen
______________________________________________________________________________
12
WEEK 2 LESSON 1
TOPIC Chemical properties of metals
Action of water
Metals high in the electrochemical series react with cold water to produce the metal hydroxide
and hydrogen
Reactive metals slightly lower in the electrochemical series react very slowly or not at all with
water However they may react with hot water or steam to produce the corresponding metal
oxide and hydrogen
Metals lower than hydrogen in the electrochemical series do not react with water
Metal Reaction with water or steam
Potassium K React with cold water forming metal hydroxide and hydrogen
eg Ca (s) + 2 H2O (l) Ca(OH))2 (aq) + H2 (g) Sodium Na
Calcium Ca
Magnesium Mg React with steam forming metal oxide and hydrogen
eg Zn (s) + H2O (g) ZnO (s) + H2 (g) Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
13
WEEK 2 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with water (or
steam if reaction does not occur with water)
Potassium + WaterSteam
______________________________________________________________________________
Sodium + WaterSteam
______________________________________________________________________________
Calcium + WaterSteam
______________________________________________________________________________
Magnesium + WaterSteam
______________________________________________________________________________
Aluminium + WaterSteam
______________________________________________________________________________
Zinc + WaterSteam
______________________________________________________________________________
14
Iron + WaterSteam
______________________________________________________________________________
Copper + WaterSteam
______________________________________________________________________________
Silver + WaterSteam
______________________________________________________________________________
15
WEEK 2 LESSON 2
TOPIC Chemical properties of metals
Action of dilute acids
Metals above hydrogen in the electrochemical series react with dilute acids to form a salt and
hydrogen gas They react with hydrochloric acid to form the metal chloride (a salt) and hydrogen
gas They also react with dilute suphuric acid to form the metal sulphate (a salt) and hydrogen
gas
Metal Reaction dilute hydrochloric or sulphuric acid
Potassium K Violent reaction forming a salt and hydrogen gas
eg 2 Na (s) + 2 HCl (aq) 2 NaCl (aq) + H2 (g) Sodium Na
Calcium Ca Vigorous reaction forming a salt and hydrogen gas
eg Mg (s) + 2 HCl (aq) MgCl2 (aq) + H2 (g) Magnesium Mg
Aluminium Al React forming a salt and hydrogen gas
eg Fe (s) + 2 HCl (aq) FeCl2 (aq) + H2 (g) Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
16
WEEK 2 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with
hydrochloric acid
Metal Balanced equation for reaction with hydrochloric acid
Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Copper
Silver
17
WEEK 2 LESSON 3
TOPIC Reactions of metal compounds
Reactions of metallic oxides with dilute acid
Metal oxides react with dilute hydrochloric acid or sulphuric acid to produce a salt and water
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
Some of these reactions may be slow and can be speeded up by adding heat
For example
zinc oxide + hydrochloric acid zinc chloride + water
ZnO (s) + 2 HCl (aq) ZnCl2 (aq) + H2O (l)
magnesium oxide + hydrochloric acid magnesium chloride + water
MgO (s) + 2 HCl (aq) MgCl2 (aq) + H2O (l)
aluminium oxide + sulphuric acid aluminium sulphate + water
Al2O3 3 H2SO4 (aq) Al2(SO4)3 (aq) + 3 H2O (l)
calcium oxide + sulphuric acid calcium sulphate + water
CaO H2SO4 (aq) CaSO4 (aq) + H2O (l)
18
WEEK 2 LESSON 3 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal oxides with the
corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium oxide Hydrochloric acid
Sodium oxide Sulphuric acid
Calcium oxide Hydrochloric acid
Magnesium oxide Sulphuric acid
Aluminium oxide Hydrochloric acid
Zinc oxide Sulphuric acid
19
WEEK 3 LESSON 1
TOPIC Reactions of metal compounds
Reactions of metallic hydroxides with dilute acid
Metal hydroxides react with dilute acids to form a salt and water in a neutralisation reaction
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
For example
magnesium hydroxide + hydrochloric acid magnesium chloride + water
Mg(OH)2 (aq) + 2 HCl (aq) MgCl2 (aq) + 2 H2O (l)
sodium hydroxide + hydrochloric acid sodium chloride + water
NaOH (aq) + HCl (aq) NaCl (aq) + H2O (l)
potassium hydroxide + sulphuric acid potassium sulphate + water
2 KOH + H2SO4 (aq) K2SO4 (aq) + 2 H2O (l)
calcium hydroxide + sulphuric acid calcium sulphate + water
Ca(OH)2 (aq) + H2SO4 (aq) CaSO4 (aq) + 2 H2O (l)
20
WEEK 3 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal hydroxides with
the corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium hydroxide Hydrochloric acid
Sodium hydroxide Sulphuric acid
Calcium hydroxide Hydrochloric acid
Magnesium hydroxide Sulphuric acid
Aluminium hydroxide Hydrochloric acid
Zinc hydroxide Sulphuric acid
21
WEEK 3 LESSON 2
TOPIC Reactions of metal compounds
Reactions of metallic carbonates with dilute acid
Metal carbonates react with dilute acid to form a salt carbon dioxide and water When
hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric acid is
used the corresponding sulphate salt is formed
For example
sodium carbonate + hydrochloric acid sodium chloride + carbon dioxide + water
Na2CO3 (s) + 2 HCl (aq) 2 NaCl (aq) + CO2 (g) + H2O (aq)
calcium carbonate + hydrochloric acid calcium chloride + carbon dioxide + water
CaCO3 (s) + 2 HCl (aq) CaCl2 (aq) + CO2 (g) + H2O (aq)
zinc carbonate + sulphuric acid zinc sulphate + carbon dioxide + water
ZnCO3 (s) + H2SO4 (aq) ZnSO4 (aq) CO2 (g) + H2O (aq)
potassium carbonate + sulphuric acid potassium sulphate + carbon dioxide + water
K2CO3 (s) H2SO4 (aq) K2SO4 (aq) CO2 (g) + 2 H2O (aq)
22
WEEK 3 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal carbonates with
the corresponding acid
Metallic
carbonate
Acid Balanced chemical equation
Potassium
carbonate
Hydrochloric
acid
Sodium
carbonate
Sulphuric acid
Zinc
carbonate
Hydrochloric
acid
Magnesium
carbonate
Sulphuric acid
Aluminium
carbonate
Hydrochloric
acid
Calcium
carbonate
Sulphuric acid
23
WEEK 3 LESSON 3
TOPIC Action of heat on metal compounds
Action of heat on nitrates
All nitrates decompose when heated The reactivity of the metal in the metal nitrate influences
the products of the decomposition
The nitrates of the alkali metals (Group I) with the exception of lithium nitrate decompose to
form the metal nitrite and oxygen
The nitrates of most other metals decompose to form the metal oxide nitrogen dioxide and
oxygen
The nitrates of the very unreactive metals decompose to form the meal nitrogen dioxide and
oxygen
Metal Nitrate Decomposition
Potassium K Products metal nitrite + oxygen
eg 2 NaNO3 (s) Heatrarr 2 NaNO2 (s) + O2 (g)
Sodium Na
Calcium Ca
Products metal oxide + nitrogen dioxide + oxygen
eg 2 Pb(NO3)2 (s)
Heatrarr 2 PbO (s) + 4 NO2 (g) + O2 (g)
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Products metal + nitrogen dioxide + oxygen
eg 2 AgNO3 (s) Heatrarr 2 Ag (s) + 2 NO2 (g) + O2 (g)
24
WEEK 3 LESSON 3 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
nitrates
Metal Balanced chemical equation
Potassium nitrate
Sodium nitrate
Calcium nitrate
Magnesium nitrate
Aluminium nitrate
Zinc nitrate
Lead nitrate
Copper nitrate
Silver nitrate
25
WEEK 4 LESSON 1
TOPIC Action of heat on metal compounds
Action of heat on carbonates
Upon application of heat many carbonates decompose to form the metal oxide and carbon
dioxide
Group I carbonates do not decompose on heating with the exception of lithium carbonate
Metal Carbonate decomposition
Potassium K
Stable not decomposed by heat Sodium Na
Calcium Ca
Decompose forming metal oxide and carbon dioxide
eg CaCO3 (s) Heatrarr CaO (s) + CO2 (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Unstable
26
WEEK 4 LESSON 1 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
carbonates
Metal Balanced chemical equation
Potassium carbonate
Sodium carbonate
Calcium carbonate
Magnesium carbonate
Aluminium carbonate
Zinc carbonate
Iron carbonate
Lead carbonate
Copper carbonate
27
WEEK 4 LESSON 2
TOPIC Action of heat on metal compounds
Action of heat on the metal hydroxides
Most metal hydroxides decompose on heating A metal oxide and water are formed
Group I hydroxides do not decompose on heating with the exception of lithium hydroxide
Metal Hydroxide decomposition
Potassium K Stable not decomposed by heat
Sodium Na
Calcium Ca Decompose forming metal oxide and water (as steam)
eg Zn(OH)2 (s) Heatrarr ZnO (s) + H2O (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag No hydroxide exist
28
WEEK 4 LESSON 2 WORKSHEET
Write the balanced chemical equations for the thermal decomposition of the following
metal hydroxides
Metal hydroxide Balanced chemical equation
Potassium hydroxide
Sodium hydroxide
Calcium hydroxide
Magnesium hydroxide
Aluminium hydroxide
Zinc hydroxide
Lead hydroxide
Copper hydroxide
29
WEEK 4 LESSON 3
TOPIC Reactivity of metals ndash The Reactivity Series
The reactivity series of metals is a list of metals arranged in order of their reactivity based on
Displacement reactions
Reactions with oxygen dilute acids and water
Relative ease of decomposition of their compounds
Metals at the top of the series are the most electropositive They lose electrons very easily and
readily form cations These ions are very stable and are not easily discharged to form atoms Due
to this fact they are the most reactive metals
Metals at the bottom of the series are the least electropositive They do not lose electrons easily
and do not readily form ions Their ions are very unstable and are easily discharged to form
atoms They are the least reactive metals
The reactivity series of metals
Mnemonic Metal Symbol Reactivity
People Potassium K Most reactive
Least reactive
Sometimes Sodium Na
Collect Calcium Ca
Magazines Magnesium Mg
About Aluminium Al
Zoos Zinc Zn
In Iron Fe
London Lead Pb
Having (Hydrogen) H
Cute Copper Cu
Monkeys and Mercury Hg
Small Silver Ag
Gorillas Gold Au
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
5 Reactivity of metals Reactivity of metals Reactivity of metals
6 Extraction of metals Extraction of metals Alloys
7 Corrosion Importance of metals
and their compounds
on living systems and
environment
Chemical properties
of non ndash metals
8 Laboratory
preparation of gases
Laboratory
preparation of gases
Laboratory
preparation of gases
9 Uses of gases Uses of non ndash metals
and their compounds
Harmful effects of
non ndash metals and
their compounds on
living systems and
the environment
10 Green Chemistry Qualitative Analysis
ndash Identification of
cations
Qualitative Analysis
ndash Identification of
cations
2
WEEK 5 LESSON 1
TOPIC Reactivity of metals
Reactivity based on displacement reactions between metals and metal ions
A metal will displace a metal which is lower than itself in the reactivity series from a solution of
the metal salt
Reaction of zinc and copper (II) sulphate
Expected observations
Explanation
The size of the zinc metal decreases
The zinc metal is reacting and forming the
salt zinc sulphate
The solution becomes lighter eventually
colourless
The Cu2+ (aq) ions (responsible for the blue
colour) is reduced to Cu (s)
A brown solid is deposited at the bottom of
the container
Copper metal is formed
Equation Zn (s) + CuSO4 (aq) ZnSO4 (aq) + Cu (s)
Ionic equation
Zn (s) + Cu2+ (aq) Zn2+ (aq) + Cu (s)
Zinc is higher in the reactivity series than copper Therefore it will displace the copper ions in
the reaction above
3
Examples of other displacement reactions
Magnesium will displace Zn2+ ions in zinc sulphate since it is higher in the series than zinc
Mg (s) + Zn2+(aq) Mg2+ (aq) + Zn (s)
Silver will not displace Cu2+ ions in copper (II) sulphate [Cu is higher in the series than Ag]
Using the information above we can arrange the metals in order of their reactivity with
magnesium being the most reactive and silver the least reactive metal among the four metals
Mg gt Zn gt Cu gt Ag
Reactivity based on reaction with oxygen
The reactivity of metals can also be deduced from their reaction with oxygen
The table below gives the observations for the reaction with oxygen with the selected metals
Reaction of metal with oxygen
Metal Observation
Copper The surface turns black upon heating
Magnesium Ribbon burns very rapidly
Sodium Burns vigorously
Gold No reaction
Based on the observations for the 4 metals the metal with highest reactivity is sodium and the
metal with the least reactivity is gold
The 4 metals can be arranged in terms of reactivity as follows
Na gt Mg gt Cu gt Au
4
WEEK 5 LESSON 1 WORKSHEET
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
5
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
6
WEEK 5 LESSON 2
TOPIC Reactivity of metals
Reactivity based on reactivity with acids
The metals that are higher than hydrogen in the electrochemical series react with non ndash oxidizing
acids to produce a salt and hydrogen gas
By using the same concentration of acid and same mass and size of the metals the order of
reactivity of the metals can be deduced
The table below shows the results for an experiment with the reaction of the named metals and
1 mol dm-3 hydrochloric acid
Reaction of metals with acid
Metal Observations
Silver No reaction
Magnesium Bubbles produced steadily
Calcium Bubbles produced very rapidly
Iron Bubbles produced slowly
Based on the above data the most reactive metal will be calcium with the least reactive being
silver The order of reactivity will be Ca gt Mg gt Fe gt Ag
By comparing this to the electrochemical series it can be seen that the reactivity of the metals
decrease as we go down the series
7
WEEK 5 LESSON 2 WORKSHEET
1 Place a next to the metals that will react with dilute acid and an X next to the metals
that will not react with dilute acid
Metal Reactivity with acid
Copper
Magnesium
Aluminium
Silver
Zinc
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
8
WEEK 5 LESSON 3
TOPIC Reactivity of metals
Reactivity based on ease of decomposition of the metal nitrates carbonates oxides and
hydroxides
The more reactive a metal the more difficult it is to decompose its nitrate carbonate oxide or
hydroxide on heating
For example Decomposition of carbonates
Procedure
1 Put a large spatula measure of the carbonate to be tested in a test tube
2 Fit a delivery tube and then clamp the test tube so that the delivery tube dips into a second test
tube containing 2ndash3 cm3 limewater
3 Heat the solid gently at first then more strongly
4 Lift the delivery tube from the limewater before or as soon as the heating is stopped This is to
avoid suck-back
5 Write down all observations Notice what happens to the limewater and how long it takes to turn
milky (if at all) Notice whether any melting occurs in the heated test tube and any colour
changes taking place Write your results in tabular form
6 Repeat the experiment with the other metal carbonates supplied and in each case write down
your observations
7 Wash your hands thoroughly at the end of these experiments since some of the metal carbonates
are toxic
9
Results
Metal Formula Gas evolved Ease of decomposition
Zinc ZnCO3 Carbon dioxide Fairly easy
Copper CuCO3 Carbon dioxide Easy
Sodium Na2CO3 None Very difficult
Using the results of the above activity the reactivity of the metals can be determined
Ease of decomposition Copper gt Zinc gt Sodium
The order of reactivity is the opposite for the ease of decomposition
Order of reactivity Sodium (most reactive) gt Zinc gt Copper (least reactive)
10
WEEK 5 LESSON 3 WORKSHEET
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
11
WEEK 6 LESSON 1
TOPIC Extraction of metals
Elements exist all over the earth Some are found as free elements eg copper silver and gold
Others are found combined with other elements in compounds To get the elements the
compounds have to be broken up These compounds are generally called ores the most
convenient sources of which are rocks sea and air
The extraction of a metal from its ore is a reduction process where the metals ions gain electrons
to form atoms
The general equation is Mn+ + n e- M
The choice of the extraction method depends on the position of the metal in the reactivity series
As we go down the series the metals become more stable and the metal ions (in the ores)
become less stable
The very reactive metals that are high in the series K Na Ca Mg Al have very stable ores
Therefore they require a powerful method of reduction namely electrolysis During the process
the cathode provides the electrons and acts as the reducing agent
The metals in the middle of the series (Zn Fe Pb) do not have stable ores and can be extracted
by reduction with carbon in the case of zinc and with carbon monoxide in the case of iron and
lead
Metals low in the reactivity series if present as ores can be extracted simply by heating the ores
in air at high temperatures
12
Extraction of Aluminium from purified bauxite
Pure bauxite is pure alumina (Al2O3) Aluminium is obtained from bauxite by electrolysis
Aluminium oxide has a very high melting point approximately 2050 0C so it is first dissolved in
molten cryolite (Na2AlF6) The addition of cryolite lowers the melting point to approximately
900 0C
The electrolyte is a molten mixture of alumina and molten cryolite The cathode is the graphite
lining of the cell The anodes are blocks of graphite or titanium alloys
Reaction at the cathode
Al3+ (l) + 3 e- Al (l)
Reaction at the anode
2 O2- (l) ndash 4 e- O2 (g)
Aluminium (melting point 660 0C) is a liquid at the temperature at which electrolysis is carried
out and is collected at the bottom of the cell and tapped off Oxygen gas which is given off in the
main cathode reaction together with the heat causes the anodes to burn away The anodes have
to be replaced from time to time The use of anodes from titanium alloys reduce the number of
times that the anodes have to be replaced
13
WEEK 6 LESSON 1 Worksheet
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 6 LESSON 2
TOPIC Extraction of metals
Extraction of Iron
The traditional method of production of iron is by reduction of haematite by carbon monoxide in
a blast furnace
Ores Haematite ndash Fe2O3 Magnetite ndash Fe3O4 Siderite ndash FeCO3 Magnetite and Siderite are
converted to Haematite
A mixture of haematite limestone (CaCO3) and coke (C) called the charge is placed into the top
of the furnace
Hot air is blown into the bottom of the furnace
Coke burns in air forming carbon dioxide
C (s) + O2(g) CO2 (g) ΔH -ve
The heat produced keeps the temperature at about 1900 0C
The carbon dioxide is reduced to carbon monoxide by the hot coke
CO2 (g) + C (s) 2 CO(g) Δ +ve
Heat absorbed reduces the temperature to about 1100 0C
The carbon monoxide reduces the hot iron ore to molten iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + 3 CO2(g)
The temperature at this part of the furnace is about 700 0C The iron runs to the bottom of the
furnace
The impurities are removed by the addition of limestone (CaCO3) The limestone at the
temperature of the furnace breaks down
CaCO3 (s) CaO (s) + CO2 (g)
15
The calcium oxide formed combines with silicon dioxide (sand) the main impurity in the iron
ore to form molten slag
CaO (s) + SiO2 (s) CaSiO3 (l)
The slag does not mix with the molten iron but floats on it The molten iron and slag are run off
separately
The iron formed in a blast furnace is an impure form of the metal Because the molten metal is
allowed to solidify in shallow trays known as casts the iron is called lsquocast ironrsquo or lsquopigrsquo iron
Cast iron is quite brittle and contains 2 - 4 carbon and other impurities Most of the cast iron is
converted to steel
A blast furnace used for extracting iron
16
WEEK 6 LESSON 2 Worksheet
(a) What are the three raw materials that are added through the top of the blast furnace
during the extraction process for iron
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______________________________________________________________________________
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
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17
WEEK 6 LESSON 3
TOPIC Alloys
An alloy is a mixture of two or more metals Alloys are made by melting the individual metals
mixing them and allowing the molten mixture to solidify
In general alloys are harder stronger and more resistant to corrosion than the actual metals they
are made up from
Alloy Use Properties
ALUMINIUM
-Duralumin
(AlMgCu)
-Magnalium (AlMg)
Alloys used in the
construction of
aircraft and ships
buses
Aluminium is used in
making cooking
utensils electrical
cables paint for fuel
storage tanks bottle
caps foil and utensils
for handling nitric
acid
The alloys have a low
density They are as
light as aluminium
and more resistant to
corrosion than
aluminium
LEAD
-Solder (PbSn)
Alloy is used in
joining metals
(soldering)
Lead is used in
underground cables
plates in
The alloy has a lower
melting point than
lead and is harder
than lead
18
Alloy Use Properties
accumulators shield
against x ndash rays
IRON
- Stainless Steel
(FeCONiC)
-Tungsten steel
(FeWC)
-Invar steel (FeNi)
Manganese steel
(FeMnC)
Iron is the main metal
of a variety of
constructions
Steel is used in
cutlery rock drills
electromagnets
vehicle body and
engine parts fences
pipes etc
Steel resists
corrosion is usually
harder than iron and
may be tough though
malleable and ductile
19
WEEK 6 LESSON 3 Worksheet
(a) Define the term alloy
______________________________________________________________________________
(b) State 3 general advantages that alloys have over the individual metals they are made
from
______________________________________________________________________________
______________________________________________________________________________
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
______________________________________________________________________________
______________________________________________________________________________
Uses
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 7 LESSON 1
TOPIC Corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
Familiar examples of corrosion are
- the formation of a green powder on copper sheeting
- the eating away of iron (rusting)
- the development by aluminum of a thin compact layer of oxide which protects the
underlying metal from further corrosion
When corrosion occurs in water ndash free environment it is called dry oxidation When it occurs in
aerated aqueous environments it is called wet corrosion Wet corrosion is the most common and
troublesome form of corrosion
The most familiar corrosion is the rusting of iron and steel On exposure to the atmosphere iron
and steel corrode to form rust which is hydrated iron (III) oxide Fe2O3xH2O Iron and steel
corrode easily and the rust formed flakes off easily thus exposing fresh surface for attack
When iron rust it loses electrons
Fe (s) ndash 2e- Fe 2+ (aq)
The iron (II) ions pass into solution and then combine with the hydroxyl (OH-) ions in the
aerated aqueous environment to form iron (II) hydroxide The oxygen present oxidises the iron
(II) hydroxide to hydrated iron (III) oxide or rust
Fe(OH)2 + O2 Fe2O3xH2O
21
Methods of preventing rusting
1 Coating the object with paint grease plastic or rubber which prevent contact with air or
water
2 Galvanising ndash coating the object with zinc The zinc forms an adherent oxide layer which
protects against further corrosion If damaged the zinc is oxidized in preference to the
iron since it is higher in the electrochemical series
3 Coating with tin lsquoTinrsquo cans are made of steel plated with tin However if scratched
rusting occurs since iron is more reactive than tin
4 Attaching a sacrificial anode to the object A piece of metal higher in the electrochemical
series such as magnesium is attached The magnesium will be oxidized in preference
since it is higher in the electrochemical series than iron
22
WEEK 7 LESSON 1 WORKSHEET
(a) Define the term corrosion
______________________________________________________________________________
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
23
WEEK 7 LESSON 2
TOPIC Importance of metals and their compounds on living systems and environment
Some metals are an integral part of different structures of living things
Metal Presence and Function
Potassium Main cation in fluid or animal cells essential for healthy plant growth
Calcium Necessary for strong bones teeth and shells needed by some enzymes Present
in dairy produce eggs nuts and cereals
Magnesium Central atom of chlorophyll needed for some enzyme action Involved in energy
and calcium metabolism
Zinc Present in many enzymes Needed for protein metabolism Essential for growth
of animals
Iron Present in haemoglobin Needed for protein metabolism Essential for growth of
animals
Chromium Needed for glucose uptake by cells and thus linked to the action of insulin
Manganese Needed for bone development and amino acid metabolism Present in several
enzymes Needed for plant growth
Cobalt Present in Vitamin B12 Needed for plant growth
Copper Involved in formation of haemoglobin and melanin Present in enzymes
controlling oxidation Needed for plant growth
24
Harmful effects of metals and their compounds to living systems and the environment
There are some metals and metal compounds which may cause harm to living systems and the
environment
Lead
Lead is a heavy metal poison that is widely encountered It may occur in food beverages paint
water formed from ndash sealed pipes in air polluted by combustion by fuels containing lead
compounds Lead is also used in some car batteries If these are paints or batteries are not
disposed of correctly lead may get into groundwater or air Lead and lead compounds harm the
nervous system including the brain especially young children
Arsenic
Arsenic compounds are poisonous They can get into the groundwater from mining waste and
from disposal of some electrical components
Cadmium
Cadmium compounds are poisonous They can get into the ground by improper disposal of
nickel ndash cadmium batteries Persons can get cadmium poisoning if they eat food grown in
contaminated soil
Mercury
Mercury can be spilled from broken thermometers in hospitals and laboratories Mercury and its
compounds are particularly poisonous to fish and it can accumulate in the food chain and
eventually poison humans
Problems of disposal of solid waste
Metals may react with water andor air and corrode to form soluble compounds that are
poisonous These toxic compounds diffuse into the soil and eventually enter rivers
Rust from iron may form unsightly pools of waste that reduce plant growth
Waste from aluminium extraction may react with water and form flammable gases
25
WEEK 7 LESSON 2 WORKSHEET
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
______________________________________________________________________________
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______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Lead
______________________________________________________________________________
Mercury
______________________________________________________________________________
26
WEEK 7 LESSON 3
TOPIC Chemical properties of non ndash metals
Reaction with oxygen
Many non ndash metals burn in excess oxygen or air to form oxides For example
S (s) + O2 (g) SO2 (g)
C (s) + O2 (g) CO2 (g)
Reactions with metals
Some non ndash metals react with metals high in the electrochemical series when heated
For example
Sodium burns in chlorine to form sodium chloride
Na (s) + Cl2 (g) NaCl (s)
Magnesium burns in oxygen to form magnesium oxide
Mg (s) + O2 (g) MgO (s)
When heated iron combines with molten sulphur to form iron (II) sulphide
Fe (s) + S (l) FeS (s)
When heated reactive metals such as sodium and aluminium react with hydrogen to form metal
hydrides
2 Na (s) + H2 (g) 2 NaH (s)
Oxidising and Reducing properties
Hydrogen and Carbon are very good reducing agents
At high temperatures hydrogen reduces metal oxides below zinc in the electrochemical series to
form the metal For example PbO (s) + H2 (g) Pb (s) + H2O (g)
Under suitable conditions hydrogen reduces nitrogen to ammonia
N2(g) + 3 H2 (g) 2 NH3 (g)
27
At high temperatures carbon reduces metal oxides below aluminium in the reactivity series to
the metal For example
ZnO (s) + C (s) Zn (s) + CO (g)
Oxygen and Chlorine are very good oxidizing agents
Oxygen oxidized most metals to form metal oxides and some non ndash metals to non ndash metal oxides
For example
2 Mg (s) + O2(g) 2 MgO (s)
4 P (s) + 5 O2 (g) P4O10 (s)
Chlorine acts as an oxidizing agent either as a gas or as an aqueous solution For example
H2 (g) + Cl2 (g) 2 HCl (g)
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
28
WEEK 7 LESSON 3 WORKSHEET
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
______________________________________________________________________________
(b) Write the ionic equation for the above reaction
______________________________________________________________________________
(c) Identify the oxidising agent in the reaction
______________________________________________________________________________
(d) Justify your answer in part (c) in terms of oxidation number
______________________________________________________________________________
29
WEEK 8 LESSON 1
TOPIC Laboratory preparation of gases
Preparation of oxygen
Oxygen can be prepared by the decomposition of hydrogen peroxide potassium chlorate (V) or
potassium nitrate The safest method is the decomposition of hydrogen peroxide
Manganese (IV) oxide catalyses the decomposition of hydrogen peroxide
Silica gel anhydrous calcium chloride or concentrated sulphuric acid can be used as a drying
agent
The gas is collected by downward delivery since it is slightly denser than air
Equation
2 H2O2 (aq) 2 H2O (l) + O2 (g)
Apparatus used for laboratory preparation of oxygen
30
WEEK 8 LESSON 1 WORKSHEET
Describe the laboratory preparation of oxygen gas
In your answer include
The starting material
A suitable catalyst
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
31
WEEK 8 LESSON 2
TOPIC Laboratory preparation of gases
Preparation of carbon dioxide
Carbon dioxide can be prepared by the action of dilute acid on carbonates Marble chips (calcium
carbonate) and dilute hydrochloric acid are the common reagents The gas is collected by
downward delivery since it is denser than air
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
Apparatus used for laboratory preparation of carbon dioxide
32
WEEK 8 LESSON 2 WORKSHEET
Describe the laboratory preparation of carbon dioxide gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
33
WEEK 8 LESSON 3
TOPIC Laboratory preparation of gases
Preparation of ammonia
Ammonia may be prepared by heating a mixture of ammonium salt and a hydroxide The
ammonia gas is collected by upward delivery since it is less dense than air
For example
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
Calcium oxide is the only suitable drying agent since ammonia reacts with conc H2SO4 and
CaCl2
Apparatus used for laboratory preparation of dry ammonia
34
11
WEEK 8 LESSON 3 WORKSHEET
Describe the laboratory preparation of ammonia gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
35
WEEK 9 LESSON 1
TOPIC Uses of gases
Carbon dioxide
Used in fire extinguishers to put out fires Carbon dioxide is denser than air and lsquoblanketsrsquo the
fire preventing oxygen from reaching it Carbon dioxide extinguishers are especially useful for
dealing with fires involving flammable liquids and electrical equipment
Carbonation in soda is created when carbon dioxide is pumped into the soda can or bottle then
held under pressure As long as the can or bottle is sealed the carbon dioxide remains mostly
stable However if the drink gets shaken up or the top is opened the tiny carbon dioxide bubbles
react by bursting
Oxygen
Oxygen is needed for aerobic respiration We need a constant supply of oxygen for this process
Oxygen is used in hospitals to improve the respiration of patients with poor blood flow blood
poisoning and heart disease
Oxygen in used in welding (joining) metals In an oxyacetylene welding torch acetylene or
ethyne (C2H2) burns in oxygen and produces a very hot flame This flame is capable of melting
most metals
Oxygen is used in steel production A blast of oxygen is blown through the molten iron The
oxygen oxidises many of the impurities of the iron and the impurities are then removed
36
WEEK 9 LESSON 1 WORKSHEET
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Put out fires
Welding metals
Create lsquofizzrsquo in drinks
Used in steel production
Aerobic respiration
37
WEEK 9 LESSON 2
TOPIC Uses of non ndash metals and their compounds
Carbon (allotrophes carbon dioxide)
Carbon is used as a reducing agent in extraction of some metals
Carbon as graphite is used as electrodes lubricants and lsquoleadrsquo for pencils
Carbon in the form of diamond is used for jewellery (because of its lustre) and in drill tips for
high ndash speed drills (because of its hardness)
Carbon dioxide is used as refrigerant (as dry ice) for carbonated beverages
Sodium hydrogen carbonate and sodium carbonate are used for water softening and raising
agent
Sulphur
Sulphur is used in the manufacture of sulphuric acid Sulphur is also used in the manufacture of
tyres to make the rubber harder (vulcanisation)
Sulphur powder is used as fungicide on plant materials
Phosphorus
Phosphorus is used in the manufacture of fertilizers
Phosphorus is used to make phosphor bronze alloys
Phosphorus sulphide is used to make the heads of lsquostrike anywherersquo matches
38
Chlorine
Chlorine is used to make sodium hypochlorite which is present in bleach It is also used in
sterilizing swimming pools and in water treatment
Chlorine is used to make the monomer vinyl chloride which is used to make the plastic PVC
Nitrogen
Nitrogen is used to make fertilisers ammonia dyes and nitric acid
Nitrogen is used as an inert atmosphere to prevent substances being oxidised and as a coolant
Silicon
Silicon is used for making silicon chips for computers
Silicon (V) oxide is present in sand Glass is made by heating sand with lime (calcium oxide) and
sodium carbonate
Silicon in the form of silicates is used in jewellery
Silica gel is used as a drying agent
39
WEEK 9 LESSON 2 WORKSHEET
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Used to make sodium hypochlorite
Used as a fungicide on plant materials
Used for lsquoleadrsquo in pencils
Used in the manufacture of bronze alloys
Used in the manufacture of nitric acid
Used in the manufacture of computer chips
Used to make fertilisers
40
WEEK 9 LESSON 3
TOPIC Harmful effects of non ndash metals and their compounds on living systems and the
environment
Sulphur dioxide
Sulphur dioxide can cause a disease of the lungs Sulphur dioxide also poisons plants in two
main ways It may enter the stomata of leaves and react with the tissue fluids to form sulphites
with the on ndash going water loss the concentration of sulphites could build up killing the cells
The second adverse effect on plants occurs when sulphur dioxide dissolves in rain thereby
increasing soil acidity A prolonged acid soil situation may lead to plasmolysis and the death of
vegetation in an area
Carbon monoxide
Carbon monoxide combines much more readily than oxygen with haemoglobin When carbon
monoxide is inhaled it prevents the haemoglobin from taking oxygen to the bodyrsquos cells
Continued breathing of air containing carbon monoxide eventually causes death
Hydrogen sulphide
Hydrogen sulphide reacts readily with many cations forming insoluble sulphides Many cations
contribute to good health by contributing to enzyme activity and to the formation of bone
pigment and haemoglobin Although these cations are required in extremely small
concentrations they are removed by being precipitated as sulphides and thus not available for
regular function Careless dumping of refuse contributes to atmospheric pollution by hydrogen
sulphide
Oxides of nitrogen
In the presence of hydrocarbons from car exhausts ozone and sunlight nitrogen oxides react to
form photochemical smog which contains many harmful chemicals
Nitrogen dioxide can harm the lungs and irritate the nose throat and eyes The other compounds
present in photochemical smog are even more harmful irritants and can cause asthma
41
Carbon dioxide
Carbon dioxide water vapour and ozone referred to as ldquogreenhouse gasesrdquo acting as a blanket
readily absorb some of the radiated heat energy and in turn warms the earthrsquos atmosphere This is
called the ldquogreenhouse effectrdquo Scientists have found direct correlation between carbon dioxide
concentration and global warming An increase in carbon dioxide concentration resulted in an
increase global temperatures Global warming is a major potential problem that the world faces
Chloroflourocarbons (CFCs)
It is believed that CFCs might be responsible for destroying the ozone layer which prevents
harmful ultraviolet (UV) radiation from reaching the earth The carbon ndash chlorine bond in CFC
molecule is easily broken by a UV photon producing an active chlorine atom This atom
combines with an ozone molecule forming a chlorine oxide radical and oxygen The radicle
reacts with more ozone producing the chlorine atom again This kind of reaction is repeated
thousands of times This type of reaction is thought to account for about eighty percent of the
loss of ozone observed
Nitrates and phospates
Nitrates and phosphates cause eutrophication The process leading to eutrophication are
Nitrates and phosphates from fertilisers spread on fields may dissolve in groundwater and
get into lakes and rivers
Nitrates and phosphates cause excessive growth of algae so that they cover the surface of
the water
Water plants including algae die because of lack of sunlight Aerobic bacteria feed on
the plant remains The bacteria multiply
The aerobic bacteria use up the oxygen in the water so aquatic animals die
42
Solid waste
The main sources of pollution from non ndash metals is from glass paper and plastics
Broken glass can cause injury to animals It can also cause fires by acting as lens focusing the
sunrsquos rays on flammable materials
Printing inks from paper dumped in the ground may contain toxic elements such as arsenic and
cadmium Bleaches and chlorine compounds from paper are also harmful
43
WEEK 9 LESSON 3 WORKSHEET
Describe ONE harmful effect of the following non ndash metals andor their compounds on
living systems and the environment
Sulphur dioxide
______________________________________________________________________________
______________________________________________________________________________
Carbon monoxide
______________________________________________________________________________
______________________________________________________________________________
Carbon dioxide
______________________________________________________________________________
______________________________________________________________________________
Oxides of nitrogen
______________________________________________________________________________
______________________________________________________________________________
Hydrogen sulphide
______________________________________________________________________________
______________________________________________________________________________
44
Chloroflourocarbons (CFCs)
______________________________________________________________________________
______________________________________________________________________________
Nitrates and phospates
______________________________________________________________________________
______________________________________________________________________________
45
WEEK 10 LESSON 1
TOPIC Green Chemistry
Green Chemistry is defined as the utilisation of a set of principles that reduces or eliminates the
use and generation of hazardous substances
There are twelve principles of green chemistry as proposed by Paul T Anastas and John C
Warner These twelve principles are
1 Prevention ndash It is better to prevent waste than to treat or clean up waste after it has been
created
2 Atom economy - Synthetic methods should be designed to maximize the incorporation of
all materials used in the process into the final product
3 Less hazardous chemical synthesis - Wherever practicable synthetic methods should be
designed to use and generate substances that possess little or no toxicity to human health
and the environment
4 Safer chemical products - Chemical products should be designed to affect their desired
function while minimizing their toxicity
5 Safer solvents and other agents - The use of auxiliary substances (eg solvents
separation agents etc) should be made unnecessary wherever possible and harmless
when used
6 Minimum energy requirements - Energy requirements of chemical processes should be
recognized for their environmental and economic impacts and should be minimized If
possible synthetic methods should be conducted at ambient temperature and pressure
7 Use of renewable raw materials - A raw material or feedstock should be renewable rather
than depleting whenever technically and economically practicable
8 Reduce use of additional chemicals or additional steps - Unnecessary derivatization (use
of blocking groups protection deprotection temporary modification of
physicalchemical processes) should be minimized or avoided if possible because such
steps require additional reagents and can generate waste
46
9 Use of catalysts ndash The use of catalysts reduce energy costs because the reactions take
place at lower temperatures The more specific the catalyst for a particular reaction is the
less it the likelihood of getting additional unwanted products
10 Nature of breakdown of products - Chemical products should be designed so that at the
end of their function they break down into innocuous degradation products and do not
persist in the environment
11 Monitoring to prevent pollution - Analytical methodologies need to be further developed
to allow for real-time in-process monitoring and control prior to the formation of
hazardous substances
12 Minimise chemical accidents - Substances and the form of a substance used in a chemical
process should be chosen to minimize the potential for chemical accidents including
releases explosions and fires
47
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
48
WEEK 10 LESSON 2
TOPIC Qualitative Analysis ndash Identification of cations
Qualitative Analysis involves identifying the constituents of single substances or mixture of
substances
Appearance
An examination of the appearance of a substance can indicate which ion it contains
Appearances of substances
Observation Indication
Blue or blue ndash green Cu2+ salt
Pale green Fe2+ salt
Yellow ndash brown Fe3+ salt
Ammonia smell NH4+ salt
49
Test for cation using sodium hydroxide
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
(d) If no precipitate forms in step b warm gently and test for ammonia
Effect of dilute sodium hydroxide solution
Effect of dilute sodium hydroxide solution Cation
Dropwise Excess
White precipitate Precipitate soluble Ca2+
White precipitate Precipitate insoluble Al3+ Pb2+ Zn2+
Blue precipitate Precipitate insoluble Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
No precipitate ndash ammonia gas
evolved on heating
ndash NH4+
The metal cations all form insoluble hydroxides with sodium hydroxide solution
For example Ca2+ (aq) + 2 OH- (aq) Ca(OH)2 (s)
Ca(OH)2 Cu(OH)2 Fe(OH)2 and Fe(OH)3 are basic and therefore do not react with excess
sodium hydroxide solution Therefore the precipitate does not dissolve in excess sodium
hydroxide solution
Al(OH)3 Pb(OH)2 and Zn(OH)2 are amphoteric Therefore the precipitates react with the excess
sodium hydroxide solution forming soluble salts and the precipitate disappears in excess sodium
hydroxide solution
The NH4+ ion forms a soluble hydroxide However on heating it reacts with the hydroxide ion to
form ammonia and water
NH4+ (aq) + OH- (aq) NH3 (g) + H2O (l)
50
WEEK 10 LESSON 2 WORKSHEET
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P _____________ Q ___________________
R _____________ S ___________________
R + NaOH
______________________________________________________________________________
51
WEEK 10 LESSON 3
TOPIC Qualitative Analysis ndash Identification of cations
Test for cation using ammonia solution (ammonium hydroxide solution)
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
Effect of dilute ammonia (ammonium hydroxide) solution
Effect of dilute ammonia solution Cation
Dropwise Excess
No precipitate ndash Ca2+
White precipitate Precipitate soluble
(forming colourless solution)
Zn2+
White precipitate Precipitate insoluble Al3+ Pb2+
Blue precipitate Precipitate soluble
(forming deep blue solution)
Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
52
Ammonia solution is a weak alkali Metal cations except Ca2+ form insoluble hydroxides with
ammonia solution as with the sodium hydroxide solution
The amphoteric hydroxides Al(OH)3 and Pb(OH)2 and the basic hydroxides Fe(OH)2 and
Fe(OH)3 do not react with excess ammonia solution Therefore the precipitates remain
However Zn(OH)2 and Cu(OH)2 do react with excess ammonia solution to form complex
soluble hydroxides each Hence their precipitates disappear on the addition of excess ammonia
solution
Confirmatory test
After carrying out test for cations using sodium hydroxide solution and ammonia solution the
only cations which cannot be distinguished are Al3+ and Pb2+ A confirmatory test is carried out
to distinguish between the two cations
Confirmatory test
Test Observation Cation Ionic equation
Add potassium
or sodium
iodide solution
Bright yellow precipitate
No precipitate
Pb2+
Al3+
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
53
WEEK 10 LESSON 3 WORKSHEET
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A __________ B ________________ C ________________________
(b) State the inference after Test 2
C _______________________
(c) Write an ionic equation to support your answer in (b) above
___________________________________________________________________________
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
54
ANSWERS TO WORKSHEETS
55
WEEK 5 LESSON 1 WORKSHEET ANSWERS
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
Answer
Zinc + Iron (II) sulphate Zinc is higher in the electrochemical series and therefore displace
iron ions in iron (II) sulphate
Equation Zn (s) + FeSO4 (aq) ZnSO4 (aq) + Fe (s)
Ionic equation Zn (s) + Fe2+ (aq) Zn2+ (aq) + Fe (s)
Iron + Zinc sulphate No reaction iron is lower in the electrochemical series and cannot
displace the zinc ions in zinc sulphate
56
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
Answer
X displaces lead from an aqueous solution of its salts
X (s) + Pb2+ (aq) Xn+ (aq) + Pb (s)
rarr X is more reactive than Pb
X did not react with iron salts
rarr X is less reactive than Fe
Y burns very easily
Y is more reactive than Fe and Pb (both forming their corresponding oxide at a slower rate)
From electrochemical series Fe is higher and therefore more reactive than Pb
Order of reactivity
Y (most reactive) gt Fe gt X gt Pb (least reactive)
57
WEEK 5 LESSON 2 WORKSHEET ANSWERS
1
Metal Reactivity with acid
Copper X
Magnesium
Aluminium
Silver X
Zinc
58
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
Answer
Y and Z are the most reactive since they can react with dilute acid
Z is more reactive than Y since a reaction occurs with Z is added to an aqueous solution of Y
X is less reactive than W since it does not occur in nature as compounds
Order of reactivity Z (most reactive) gt Y gt W gt X
59
WEEK 5 LESSON 3 WORKSHEET ANSWERS
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
Answer
Ease of decomposition (from easiest to decompose to most difficult to decompose)
B rarrD rarrArarr C
Reactivity (most reactive to least reactive)
C (most reactive) gt A gt D gt B (least reactive)
60
WEEK 6 LESSON 1 Worksheet Answers
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
Potassium Zinc Copper
Calcium Lead Gold
Magnesium Iron
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
Aluminium is extracted from its ore bauxite through the process of electrolysis
Cryolite is added to bauxite to lower the melting point to about 900 0C The melting point of
bauxite is very high (about 2040 0C) It is difficult and expensive to keep the molten aluminium
oxide at this temperature
Reaction at the cathode Al3+ (l) + 3 e- Al (l)
61
WEEK 6 LESSON 2 Worksheet Answers
(a) What are the three raw materials that are added through the top of the blast
furnace during the extraction process for iron
Coke (carbon)
iron ore (haematitie mainly iron (II) oxide)
limestone (calcium carbonate)
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
Coke ndash coke burns to produce carbon dioxide The carbon dioxide further reacts with coke to
form carbon monoxide (reducing agent in the process)
C (s) + O2 (g) CO2 (g)
C (s) + CO2 (g) 2 CO
Haematite ndash iron ore provides the iron which is reduced by the carbon monoxide to produce
iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + CO2 (g)
Limestone ndash decomposes to form calcium oxide The calcium oxide reacts with the impurity
silicon dioxide to form slag (calcium silicate)
CaCO3 (s) CaO (s) + CO2 (g)
CaO (s) + SiO2 (l) CaSiO3(l)
62
WEEK 6 LESSON 3 Worksheet Answers
(a) Define the term alloy
An alloy is a material made from a mixture of two or more metals
(b) State 3 general advantages that alloys have over the individual metals they are made
from
They are harder stronger and more resistant to corrosion
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
1 High strength
2 Low density
Uses
1 Used to make aircraft bodies
2 Used to make space satellites
63
WEEK 7 LESSON 1 WORKSHEET ANSWERS
(a) Define the term corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
The paint forms a barrier which stops contact with air or water and the iron Hence rusting
will not take place
However when the paint is scratched that part of the iron nail is exposed to air or water and
rusting will take place
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
Magnesium is higher in the electrochemical series and will be oxidised in preference to iron
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
Aluminium is partly protected from corrosion by its coat of aluminium oxide However as the
iron rust it flakes and fall off and the rusting process continues
64
WEEK 7 LESSON 2 WORKSHEET ANSWERS
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
Magnesium is the ion found in chlorophyll Chlorophyll plays a vital part in the process of
photosynthesis A deficiency in magnesium will lead to low chlorophyll level in the tomato
plants and hence reduce the process of photosynthesis There will be less food storage and
hence will lead to smaller yield of tomatoes
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Any correct harmful effect of lead on health or environment
Any correct harmful effect of mercury on health or environment
65
WEEK 7 LESSON 3 WORKSHEET ANSWERS
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
(b) Write the ionic equation for the above reaction
2 Br- (aq) + Cl2 (aq) 2 Cl- (aq) + Br2 (aq)
(c) Identify the oxidising agent in the reaction
Cl2 (aq)
(d) Justify your answer in part (c) in terms of oxidation number
There is a reduction of the oxidation number for chlorine from 0 to ndash1
hence it has been reduced Therefore chlorine is the oxidising agent
66
WEEK 8 LESSON 1 WORKSHEET ANSWERS
Describe the laboratory preparation of oxygen gas
Oxygen is prepared in the laboratory by the decomposition of hydrogen peroxide
A suitable catalyst is manganese (IV) oxide
Drying agent silica gel OR anhydrous calcium chloride OR conc sulphuric acid
The gas is collected by downward delivery since oxygen is slightly denser than air
Balanced chemical equation 2 H2O2 (aq) 2 H2O (l) + O2 (g)
67
WEEK 8 LESSON 2 WORKSHEET ANSWERS
Describe the laboratory preparation of carbon dioxide gas
Carbon dioxide is commonly prepared in the laboratory by the reacting hydrochloric acid and
marble chips (calcium carbonate)
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
The carbon dioxide gas is collected by downward delivery since it is denser than air
Balanced chemical equation
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
68
WEEK 8 LESSON 3 WORKSHEET ANSWERS
Describe the laboratory preparation of ammonia gas
An ammonium salt (ammonium chloride) and a base (sodium hydroxide) are mixed together and
heated
Calcium oxide is used as the drying agent Calcium chloride and concentrated sulphuric acid
cannot be used since ammonia can react with them
The gas is collected by upward delivery since ammonia is less dense than air
Balanced chemical equation
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
69
WEEK 9 LESSON 1 WORKSHEET ANSWERS
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Carbon dioxide Put out fires
Oxygen Welding metals
Carbon dioxide Create lsquofizzrsquo in drinks
Oxygen Used in steel production
Oxygen Aerobic respiration
70
WEEK 9 LESSON 2 WORKSHEET ANSWERS
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Chlorine Used to make sodium hypochlorite
Sulphur Used as a fungicide on plant materials
Carbon (graphite) Used for lsquoleadrsquo in pencils
Phosphorus Used in the manufacture of bronze alloys
Nitrogen Used in the manufacture of nitric acid
Silicon Used in the manufacture of computer chips
Nitrogen Phosphorus Used to make fertilisers
71
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
Green Chemistry is using principles that reduceeliminate the use of hazardous materials in
the design manufacture and application of chemical products
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
Makes the environment safer
Reduces waste
Creates new jobs
Reduces respiratory illnesses
Atom economy
72
WEEK 10 LESSON 2 WORKSHEET ANSWERS
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P Cu2+ Q Fe2+
R Fe3+ S Ca2+
Ionic equation for R + NaOH
Fe3+ (aq) + 3 OH- (aq) Fe(OH)3 (s)
73
WEEK 10 LESSON 3 WORKSHEET ANSWERS
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A Fe3+ B Ca2+ C Al3+ Pb2+
(b) State the inference after Test 2
C Pb2+
(c) Write an ionic equation to support your answer in (b) above
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
11 Qualitative Analysis
ndash Test for gases
Qualitative Analysis
ndash Identification of
anions
Qualitative Analysis
ndash Identification of
anions
12 Problem solving of
Past CSEC Chemistry Paper 2
on topics completed in the term
13
14
15
2
WEEK 11 LESSON 1
TOPIC Qualitative Analysis ndash Test for gases
Identification of gases
Gas Colour Odour Effect on moist
litmus
Method of identification
Oxygen
O2
Colourless Odourless Neutral ndash no
effect
Relights a glowing splint
Hydrogen
H2
Colourless Odourless Neutral ndash no
effect
Lighted splint lsquopopsrsquo if air is also
present
Carbon
dioxide
CO2
Colourless Odourless Weakly acidic ndash
blue to slightly
red
A white precipitate forms in
limewater
Ca(OH)2 (aq) + CO2
CaCO3 (s) + H2O (l)
Precipitate redissolves on
continued bubbling
CaCO3 (s) + H2O (l) + CO2 (g)
Ca(HCO3)2 (aq)
Ammonia
NH3
Colourless Pungent Alkaline ndash red
to blue (only
common
alkaline gas)
Turns moist red litmus blue forms
dense white fumes with hydrogen
chloride gas
NH3 (g) + HCl (g) NH4Cl (s)
Gas Colour Odour Effect on moist
litmus
Method of identification
3
Sulphur
dioxide
SO2
Colourless Choking
smell
Acidic ndash blue to
red
Turns acidified potassium
manganate (VII) solution from
purple to colourless
Turns acidified potassium
dichromate (VI) solution from
orange to green
Chlorine
Cl2
Yellow ndash
green
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Bromine
Br2
Red ndash
brown
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Nitrogen
dioxide
NO2
Red ndash
brown
Irritating
smell
Acidic blue to
red
Turns moist blue litmus red but
does not bleach it
Water
vapour
H2O
Colourless Odourless Neutral ndash no
effect
Turns anhydrous cobalt (II)
chloride from blue to pink
Turns anhydrous copper (II)
sulphate from white to blue
4
WEEK 11 LESSON 1 WORKSHEET
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless
Yellow ndash green
Red ndash brown
Gases according to their odour
Odour of gas Identity of gas
Odourless
Pungent smell
Choking smell
Irritating smell
5
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect
Red to blue
Blue to red
Blue to red then bleaches it
6
WEEK 11 LESSON 2
TOPIC Qualitative Analysis ndash Identification of anions
Effect of heating
Method Heat a sample of the solid in a dry test tube
Effect of heating
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) not
of K or Na
CO32- (s) O2- (s) + CO2 (g)
Oxygen evolved NO3- of K or Na 2 NO3
- (s) 2 NO2- (s) + O2
(g)
Oxygen and nitrogen
dioxide evolved
NO3- of Ca and below
in reactivity series
4 NO3- (s) 2 O2- (s) + 4 NO2
(g) + O2
(g)
Sulphur dioxide evolved SO32- SO3
2- O2- (s) + SO2 (g)
Effect of dilute acid
Add dilute hydrochloric acid or nitric acid to a sample of the solid Warm if no reaction occurs
when cold
Effect of dilute acid
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) CO32- (s) + 2 H+ (aq) H2O (l) + CO2 (g)
Sulphur dioxide evolved SO32- SO3
2- (s) + 2 H+ (aq) H2O (l) + SO2 (g)
7
Effect of concentrated acid
Add concentrated sulphuric acid to a sample of the solid Warm if not reaction occurs when cold
Effect of concentrated sulphuric acid
Observation Anion
Carbon dioxide evolved CO32- or HCO3
-
Sulphur dioxide evolved SO3-
Hydrogen chloride evolved Cl-
Hydrogen bromide (colourless) and bromine
vapour (brown) evolved
Br-
Black iodine present and purple iodine vapour
evolved
I-
8
WEEK 11 LESSON 2 WORKSHEET
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater
Produces a gas which relights a glowing splint as the only gas
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green
Produces a gas forms a precipitate in limewater
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia
Black iodine present and purple iodine vapour evolved
9
WEEK 11 LESSON 3
TOPIC Qualitative Analysis ndash Identification of anions
Test for the halides ndash using silver nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous silver nitrate and
observe the precipitate Add ammonia solution and observe the solubility of the precipitate
Test for halides using silver nitrate solution
Effect of silver
nitrate solution
Anion Explanation Effect of aqueous
ammonia
White precipitate ndash
turns white in
sunlight
Cl- Ag+ (aq) + Cl- AgCl (s) Precipitate soluble
Cream precipitate ndash
turns yellow ndash green
in sunlight
Br- Ag+ (aq) + Br- AgBr (s) Precipitate slightly
soluble
Pale yellow
precipitate
I- Ag+ (aq) + I- AgI (s) Precipitate insoluble
Test for the halides ndash using lead nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous lead nitrate and
observe the precipitate
Test for halides using lead nitrate solution
Effect of lead nitrate solution Anion Explanation
White precipitate Cl- Pb2+ (aq) + 2 Cl- PbCl2 (s)
Pale yellow Br- Pb2+ (aq) + 2 Br- PbBr2 (s)
Deep yellow I- Pb2+ (aq) + 2 I- PbI2 (s)
10
Effect of barium nitrate or chloride solution followed by dilute acid
Make a solution of the solid Add barium nitrate or chloride solution and observe the precipitate
Add dilute hydrochloric or nitric acid warn if necessary and observe the solubility of the
precipitate
Effect of barium nitrate or chloride solution followed by dilute acid
Effect of
Ba(NO3)2 (aq)
or BaCl2 (aq)
Effect of HCl (aq)
or HNO3 (aq)
Anion Explanation
White precipitate Precipitate insoluble SO42- Ba2+ (aq) + SO4
2- (aq) BaSO4 (s)
BaSO4 does not react with dilute acids
White precipitate Precipitate soluble ndash
CO2 evolved
CO32- Ba2+ (aq) + CO3
2- (aq) BaCO3 (s)
BaCO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + CO2 (g)
White precipitate Precipitate soluble ndash
SO2 evolved on
warming
SO32- Ba2+ (aq) + SO3
2- (aq) BaSO3 (s)
BaSO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + SO2 (g)
11
WEEK 11 LESSON 3 WORKSHEET
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
(Ionic equation required)
12
WEEK 12 LESSON 1 WORKSHEET
(a) The Caribbean islands are known for their many resources For example the ore of
aluminium is found in Jamaica and Guyana
(i) Briefly describe the extraction of aluminium from its named ore Include in your
description one ionic equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Although aluminium ore is mined in the Caribbean the extraction of aluminium usually
takes place in other countries Suggest ONE reason why it may be difficult to extract
aluminium in the Caribbean
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) An alloy can be described as a lsquomixed metal solutionrsquo Aluminium forms an alloy with
magnesium that is used to make an aircraft
13
Identify this alloy and suggest why it is better to use it rather than the pure metal in the
manufacture of aircraft
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) ldquoSome metals can be useful to man yet harmful to the environmentrdquo Comment on this
statement with reference to mercury
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 12 LESSON 2 Worksheet
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate formed
Soluble in excess
15
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate formed
Insoluble in excess
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate formed
(Ionic equation required)
16
WEEK 12 LESSON 3 Worksheet
Dry ammonia gas can be produced in a school laboratory
(a) Identify TWO reagents that are necessary for the laboratory production of ammonia
______________________________________________________________________________
______________________________________________________________________________
(b) Two common drying agents used in the laboratory are calcium oxide and concentrated
sulphuric acid However calcium oxide is the preferred choice for drying ammonia gas
Explain why concentrated sulphuric acid is now used Include in your answer a balanced
chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) When gases are prepared in the laboratory there are three main ways in which they can
be collected
- Upward delivery
- Downward delivery
- Displacement of water
(i) What TWO other factors should be considered when choosing an appropriate method for
the collection of gases in the laboratory
______________________________________________________________________________
______________________________________________________________________________
(ii) Identify ONE of the three methods that is best suited for the collection of ammonia gas in
the laboratory Explain why EACH of the other two methods would NOT have been
appropriate
______________________________________________________________________________
17
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(d) Hence draw a labelled diagram of the apparatus which could be used for the preparation
of dry ammonia in the laboratory
Be sure to identify in your diagram
- where the reagents are placed
- where the ammonia is dried and
- where the ammonia is collected
18
WEEK 13 LESSON 1 Worksheet
(a) In solution two metals A and B form A+ and B2+ ions respectively Metal A displaces Fe
from a solution containing Fe2+ ions but metal B does NOT
(i) Arrange the metals A B and Fe in order of reactivity from LEAST reactive to MOST
reactive Write a balanced chemical equation to show the reaction between metal A and
Fe2+ ions
______________________________________________________________________________
______________________________________________________________________________
(ii) Metal A is placed in a solution of copper (II) sulphate CuSO4 (aq) Write an equation for
the reaction State ONE observable change that will occur and explain why this reaction
takes place
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) For EACH metal A and B state ONE method that can be used to extract it from its
respective oxide Give a reason for EACH answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
19
______________________________________________________________________________
(b) Metal alloys are often used for making objects found in our daily lives Name an alloy of
iron and state ONE of its uses
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 13 LESSON 2 Worksheet
(a) Many important biological processes in plants and animals depend on the specific roles
of certain metal ions
(i) Farmer Jones reaped a crop of tomatoes and reported that the yield was far below what
was expected Analysis of the soil revealed that there was a deficiency of magnesium
Discuss the importance of magnesium in plant health and explain how a magnesium
deficiency can result in the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE other metal ion which is important to plant health and state the result of its
deficiency
______________________________________________________________________________
______________________________________________________________________________
21
(b) Many years ago car exhaust fumes were known to contain compounds of metals and
non ndash metals which could negatively impact both humans and the environment Identify
ONE metal and ONE non ndash metal whose compounds were present in car exhaust fumes
Discuss the effect of these compounds on human health and the environment
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) Define lsquogreen chemistryrsquo and discuss the measures that have been taken to produce a
lsquogreenerrsquo automotive fuel
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
22
WEEK 13 LESSON 3 Worksheet
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
Zn2+ ions are present
23
WEEK 14 LESSON 1 Worksheet
(a) Metal alloys are often used in place of metals because of their enhanced properties
(i) Define the term lsquoalloyrsquo
______________________________________________________________________________
______________________________________________________________________________
(ii) Name ONE alloy of aluminium and state its use based on one of its enhanced properties
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) A student conducted an experiment to investigate the reactivity of each of the following
metals (copper iron zinc and lead) by using solutionPs of their sulphate salts
The data presented in the table below shows whether a visible chemical reaction took
place when each metal was added to the four sulphate solutions
Key Visible chemical reaction took place
X No visible chemical reaction
CHEMICAL REACTION OF METALS IN SULPHATE SOLUTIONS
Sulphate solution Cu Fe Zn Pb
CuSO4 X
FeSO4 X X X
ZnSO4 X X X X
PbSO4 X X
24
(i) State which of the TWO metals is more reaction Fe or Zn Give a reason for our answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Using the data in the previous Table deduce the order of reactivity of the four metals Cu
Fe Zn and Pb from the most reactive to the least reactive metal
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The student recorded the following observations from the reaction between the iron and
copper (II) sulphate solution
Observations Reddish ndash brown solid coating formed on the iron strip
Blue colour of the solution changed to dirty green
Account for the observations made from the reaction between the iron and copper (II)
sulphate solution
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iv) Write an ionic equation including state symbols for the reaction between the iron and
copper (II) sulphate solution
______________________________________________________________________________
25
(c) Some metal compounds are health and environmental hazards
(i) Identify which of the metals used in the experiment in (b) is MOST hazardous to the
environment
______________________________________________________________________________
______________________________________________________________________________
(ii) State TWO harmful effects of continuous exposure to the metal identified in (c) (i) on
human beings
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
26
WEEK 14 LESSON 2 Worksheet
(a) Carbon is found in the form of diamond and graphite and is a main component in many
naturally occurring compounds such as organic matter and carbon dioxide gas
(i) State ONE way in which diamond differs physically from graphite
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE similarity between diamond and graphite other than they both contain carbon
______________________________________________________________________________
______________________________________________________________________________
(b) Carbon can react with a limited supply of oxygen to form carbon monoxide which can
negatively affect human health
(i) Write a balanced chemical equation including state symbols to show the formation of
carbon monoxide
______________________________________________________________________________
(ii) State TWO effects of carbon monoxide inhalation on the human body
______________________________________________________________________________
______________________________________________________________________________
(c) Jamal wants to prepare and collect a sample of carbon dioxide gas in the laboratory using
calcium carbonate
(i) Write a balanced chemical equation including state symbols for the laboratory
preparation of carbon dioxide gas from calcium carbonate
______________________________________________________________________________
______________________________________________________________________________
(ii) Draw a clearly labelled diagram to show the arrangement of the apparatus and materials
that could be used in the laboratory to prepare and collect the carbon dioxide gas
(iii) State ONE use of carbon dioxide as it relates to the beverage industry
______________________________________________________________________________
27
WEEK 14 LESSON 3 Worksheet
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
(Ionic equation required)
Suggest a possible identity of the solid R __________________________
28
WEEK 15 LESSON 1 Worksheet
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a small
portion of solid Y gently at
first and then strongly
Colourless gas evolved
with a choking odour
Turns acidified potassium
dichromate solution from
orange to green
(ii) To the remaining portion
of solid Y add 20 cm3 of
distilled water stir to dissolve
and filter Collect the filtrate
and divide into 3 equal
portions
Filtrate is pale green in
colour
(iii) To the first portion of the
filtrate from (ii) add aqueous
sodium hydroxide slowly
until in excess
A green precipitate
Insoluble in excess sodium
hydroxide
Ionic equation required
29
TEST OBSERVATIONS INFERENCES
(iv) To the second portion of
the filtrate from (ii) add
aqueous silver nitrate
followed by aqueous
ammonia
White precipitate
Soluble in aqueous
ammonia
(v) To the third portion of the
filtrate from (ii) add aqueous
barium nitrate followed by
aqueous hydrochloric acid
White precipitate formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with the
evolution of a colourless
gas with a choking smell
30
WEEK 15 LESSON 2 Worksheet
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
31
WEEK 15 LESSON 3 Worksheet
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in excess
aqueous NH3
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change
32
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
warm filter and then divide
the filtrate into two portions
Vigorous effervescence
observed upon addition of
dilute HNO3
Gas evolved turns lime water
cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Cu2+ ions present
33
ANSWERS TO WORKSHEETS
34
WEEK 11 LESSON 1 WORKSHEET ANSWERS
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless O2 H2 CO2 NH3 SO2 H2O
Yellow ndash green Cl2
Red ndash brown Br2 NO2
Gases according to their odour
Odour of gas Identity of gas
Odourless O2 H2 CO2 H2O
Pungent smell NH3
Choking smell SO2 Cl2 Br2
Irritating smell NO2
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect Neutral O2 H2 H2O
Red to blue Alkaline NH3
Blue to red Acidic CO2 SO2 NO2
Blue to red then bleaches it Acidic Cl2 Br2
35
WEEK 11 LESSON 2 WORKSHEET ANSWERS
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-) not
of K or Na
Produces a gas which relights a glowing splint as the only gas NO3- of K or Na
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green SO32-
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-)
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia Cl-
Black iodine present and purple iodine vapour evolved I-
36
WEEK 11 LESSON 3 WORKSHEET ANSWERS
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Br-
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
Cl-
Ag+ (aq) + Cl- AgCl (s)
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow Br-
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
SO42-
Ba2+ (aq) + SO42- (aq)
BaSO4 (s)
(Ionic equation required)
37
WEEK 12 LESSON 1 Worksheet Answers
(a) (i)
The ore bauxite is purified
The purified bauxite is dissolved in molten cryolite
The aluminium oxidecryolite solution is then eletrolysed
Equation at the cathode Al3+ (l) + 3 e- Al (l)
Equation at the anode 2 O2- (l) ndash 4 e- O2 (g)
(ii) The process is too expensive mainly because too much electricity or energy is needed
(b) The alloy of Al and Mg is magnalium It is less dense than the pure metals and hence allow
aircraft to be lighter It is also stronger than the pure metals and hence allows aircraft to last
longer since it is not easily destroyed
(c) Your answer should cater for the following aspects
Benefits of mercury to humans for example in thermometers barometers in dentistry
and gold mining
Entry of mercury to the environment For example this could have been through broken
thermometers barometers or lightbulbs or improper disposal of them or batteries and
indiscriminate use in gold mining in Guyana
The identification of a negative impact on the environment such as poisoned fish and the
persons who eat the fish death mood swings and psychosis
38
WEEK 12 LESSON 2 Worksheet Answers
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas
evolved
NO2 evolved OR nitrates
present OR
Br2 gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate
formed
Soluble in excess
Pb2+ Zn2+ Al3+ or Ca2+
present
Pb2+ Zn2+ Al3+ or present
39
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate
formed
Insoluble in excess
Pb2+ Zn2+ Al3+ or present
Pb2+ or Al3+ present
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate
formed
Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
40
WEEK 12 LESSON 3 Worksheet Answers
(a) an ammonium salt and a strong alkali
(b) Ammonia is basic and it will react with H2SO4
Equation 2 NH3 (aq) + H2SO4 (aq) (NH4)2SO4 (aq)
(c) (i) ndash Density of the gas relative to air ndash The solubility of the gas in water
(ii) Ammonia is collected by upward delivery
It cannot be collected by downward delivery since ammonia is less dense than air
It cannot be collected by displacement of water since it is soluble in water
(d)
41
WEEK 13 LESSON 1 Worksheet Answer
a) i) B ˂ Fe ˂ A
2A (s) + Fe 2+ (aq) rarr 2A+ (aq) + Fe (s)
ii) 2A (s) + CuSO4 (aq) rarr A2SO4 (aq) + Cu (s)
Observation blue colour fades gets lighter OR brown solid forms is deposited OR metal A
decreases in size dissolves
Explanation Metal A is higher (than Fe which is higher) than Cu in the reactivity series OR
Metal A is more reactive (than Fe which is more reactive) than Cu so Metal A can displace Cu
iii) Metal A can be extracted by electrolysis (of its molten oxide) because Metal A is a very
reactive metal is high in the reactivity series forms stable oxides needs a lot of energy to be
extracted and very reactive metals are extracted by electrolysis
Metal B can be extracted by heating with carbon carbon monoxide OR by chemical reduction
of the oxide because Metal B is less reactive than Fe is low in the reactivity series forms less
stable oxides does not need a lot of energy to be extracted and oxides of less reactive metals are
easily reduced
b) Alloy of iron steel
Use of alloy making buildings bridges ships motor vehicles furniture utensils
42
WEEK 13 LESSON 2 Worksheet Answer
(a) (i)
Magensium is the metal ion found in chlorophyll
Chlorophyll is essential for photosynthesis
A deficiency in magnesium will result in low chlorophyll yellow leaves and a reduction in
photosynthesis
Hence there will be low carbohydrates or energy production
Hence small fruits stunted growth and lower yield will result
(ii)
Metal ion Results of deficiency
Potassium Stunted growth premature loss of leaves yellowing of leaves curling of leaf tips
Calcium Growth abnormalities in tips of roots and shoots curling of leaves
Iron Yellowing of leaves
Zinc Low chlorophyll content yellowing of leaves
Manganese Yellowing of leaves poor flavors in some crops for example potato
(b)
Metal Lead is present in some types of gasoline Upon combustion lead compounds escape into
the atmosphere It accumulates in body tissues and slowly poisons the person It causes mental
illness
Non ndash metal SulphurSulphur dioxide or NitrogenNitrogen dioxide
Dissolves in rain water to form acid rain or cause respiratory illnessproblems Acid rain can
cause corrosion damage in buildings
(c)
Green chemistry is the utilisation of a set of principles that reduces or eliminates the use or
generation of hazardous substances
43
Automotive fuels are now produced without lead so as to eliminate the release of lead
compounds into the atmosphere
Low sulphur fuel is being produced with much reduced sulphur content which causes a reduction
of sulphur dioxide release into the atmosphere
44
WEEK 13 LESSON 3 Worksheet Answer
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
gas turns litmus blue
red
brown gas
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
white precipitate
precipitate soluble in
excess
Zn2+ ions are present
45
WEEK 14 LESSON 1 Worksheet Answers
(a)(i) An alloy is a material made from a mixture of two or more metals
(ii) Any suitable answer chosen from below
Alloy Enhance Property Use
Duralumin High strength
Low density
Light
Hard
Used to make aircraft bodies
space satellites
Magnalium Light
Hard
Easier to weld
Corrosion resistant
Strong
High ductability
Used in pyrotechnics
(fireworks)
Mirrors
Aircraft parts
To make scientific
instruments
Used to make marine castings
Alchlad Strong
Corrosion resistant
Cladding for buildings
(b) (i) Zinc is more reactive than iron
Zinc displaces iron from iron (II) sulphate
Zinc is higher in the reactivity series than iron
Iron does not displace zinc from zinc sulphate
(ii) Order of reactivity Zn gt Fe gt Pb gt Cu
(iii) Reddish brown solid ndash copper metal formed
46
Dirty green solution ndash presence of Fe2+ ion
(iv) Fe (s) + Cu2+ (aq) Fe2+ (aq) + Cu (s)
(c) (i) Lead
(ii) Any two correct harmful effects of lead on the body
Impedes brain development (in young children)
Affectimpede development of the immune system in humans
Affecthamper development of nervous system in humans
Long term exposure can result in kidney and liver damage
Mental retardation
Anaemia
Death
47
WEEK 14 LESSON 2 Worksheet Answers
a) i) Diamond is transparent clear Graphite is opaque black
OR hard OR brittle
OR does not conduct electricity OR conducts electricity
a) ii) Both have a macromolecular giant molecular giant covalent structure (lattice)
OR Both have high melting point boiling point
OR Both are insoluble in water organic solvent
b) i) 2C (s) + O2 (g) rarr 2CO (g)
ii) CO reduction in amount of oxygen carried by (the haemoglobin in the red blood
cells of) the blood
Headache OR dizziness OR nausea OR fatigue OR loss of consciousness OR
death
c) i) CaCO3 (s) + 2HCl (aq) rarr CaCl2 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) + H2SO4 (aq) rarr CaSO4 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) rarr CaO (s) + CO2 (g)
48
ii)
OR
OR
Entirely closed system thistle funnel below the level of the liquid OR tap that could be
closed
Two reagents labelled CaCO3marble chips and HCl H2SO4 or heat source
collection of CO2 upward displacement of air OR over watersulphuric acid OR in gas
syringe
iii) CO2 use put in aerated drinks carbonated beverages
OR put in carbon dioxide fire extinguishers
49
WEEK 14 LESSON 3 Worksheet Answers
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
NH4+
NH4+ confirmed OR
NH3 (g) produced
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
Cl- ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation required)
Suggest a possible identity of the solid R NH4Cl (ammonium chloride)
50
WEEK 15 LESSON 1 Worksheet Answers
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a
small portion of solid Y
gently at first and then
strongly
Colourless gas
evolved with a
choking odour
Turns acidified
potassium dichromate
solution from orange
to green
SO2 evolved
Presence of a sulphite
(ii) To the remaining
portion of solid Y add 20
cm3 of distilled water stir
to dissolve and filter
Collect the filtrate and
divide into 3 equal portions
Filtrate is pale green
in colour
Fe2+ ions present
(iii) To the first portion of
the filtrate from (ii) add
aqueous sodium hydroxide
slowly until in excess
A green precipitate
Insoluble in excess
sodium hydroxide
Fe2+ ions present
Fe2+ (aq) + 2 OH- (aq) Fe(OH)2 (s)
Ionic equation required
TEST OBSERVATIONS INFERENCES
(iv) To the second portion
of the filtrate from (ii) add
aqueous silver nitrate
White precipitate
Soluble in aqueous
ammonia
Cl- ions present
51
followed by aqueous
ammonia
(v) To the third portion of
the filtrate from (ii) add
aqueous barium nitrate
followed by aqueous
hydrochloric acid
White precipitate
formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with
the evolution of a
colourless gas with a
choking smell
SO32- CO3
2- SO42- ions present
SO32- ions present
52
WEEK 15 LESSON 2 Worksheet Answers
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
Chloride ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
Cu2+ ions present
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
X contains a reducing agent
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
SO32- SO4
2- or CO32- ions are
present
SO32- ions are present
53
WEEK 15 LESSON 3 Worksheet Answers
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
White ppt
Ppt soluble in excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in
excess aqueous NH3
Al3+ Pb2+ Zn2+ present
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change Cl- Br- I- absent
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
Vigorous effervescence
observed upon addition of
dilute HNO3
CO2 evolved OR
Carbonate present
54
warm filter and then divide
the filtrate into two portions
Gas evolved turns lime
water cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
Cu2+ (aq) + OH- (aq)
Cu(OH)2 (s)
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Blue ppt
ppt dissolves in excess
NH3 to give a deep blue
solution
Cu2+ ions present
55
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
REFERENCES
Hunte-King J Maragh P Nagir F amp Norris R (2013) Chemistry for CSEC United
Kingdom Nelson Thornes Ltd
Remy C Mason L Lambert N amp Mohammed M (2007) Chemistry for CSEC England and
Wales Pearson Education Limited
Taylor M amp Chung-Harris T (2010) CXC Chemistry England Macmillan Publishers
Limited
Tindale A (2016) Chemistry A Concise Revision for CXC London HarperCollins Publishers
Limited
6
4 Consider the following information about four substances
Substance Melting point
0C
Electrical conductivity Water
solubility in solid in liquid
I 1050 Low High High
II 75 Low Low Low
III 1234 High High Low
IV 1913 Low Low Low
The substance which is MOST likely to be a metal is
(A) I (B) II (C) III (D) IV
5 Read the following and answer the question that follows
A new element was discovered to have the following properties
Lustrous solid
Can be beaten into shapes
High density
(a) Based only on the facts stated above is the element a metal or non metal
_______________________
(b) State 3 other properties that you expect this element to exhibit
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
7
WEEK 1 LESSON 2
TOPIC Physical properties of metals
Physical properties of some metals
Metals Melting point 0C
Boiling point
0C
Density
g cm-3
Other characteristics
Sodium 90 900 097 Very soft grey metal
Calcium 850 1487 153 Grey metal
Magnesium 650 1103 174 Soft grey metal
Aluminium 660 2350 270 Grey metal
Zinc 419 907 719 White metal
Iron 1535 2760 797 Dark grey metal
Copper 1083 2580 894 Gold coloured metal
conductivity second only to
silver
Sodium Calcium Magnesium Aluminium
Zinc Iron Copper
8
WEEK 1 LESSON 2 WORKSHEET
A group of students carried out an experiment to find the density of three different metals
aluminium calcium and an unknown metal X They measured the mass of each metal sample
using a balance The volumes of the metals were determined by displacement of oil The results
of their experiment are as follows
Aluminium Calcium Metal X
Mass (g) 100 100 100
Final volume (cm3) 335 365 310
Initial volume (cm3 300 300 300
Volume of metal (cm3)
Density (gcm-3)
Complete the table using the following formulae
Volume of metal = Final volume ndash Initial volume
Density = 119872119886119904119904
119881119900119897119906119898119890
Arrange the metals in order of increasing density _____________________________________
9
WEEK 1 LESSON 3
TOPIC Chemical properties of metals
Action of oxygen
Most metals react with oxygen or air to form the corresponding oxide These oxides are basic
oxides with the exception of aluminium zinc and lead which form amphoteric oxides Metals
lower in the electrochemical series do not react
Metal Reaction with air or oxygen
Potassium K
Burn very easily forming oxide
eg 4 Na (s) + O2 (g) 2 Na2O (s)
Sodium Na
Calcium Ca
Magnesium Mg
Aluminium Al
Burn especially if powered forming oxide
eg 4 Al (s) + 3 O2 (g) 2 Al2O3 (s)
Zinc Zn
Iron Fe
Lead Pb Do not burn form oxide when heated strongly
Copper Cu
Silver Ag No reaction
10
WEEK 1 LESSON 3 WORKSHEET
Write balanced chemical equations for the reaction of the named metals and air or oxygen
State the nature of the oxide formed (basic or amphoteric)
Potassium + Oxygen
______________________________________________________________________________
Sodium + Oxygen
______________________________________________________________________________
Calcium + Oxygen
______________________________________________________________________________
Magnesium + Oxygen
______________________________________________________________________________
Aluminium + Oxygen
______________________________________________________________________________
Zinc + Oxygen
______________________________________________________________________________
11
Iron + Oxygen
______________________________________________________________________________
Lead + Oxygen
______________________________________________________________________________
Copper + Oxygen
______________________________________________________________________________
Silver + Oxygen
______________________________________________________________________________
12
WEEK 2 LESSON 1
TOPIC Chemical properties of metals
Action of water
Metals high in the electrochemical series react with cold water to produce the metal hydroxide
and hydrogen
Reactive metals slightly lower in the electrochemical series react very slowly or not at all with
water However they may react with hot water or steam to produce the corresponding metal
oxide and hydrogen
Metals lower than hydrogen in the electrochemical series do not react with water
Metal Reaction with water or steam
Potassium K React with cold water forming metal hydroxide and hydrogen
eg Ca (s) + 2 H2O (l) Ca(OH))2 (aq) + H2 (g) Sodium Na
Calcium Ca
Magnesium Mg React with steam forming metal oxide and hydrogen
eg Zn (s) + H2O (g) ZnO (s) + H2 (g) Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
13
WEEK 2 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with water (or
steam if reaction does not occur with water)
Potassium + WaterSteam
______________________________________________________________________________
Sodium + WaterSteam
______________________________________________________________________________
Calcium + WaterSteam
______________________________________________________________________________
Magnesium + WaterSteam
______________________________________________________________________________
Aluminium + WaterSteam
______________________________________________________________________________
Zinc + WaterSteam
______________________________________________________________________________
14
Iron + WaterSteam
______________________________________________________________________________
Copper + WaterSteam
______________________________________________________________________________
Silver + WaterSteam
______________________________________________________________________________
15
WEEK 2 LESSON 2
TOPIC Chemical properties of metals
Action of dilute acids
Metals above hydrogen in the electrochemical series react with dilute acids to form a salt and
hydrogen gas They react with hydrochloric acid to form the metal chloride (a salt) and hydrogen
gas They also react with dilute suphuric acid to form the metal sulphate (a salt) and hydrogen
gas
Metal Reaction dilute hydrochloric or sulphuric acid
Potassium K Violent reaction forming a salt and hydrogen gas
eg 2 Na (s) + 2 HCl (aq) 2 NaCl (aq) + H2 (g) Sodium Na
Calcium Ca Vigorous reaction forming a salt and hydrogen gas
eg Mg (s) + 2 HCl (aq) MgCl2 (aq) + H2 (g) Magnesium Mg
Aluminium Al React forming a salt and hydrogen gas
eg Fe (s) + 2 HCl (aq) FeCl2 (aq) + H2 (g) Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
16
WEEK 2 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with
hydrochloric acid
Metal Balanced equation for reaction with hydrochloric acid
Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Copper
Silver
17
WEEK 2 LESSON 3
TOPIC Reactions of metal compounds
Reactions of metallic oxides with dilute acid
Metal oxides react with dilute hydrochloric acid or sulphuric acid to produce a salt and water
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
Some of these reactions may be slow and can be speeded up by adding heat
For example
zinc oxide + hydrochloric acid zinc chloride + water
ZnO (s) + 2 HCl (aq) ZnCl2 (aq) + H2O (l)
magnesium oxide + hydrochloric acid magnesium chloride + water
MgO (s) + 2 HCl (aq) MgCl2 (aq) + H2O (l)
aluminium oxide + sulphuric acid aluminium sulphate + water
Al2O3 3 H2SO4 (aq) Al2(SO4)3 (aq) + 3 H2O (l)
calcium oxide + sulphuric acid calcium sulphate + water
CaO H2SO4 (aq) CaSO4 (aq) + H2O (l)
18
WEEK 2 LESSON 3 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal oxides with the
corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium oxide Hydrochloric acid
Sodium oxide Sulphuric acid
Calcium oxide Hydrochloric acid
Magnesium oxide Sulphuric acid
Aluminium oxide Hydrochloric acid
Zinc oxide Sulphuric acid
19
WEEK 3 LESSON 1
TOPIC Reactions of metal compounds
Reactions of metallic hydroxides with dilute acid
Metal hydroxides react with dilute acids to form a salt and water in a neutralisation reaction
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
For example
magnesium hydroxide + hydrochloric acid magnesium chloride + water
Mg(OH)2 (aq) + 2 HCl (aq) MgCl2 (aq) + 2 H2O (l)
sodium hydroxide + hydrochloric acid sodium chloride + water
NaOH (aq) + HCl (aq) NaCl (aq) + H2O (l)
potassium hydroxide + sulphuric acid potassium sulphate + water
2 KOH + H2SO4 (aq) K2SO4 (aq) + 2 H2O (l)
calcium hydroxide + sulphuric acid calcium sulphate + water
Ca(OH)2 (aq) + H2SO4 (aq) CaSO4 (aq) + 2 H2O (l)
20
WEEK 3 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal hydroxides with
the corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium hydroxide Hydrochloric acid
Sodium hydroxide Sulphuric acid
Calcium hydroxide Hydrochloric acid
Magnesium hydroxide Sulphuric acid
Aluminium hydroxide Hydrochloric acid
Zinc hydroxide Sulphuric acid
21
WEEK 3 LESSON 2
TOPIC Reactions of metal compounds
Reactions of metallic carbonates with dilute acid
Metal carbonates react with dilute acid to form a salt carbon dioxide and water When
hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric acid is
used the corresponding sulphate salt is formed
For example
sodium carbonate + hydrochloric acid sodium chloride + carbon dioxide + water
Na2CO3 (s) + 2 HCl (aq) 2 NaCl (aq) + CO2 (g) + H2O (aq)
calcium carbonate + hydrochloric acid calcium chloride + carbon dioxide + water
CaCO3 (s) + 2 HCl (aq) CaCl2 (aq) + CO2 (g) + H2O (aq)
zinc carbonate + sulphuric acid zinc sulphate + carbon dioxide + water
ZnCO3 (s) + H2SO4 (aq) ZnSO4 (aq) CO2 (g) + H2O (aq)
potassium carbonate + sulphuric acid potassium sulphate + carbon dioxide + water
K2CO3 (s) H2SO4 (aq) K2SO4 (aq) CO2 (g) + 2 H2O (aq)
22
WEEK 3 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal carbonates with
the corresponding acid
Metallic
carbonate
Acid Balanced chemical equation
Potassium
carbonate
Hydrochloric
acid
Sodium
carbonate
Sulphuric acid
Zinc
carbonate
Hydrochloric
acid
Magnesium
carbonate
Sulphuric acid
Aluminium
carbonate
Hydrochloric
acid
Calcium
carbonate
Sulphuric acid
23
WEEK 3 LESSON 3
TOPIC Action of heat on metal compounds
Action of heat on nitrates
All nitrates decompose when heated The reactivity of the metal in the metal nitrate influences
the products of the decomposition
The nitrates of the alkali metals (Group I) with the exception of lithium nitrate decompose to
form the metal nitrite and oxygen
The nitrates of most other metals decompose to form the metal oxide nitrogen dioxide and
oxygen
The nitrates of the very unreactive metals decompose to form the meal nitrogen dioxide and
oxygen
Metal Nitrate Decomposition
Potassium K Products metal nitrite + oxygen
eg 2 NaNO3 (s) Heatrarr 2 NaNO2 (s) + O2 (g)
Sodium Na
Calcium Ca
Products metal oxide + nitrogen dioxide + oxygen
eg 2 Pb(NO3)2 (s)
Heatrarr 2 PbO (s) + 4 NO2 (g) + O2 (g)
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Products metal + nitrogen dioxide + oxygen
eg 2 AgNO3 (s) Heatrarr 2 Ag (s) + 2 NO2 (g) + O2 (g)
24
WEEK 3 LESSON 3 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
nitrates
Metal Balanced chemical equation
Potassium nitrate
Sodium nitrate
Calcium nitrate
Magnesium nitrate
Aluminium nitrate
Zinc nitrate
Lead nitrate
Copper nitrate
Silver nitrate
25
WEEK 4 LESSON 1
TOPIC Action of heat on metal compounds
Action of heat on carbonates
Upon application of heat many carbonates decompose to form the metal oxide and carbon
dioxide
Group I carbonates do not decompose on heating with the exception of lithium carbonate
Metal Carbonate decomposition
Potassium K
Stable not decomposed by heat Sodium Na
Calcium Ca
Decompose forming metal oxide and carbon dioxide
eg CaCO3 (s) Heatrarr CaO (s) + CO2 (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Unstable
26
WEEK 4 LESSON 1 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
carbonates
Metal Balanced chemical equation
Potassium carbonate
Sodium carbonate
Calcium carbonate
Magnesium carbonate
Aluminium carbonate
Zinc carbonate
Iron carbonate
Lead carbonate
Copper carbonate
27
WEEK 4 LESSON 2
TOPIC Action of heat on metal compounds
Action of heat on the metal hydroxides
Most metal hydroxides decompose on heating A metal oxide and water are formed
Group I hydroxides do not decompose on heating with the exception of lithium hydroxide
Metal Hydroxide decomposition
Potassium K Stable not decomposed by heat
Sodium Na
Calcium Ca Decompose forming metal oxide and water (as steam)
eg Zn(OH)2 (s) Heatrarr ZnO (s) + H2O (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag No hydroxide exist
28
WEEK 4 LESSON 2 WORKSHEET
Write the balanced chemical equations for the thermal decomposition of the following
metal hydroxides
Metal hydroxide Balanced chemical equation
Potassium hydroxide
Sodium hydroxide
Calcium hydroxide
Magnesium hydroxide
Aluminium hydroxide
Zinc hydroxide
Lead hydroxide
Copper hydroxide
29
WEEK 4 LESSON 3
TOPIC Reactivity of metals ndash The Reactivity Series
The reactivity series of metals is a list of metals arranged in order of their reactivity based on
Displacement reactions
Reactions with oxygen dilute acids and water
Relative ease of decomposition of their compounds
Metals at the top of the series are the most electropositive They lose electrons very easily and
readily form cations These ions are very stable and are not easily discharged to form atoms Due
to this fact they are the most reactive metals
Metals at the bottom of the series are the least electropositive They do not lose electrons easily
and do not readily form ions Their ions are very unstable and are easily discharged to form
atoms They are the least reactive metals
The reactivity series of metals
Mnemonic Metal Symbol Reactivity
People Potassium K Most reactive
Least reactive
Sometimes Sodium Na
Collect Calcium Ca
Magazines Magnesium Mg
About Aluminium Al
Zoos Zinc Zn
In Iron Fe
London Lead Pb
Having (Hydrogen) H
Cute Copper Cu
Monkeys and Mercury Hg
Small Silver Ag
Gorillas Gold Au
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
5 Reactivity of metals Reactivity of metals Reactivity of metals
6 Extraction of metals Extraction of metals Alloys
7 Corrosion Importance of metals
and their compounds
on living systems and
environment
Chemical properties
of non ndash metals
8 Laboratory
preparation of gases
Laboratory
preparation of gases
Laboratory
preparation of gases
9 Uses of gases Uses of non ndash metals
and their compounds
Harmful effects of
non ndash metals and
their compounds on
living systems and
the environment
10 Green Chemistry Qualitative Analysis
ndash Identification of
cations
Qualitative Analysis
ndash Identification of
cations
2
WEEK 5 LESSON 1
TOPIC Reactivity of metals
Reactivity based on displacement reactions between metals and metal ions
A metal will displace a metal which is lower than itself in the reactivity series from a solution of
the metal salt
Reaction of zinc and copper (II) sulphate
Expected observations
Explanation
The size of the zinc metal decreases
The zinc metal is reacting and forming the
salt zinc sulphate
The solution becomes lighter eventually
colourless
The Cu2+ (aq) ions (responsible for the blue
colour) is reduced to Cu (s)
A brown solid is deposited at the bottom of
the container
Copper metal is formed
Equation Zn (s) + CuSO4 (aq) ZnSO4 (aq) + Cu (s)
Ionic equation
Zn (s) + Cu2+ (aq) Zn2+ (aq) + Cu (s)
Zinc is higher in the reactivity series than copper Therefore it will displace the copper ions in
the reaction above
3
Examples of other displacement reactions
Magnesium will displace Zn2+ ions in zinc sulphate since it is higher in the series than zinc
Mg (s) + Zn2+(aq) Mg2+ (aq) + Zn (s)
Silver will not displace Cu2+ ions in copper (II) sulphate [Cu is higher in the series than Ag]
Using the information above we can arrange the metals in order of their reactivity with
magnesium being the most reactive and silver the least reactive metal among the four metals
Mg gt Zn gt Cu gt Ag
Reactivity based on reaction with oxygen
The reactivity of metals can also be deduced from their reaction with oxygen
The table below gives the observations for the reaction with oxygen with the selected metals
Reaction of metal with oxygen
Metal Observation
Copper The surface turns black upon heating
Magnesium Ribbon burns very rapidly
Sodium Burns vigorously
Gold No reaction
Based on the observations for the 4 metals the metal with highest reactivity is sodium and the
metal with the least reactivity is gold
The 4 metals can be arranged in terms of reactivity as follows
Na gt Mg gt Cu gt Au
4
WEEK 5 LESSON 1 WORKSHEET
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
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5
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
6
WEEK 5 LESSON 2
TOPIC Reactivity of metals
Reactivity based on reactivity with acids
The metals that are higher than hydrogen in the electrochemical series react with non ndash oxidizing
acids to produce a salt and hydrogen gas
By using the same concentration of acid and same mass and size of the metals the order of
reactivity of the metals can be deduced
The table below shows the results for an experiment with the reaction of the named metals and
1 mol dm-3 hydrochloric acid
Reaction of metals with acid
Metal Observations
Silver No reaction
Magnesium Bubbles produced steadily
Calcium Bubbles produced very rapidly
Iron Bubbles produced slowly
Based on the above data the most reactive metal will be calcium with the least reactive being
silver The order of reactivity will be Ca gt Mg gt Fe gt Ag
By comparing this to the electrochemical series it can be seen that the reactivity of the metals
decrease as we go down the series
7
WEEK 5 LESSON 2 WORKSHEET
1 Place a next to the metals that will react with dilute acid and an X next to the metals
that will not react with dilute acid
Metal Reactivity with acid
Copper
Magnesium
Aluminium
Silver
Zinc
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
8
WEEK 5 LESSON 3
TOPIC Reactivity of metals
Reactivity based on ease of decomposition of the metal nitrates carbonates oxides and
hydroxides
The more reactive a metal the more difficult it is to decompose its nitrate carbonate oxide or
hydroxide on heating
For example Decomposition of carbonates
Procedure
1 Put a large spatula measure of the carbonate to be tested in a test tube
2 Fit a delivery tube and then clamp the test tube so that the delivery tube dips into a second test
tube containing 2ndash3 cm3 limewater
3 Heat the solid gently at first then more strongly
4 Lift the delivery tube from the limewater before or as soon as the heating is stopped This is to
avoid suck-back
5 Write down all observations Notice what happens to the limewater and how long it takes to turn
milky (if at all) Notice whether any melting occurs in the heated test tube and any colour
changes taking place Write your results in tabular form
6 Repeat the experiment with the other metal carbonates supplied and in each case write down
your observations
7 Wash your hands thoroughly at the end of these experiments since some of the metal carbonates
are toxic
9
Results
Metal Formula Gas evolved Ease of decomposition
Zinc ZnCO3 Carbon dioxide Fairly easy
Copper CuCO3 Carbon dioxide Easy
Sodium Na2CO3 None Very difficult
Using the results of the above activity the reactivity of the metals can be determined
Ease of decomposition Copper gt Zinc gt Sodium
The order of reactivity is the opposite for the ease of decomposition
Order of reactivity Sodium (most reactive) gt Zinc gt Copper (least reactive)
10
WEEK 5 LESSON 3 WORKSHEET
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
11
WEEK 6 LESSON 1
TOPIC Extraction of metals
Elements exist all over the earth Some are found as free elements eg copper silver and gold
Others are found combined with other elements in compounds To get the elements the
compounds have to be broken up These compounds are generally called ores the most
convenient sources of which are rocks sea and air
The extraction of a metal from its ore is a reduction process where the metals ions gain electrons
to form atoms
The general equation is Mn+ + n e- M
The choice of the extraction method depends on the position of the metal in the reactivity series
As we go down the series the metals become more stable and the metal ions (in the ores)
become less stable
The very reactive metals that are high in the series K Na Ca Mg Al have very stable ores
Therefore they require a powerful method of reduction namely electrolysis During the process
the cathode provides the electrons and acts as the reducing agent
The metals in the middle of the series (Zn Fe Pb) do not have stable ores and can be extracted
by reduction with carbon in the case of zinc and with carbon monoxide in the case of iron and
lead
Metals low in the reactivity series if present as ores can be extracted simply by heating the ores
in air at high temperatures
12
Extraction of Aluminium from purified bauxite
Pure bauxite is pure alumina (Al2O3) Aluminium is obtained from bauxite by electrolysis
Aluminium oxide has a very high melting point approximately 2050 0C so it is first dissolved in
molten cryolite (Na2AlF6) The addition of cryolite lowers the melting point to approximately
900 0C
The electrolyte is a molten mixture of alumina and molten cryolite The cathode is the graphite
lining of the cell The anodes are blocks of graphite or titanium alloys
Reaction at the cathode
Al3+ (l) + 3 e- Al (l)
Reaction at the anode
2 O2- (l) ndash 4 e- O2 (g)
Aluminium (melting point 660 0C) is a liquid at the temperature at which electrolysis is carried
out and is collected at the bottom of the cell and tapped off Oxygen gas which is given off in the
main cathode reaction together with the heat causes the anodes to burn away The anodes have
to be replaced from time to time The use of anodes from titanium alloys reduce the number of
times that the anodes have to be replaced
13
WEEK 6 LESSON 1 Worksheet
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
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14
WEEK 6 LESSON 2
TOPIC Extraction of metals
Extraction of Iron
The traditional method of production of iron is by reduction of haematite by carbon monoxide in
a blast furnace
Ores Haematite ndash Fe2O3 Magnetite ndash Fe3O4 Siderite ndash FeCO3 Magnetite and Siderite are
converted to Haematite
A mixture of haematite limestone (CaCO3) and coke (C) called the charge is placed into the top
of the furnace
Hot air is blown into the bottom of the furnace
Coke burns in air forming carbon dioxide
C (s) + O2(g) CO2 (g) ΔH -ve
The heat produced keeps the temperature at about 1900 0C
The carbon dioxide is reduced to carbon monoxide by the hot coke
CO2 (g) + C (s) 2 CO(g) Δ +ve
Heat absorbed reduces the temperature to about 1100 0C
The carbon monoxide reduces the hot iron ore to molten iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + 3 CO2(g)
The temperature at this part of the furnace is about 700 0C The iron runs to the bottom of the
furnace
The impurities are removed by the addition of limestone (CaCO3) The limestone at the
temperature of the furnace breaks down
CaCO3 (s) CaO (s) + CO2 (g)
15
The calcium oxide formed combines with silicon dioxide (sand) the main impurity in the iron
ore to form molten slag
CaO (s) + SiO2 (s) CaSiO3 (l)
The slag does not mix with the molten iron but floats on it The molten iron and slag are run off
separately
The iron formed in a blast furnace is an impure form of the metal Because the molten metal is
allowed to solidify in shallow trays known as casts the iron is called lsquocast ironrsquo or lsquopigrsquo iron
Cast iron is quite brittle and contains 2 - 4 carbon and other impurities Most of the cast iron is
converted to steel
A blast furnace used for extracting iron
16
WEEK 6 LESSON 2 Worksheet
(a) What are the three raw materials that are added through the top of the blast furnace
during the extraction process for iron
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______________________________________________________________________________
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
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17
WEEK 6 LESSON 3
TOPIC Alloys
An alloy is a mixture of two or more metals Alloys are made by melting the individual metals
mixing them and allowing the molten mixture to solidify
In general alloys are harder stronger and more resistant to corrosion than the actual metals they
are made up from
Alloy Use Properties
ALUMINIUM
-Duralumin
(AlMgCu)
-Magnalium (AlMg)
Alloys used in the
construction of
aircraft and ships
buses
Aluminium is used in
making cooking
utensils electrical
cables paint for fuel
storage tanks bottle
caps foil and utensils
for handling nitric
acid
The alloys have a low
density They are as
light as aluminium
and more resistant to
corrosion than
aluminium
LEAD
-Solder (PbSn)
Alloy is used in
joining metals
(soldering)
Lead is used in
underground cables
plates in
The alloy has a lower
melting point than
lead and is harder
than lead
18
Alloy Use Properties
accumulators shield
against x ndash rays
IRON
- Stainless Steel
(FeCONiC)
-Tungsten steel
(FeWC)
-Invar steel (FeNi)
Manganese steel
(FeMnC)
Iron is the main metal
of a variety of
constructions
Steel is used in
cutlery rock drills
electromagnets
vehicle body and
engine parts fences
pipes etc
Steel resists
corrosion is usually
harder than iron and
may be tough though
malleable and ductile
19
WEEK 6 LESSON 3 Worksheet
(a) Define the term alloy
______________________________________________________________________________
(b) State 3 general advantages that alloys have over the individual metals they are made
from
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______________________________________________________________________________
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
______________________________________________________________________________
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Uses
______________________________________________________________________________
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20
WEEK 7 LESSON 1
TOPIC Corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
Familiar examples of corrosion are
- the formation of a green powder on copper sheeting
- the eating away of iron (rusting)
- the development by aluminum of a thin compact layer of oxide which protects the
underlying metal from further corrosion
When corrosion occurs in water ndash free environment it is called dry oxidation When it occurs in
aerated aqueous environments it is called wet corrosion Wet corrosion is the most common and
troublesome form of corrosion
The most familiar corrosion is the rusting of iron and steel On exposure to the atmosphere iron
and steel corrode to form rust which is hydrated iron (III) oxide Fe2O3xH2O Iron and steel
corrode easily and the rust formed flakes off easily thus exposing fresh surface for attack
When iron rust it loses electrons
Fe (s) ndash 2e- Fe 2+ (aq)
The iron (II) ions pass into solution and then combine with the hydroxyl (OH-) ions in the
aerated aqueous environment to form iron (II) hydroxide The oxygen present oxidises the iron
(II) hydroxide to hydrated iron (III) oxide or rust
Fe(OH)2 + O2 Fe2O3xH2O
21
Methods of preventing rusting
1 Coating the object with paint grease plastic or rubber which prevent contact with air or
water
2 Galvanising ndash coating the object with zinc The zinc forms an adherent oxide layer which
protects against further corrosion If damaged the zinc is oxidized in preference to the
iron since it is higher in the electrochemical series
3 Coating with tin lsquoTinrsquo cans are made of steel plated with tin However if scratched
rusting occurs since iron is more reactive than tin
4 Attaching a sacrificial anode to the object A piece of metal higher in the electrochemical
series such as magnesium is attached The magnesium will be oxidized in preference
since it is higher in the electrochemical series than iron
22
WEEK 7 LESSON 1 WORKSHEET
(a) Define the term corrosion
______________________________________________________________________________
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
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______________________________________________________________________________
______________________________________________________________________________
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
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(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
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23
WEEK 7 LESSON 2
TOPIC Importance of metals and their compounds on living systems and environment
Some metals are an integral part of different structures of living things
Metal Presence and Function
Potassium Main cation in fluid or animal cells essential for healthy plant growth
Calcium Necessary for strong bones teeth and shells needed by some enzymes Present
in dairy produce eggs nuts and cereals
Magnesium Central atom of chlorophyll needed for some enzyme action Involved in energy
and calcium metabolism
Zinc Present in many enzymes Needed for protein metabolism Essential for growth
of animals
Iron Present in haemoglobin Needed for protein metabolism Essential for growth of
animals
Chromium Needed for glucose uptake by cells and thus linked to the action of insulin
Manganese Needed for bone development and amino acid metabolism Present in several
enzymes Needed for plant growth
Cobalt Present in Vitamin B12 Needed for plant growth
Copper Involved in formation of haemoglobin and melanin Present in enzymes
controlling oxidation Needed for plant growth
24
Harmful effects of metals and their compounds to living systems and the environment
There are some metals and metal compounds which may cause harm to living systems and the
environment
Lead
Lead is a heavy metal poison that is widely encountered It may occur in food beverages paint
water formed from ndash sealed pipes in air polluted by combustion by fuels containing lead
compounds Lead is also used in some car batteries If these are paints or batteries are not
disposed of correctly lead may get into groundwater or air Lead and lead compounds harm the
nervous system including the brain especially young children
Arsenic
Arsenic compounds are poisonous They can get into the groundwater from mining waste and
from disposal of some electrical components
Cadmium
Cadmium compounds are poisonous They can get into the ground by improper disposal of
nickel ndash cadmium batteries Persons can get cadmium poisoning if they eat food grown in
contaminated soil
Mercury
Mercury can be spilled from broken thermometers in hospitals and laboratories Mercury and its
compounds are particularly poisonous to fish and it can accumulate in the food chain and
eventually poison humans
Problems of disposal of solid waste
Metals may react with water andor air and corrode to form soluble compounds that are
poisonous These toxic compounds diffuse into the soil and eventually enter rivers
Rust from iron may form unsightly pools of waste that reduce plant growth
Waste from aluminium extraction may react with water and form flammable gases
25
WEEK 7 LESSON 2 WORKSHEET
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
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______________________________________________________________________________
______________________________________________________________________________
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Lead
______________________________________________________________________________
Mercury
______________________________________________________________________________
26
WEEK 7 LESSON 3
TOPIC Chemical properties of non ndash metals
Reaction with oxygen
Many non ndash metals burn in excess oxygen or air to form oxides For example
S (s) + O2 (g) SO2 (g)
C (s) + O2 (g) CO2 (g)
Reactions with metals
Some non ndash metals react with metals high in the electrochemical series when heated
For example
Sodium burns in chlorine to form sodium chloride
Na (s) + Cl2 (g) NaCl (s)
Magnesium burns in oxygen to form magnesium oxide
Mg (s) + O2 (g) MgO (s)
When heated iron combines with molten sulphur to form iron (II) sulphide
Fe (s) + S (l) FeS (s)
When heated reactive metals such as sodium and aluminium react with hydrogen to form metal
hydrides
2 Na (s) + H2 (g) 2 NaH (s)
Oxidising and Reducing properties
Hydrogen and Carbon are very good reducing agents
At high temperatures hydrogen reduces metal oxides below zinc in the electrochemical series to
form the metal For example PbO (s) + H2 (g) Pb (s) + H2O (g)
Under suitable conditions hydrogen reduces nitrogen to ammonia
N2(g) + 3 H2 (g) 2 NH3 (g)
27
At high temperatures carbon reduces metal oxides below aluminium in the reactivity series to
the metal For example
ZnO (s) + C (s) Zn (s) + CO (g)
Oxygen and Chlorine are very good oxidizing agents
Oxygen oxidized most metals to form metal oxides and some non ndash metals to non ndash metal oxides
For example
2 Mg (s) + O2(g) 2 MgO (s)
4 P (s) + 5 O2 (g) P4O10 (s)
Chlorine acts as an oxidizing agent either as a gas or as an aqueous solution For example
H2 (g) + Cl2 (g) 2 HCl (g)
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
28
WEEK 7 LESSON 3 WORKSHEET
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
______________________________________________________________________________
(b) Write the ionic equation for the above reaction
______________________________________________________________________________
(c) Identify the oxidising agent in the reaction
______________________________________________________________________________
(d) Justify your answer in part (c) in terms of oxidation number
______________________________________________________________________________
29
WEEK 8 LESSON 1
TOPIC Laboratory preparation of gases
Preparation of oxygen
Oxygen can be prepared by the decomposition of hydrogen peroxide potassium chlorate (V) or
potassium nitrate The safest method is the decomposition of hydrogen peroxide
Manganese (IV) oxide catalyses the decomposition of hydrogen peroxide
Silica gel anhydrous calcium chloride or concentrated sulphuric acid can be used as a drying
agent
The gas is collected by downward delivery since it is slightly denser than air
Equation
2 H2O2 (aq) 2 H2O (l) + O2 (g)
Apparatus used for laboratory preparation of oxygen
30
WEEK 8 LESSON 1 WORKSHEET
Describe the laboratory preparation of oxygen gas
In your answer include
The starting material
A suitable catalyst
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
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31
WEEK 8 LESSON 2
TOPIC Laboratory preparation of gases
Preparation of carbon dioxide
Carbon dioxide can be prepared by the action of dilute acid on carbonates Marble chips (calcium
carbonate) and dilute hydrochloric acid are the common reagents The gas is collected by
downward delivery since it is denser than air
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
Apparatus used for laboratory preparation of carbon dioxide
32
WEEK 8 LESSON 2 WORKSHEET
Describe the laboratory preparation of carbon dioxide gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
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33
WEEK 8 LESSON 3
TOPIC Laboratory preparation of gases
Preparation of ammonia
Ammonia may be prepared by heating a mixture of ammonium salt and a hydroxide The
ammonia gas is collected by upward delivery since it is less dense than air
For example
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
Calcium oxide is the only suitable drying agent since ammonia reacts with conc H2SO4 and
CaCl2
Apparatus used for laboratory preparation of dry ammonia
34
11
WEEK 8 LESSON 3 WORKSHEET
Describe the laboratory preparation of ammonia gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
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______________________________________________________________________________
______________________________________________________________________________
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35
WEEK 9 LESSON 1
TOPIC Uses of gases
Carbon dioxide
Used in fire extinguishers to put out fires Carbon dioxide is denser than air and lsquoblanketsrsquo the
fire preventing oxygen from reaching it Carbon dioxide extinguishers are especially useful for
dealing with fires involving flammable liquids and electrical equipment
Carbonation in soda is created when carbon dioxide is pumped into the soda can or bottle then
held under pressure As long as the can or bottle is sealed the carbon dioxide remains mostly
stable However if the drink gets shaken up or the top is opened the tiny carbon dioxide bubbles
react by bursting
Oxygen
Oxygen is needed for aerobic respiration We need a constant supply of oxygen for this process
Oxygen is used in hospitals to improve the respiration of patients with poor blood flow blood
poisoning and heart disease
Oxygen in used in welding (joining) metals In an oxyacetylene welding torch acetylene or
ethyne (C2H2) burns in oxygen and produces a very hot flame This flame is capable of melting
most metals
Oxygen is used in steel production A blast of oxygen is blown through the molten iron The
oxygen oxidises many of the impurities of the iron and the impurities are then removed
36
WEEK 9 LESSON 1 WORKSHEET
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Put out fires
Welding metals
Create lsquofizzrsquo in drinks
Used in steel production
Aerobic respiration
37
WEEK 9 LESSON 2
TOPIC Uses of non ndash metals and their compounds
Carbon (allotrophes carbon dioxide)
Carbon is used as a reducing agent in extraction of some metals
Carbon as graphite is used as electrodes lubricants and lsquoleadrsquo for pencils
Carbon in the form of diamond is used for jewellery (because of its lustre) and in drill tips for
high ndash speed drills (because of its hardness)
Carbon dioxide is used as refrigerant (as dry ice) for carbonated beverages
Sodium hydrogen carbonate and sodium carbonate are used for water softening and raising
agent
Sulphur
Sulphur is used in the manufacture of sulphuric acid Sulphur is also used in the manufacture of
tyres to make the rubber harder (vulcanisation)
Sulphur powder is used as fungicide on plant materials
Phosphorus
Phosphorus is used in the manufacture of fertilizers
Phosphorus is used to make phosphor bronze alloys
Phosphorus sulphide is used to make the heads of lsquostrike anywherersquo matches
38
Chlorine
Chlorine is used to make sodium hypochlorite which is present in bleach It is also used in
sterilizing swimming pools and in water treatment
Chlorine is used to make the monomer vinyl chloride which is used to make the plastic PVC
Nitrogen
Nitrogen is used to make fertilisers ammonia dyes and nitric acid
Nitrogen is used as an inert atmosphere to prevent substances being oxidised and as a coolant
Silicon
Silicon is used for making silicon chips for computers
Silicon (V) oxide is present in sand Glass is made by heating sand with lime (calcium oxide) and
sodium carbonate
Silicon in the form of silicates is used in jewellery
Silica gel is used as a drying agent
39
WEEK 9 LESSON 2 WORKSHEET
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Used to make sodium hypochlorite
Used as a fungicide on plant materials
Used for lsquoleadrsquo in pencils
Used in the manufacture of bronze alloys
Used in the manufacture of nitric acid
Used in the manufacture of computer chips
Used to make fertilisers
40
WEEK 9 LESSON 3
TOPIC Harmful effects of non ndash metals and their compounds on living systems and the
environment
Sulphur dioxide
Sulphur dioxide can cause a disease of the lungs Sulphur dioxide also poisons plants in two
main ways It may enter the stomata of leaves and react with the tissue fluids to form sulphites
with the on ndash going water loss the concentration of sulphites could build up killing the cells
The second adverse effect on plants occurs when sulphur dioxide dissolves in rain thereby
increasing soil acidity A prolonged acid soil situation may lead to plasmolysis and the death of
vegetation in an area
Carbon monoxide
Carbon monoxide combines much more readily than oxygen with haemoglobin When carbon
monoxide is inhaled it prevents the haemoglobin from taking oxygen to the bodyrsquos cells
Continued breathing of air containing carbon monoxide eventually causes death
Hydrogen sulphide
Hydrogen sulphide reacts readily with many cations forming insoluble sulphides Many cations
contribute to good health by contributing to enzyme activity and to the formation of bone
pigment and haemoglobin Although these cations are required in extremely small
concentrations they are removed by being precipitated as sulphides and thus not available for
regular function Careless dumping of refuse contributes to atmospheric pollution by hydrogen
sulphide
Oxides of nitrogen
In the presence of hydrocarbons from car exhausts ozone and sunlight nitrogen oxides react to
form photochemical smog which contains many harmful chemicals
Nitrogen dioxide can harm the lungs and irritate the nose throat and eyes The other compounds
present in photochemical smog are even more harmful irritants and can cause asthma
41
Carbon dioxide
Carbon dioxide water vapour and ozone referred to as ldquogreenhouse gasesrdquo acting as a blanket
readily absorb some of the radiated heat energy and in turn warms the earthrsquos atmosphere This is
called the ldquogreenhouse effectrdquo Scientists have found direct correlation between carbon dioxide
concentration and global warming An increase in carbon dioxide concentration resulted in an
increase global temperatures Global warming is a major potential problem that the world faces
Chloroflourocarbons (CFCs)
It is believed that CFCs might be responsible for destroying the ozone layer which prevents
harmful ultraviolet (UV) radiation from reaching the earth The carbon ndash chlorine bond in CFC
molecule is easily broken by a UV photon producing an active chlorine atom This atom
combines with an ozone molecule forming a chlorine oxide radical and oxygen The radicle
reacts with more ozone producing the chlorine atom again This kind of reaction is repeated
thousands of times This type of reaction is thought to account for about eighty percent of the
loss of ozone observed
Nitrates and phospates
Nitrates and phosphates cause eutrophication The process leading to eutrophication are
Nitrates and phosphates from fertilisers spread on fields may dissolve in groundwater and
get into lakes and rivers
Nitrates and phosphates cause excessive growth of algae so that they cover the surface of
the water
Water plants including algae die because of lack of sunlight Aerobic bacteria feed on
the plant remains The bacteria multiply
The aerobic bacteria use up the oxygen in the water so aquatic animals die
42
Solid waste
The main sources of pollution from non ndash metals is from glass paper and plastics
Broken glass can cause injury to animals It can also cause fires by acting as lens focusing the
sunrsquos rays on flammable materials
Printing inks from paper dumped in the ground may contain toxic elements such as arsenic and
cadmium Bleaches and chlorine compounds from paper are also harmful
43
WEEK 9 LESSON 3 WORKSHEET
Describe ONE harmful effect of the following non ndash metals andor their compounds on
living systems and the environment
Sulphur dioxide
______________________________________________________________________________
______________________________________________________________________________
Carbon monoxide
______________________________________________________________________________
______________________________________________________________________________
Carbon dioxide
______________________________________________________________________________
______________________________________________________________________________
Oxides of nitrogen
______________________________________________________________________________
______________________________________________________________________________
Hydrogen sulphide
______________________________________________________________________________
______________________________________________________________________________
44
Chloroflourocarbons (CFCs)
______________________________________________________________________________
______________________________________________________________________________
Nitrates and phospates
______________________________________________________________________________
______________________________________________________________________________
45
WEEK 10 LESSON 1
TOPIC Green Chemistry
Green Chemistry is defined as the utilisation of a set of principles that reduces or eliminates the
use and generation of hazardous substances
There are twelve principles of green chemistry as proposed by Paul T Anastas and John C
Warner These twelve principles are
1 Prevention ndash It is better to prevent waste than to treat or clean up waste after it has been
created
2 Atom economy - Synthetic methods should be designed to maximize the incorporation of
all materials used in the process into the final product
3 Less hazardous chemical synthesis - Wherever practicable synthetic methods should be
designed to use and generate substances that possess little or no toxicity to human health
and the environment
4 Safer chemical products - Chemical products should be designed to affect their desired
function while minimizing their toxicity
5 Safer solvents and other agents - The use of auxiliary substances (eg solvents
separation agents etc) should be made unnecessary wherever possible and harmless
when used
6 Minimum energy requirements - Energy requirements of chemical processes should be
recognized for their environmental and economic impacts and should be minimized If
possible synthetic methods should be conducted at ambient temperature and pressure
7 Use of renewable raw materials - A raw material or feedstock should be renewable rather
than depleting whenever technically and economically practicable
8 Reduce use of additional chemicals or additional steps - Unnecessary derivatization (use
of blocking groups protection deprotection temporary modification of
physicalchemical processes) should be minimized or avoided if possible because such
steps require additional reagents and can generate waste
46
9 Use of catalysts ndash The use of catalysts reduce energy costs because the reactions take
place at lower temperatures The more specific the catalyst for a particular reaction is the
less it the likelihood of getting additional unwanted products
10 Nature of breakdown of products - Chemical products should be designed so that at the
end of their function they break down into innocuous degradation products and do not
persist in the environment
11 Monitoring to prevent pollution - Analytical methodologies need to be further developed
to allow for real-time in-process monitoring and control prior to the formation of
hazardous substances
12 Minimise chemical accidents - Substances and the form of a substance used in a chemical
process should be chosen to minimize the potential for chemical accidents including
releases explosions and fires
47
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
48
WEEK 10 LESSON 2
TOPIC Qualitative Analysis ndash Identification of cations
Qualitative Analysis involves identifying the constituents of single substances or mixture of
substances
Appearance
An examination of the appearance of a substance can indicate which ion it contains
Appearances of substances
Observation Indication
Blue or blue ndash green Cu2+ salt
Pale green Fe2+ salt
Yellow ndash brown Fe3+ salt
Ammonia smell NH4+ salt
49
Test for cation using sodium hydroxide
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
(d) If no precipitate forms in step b warm gently and test for ammonia
Effect of dilute sodium hydroxide solution
Effect of dilute sodium hydroxide solution Cation
Dropwise Excess
White precipitate Precipitate soluble Ca2+
White precipitate Precipitate insoluble Al3+ Pb2+ Zn2+
Blue precipitate Precipitate insoluble Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
No precipitate ndash ammonia gas
evolved on heating
ndash NH4+
The metal cations all form insoluble hydroxides with sodium hydroxide solution
For example Ca2+ (aq) + 2 OH- (aq) Ca(OH)2 (s)
Ca(OH)2 Cu(OH)2 Fe(OH)2 and Fe(OH)3 are basic and therefore do not react with excess
sodium hydroxide solution Therefore the precipitate does not dissolve in excess sodium
hydroxide solution
Al(OH)3 Pb(OH)2 and Zn(OH)2 are amphoteric Therefore the precipitates react with the excess
sodium hydroxide solution forming soluble salts and the precipitate disappears in excess sodium
hydroxide solution
The NH4+ ion forms a soluble hydroxide However on heating it reacts with the hydroxide ion to
form ammonia and water
NH4+ (aq) + OH- (aq) NH3 (g) + H2O (l)
50
WEEK 10 LESSON 2 WORKSHEET
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P _____________ Q ___________________
R _____________ S ___________________
R + NaOH
______________________________________________________________________________
51
WEEK 10 LESSON 3
TOPIC Qualitative Analysis ndash Identification of cations
Test for cation using ammonia solution (ammonium hydroxide solution)
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
Effect of dilute ammonia (ammonium hydroxide) solution
Effect of dilute ammonia solution Cation
Dropwise Excess
No precipitate ndash Ca2+
White precipitate Precipitate soluble
(forming colourless solution)
Zn2+
White precipitate Precipitate insoluble Al3+ Pb2+
Blue precipitate Precipitate soluble
(forming deep blue solution)
Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
52
Ammonia solution is a weak alkali Metal cations except Ca2+ form insoluble hydroxides with
ammonia solution as with the sodium hydroxide solution
The amphoteric hydroxides Al(OH)3 and Pb(OH)2 and the basic hydroxides Fe(OH)2 and
Fe(OH)3 do not react with excess ammonia solution Therefore the precipitates remain
However Zn(OH)2 and Cu(OH)2 do react with excess ammonia solution to form complex
soluble hydroxides each Hence their precipitates disappear on the addition of excess ammonia
solution
Confirmatory test
After carrying out test for cations using sodium hydroxide solution and ammonia solution the
only cations which cannot be distinguished are Al3+ and Pb2+ A confirmatory test is carried out
to distinguish between the two cations
Confirmatory test
Test Observation Cation Ionic equation
Add potassium
or sodium
iodide solution
Bright yellow precipitate
No precipitate
Pb2+
Al3+
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
53
WEEK 10 LESSON 3 WORKSHEET
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A __________ B ________________ C ________________________
(b) State the inference after Test 2
C _______________________
(c) Write an ionic equation to support your answer in (b) above
___________________________________________________________________________
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
54
ANSWERS TO WORKSHEETS
55
WEEK 5 LESSON 1 WORKSHEET ANSWERS
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
Answer
Zinc + Iron (II) sulphate Zinc is higher in the electrochemical series and therefore displace
iron ions in iron (II) sulphate
Equation Zn (s) + FeSO4 (aq) ZnSO4 (aq) + Fe (s)
Ionic equation Zn (s) + Fe2+ (aq) Zn2+ (aq) + Fe (s)
Iron + Zinc sulphate No reaction iron is lower in the electrochemical series and cannot
displace the zinc ions in zinc sulphate
56
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
Answer
X displaces lead from an aqueous solution of its salts
X (s) + Pb2+ (aq) Xn+ (aq) + Pb (s)
rarr X is more reactive than Pb
X did not react with iron salts
rarr X is less reactive than Fe
Y burns very easily
Y is more reactive than Fe and Pb (both forming their corresponding oxide at a slower rate)
From electrochemical series Fe is higher and therefore more reactive than Pb
Order of reactivity
Y (most reactive) gt Fe gt X gt Pb (least reactive)
57
WEEK 5 LESSON 2 WORKSHEET ANSWERS
1
Metal Reactivity with acid
Copper X
Magnesium
Aluminium
Silver X
Zinc
58
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
Answer
Y and Z are the most reactive since they can react with dilute acid
Z is more reactive than Y since a reaction occurs with Z is added to an aqueous solution of Y
X is less reactive than W since it does not occur in nature as compounds
Order of reactivity Z (most reactive) gt Y gt W gt X
59
WEEK 5 LESSON 3 WORKSHEET ANSWERS
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
Answer
Ease of decomposition (from easiest to decompose to most difficult to decompose)
B rarrD rarrArarr C
Reactivity (most reactive to least reactive)
C (most reactive) gt A gt D gt B (least reactive)
60
WEEK 6 LESSON 1 Worksheet Answers
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
Potassium Zinc Copper
Calcium Lead Gold
Magnesium Iron
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
Aluminium is extracted from its ore bauxite through the process of electrolysis
Cryolite is added to bauxite to lower the melting point to about 900 0C The melting point of
bauxite is very high (about 2040 0C) It is difficult and expensive to keep the molten aluminium
oxide at this temperature
Reaction at the cathode Al3+ (l) + 3 e- Al (l)
61
WEEK 6 LESSON 2 Worksheet Answers
(a) What are the three raw materials that are added through the top of the blast
furnace during the extraction process for iron
Coke (carbon)
iron ore (haematitie mainly iron (II) oxide)
limestone (calcium carbonate)
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
Coke ndash coke burns to produce carbon dioxide The carbon dioxide further reacts with coke to
form carbon monoxide (reducing agent in the process)
C (s) + O2 (g) CO2 (g)
C (s) + CO2 (g) 2 CO
Haematite ndash iron ore provides the iron which is reduced by the carbon monoxide to produce
iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + CO2 (g)
Limestone ndash decomposes to form calcium oxide The calcium oxide reacts with the impurity
silicon dioxide to form slag (calcium silicate)
CaCO3 (s) CaO (s) + CO2 (g)
CaO (s) + SiO2 (l) CaSiO3(l)
62
WEEK 6 LESSON 3 Worksheet Answers
(a) Define the term alloy
An alloy is a material made from a mixture of two or more metals
(b) State 3 general advantages that alloys have over the individual metals they are made
from
They are harder stronger and more resistant to corrosion
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
1 High strength
2 Low density
Uses
1 Used to make aircraft bodies
2 Used to make space satellites
63
WEEK 7 LESSON 1 WORKSHEET ANSWERS
(a) Define the term corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
The paint forms a barrier which stops contact with air or water and the iron Hence rusting
will not take place
However when the paint is scratched that part of the iron nail is exposed to air or water and
rusting will take place
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
Magnesium is higher in the electrochemical series and will be oxidised in preference to iron
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
Aluminium is partly protected from corrosion by its coat of aluminium oxide However as the
iron rust it flakes and fall off and the rusting process continues
64
WEEK 7 LESSON 2 WORKSHEET ANSWERS
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
Magnesium is the ion found in chlorophyll Chlorophyll plays a vital part in the process of
photosynthesis A deficiency in magnesium will lead to low chlorophyll level in the tomato
plants and hence reduce the process of photosynthesis There will be less food storage and
hence will lead to smaller yield of tomatoes
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Any correct harmful effect of lead on health or environment
Any correct harmful effect of mercury on health or environment
65
WEEK 7 LESSON 3 WORKSHEET ANSWERS
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
(b) Write the ionic equation for the above reaction
2 Br- (aq) + Cl2 (aq) 2 Cl- (aq) + Br2 (aq)
(c) Identify the oxidising agent in the reaction
Cl2 (aq)
(d) Justify your answer in part (c) in terms of oxidation number
There is a reduction of the oxidation number for chlorine from 0 to ndash1
hence it has been reduced Therefore chlorine is the oxidising agent
66
WEEK 8 LESSON 1 WORKSHEET ANSWERS
Describe the laboratory preparation of oxygen gas
Oxygen is prepared in the laboratory by the decomposition of hydrogen peroxide
A suitable catalyst is manganese (IV) oxide
Drying agent silica gel OR anhydrous calcium chloride OR conc sulphuric acid
The gas is collected by downward delivery since oxygen is slightly denser than air
Balanced chemical equation 2 H2O2 (aq) 2 H2O (l) + O2 (g)
67
WEEK 8 LESSON 2 WORKSHEET ANSWERS
Describe the laboratory preparation of carbon dioxide gas
Carbon dioxide is commonly prepared in the laboratory by the reacting hydrochloric acid and
marble chips (calcium carbonate)
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
The carbon dioxide gas is collected by downward delivery since it is denser than air
Balanced chemical equation
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
68
WEEK 8 LESSON 3 WORKSHEET ANSWERS
Describe the laboratory preparation of ammonia gas
An ammonium salt (ammonium chloride) and a base (sodium hydroxide) are mixed together and
heated
Calcium oxide is used as the drying agent Calcium chloride and concentrated sulphuric acid
cannot be used since ammonia can react with them
The gas is collected by upward delivery since ammonia is less dense than air
Balanced chemical equation
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
69
WEEK 9 LESSON 1 WORKSHEET ANSWERS
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Carbon dioxide Put out fires
Oxygen Welding metals
Carbon dioxide Create lsquofizzrsquo in drinks
Oxygen Used in steel production
Oxygen Aerobic respiration
70
WEEK 9 LESSON 2 WORKSHEET ANSWERS
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Chlorine Used to make sodium hypochlorite
Sulphur Used as a fungicide on plant materials
Carbon (graphite) Used for lsquoleadrsquo in pencils
Phosphorus Used in the manufacture of bronze alloys
Nitrogen Used in the manufacture of nitric acid
Silicon Used in the manufacture of computer chips
Nitrogen Phosphorus Used to make fertilisers
71
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
Green Chemistry is using principles that reduceeliminate the use of hazardous materials in
the design manufacture and application of chemical products
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
Makes the environment safer
Reduces waste
Creates new jobs
Reduces respiratory illnesses
Atom economy
72
WEEK 10 LESSON 2 WORKSHEET ANSWERS
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P Cu2+ Q Fe2+
R Fe3+ S Ca2+
Ionic equation for R + NaOH
Fe3+ (aq) + 3 OH- (aq) Fe(OH)3 (s)
73
WEEK 10 LESSON 3 WORKSHEET ANSWERS
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A Fe3+ B Ca2+ C Al3+ Pb2+
(b) State the inference after Test 2
C Pb2+
(c) Write an ionic equation to support your answer in (b) above
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
11 Qualitative Analysis
ndash Test for gases
Qualitative Analysis
ndash Identification of
anions
Qualitative Analysis
ndash Identification of
anions
12 Problem solving of
Past CSEC Chemistry Paper 2
on topics completed in the term
13
14
15
2
WEEK 11 LESSON 1
TOPIC Qualitative Analysis ndash Test for gases
Identification of gases
Gas Colour Odour Effect on moist
litmus
Method of identification
Oxygen
O2
Colourless Odourless Neutral ndash no
effect
Relights a glowing splint
Hydrogen
H2
Colourless Odourless Neutral ndash no
effect
Lighted splint lsquopopsrsquo if air is also
present
Carbon
dioxide
CO2
Colourless Odourless Weakly acidic ndash
blue to slightly
red
A white precipitate forms in
limewater
Ca(OH)2 (aq) + CO2
CaCO3 (s) + H2O (l)
Precipitate redissolves on
continued bubbling
CaCO3 (s) + H2O (l) + CO2 (g)
Ca(HCO3)2 (aq)
Ammonia
NH3
Colourless Pungent Alkaline ndash red
to blue (only
common
alkaline gas)
Turns moist red litmus blue forms
dense white fumes with hydrogen
chloride gas
NH3 (g) + HCl (g) NH4Cl (s)
Gas Colour Odour Effect on moist
litmus
Method of identification
3
Sulphur
dioxide
SO2
Colourless Choking
smell
Acidic ndash blue to
red
Turns acidified potassium
manganate (VII) solution from
purple to colourless
Turns acidified potassium
dichromate (VI) solution from
orange to green
Chlorine
Cl2
Yellow ndash
green
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Bromine
Br2
Red ndash
brown
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Nitrogen
dioxide
NO2
Red ndash
brown
Irritating
smell
Acidic blue to
red
Turns moist blue litmus red but
does not bleach it
Water
vapour
H2O
Colourless Odourless Neutral ndash no
effect
Turns anhydrous cobalt (II)
chloride from blue to pink
Turns anhydrous copper (II)
sulphate from white to blue
4
WEEK 11 LESSON 1 WORKSHEET
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless
Yellow ndash green
Red ndash brown
Gases according to their odour
Odour of gas Identity of gas
Odourless
Pungent smell
Choking smell
Irritating smell
5
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect
Red to blue
Blue to red
Blue to red then bleaches it
6
WEEK 11 LESSON 2
TOPIC Qualitative Analysis ndash Identification of anions
Effect of heating
Method Heat a sample of the solid in a dry test tube
Effect of heating
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) not
of K or Na
CO32- (s) O2- (s) + CO2 (g)
Oxygen evolved NO3- of K or Na 2 NO3
- (s) 2 NO2- (s) + O2
(g)
Oxygen and nitrogen
dioxide evolved
NO3- of Ca and below
in reactivity series
4 NO3- (s) 2 O2- (s) + 4 NO2
(g) + O2
(g)
Sulphur dioxide evolved SO32- SO3
2- O2- (s) + SO2 (g)
Effect of dilute acid
Add dilute hydrochloric acid or nitric acid to a sample of the solid Warm if no reaction occurs
when cold
Effect of dilute acid
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) CO32- (s) + 2 H+ (aq) H2O (l) + CO2 (g)
Sulphur dioxide evolved SO32- SO3
2- (s) + 2 H+ (aq) H2O (l) + SO2 (g)
7
Effect of concentrated acid
Add concentrated sulphuric acid to a sample of the solid Warm if not reaction occurs when cold
Effect of concentrated sulphuric acid
Observation Anion
Carbon dioxide evolved CO32- or HCO3
-
Sulphur dioxide evolved SO3-
Hydrogen chloride evolved Cl-
Hydrogen bromide (colourless) and bromine
vapour (brown) evolved
Br-
Black iodine present and purple iodine vapour
evolved
I-
8
WEEK 11 LESSON 2 WORKSHEET
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater
Produces a gas which relights a glowing splint as the only gas
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green
Produces a gas forms a precipitate in limewater
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia
Black iodine present and purple iodine vapour evolved
9
WEEK 11 LESSON 3
TOPIC Qualitative Analysis ndash Identification of anions
Test for the halides ndash using silver nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous silver nitrate and
observe the precipitate Add ammonia solution and observe the solubility of the precipitate
Test for halides using silver nitrate solution
Effect of silver
nitrate solution
Anion Explanation Effect of aqueous
ammonia
White precipitate ndash
turns white in
sunlight
Cl- Ag+ (aq) + Cl- AgCl (s) Precipitate soluble
Cream precipitate ndash
turns yellow ndash green
in sunlight
Br- Ag+ (aq) + Br- AgBr (s) Precipitate slightly
soluble
Pale yellow
precipitate
I- Ag+ (aq) + I- AgI (s) Precipitate insoluble
Test for the halides ndash using lead nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous lead nitrate and
observe the precipitate
Test for halides using lead nitrate solution
Effect of lead nitrate solution Anion Explanation
White precipitate Cl- Pb2+ (aq) + 2 Cl- PbCl2 (s)
Pale yellow Br- Pb2+ (aq) + 2 Br- PbBr2 (s)
Deep yellow I- Pb2+ (aq) + 2 I- PbI2 (s)
10
Effect of barium nitrate or chloride solution followed by dilute acid
Make a solution of the solid Add barium nitrate or chloride solution and observe the precipitate
Add dilute hydrochloric or nitric acid warn if necessary and observe the solubility of the
precipitate
Effect of barium nitrate or chloride solution followed by dilute acid
Effect of
Ba(NO3)2 (aq)
or BaCl2 (aq)
Effect of HCl (aq)
or HNO3 (aq)
Anion Explanation
White precipitate Precipitate insoluble SO42- Ba2+ (aq) + SO4
2- (aq) BaSO4 (s)
BaSO4 does not react with dilute acids
White precipitate Precipitate soluble ndash
CO2 evolved
CO32- Ba2+ (aq) + CO3
2- (aq) BaCO3 (s)
BaCO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + CO2 (g)
White precipitate Precipitate soluble ndash
SO2 evolved on
warming
SO32- Ba2+ (aq) + SO3
2- (aq) BaSO3 (s)
BaSO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + SO2 (g)
11
WEEK 11 LESSON 3 WORKSHEET
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
(Ionic equation required)
12
WEEK 12 LESSON 1 WORKSHEET
(a) The Caribbean islands are known for their many resources For example the ore of
aluminium is found in Jamaica and Guyana
(i) Briefly describe the extraction of aluminium from its named ore Include in your
description one ionic equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Although aluminium ore is mined in the Caribbean the extraction of aluminium usually
takes place in other countries Suggest ONE reason why it may be difficult to extract
aluminium in the Caribbean
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) An alloy can be described as a lsquomixed metal solutionrsquo Aluminium forms an alloy with
magnesium that is used to make an aircraft
13
Identify this alloy and suggest why it is better to use it rather than the pure metal in the
manufacture of aircraft
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) ldquoSome metals can be useful to man yet harmful to the environmentrdquo Comment on this
statement with reference to mercury
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 12 LESSON 2 Worksheet
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate formed
Soluble in excess
15
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate formed
Insoluble in excess
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate formed
(Ionic equation required)
16
WEEK 12 LESSON 3 Worksheet
Dry ammonia gas can be produced in a school laboratory
(a) Identify TWO reagents that are necessary for the laboratory production of ammonia
______________________________________________________________________________
______________________________________________________________________________
(b) Two common drying agents used in the laboratory are calcium oxide and concentrated
sulphuric acid However calcium oxide is the preferred choice for drying ammonia gas
Explain why concentrated sulphuric acid is now used Include in your answer a balanced
chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) When gases are prepared in the laboratory there are three main ways in which they can
be collected
- Upward delivery
- Downward delivery
- Displacement of water
(i) What TWO other factors should be considered when choosing an appropriate method for
the collection of gases in the laboratory
______________________________________________________________________________
______________________________________________________________________________
(ii) Identify ONE of the three methods that is best suited for the collection of ammonia gas in
the laboratory Explain why EACH of the other two methods would NOT have been
appropriate
______________________________________________________________________________
17
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(d) Hence draw a labelled diagram of the apparatus which could be used for the preparation
of dry ammonia in the laboratory
Be sure to identify in your diagram
- where the reagents are placed
- where the ammonia is dried and
- where the ammonia is collected
18
WEEK 13 LESSON 1 Worksheet
(a) In solution two metals A and B form A+ and B2+ ions respectively Metal A displaces Fe
from a solution containing Fe2+ ions but metal B does NOT
(i) Arrange the metals A B and Fe in order of reactivity from LEAST reactive to MOST
reactive Write a balanced chemical equation to show the reaction between metal A and
Fe2+ ions
______________________________________________________________________________
______________________________________________________________________________
(ii) Metal A is placed in a solution of copper (II) sulphate CuSO4 (aq) Write an equation for
the reaction State ONE observable change that will occur and explain why this reaction
takes place
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) For EACH metal A and B state ONE method that can be used to extract it from its
respective oxide Give a reason for EACH answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
19
______________________________________________________________________________
(b) Metal alloys are often used for making objects found in our daily lives Name an alloy of
iron and state ONE of its uses
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 13 LESSON 2 Worksheet
(a) Many important biological processes in plants and animals depend on the specific roles
of certain metal ions
(i) Farmer Jones reaped a crop of tomatoes and reported that the yield was far below what
was expected Analysis of the soil revealed that there was a deficiency of magnesium
Discuss the importance of magnesium in plant health and explain how a magnesium
deficiency can result in the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE other metal ion which is important to plant health and state the result of its
deficiency
______________________________________________________________________________
______________________________________________________________________________
21
(b) Many years ago car exhaust fumes were known to contain compounds of metals and
non ndash metals which could negatively impact both humans and the environment Identify
ONE metal and ONE non ndash metal whose compounds were present in car exhaust fumes
Discuss the effect of these compounds on human health and the environment
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) Define lsquogreen chemistryrsquo and discuss the measures that have been taken to produce a
lsquogreenerrsquo automotive fuel
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
22
WEEK 13 LESSON 3 Worksheet
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
Zn2+ ions are present
23
WEEK 14 LESSON 1 Worksheet
(a) Metal alloys are often used in place of metals because of their enhanced properties
(i) Define the term lsquoalloyrsquo
______________________________________________________________________________
______________________________________________________________________________
(ii) Name ONE alloy of aluminium and state its use based on one of its enhanced properties
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) A student conducted an experiment to investigate the reactivity of each of the following
metals (copper iron zinc and lead) by using solutionPs of their sulphate salts
The data presented in the table below shows whether a visible chemical reaction took
place when each metal was added to the four sulphate solutions
Key Visible chemical reaction took place
X No visible chemical reaction
CHEMICAL REACTION OF METALS IN SULPHATE SOLUTIONS
Sulphate solution Cu Fe Zn Pb
CuSO4 X
FeSO4 X X X
ZnSO4 X X X X
PbSO4 X X
24
(i) State which of the TWO metals is more reaction Fe or Zn Give a reason for our answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Using the data in the previous Table deduce the order of reactivity of the four metals Cu
Fe Zn and Pb from the most reactive to the least reactive metal
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The student recorded the following observations from the reaction between the iron and
copper (II) sulphate solution
Observations Reddish ndash brown solid coating formed on the iron strip
Blue colour of the solution changed to dirty green
Account for the observations made from the reaction between the iron and copper (II)
sulphate solution
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iv) Write an ionic equation including state symbols for the reaction between the iron and
copper (II) sulphate solution
______________________________________________________________________________
25
(c) Some metal compounds are health and environmental hazards
(i) Identify which of the metals used in the experiment in (b) is MOST hazardous to the
environment
______________________________________________________________________________
______________________________________________________________________________
(ii) State TWO harmful effects of continuous exposure to the metal identified in (c) (i) on
human beings
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
26
WEEK 14 LESSON 2 Worksheet
(a) Carbon is found in the form of diamond and graphite and is a main component in many
naturally occurring compounds such as organic matter and carbon dioxide gas
(i) State ONE way in which diamond differs physically from graphite
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE similarity between diamond and graphite other than they both contain carbon
______________________________________________________________________________
______________________________________________________________________________
(b) Carbon can react with a limited supply of oxygen to form carbon monoxide which can
negatively affect human health
(i) Write a balanced chemical equation including state symbols to show the formation of
carbon monoxide
______________________________________________________________________________
(ii) State TWO effects of carbon monoxide inhalation on the human body
______________________________________________________________________________
______________________________________________________________________________
(c) Jamal wants to prepare and collect a sample of carbon dioxide gas in the laboratory using
calcium carbonate
(i) Write a balanced chemical equation including state symbols for the laboratory
preparation of carbon dioxide gas from calcium carbonate
______________________________________________________________________________
______________________________________________________________________________
(ii) Draw a clearly labelled diagram to show the arrangement of the apparatus and materials
that could be used in the laboratory to prepare and collect the carbon dioxide gas
(iii) State ONE use of carbon dioxide as it relates to the beverage industry
______________________________________________________________________________
27
WEEK 14 LESSON 3 Worksheet
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
(Ionic equation required)
Suggest a possible identity of the solid R __________________________
28
WEEK 15 LESSON 1 Worksheet
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a small
portion of solid Y gently at
first and then strongly
Colourless gas evolved
with a choking odour
Turns acidified potassium
dichromate solution from
orange to green
(ii) To the remaining portion
of solid Y add 20 cm3 of
distilled water stir to dissolve
and filter Collect the filtrate
and divide into 3 equal
portions
Filtrate is pale green in
colour
(iii) To the first portion of the
filtrate from (ii) add aqueous
sodium hydroxide slowly
until in excess
A green precipitate
Insoluble in excess sodium
hydroxide
Ionic equation required
29
TEST OBSERVATIONS INFERENCES
(iv) To the second portion of
the filtrate from (ii) add
aqueous silver nitrate
followed by aqueous
ammonia
White precipitate
Soluble in aqueous
ammonia
(v) To the third portion of the
filtrate from (ii) add aqueous
barium nitrate followed by
aqueous hydrochloric acid
White precipitate formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with the
evolution of a colourless
gas with a choking smell
30
WEEK 15 LESSON 2 Worksheet
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
31
WEEK 15 LESSON 3 Worksheet
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in excess
aqueous NH3
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change
32
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
warm filter and then divide
the filtrate into two portions
Vigorous effervescence
observed upon addition of
dilute HNO3
Gas evolved turns lime water
cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Cu2+ ions present
33
ANSWERS TO WORKSHEETS
34
WEEK 11 LESSON 1 WORKSHEET ANSWERS
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless O2 H2 CO2 NH3 SO2 H2O
Yellow ndash green Cl2
Red ndash brown Br2 NO2
Gases according to their odour
Odour of gas Identity of gas
Odourless O2 H2 CO2 H2O
Pungent smell NH3
Choking smell SO2 Cl2 Br2
Irritating smell NO2
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect Neutral O2 H2 H2O
Red to blue Alkaline NH3
Blue to red Acidic CO2 SO2 NO2
Blue to red then bleaches it Acidic Cl2 Br2
35
WEEK 11 LESSON 2 WORKSHEET ANSWERS
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-) not
of K or Na
Produces a gas which relights a glowing splint as the only gas NO3- of K or Na
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green SO32-
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-)
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia Cl-
Black iodine present and purple iodine vapour evolved I-
36
WEEK 11 LESSON 3 WORKSHEET ANSWERS
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Br-
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
Cl-
Ag+ (aq) + Cl- AgCl (s)
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow Br-
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
SO42-
Ba2+ (aq) + SO42- (aq)
BaSO4 (s)
(Ionic equation required)
37
WEEK 12 LESSON 1 Worksheet Answers
(a) (i)
The ore bauxite is purified
The purified bauxite is dissolved in molten cryolite
The aluminium oxidecryolite solution is then eletrolysed
Equation at the cathode Al3+ (l) + 3 e- Al (l)
Equation at the anode 2 O2- (l) ndash 4 e- O2 (g)
(ii) The process is too expensive mainly because too much electricity or energy is needed
(b) The alloy of Al and Mg is magnalium It is less dense than the pure metals and hence allow
aircraft to be lighter It is also stronger than the pure metals and hence allows aircraft to last
longer since it is not easily destroyed
(c) Your answer should cater for the following aspects
Benefits of mercury to humans for example in thermometers barometers in dentistry
and gold mining
Entry of mercury to the environment For example this could have been through broken
thermometers barometers or lightbulbs or improper disposal of them or batteries and
indiscriminate use in gold mining in Guyana
The identification of a negative impact on the environment such as poisoned fish and the
persons who eat the fish death mood swings and psychosis
38
WEEK 12 LESSON 2 Worksheet Answers
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas
evolved
NO2 evolved OR nitrates
present OR
Br2 gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate
formed
Soluble in excess
Pb2+ Zn2+ Al3+ or Ca2+
present
Pb2+ Zn2+ Al3+ or present
39
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate
formed
Insoluble in excess
Pb2+ Zn2+ Al3+ or present
Pb2+ or Al3+ present
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate
formed
Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
40
WEEK 12 LESSON 3 Worksheet Answers
(a) an ammonium salt and a strong alkali
(b) Ammonia is basic and it will react with H2SO4
Equation 2 NH3 (aq) + H2SO4 (aq) (NH4)2SO4 (aq)
(c) (i) ndash Density of the gas relative to air ndash The solubility of the gas in water
(ii) Ammonia is collected by upward delivery
It cannot be collected by downward delivery since ammonia is less dense than air
It cannot be collected by displacement of water since it is soluble in water
(d)
41
WEEK 13 LESSON 1 Worksheet Answer
a) i) B ˂ Fe ˂ A
2A (s) + Fe 2+ (aq) rarr 2A+ (aq) + Fe (s)
ii) 2A (s) + CuSO4 (aq) rarr A2SO4 (aq) + Cu (s)
Observation blue colour fades gets lighter OR brown solid forms is deposited OR metal A
decreases in size dissolves
Explanation Metal A is higher (than Fe which is higher) than Cu in the reactivity series OR
Metal A is more reactive (than Fe which is more reactive) than Cu so Metal A can displace Cu
iii) Metal A can be extracted by electrolysis (of its molten oxide) because Metal A is a very
reactive metal is high in the reactivity series forms stable oxides needs a lot of energy to be
extracted and very reactive metals are extracted by electrolysis
Metal B can be extracted by heating with carbon carbon monoxide OR by chemical reduction
of the oxide because Metal B is less reactive than Fe is low in the reactivity series forms less
stable oxides does not need a lot of energy to be extracted and oxides of less reactive metals are
easily reduced
b) Alloy of iron steel
Use of alloy making buildings bridges ships motor vehicles furniture utensils
42
WEEK 13 LESSON 2 Worksheet Answer
(a) (i)
Magensium is the metal ion found in chlorophyll
Chlorophyll is essential for photosynthesis
A deficiency in magnesium will result in low chlorophyll yellow leaves and a reduction in
photosynthesis
Hence there will be low carbohydrates or energy production
Hence small fruits stunted growth and lower yield will result
(ii)
Metal ion Results of deficiency
Potassium Stunted growth premature loss of leaves yellowing of leaves curling of leaf tips
Calcium Growth abnormalities in tips of roots and shoots curling of leaves
Iron Yellowing of leaves
Zinc Low chlorophyll content yellowing of leaves
Manganese Yellowing of leaves poor flavors in some crops for example potato
(b)
Metal Lead is present in some types of gasoline Upon combustion lead compounds escape into
the atmosphere It accumulates in body tissues and slowly poisons the person It causes mental
illness
Non ndash metal SulphurSulphur dioxide or NitrogenNitrogen dioxide
Dissolves in rain water to form acid rain or cause respiratory illnessproblems Acid rain can
cause corrosion damage in buildings
(c)
Green chemistry is the utilisation of a set of principles that reduces or eliminates the use or
generation of hazardous substances
43
Automotive fuels are now produced without lead so as to eliminate the release of lead
compounds into the atmosphere
Low sulphur fuel is being produced with much reduced sulphur content which causes a reduction
of sulphur dioxide release into the atmosphere
44
WEEK 13 LESSON 3 Worksheet Answer
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
gas turns litmus blue
red
brown gas
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
white precipitate
precipitate soluble in
excess
Zn2+ ions are present
45
WEEK 14 LESSON 1 Worksheet Answers
(a)(i) An alloy is a material made from a mixture of two or more metals
(ii) Any suitable answer chosen from below
Alloy Enhance Property Use
Duralumin High strength
Low density
Light
Hard
Used to make aircraft bodies
space satellites
Magnalium Light
Hard
Easier to weld
Corrosion resistant
Strong
High ductability
Used in pyrotechnics
(fireworks)
Mirrors
Aircraft parts
To make scientific
instruments
Used to make marine castings
Alchlad Strong
Corrosion resistant
Cladding for buildings
(b) (i) Zinc is more reactive than iron
Zinc displaces iron from iron (II) sulphate
Zinc is higher in the reactivity series than iron
Iron does not displace zinc from zinc sulphate
(ii) Order of reactivity Zn gt Fe gt Pb gt Cu
(iii) Reddish brown solid ndash copper metal formed
46
Dirty green solution ndash presence of Fe2+ ion
(iv) Fe (s) + Cu2+ (aq) Fe2+ (aq) + Cu (s)
(c) (i) Lead
(ii) Any two correct harmful effects of lead on the body
Impedes brain development (in young children)
Affectimpede development of the immune system in humans
Affecthamper development of nervous system in humans
Long term exposure can result in kidney and liver damage
Mental retardation
Anaemia
Death
47
WEEK 14 LESSON 2 Worksheet Answers
a) i) Diamond is transparent clear Graphite is opaque black
OR hard OR brittle
OR does not conduct electricity OR conducts electricity
a) ii) Both have a macromolecular giant molecular giant covalent structure (lattice)
OR Both have high melting point boiling point
OR Both are insoluble in water organic solvent
b) i) 2C (s) + O2 (g) rarr 2CO (g)
ii) CO reduction in amount of oxygen carried by (the haemoglobin in the red blood
cells of) the blood
Headache OR dizziness OR nausea OR fatigue OR loss of consciousness OR
death
c) i) CaCO3 (s) + 2HCl (aq) rarr CaCl2 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) + H2SO4 (aq) rarr CaSO4 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) rarr CaO (s) + CO2 (g)
48
ii)
OR
OR
Entirely closed system thistle funnel below the level of the liquid OR tap that could be
closed
Two reagents labelled CaCO3marble chips and HCl H2SO4 or heat source
collection of CO2 upward displacement of air OR over watersulphuric acid OR in gas
syringe
iii) CO2 use put in aerated drinks carbonated beverages
OR put in carbon dioxide fire extinguishers
49
WEEK 14 LESSON 3 Worksheet Answers
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
NH4+
NH4+ confirmed OR
NH3 (g) produced
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
Cl- ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation required)
Suggest a possible identity of the solid R NH4Cl (ammonium chloride)
50
WEEK 15 LESSON 1 Worksheet Answers
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a
small portion of solid Y
gently at first and then
strongly
Colourless gas
evolved with a
choking odour
Turns acidified
potassium dichromate
solution from orange
to green
SO2 evolved
Presence of a sulphite
(ii) To the remaining
portion of solid Y add 20
cm3 of distilled water stir
to dissolve and filter
Collect the filtrate and
divide into 3 equal portions
Filtrate is pale green
in colour
Fe2+ ions present
(iii) To the first portion of
the filtrate from (ii) add
aqueous sodium hydroxide
slowly until in excess
A green precipitate
Insoluble in excess
sodium hydroxide
Fe2+ ions present
Fe2+ (aq) + 2 OH- (aq) Fe(OH)2 (s)
Ionic equation required
TEST OBSERVATIONS INFERENCES
(iv) To the second portion
of the filtrate from (ii) add
aqueous silver nitrate
White precipitate
Soluble in aqueous
ammonia
Cl- ions present
51
followed by aqueous
ammonia
(v) To the third portion of
the filtrate from (ii) add
aqueous barium nitrate
followed by aqueous
hydrochloric acid
White precipitate
formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with
the evolution of a
colourless gas with a
choking smell
SO32- CO3
2- SO42- ions present
SO32- ions present
52
WEEK 15 LESSON 2 Worksheet Answers
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
Chloride ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
Cu2+ ions present
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
X contains a reducing agent
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
SO32- SO4
2- or CO32- ions are
present
SO32- ions are present
53
WEEK 15 LESSON 3 Worksheet Answers
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
White ppt
Ppt soluble in excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in
excess aqueous NH3
Al3+ Pb2+ Zn2+ present
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change Cl- Br- I- absent
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
Vigorous effervescence
observed upon addition of
dilute HNO3
CO2 evolved OR
Carbonate present
54
warm filter and then divide
the filtrate into two portions
Gas evolved turns lime
water cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
Cu2+ (aq) + OH- (aq)
Cu(OH)2 (s)
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Blue ppt
ppt dissolves in excess
NH3 to give a deep blue
solution
Cu2+ ions present
55
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
REFERENCES
Hunte-King J Maragh P Nagir F amp Norris R (2013) Chemistry for CSEC United
Kingdom Nelson Thornes Ltd
Remy C Mason L Lambert N amp Mohammed M (2007) Chemistry for CSEC England and
Wales Pearson Education Limited
Taylor M amp Chung-Harris T (2010) CXC Chemistry England Macmillan Publishers
Limited
Tindale A (2016) Chemistry A Concise Revision for CXC London HarperCollins Publishers
Limited
7
WEEK 1 LESSON 2
TOPIC Physical properties of metals
Physical properties of some metals
Metals Melting point 0C
Boiling point
0C
Density
g cm-3
Other characteristics
Sodium 90 900 097 Very soft grey metal
Calcium 850 1487 153 Grey metal
Magnesium 650 1103 174 Soft grey metal
Aluminium 660 2350 270 Grey metal
Zinc 419 907 719 White metal
Iron 1535 2760 797 Dark grey metal
Copper 1083 2580 894 Gold coloured metal
conductivity second only to
silver
Sodium Calcium Magnesium Aluminium
Zinc Iron Copper
8
WEEK 1 LESSON 2 WORKSHEET
A group of students carried out an experiment to find the density of three different metals
aluminium calcium and an unknown metal X They measured the mass of each metal sample
using a balance The volumes of the metals were determined by displacement of oil The results
of their experiment are as follows
Aluminium Calcium Metal X
Mass (g) 100 100 100
Final volume (cm3) 335 365 310
Initial volume (cm3 300 300 300
Volume of metal (cm3)
Density (gcm-3)
Complete the table using the following formulae
Volume of metal = Final volume ndash Initial volume
Density = 119872119886119904119904
119881119900119897119906119898119890
Arrange the metals in order of increasing density _____________________________________
9
WEEK 1 LESSON 3
TOPIC Chemical properties of metals
Action of oxygen
Most metals react with oxygen or air to form the corresponding oxide These oxides are basic
oxides with the exception of aluminium zinc and lead which form amphoteric oxides Metals
lower in the electrochemical series do not react
Metal Reaction with air or oxygen
Potassium K
Burn very easily forming oxide
eg 4 Na (s) + O2 (g) 2 Na2O (s)
Sodium Na
Calcium Ca
Magnesium Mg
Aluminium Al
Burn especially if powered forming oxide
eg 4 Al (s) + 3 O2 (g) 2 Al2O3 (s)
Zinc Zn
Iron Fe
Lead Pb Do not burn form oxide when heated strongly
Copper Cu
Silver Ag No reaction
10
WEEK 1 LESSON 3 WORKSHEET
Write balanced chemical equations for the reaction of the named metals and air or oxygen
State the nature of the oxide formed (basic or amphoteric)
Potassium + Oxygen
______________________________________________________________________________
Sodium + Oxygen
______________________________________________________________________________
Calcium + Oxygen
______________________________________________________________________________
Magnesium + Oxygen
______________________________________________________________________________
Aluminium + Oxygen
______________________________________________________________________________
Zinc + Oxygen
______________________________________________________________________________
11
Iron + Oxygen
______________________________________________________________________________
Lead + Oxygen
______________________________________________________________________________
Copper + Oxygen
______________________________________________________________________________
Silver + Oxygen
______________________________________________________________________________
12
WEEK 2 LESSON 1
TOPIC Chemical properties of metals
Action of water
Metals high in the electrochemical series react with cold water to produce the metal hydroxide
and hydrogen
Reactive metals slightly lower in the electrochemical series react very slowly or not at all with
water However they may react with hot water or steam to produce the corresponding metal
oxide and hydrogen
Metals lower than hydrogen in the electrochemical series do not react with water
Metal Reaction with water or steam
Potassium K React with cold water forming metal hydroxide and hydrogen
eg Ca (s) + 2 H2O (l) Ca(OH))2 (aq) + H2 (g) Sodium Na
Calcium Ca
Magnesium Mg React with steam forming metal oxide and hydrogen
eg Zn (s) + H2O (g) ZnO (s) + H2 (g) Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
13
WEEK 2 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with water (or
steam if reaction does not occur with water)
Potassium + WaterSteam
______________________________________________________________________________
Sodium + WaterSteam
______________________________________________________________________________
Calcium + WaterSteam
______________________________________________________________________________
Magnesium + WaterSteam
______________________________________________________________________________
Aluminium + WaterSteam
______________________________________________________________________________
Zinc + WaterSteam
______________________________________________________________________________
14
Iron + WaterSteam
______________________________________________________________________________
Copper + WaterSteam
______________________________________________________________________________
Silver + WaterSteam
______________________________________________________________________________
15
WEEK 2 LESSON 2
TOPIC Chemical properties of metals
Action of dilute acids
Metals above hydrogen in the electrochemical series react with dilute acids to form a salt and
hydrogen gas They react with hydrochloric acid to form the metal chloride (a salt) and hydrogen
gas They also react with dilute suphuric acid to form the metal sulphate (a salt) and hydrogen
gas
Metal Reaction dilute hydrochloric or sulphuric acid
Potassium K Violent reaction forming a salt and hydrogen gas
eg 2 Na (s) + 2 HCl (aq) 2 NaCl (aq) + H2 (g) Sodium Na
Calcium Ca Vigorous reaction forming a salt and hydrogen gas
eg Mg (s) + 2 HCl (aq) MgCl2 (aq) + H2 (g) Magnesium Mg
Aluminium Al React forming a salt and hydrogen gas
eg Fe (s) + 2 HCl (aq) FeCl2 (aq) + H2 (g) Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
16
WEEK 2 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with
hydrochloric acid
Metal Balanced equation for reaction with hydrochloric acid
Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Copper
Silver
17
WEEK 2 LESSON 3
TOPIC Reactions of metal compounds
Reactions of metallic oxides with dilute acid
Metal oxides react with dilute hydrochloric acid or sulphuric acid to produce a salt and water
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
Some of these reactions may be slow and can be speeded up by adding heat
For example
zinc oxide + hydrochloric acid zinc chloride + water
ZnO (s) + 2 HCl (aq) ZnCl2 (aq) + H2O (l)
magnesium oxide + hydrochloric acid magnesium chloride + water
MgO (s) + 2 HCl (aq) MgCl2 (aq) + H2O (l)
aluminium oxide + sulphuric acid aluminium sulphate + water
Al2O3 3 H2SO4 (aq) Al2(SO4)3 (aq) + 3 H2O (l)
calcium oxide + sulphuric acid calcium sulphate + water
CaO H2SO4 (aq) CaSO4 (aq) + H2O (l)
18
WEEK 2 LESSON 3 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal oxides with the
corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium oxide Hydrochloric acid
Sodium oxide Sulphuric acid
Calcium oxide Hydrochloric acid
Magnesium oxide Sulphuric acid
Aluminium oxide Hydrochloric acid
Zinc oxide Sulphuric acid
19
WEEK 3 LESSON 1
TOPIC Reactions of metal compounds
Reactions of metallic hydroxides with dilute acid
Metal hydroxides react with dilute acids to form a salt and water in a neutralisation reaction
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
For example
magnesium hydroxide + hydrochloric acid magnesium chloride + water
Mg(OH)2 (aq) + 2 HCl (aq) MgCl2 (aq) + 2 H2O (l)
sodium hydroxide + hydrochloric acid sodium chloride + water
NaOH (aq) + HCl (aq) NaCl (aq) + H2O (l)
potassium hydroxide + sulphuric acid potassium sulphate + water
2 KOH + H2SO4 (aq) K2SO4 (aq) + 2 H2O (l)
calcium hydroxide + sulphuric acid calcium sulphate + water
Ca(OH)2 (aq) + H2SO4 (aq) CaSO4 (aq) + 2 H2O (l)
20
WEEK 3 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal hydroxides with
the corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium hydroxide Hydrochloric acid
Sodium hydroxide Sulphuric acid
Calcium hydroxide Hydrochloric acid
Magnesium hydroxide Sulphuric acid
Aluminium hydroxide Hydrochloric acid
Zinc hydroxide Sulphuric acid
21
WEEK 3 LESSON 2
TOPIC Reactions of metal compounds
Reactions of metallic carbonates with dilute acid
Metal carbonates react with dilute acid to form a salt carbon dioxide and water When
hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric acid is
used the corresponding sulphate salt is formed
For example
sodium carbonate + hydrochloric acid sodium chloride + carbon dioxide + water
Na2CO3 (s) + 2 HCl (aq) 2 NaCl (aq) + CO2 (g) + H2O (aq)
calcium carbonate + hydrochloric acid calcium chloride + carbon dioxide + water
CaCO3 (s) + 2 HCl (aq) CaCl2 (aq) + CO2 (g) + H2O (aq)
zinc carbonate + sulphuric acid zinc sulphate + carbon dioxide + water
ZnCO3 (s) + H2SO4 (aq) ZnSO4 (aq) CO2 (g) + H2O (aq)
potassium carbonate + sulphuric acid potassium sulphate + carbon dioxide + water
K2CO3 (s) H2SO4 (aq) K2SO4 (aq) CO2 (g) + 2 H2O (aq)
22
WEEK 3 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal carbonates with
the corresponding acid
Metallic
carbonate
Acid Balanced chemical equation
Potassium
carbonate
Hydrochloric
acid
Sodium
carbonate
Sulphuric acid
Zinc
carbonate
Hydrochloric
acid
Magnesium
carbonate
Sulphuric acid
Aluminium
carbonate
Hydrochloric
acid
Calcium
carbonate
Sulphuric acid
23
WEEK 3 LESSON 3
TOPIC Action of heat on metal compounds
Action of heat on nitrates
All nitrates decompose when heated The reactivity of the metal in the metal nitrate influences
the products of the decomposition
The nitrates of the alkali metals (Group I) with the exception of lithium nitrate decompose to
form the metal nitrite and oxygen
The nitrates of most other metals decompose to form the metal oxide nitrogen dioxide and
oxygen
The nitrates of the very unreactive metals decompose to form the meal nitrogen dioxide and
oxygen
Metal Nitrate Decomposition
Potassium K Products metal nitrite + oxygen
eg 2 NaNO3 (s) Heatrarr 2 NaNO2 (s) + O2 (g)
Sodium Na
Calcium Ca
Products metal oxide + nitrogen dioxide + oxygen
eg 2 Pb(NO3)2 (s)
Heatrarr 2 PbO (s) + 4 NO2 (g) + O2 (g)
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Products metal + nitrogen dioxide + oxygen
eg 2 AgNO3 (s) Heatrarr 2 Ag (s) + 2 NO2 (g) + O2 (g)
24
WEEK 3 LESSON 3 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
nitrates
Metal Balanced chemical equation
Potassium nitrate
Sodium nitrate
Calcium nitrate
Magnesium nitrate
Aluminium nitrate
Zinc nitrate
Lead nitrate
Copper nitrate
Silver nitrate
25
WEEK 4 LESSON 1
TOPIC Action of heat on metal compounds
Action of heat on carbonates
Upon application of heat many carbonates decompose to form the metal oxide and carbon
dioxide
Group I carbonates do not decompose on heating with the exception of lithium carbonate
Metal Carbonate decomposition
Potassium K
Stable not decomposed by heat Sodium Na
Calcium Ca
Decompose forming metal oxide and carbon dioxide
eg CaCO3 (s) Heatrarr CaO (s) + CO2 (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Unstable
26
WEEK 4 LESSON 1 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
carbonates
Metal Balanced chemical equation
Potassium carbonate
Sodium carbonate
Calcium carbonate
Magnesium carbonate
Aluminium carbonate
Zinc carbonate
Iron carbonate
Lead carbonate
Copper carbonate
27
WEEK 4 LESSON 2
TOPIC Action of heat on metal compounds
Action of heat on the metal hydroxides
Most metal hydroxides decompose on heating A metal oxide and water are formed
Group I hydroxides do not decompose on heating with the exception of lithium hydroxide
Metal Hydroxide decomposition
Potassium K Stable not decomposed by heat
Sodium Na
Calcium Ca Decompose forming metal oxide and water (as steam)
eg Zn(OH)2 (s) Heatrarr ZnO (s) + H2O (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag No hydroxide exist
28
WEEK 4 LESSON 2 WORKSHEET
Write the balanced chemical equations for the thermal decomposition of the following
metal hydroxides
Metal hydroxide Balanced chemical equation
Potassium hydroxide
Sodium hydroxide
Calcium hydroxide
Magnesium hydroxide
Aluminium hydroxide
Zinc hydroxide
Lead hydroxide
Copper hydroxide
29
WEEK 4 LESSON 3
TOPIC Reactivity of metals ndash The Reactivity Series
The reactivity series of metals is a list of metals arranged in order of their reactivity based on
Displacement reactions
Reactions with oxygen dilute acids and water
Relative ease of decomposition of their compounds
Metals at the top of the series are the most electropositive They lose electrons very easily and
readily form cations These ions are very stable and are not easily discharged to form atoms Due
to this fact they are the most reactive metals
Metals at the bottom of the series are the least electropositive They do not lose electrons easily
and do not readily form ions Their ions are very unstable and are easily discharged to form
atoms They are the least reactive metals
The reactivity series of metals
Mnemonic Metal Symbol Reactivity
People Potassium K Most reactive
Least reactive
Sometimes Sodium Na
Collect Calcium Ca
Magazines Magnesium Mg
About Aluminium Al
Zoos Zinc Zn
In Iron Fe
London Lead Pb
Having (Hydrogen) H
Cute Copper Cu
Monkeys and Mercury Hg
Small Silver Ag
Gorillas Gold Au
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
5 Reactivity of metals Reactivity of metals Reactivity of metals
6 Extraction of metals Extraction of metals Alloys
7 Corrosion Importance of metals
and their compounds
on living systems and
environment
Chemical properties
of non ndash metals
8 Laboratory
preparation of gases
Laboratory
preparation of gases
Laboratory
preparation of gases
9 Uses of gases Uses of non ndash metals
and their compounds
Harmful effects of
non ndash metals and
their compounds on
living systems and
the environment
10 Green Chemistry Qualitative Analysis
ndash Identification of
cations
Qualitative Analysis
ndash Identification of
cations
2
WEEK 5 LESSON 1
TOPIC Reactivity of metals
Reactivity based on displacement reactions between metals and metal ions
A metal will displace a metal which is lower than itself in the reactivity series from a solution of
the metal salt
Reaction of zinc and copper (II) sulphate
Expected observations
Explanation
The size of the zinc metal decreases
The zinc metal is reacting and forming the
salt zinc sulphate
The solution becomes lighter eventually
colourless
The Cu2+ (aq) ions (responsible for the blue
colour) is reduced to Cu (s)
A brown solid is deposited at the bottom of
the container
Copper metal is formed
Equation Zn (s) + CuSO4 (aq) ZnSO4 (aq) + Cu (s)
Ionic equation
Zn (s) + Cu2+ (aq) Zn2+ (aq) + Cu (s)
Zinc is higher in the reactivity series than copper Therefore it will displace the copper ions in
the reaction above
3
Examples of other displacement reactions
Magnesium will displace Zn2+ ions in zinc sulphate since it is higher in the series than zinc
Mg (s) + Zn2+(aq) Mg2+ (aq) + Zn (s)
Silver will not displace Cu2+ ions in copper (II) sulphate [Cu is higher in the series than Ag]
Using the information above we can arrange the metals in order of their reactivity with
magnesium being the most reactive and silver the least reactive metal among the four metals
Mg gt Zn gt Cu gt Ag
Reactivity based on reaction with oxygen
The reactivity of metals can also be deduced from their reaction with oxygen
The table below gives the observations for the reaction with oxygen with the selected metals
Reaction of metal with oxygen
Metal Observation
Copper The surface turns black upon heating
Magnesium Ribbon burns very rapidly
Sodium Burns vigorously
Gold No reaction
Based on the observations for the 4 metals the metal with highest reactivity is sodium and the
metal with the least reactivity is gold
The 4 metals can be arranged in terms of reactivity as follows
Na gt Mg gt Cu gt Au
4
WEEK 5 LESSON 1 WORKSHEET
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
5
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
6
WEEK 5 LESSON 2
TOPIC Reactivity of metals
Reactivity based on reactivity with acids
The metals that are higher than hydrogen in the electrochemical series react with non ndash oxidizing
acids to produce a salt and hydrogen gas
By using the same concentration of acid and same mass and size of the metals the order of
reactivity of the metals can be deduced
The table below shows the results for an experiment with the reaction of the named metals and
1 mol dm-3 hydrochloric acid
Reaction of metals with acid
Metal Observations
Silver No reaction
Magnesium Bubbles produced steadily
Calcium Bubbles produced very rapidly
Iron Bubbles produced slowly
Based on the above data the most reactive metal will be calcium with the least reactive being
silver The order of reactivity will be Ca gt Mg gt Fe gt Ag
By comparing this to the electrochemical series it can be seen that the reactivity of the metals
decrease as we go down the series
7
WEEK 5 LESSON 2 WORKSHEET
1 Place a next to the metals that will react with dilute acid and an X next to the metals
that will not react with dilute acid
Metal Reactivity with acid
Copper
Magnesium
Aluminium
Silver
Zinc
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
8
WEEK 5 LESSON 3
TOPIC Reactivity of metals
Reactivity based on ease of decomposition of the metal nitrates carbonates oxides and
hydroxides
The more reactive a metal the more difficult it is to decompose its nitrate carbonate oxide or
hydroxide on heating
For example Decomposition of carbonates
Procedure
1 Put a large spatula measure of the carbonate to be tested in a test tube
2 Fit a delivery tube and then clamp the test tube so that the delivery tube dips into a second test
tube containing 2ndash3 cm3 limewater
3 Heat the solid gently at first then more strongly
4 Lift the delivery tube from the limewater before or as soon as the heating is stopped This is to
avoid suck-back
5 Write down all observations Notice what happens to the limewater and how long it takes to turn
milky (if at all) Notice whether any melting occurs in the heated test tube and any colour
changes taking place Write your results in tabular form
6 Repeat the experiment with the other metal carbonates supplied and in each case write down
your observations
7 Wash your hands thoroughly at the end of these experiments since some of the metal carbonates
are toxic
9
Results
Metal Formula Gas evolved Ease of decomposition
Zinc ZnCO3 Carbon dioxide Fairly easy
Copper CuCO3 Carbon dioxide Easy
Sodium Na2CO3 None Very difficult
Using the results of the above activity the reactivity of the metals can be determined
Ease of decomposition Copper gt Zinc gt Sodium
The order of reactivity is the opposite for the ease of decomposition
Order of reactivity Sodium (most reactive) gt Zinc gt Copper (least reactive)
10
WEEK 5 LESSON 3 WORKSHEET
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
11
WEEK 6 LESSON 1
TOPIC Extraction of metals
Elements exist all over the earth Some are found as free elements eg copper silver and gold
Others are found combined with other elements in compounds To get the elements the
compounds have to be broken up These compounds are generally called ores the most
convenient sources of which are rocks sea and air
The extraction of a metal from its ore is a reduction process where the metals ions gain electrons
to form atoms
The general equation is Mn+ + n e- M
The choice of the extraction method depends on the position of the metal in the reactivity series
As we go down the series the metals become more stable and the metal ions (in the ores)
become less stable
The very reactive metals that are high in the series K Na Ca Mg Al have very stable ores
Therefore they require a powerful method of reduction namely electrolysis During the process
the cathode provides the electrons and acts as the reducing agent
The metals in the middle of the series (Zn Fe Pb) do not have stable ores and can be extracted
by reduction with carbon in the case of zinc and with carbon monoxide in the case of iron and
lead
Metals low in the reactivity series if present as ores can be extracted simply by heating the ores
in air at high temperatures
12
Extraction of Aluminium from purified bauxite
Pure bauxite is pure alumina (Al2O3) Aluminium is obtained from bauxite by electrolysis
Aluminium oxide has a very high melting point approximately 2050 0C so it is first dissolved in
molten cryolite (Na2AlF6) The addition of cryolite lowers the melting point to approximately
900 0C
The electrolyte is a molten mixture of alumina and molten cryolite The cathode is the graphite
lining of the cell The anodes are blocks of graphite or titanium alloys
Reaction at the cathode
Al3+ (l) + 3 e- Al (l)
Reaction at the anode
2 O2- (l) ndash 4 e- O2 (g)
Aluminium (melting point 660 0C) is a liquid at the temperature at which electrolysis is carried
out and is collected at the bottom of the cell and tapped off Oxygen gas which is given off in the
main cathode reaction together with the heat causes the anodes to burn away The anodes have
to be replaced from time to time The use of anodes from titanium alloys reduce the number of
times that the anodes have to be replaced
13
WEEK 6 LESSON 1 Worksheet
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 6 LESSON 2
TOPIC Extraction of metals
Extraction of Iron
The traditional method of production of iron is by reduction of haematite by carbon monoxide in
a blast furnace
Ores Haematite ndash Fe2O3 Magnetite ndash Fe3O4 Siderite ndash FeCO3 Magnetite and Siderite are
converted to Haematite
A mixture of haematite limestone (CaCO3) and coke (C) called the charge is placed into the top
of the furnace
Hot air is blown into the bottom of the furnace
Coke burns in air forming carbon dioxide
C (s) + O2(g) CO2 (g) ΔH -ve
The heat produced keeps the temperature at about 1900 0C
The carbon dioxide is reduced to carbon monoxide by the hot coke
CO2 (g) + C (s) 2 CO(g) Δ +ve
Heat absorbed reduces the temperature to about 1100 0C
The carbon monoxide reduces the hot iron ore to molten iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + 3 CO2(g)
The temperature at this part of the furnace is about 700 0C The iron runs to the bottom of the
furnace
The impurities are removed by the addition of limestone (CaCO3) The limestone at the
temperature of the furnace breaks down
CaCO3 (s) CaO (s) + CO2 (g)
15
The calcium oxide formed combines with silicon dioxide (sand) the main impurity in the iron
ore to form molten slag
CaO (s) + SiO2 (s) CaSiO3 (l)
The slag does not mix with the molten iron but floats on it The molten iron and slag are run off
separately
The iron formed in a blast furnace is an impure form of the metal Because the molten metal is
allowed to solidify in shallow trays known as casts the iron is called lsquocast ironrsquo or lsquopigrsquo iron
Cast iron is quite brittle and contains 2 - 4 carbon and other impurities Most of the cast iron is
converted to steel
A blast furnace used for extracting iron
16
WEEK 6 LESSON 2 Worksheet
(a) What are the three raw materials that are added through the top of the blast furnace
during the extraction process for iron
______________________________________________________________________________
______________________________________________________________________________
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
17
WEEK 6 LESSON 3
TOPIC Alloys
An alloy is a mixture of two or more metals Alloys are made by melting the individual metals
mixing them and allowing the molten mixture to solidify
In general alloys are harder stronger and more resistant to corrosion than the actual metals they
are made up from
Alloy Use Properties
ALUMINIUM
-Duralumin
(AlMgCu)
-Magnalium (AlMg)
Alloys used in the
construction of
aircraft and ships
buses
Aluminium is used in
making cooking
utensils electrical
cables paint for fuel
storage tanks bottle
caps foil and utensils
for handling nitric
acid
The alloys have a low
density They are as
light as aluminium
and more resistant to
corrosion than
aluminium
LEAD
-Solder (PbSn)
Alloy is used in
joining metals
(soldering)
Lead is used in
underground cables
plates in
The alloy has a lower
melting point than
lead and is harder
than lead
18
Alloy Use Properties
accumulators shield
against x ndash rays
IRON
- Stainless Steel
(FeCONiC)
-Tungsten steel
(FeWC)
-Invar steel (FeNi)
Manganese steel
(FeMnC)
Iron is the main metal
of a variety of
constructions
Steel is used in
cutlery rock drills
electromagnets
vehicle body and
engine parts fences
pipes etc
Steel resists
corrosion is usually
harder than iron and
may be tough though
malleable and ductile
19
WEEK 6 LESSON 3 Worksheet
(a) Define the term alloy
______________________________________________________________________________
(b) State 3 general advantages that alloys have over the individual metals they are made
from
______________________________________________________________________________
______________________________________________________________________________
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
______________________________________________________________________________
______________________________________________________________________________
Uses
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 7 LESSON 1
TOPIC Corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
Familiar examples of corrosion are
- the formation of a green powder on copper sheeting
- the eating away of iron (rusting)
- the development by aluminum of a thin compact layer of oxide which protects the
underlying metal from further corrosion
When corrosion occurs in water ndash free environment it is called dry oxidation When it occurs in
aerated aqueous environments it is called wet corrosion Wet corrosion is the most common and
troublesome form of corrosion
The most familiar corrosion is the rusting of iron and steel On exposure to the atmosphere iron
and steel corrode to form rust which is hydrated iron (III) oxide Fe2O3xH2O Iron and steel
corrode easily and the rust formed flakes off easily thus exposing fresh surface for attack
When iron rust it loses electrons
Fe (s) ndash 2e- Fe 2+ (aq)
The iron (II) ions pass into solution and then combine with the hydroxyl (OH-) ions in the
aerated aqueous environment to form iron (II) hydroxide The oxygen present oxidises the iron
(II) hydroxide to hydrated iron (III) oxide or rust
Fe(OH)2 + O2 Fe2O3xH2O
21
Methods of preventing rusting
1 Coating the object with paint grease plastic or rubber which prevent contact with air or
water
2 Galvanising ndash coating the object with zinc The zinc forms an adherent oxide layer which
protects against further corrosion If damaged the zinc is oxidized in preference to the
iron since it is higher in the electrochemical series
3 Coating with tin lsquoTinrsquo cans are made of steel plated with tin However if scratched
rusting occurs since iron is more reactive than tin
4 Attaching a sacrificial anode to the object A piece of metal higher in the electrochemical
series such as magnesium is attached The magnesium will be oxidized in preference
since it is higher in the electrochemical series than iron
22
WEEK 7 LESSON 1 WORKSHEET
(a) Define the term corrosion
______________________________________________________________________________
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
23
WEEK 7 LESSON 2
TOPIC Importance of metals and their compounds on living systems and environment
Some metals are an integral part of different structures of living things
Metal Presence and Function
Potassium Main cation in fluid or animal cells essential for healthy plant growth
Calcium Necessary for strong bones teeth and shells needed by some enzymes Present
in dairy produce eggs nuts and cereals
Magnesium Central atom of chlorophyll needed for some enzyme action Involved in energy
and calcium metabolism
Zinc Present in many enzymes Needed for protein metabolism Essential for growth
of animals
Iron Present in haemoglobin Needed for protein metabolism Essential for growth of
animals
Chromium Needed for glucose uptake by cells and thus linked to the action of insulin
Manganese Needed for bone development and amino acid metabolism Present in several
enzymes Needed for plant growth
Cobalt Present in Vitamin B12 Needed for plant growth
Copper Involved in formation of haemoglobin and melanin Present in enzymes
controlling oxidation Needed for plant growth
24
Harmful effects of metals and their compounds to living systems and the environment
There are some metals and metal compounds which may cause harm to living systems and the
environment
Lead
Lead is a heavy metal poison that is widely encountered It may occur in food beverages paint
water formed from ndash sealed pipes in air polluted by combustion by fuels containing lead
compounds Lead is also used in some car batteries If these are paints or batteries are not
disposed of correctly lead may get into groundwater or air Lead and lead compounds harm the
nervous system including the brain especially young children
Arsenic
Arsenic compounds are poisonous They can get into the groundwater from mining waste and
from disposal of some electrical components
Cadmium
Cadmium compounds are poisonous They can get into the ground by improper disposal of
nickel ndash cadmium batteries Persons can get cadmium poisoning if they eat food grown in
contaminated soil
Mercury
Mercury can be spilled from broken thermometers in hospitals and laboratories Mercury and its
compounds are particularly poisonous to fish and it can accumulate in the food chain and
eventually poison humans
Problems of disposal of solid waste
Metals may react with water andor air and corrode to form soluble compounds that are
poisonous These toxic compounds diffuse into the soil and eventually enter rivers
Rust from iron may form unsightly pools of waste that reduce plant growth
Waste from aluminium extraction may react with water and form flammable gases
25
WEEK 7 LESSON 2 WORKSHEET
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Lead
______________________________________________________________________________
Mercury
______________________________________________________________________________
26
WEEK 7 LESSON 3
TOPIC Chemical properties of non ndash metals
Reaction with oxygen
Many non ndash metals burn in excess oxygen or air to form oxides For example
S (s) + O2 (g) SO2 (g)
C (s) + O2 (g) CO2 (g)
Reactions with metals
Some non ndash metals react with metals high in the electrochemical series when heated
For example
Sodium burns in chlorine to form sodium chloride
Na (s) + Cl2 (g) NaCl (s)
Magnesium burns in oxygen to form magnesium oxide
Mg (s) + O2 (g) MgO (s)
When heated iron combines with molten sulphur to form iron (II) sulphide
Fe (s) + S (l) FeS (s)
When heated reactive metals such as sodium and aluminium react with hydrogen to form metal
hydrides
2 Na (s) + H2 (g) 2 NaH (s)
Oxidising and Reducing properties
Hydrogen and Carbon are very good reducing agents
At high temperatures hydrogen reduces metal oxides below zinc in the electrochemical series to
form the metal For example PbO (s) + H2 (g) Pb (s) + H2O (g)
Under suitable conditions hydrogen reduces nitrogen to ammonia
N2(g) + 3 H2 (g) 2 NH3 (g)
27
At high temperatures carbon reduces metal oxides below aluminium in the reactivity series to
the metal For example
ZnO (s) + C (s) Zn (s) + CO (g)
Oxygen and Chlorine are very good oxidizing agents
Oxygen oxidized most metals to form metal oxides and some non ndash metals to non ndash metal oxides
For example
2 Mg (s) + O2(g) 2 MgO (s)
4 P (s) + 5 O2 (g) P4O10 (s)
Chlorine acts as an oxidizing agent either as a gas or as an aqueous solution For example
H2 (g) + Cl2 (g) 2 HCl (g)
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
28
WEEK 7 LESSON 3 WORKSHEET
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
______________________________________________________________________________
(b) Write the ionic equation for the above reaction
______________________________________________________________________________
(c) Identify the oxidising agent in the reaction
______________________________________________________________________________
(d) Justify your answer in part (c) in terms of oxidation number
______________________________________________________________________________
29
WEEK 8 LESSON 1
TOPIC Laboratory preparation of gases
Preparation of oxygen
Oxygen can be prepared by the decomposition of hydrogen peroxide potassium chlorate (V) or
potassium nitrate The safest method is the decomposition of hydrogen peroxide
Manganese (IV) oxide catalyses the decomposition of hydrogen peroxide
Silica gel anhydrous calcium chloride or concentrated sulphuric acid can be used as a drying
agent
The gas is collected by downward delivery since it is slightly denser than air
Equation
2 H2O2 (aq) 2 H2O (l) + O2 (g)
Apparatus used for laboratory preparation of oxygen
30
WEEK 8 LESSON 1 WORKSHEET
Describe the laboratory preparation of oxygen gas
In your answer include
The starting material
A suitable catalyst
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
31
WEEK 8 LESSON 2
TOPIC Laboratory preparation of gases
Preparation of carbon dioxide
Carbon dioxide can be prepared by the action of dilute acid on carbonates Marble chips (calcium
carbonate) and dilute hydrochloric acid are the common reagents The gas is collected by
downward delivery since it is denser than air
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
Apparatus used for laboratory preparation of carbon dioxide
32
WEEK 8 LESSON 2 WORKSHEET
Describe the laboratory preparation of carbon dioxide gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
33
WEEK 8 LESSON 3
TOPIC Laboratory preparation of gases
Preparation of ammonia
Ammonia may be prepared by heating a mixture of ammonium salt and a hydroxide The
ammonia gas is collected by upward delivery since it is less dense than air
For example
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
Calcium oxide is the only suitable drying agent since ammonia reacts with conc H2SO4 and
CaCl2
Apparatus used for laboratory preparation of dry ammonia
34
11
WEEK 8 LESSON 3 WORKSHEET
Describe the laboratory preparation of ammonia gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
35
WEEK 9 LESSON 1
TOPIC Uses of gases
Carbon dioxide
Used in fire extinguishers to put out fires Carbon dioxide is denser than air and lsquoblanketsrsquo the
fire preventing oxygen from reaching it Carbon dioxide extinguishers are especially useful for
dealing with fires involving flammable liquids and electrical equipment
Carbonation in soda is created when carbon dioxide is pumped into the soda can or bottle then
held under pressure As long as the can or bottle is sealed the carbon dioxide remains mostly
stable However if the drink gets shaken up or the top is opened the tiny carbon dioxide bubbles
react by bursting
Oxygen
Oxygen is needed for aerobic respiration We need a constant supply of oxygen for this process
Oxygen is used in hospitals to improve the respiration of patients with poor blood flow blood
poisoning and heart disease
Oxygen in used in welding (joining) metals In an oxyacetylene welding torch acetylene or
ethyne (C2H2) burns in oxygen and produces a very hot flame This flame is capable of melting
most metals
Oxygen is used in steel production A blast of oxygen is blown through the molten iron The
oxygen oxidises many of the impurities of the iron and the impurities are then removed
36
WEEK 9 LESSON 1 WORKSHEET
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Put out fires
Welding metals
Create lsquofizzrsquo in drinks
Used in steel production
Aerobic respiration
37
WEEK 9 LESSON 2
TOPIC Uses of non ndash metals and their compounds
Carbon (allotrophes carbon dioxide)
Carbon is used as a reducing agent in extraction of some metals
Carbon as graphite is used as electrodes lubricants and lsquoleadrsquo for pencils
Carbon in the form of diamond is used for jewellery (because of its lustre) and in drill tips for
high ndash speed drills (because of its hardness)
Carbon dioxide is used as refrigerant (as dry ice) for carbonated beverages
Sodium hydrogen carbonate and sodium carbonate are used for water softening and raising
agent
Sulphur
Sulphur is used in the manufacture of sulphuric acid Sulphur is also used in the manufacture of
tyres to make the rubber harder (vulcanisation)
Sulphur powder is used as fungicide on plant materials
Phosphorus
Phosphorus is used in the manufacture of fertilizers
Phosphorus is used to make phosphor bronze alloys
Phosphorus sulphide is used to make the heads of lsquostrike anywherersquo matches
38
Chlorine
Chlorine is used to make sodium hypochlorite which is present in bleach It is also used in
sterilizing swimming pools and in water treatment
Chlorine is used to make the monomer vinyl chloride which is used to make the plastic PVC
Nitrogen
Nitrogen is used to make fertilisers ammonia dyes and nitric acid
Nitrogen is used as an inert atmosphere to prevent substances being oxidised and as a coolant
Silicon
Silicon is used for making silicon chips for computers
Silicon (V) oxide is present in sand Glass is made by heating sand with lime (calcium oxide) and
sodium carbonate
Silicon in the form of silicates is used in jewellery
Silica gel is used as a drying agent
39
WEEK 9 LESSON 2 WORKSHEET
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Used to make sodium hypochlorite
Used as a fungicide on plant materials
Used for lsquoleadrsquo in pencils
Used in the manufacture of bronze alloys
Used in the manufacture of nitric acid
Used in the manufacture of computer chips
Used to make fertilisers
40
WEEK 9 LESSON 3
TOPIC Harmful effects of non ndash metals and their compounds on living systems and the
environment
Sulphur dioxide
Sulphur dioxide can cause a disease of the lungs Sulphur dioxide also poisons plants in two
main ways It may enter the stomata of leaves and react with the tissue fluids to form sulphites
with the on ndash going water loss the concentration of sulphites could build up killing the cells
The second adverse effect on plants occurs when sulphur dioxide dissolves in rain thereby
increasing soil acidity A prolonged acid soil situation may lead to plasmolysis and the death of
vegetation in an area
Carbon monoxide
Carbon monoxide combines much more readily than oxygen with haemoglobin When carbon
monoxide is inhaled it prevents the haemoglobin from taking oxygen to the bodyrsquos cells
Continued breathing of air containing carbon monoxide eventually causes death
Hydrogen sulphide
Hydrogen sulphide reacts readily with many cations forming insoluble sulphides Many cations
contribute to good health by contributing to enzyme activity and to the formation of bone
pigment and haemoglobin Although these cations are required in extremely small
concentrations they are removed by being precipitated as sulphides and thus not available for
regular function Careless dumping of refuse contributes to atmospheric pollution by hydrogen
sulphide
Oxides of nitrogen
In the presence of hydrocarbons from car exhausts ozone and sunlight nitrogen oxides react to
form photochemical smog which contains many harmful chemicals
Nitrogen dioxide can harm the lungs and irritate the nose throat and eyes The other compounds
present in photochemical smog are even more harmful irritants and can cause asthma
41
Carbon dioxide
Carbon dioxide water vapour and ozone referred to as ldquogreenhouse gasesrdquo acting as a blanket
readily absorb some of the radiated heat energy and in turn warms the earthrsquos atmosphere This is
called the ldquogreenhouse effectrdquo Scientists have found direct correlation between carbon dioxide
concentration and global warming An increase in carbon dioxide concentration resulted in an
increase global temperatures Global warming is a major potential problem that the world faces
Chloroflourocarbons (CFCs)
It is believed that CFCs might be responsible for destroying the ozone layer which prevents
harmful ultraviolet (UV) radiation from reaching the earth The carbon ndash chlorine bond in CFC
molecule is easily broken by a UV photon producing an active chlorine atom This atom
combines with an ozone molecule forming a chlorine oxide radical and oxygen The radicle
reacts with more ozone producing the chlorine atom again This kind of reaction is repeated
thousands of times This type of reaction is thought to account for about eighty percent of the
loss of ozone observed
Nitrates and phospates
Nitrates and phosphates cause eutrophication The process leading to eutrophication are
Nitrates and phosphates from fertilisers spread on fields may dissolve in groundwater and
get into lakes and rivers
Nitrates and phosphates cause excessive growth of algae so that they cover the surface of
the water
Water plants including algae die because of lack of sunlight Aerobic bacteria feed on
the plant remains The bacteria multiply
The aerobic bacteria use up the oxygen in the water so aquatic animals die
42
Solid waste
The main sources of pollution from non ndash metals is from glass paper and plastics
Broken glass can cause injury to animals It can also cause fires by acting as lens focusing the
sunrsquos rays on flammable materials
Printing inks from paper dumped in the ground may contain toxic elements such as arsenic and
cadmium Bleaches and chlorine compounds from paper are also harmful
43
WEEK 9 LESSON 3 WORKSHEET
Describe ONE harmful effect of the following non ndash metals andor their compounds on
living systems and the environment
Sulphur dioxide
______________________________________________________________________________
______________________________________________________________________________
Carbon monoxide
______________________________________________________________________________
______________________________________________________________________________
Carbon dioxide
______________________________________________________________________________
______________________________________________________________________________
Oxides of nitrogen
______________________________________________________________________________
______________________________________________________________________________
Hydrogen sulphide
______________________________________________________________________________
______________________________________________________________________________
44
Chloroflourocarbons (CFCs)
______________________________________________________________________________
______________________________________________________________________________
Nitrates and phospates
______________________________________________________________________________
______________________________________________________________________________
45
WEEK 10 LESSON 1
TOPIC Green Chemistry
Green Chemistry is defined as the utilisation of a set of principles that reduces or eliminates the
use and generation of hazardous substances
There are twelve principles of green chemistry as proposed by Paul T Anastas and John C
Warner These twelve principles are
1 Prevention ndash It is better to prevent waste than to treat or clean up waste after it has been
created
2 Atom economy - Synthetic methods should be designed to maximize the incorporation of
all materials used in the process into the final product
3 Less hazardous chemical synthesis - Wherever practicable synthetic methods should be
designed to use and generate substances that possess little or no toxicity to human health
and the environment
4 Safer chemical products - Chemical products should be designed to affect their desired
function while minimizing their toxicity
5 Safer solvents and other agents - The use of auxiliary substances (eg solvents
separation agents etc) should be made unnecessary wherever possible and harmless
when used
6 Minimum energy requirements - Energy requirements of chemical processes should be
recognized for their environmental and economic impacts and should be minimized If
possible synthetic methods should be conducted at ambient temperature and pressure
7 Use of renewable raw materials - A raw material or feedstock should be renewable rather
than depleting whenever technically and economically practicable
8 Reduce use of additional chemicals or additional steps - Unnecessary derivatization (use
of blocking groups protection deprotection temporary modification of
physicalchemical processes) should be minimized or avoided if possible because such
steps require additional reagents and can generate waste
46
9 Use of catalysts ndash The use of catalysts reduce energy costs because the reactions take
place at lower temperatures The more specific the catalyst for a particular reaction is the
less it the likelihood of getting additional unwanted products
10 Nature of breakdown of products - Chemical products should be designed so that at the
end of their function they break down into innocuous degradation products and do not
persist in the environment
11 Monitoring to prevent pollution - Analytical methodologies need to be further developed
to allow for real-time in-process monitoring and control prior to the formation of
hazardous substances
12 Minimise chemical accidents - Substances and the form of a substance used in a chemical
process should be chosen to minimize the potential for chemical accidents including
releases explosions and fires
47
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
48
WEEK 10 LESSON 2
TOPIC Qualitative Analysis ndash Identification of cations
Qualitative Analysis involves identifying the constituents of single substances or mixture of
substances
Appearance
An examination of the appearance of a substance can indicate which ion it contains
Appearances of substances
Observation Indication
Blue or blue ndash green Cu2+ salt
Pale green Fe2+ salt
Yellow ndash brown Fe3+ salt
Ammonia smell NH4+ salt
49
Test for cation using sodium hydroxide
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
(d) If no precipitate forms in step b warm gently and test for ammonia
Effect of dilute sodium hydroxide solution
Effect of dilute sodium hydroxide solution Cation
Dropwise Excess
White precipitate Precipitate soluble Ca2+
White precipitate Precipitate insoluble Al3+ Pb2+ Zn2+
Blue precipitate Precipitate insoluble Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
No precipitate ndash ammonia gas
evolved on heating
ndash NH4+
The metal cations all form insoluble hydroxides with sodium hydroxide solution
For example Ca2+ (aq) + 2 OH- (aq) Ca(OH)2 (s)
Ca(OH)2 Cu(OH)2 Fe(OH)2 and Fe(OH)3 are basic and therefore do not react with excess
sodium hydroxide solution Therefore the precipitate does not dissolve in excess sodium
hydroxide solution
Al(OH)3 Pb(OH)2 and Zn(OH)2 are amphoteric Therefore the precipitates react with the excess
sodium hydroxide solution forming soluble salts and the precipitate disappears in excess sodium
hydroxide solution
The NH4+ ion forms a soluble hydroxide However on heating it reacts with the hydroxide ion to
form ammonia and water
NH4+ (aq) + OH- (aq) NH3 (g) + H2O (l)
50
WEEK 10 LESSON 2 WORKSHEET
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P _____________ Q ___________________
R _____________ S ___________________
R + NaOH
______________________________________________________________________________
51
WEEK 10 LESSON 3
TOPIC Qualitative Analysis ndash Identification of cations
Test for cation using ammonia solution (ammonium hydroxide solution)
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
Effect of dilute ammonia (ammonium hydroxide) solution
Effect of dilute ammonia solution Cation
Dropwise Excess
No precipitate ndash Ca2+
White precipitate Precipitate soluble
(forming colourless solution)
Zn2+
White precipitate Precipitate insoluble Al3+ Pb2+
Blue precipitate Precipitate soluble
(forming deep blue solution)
Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
52
Ammonia solution is a weak alkali Metal cations except Ca2+ form insoluble hydroxides with
ammonia solution as with the sodium hydroxide solution
The amphoteric hydroxides Al(OH)3 and Pb(OH)2 and the basic hydroxides Fe(OH)2 and
Fe(OH)3 do not react with excess ammonia solution Therefore the precipitates remain
However Zn(OH)2 and Cu(OH)2 do react with excess ammonia solution to form complex
soluble hydroxides each Hence their precipitates disappear on the addition of excess ammonia
solution
Confirmatory test
After carrying out test for cations using sodium hydroxide solution and ammonia solution the
only cations which cannot be distinguished are Al3+ and Pb2+ A confirmatory test is carried out
to distinguish between the two cations
Confirmatory test
Test Observation Cation Ionic equation
Add potassium
or sodium
iodide solution
Bright yellow precipitate
No precipitate
Pb2+
Al3+
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
53
WEEK 10 LESSON 3 WORKSHEET
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A __________ B ________________ C ________________________
(b) State the inference after Test 2
C _______________________
(c) Write an ionic equation to support your answer in (b) above
___________________________________________________________________________
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
54
ANSWERS TO WORKSHEETS
55
WEEK 5 LESSON 1 WORKSHEET ANSWERS
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
Answer
Zinc + Iron (II) sulphate Zinc is higher in the electrochemical series and therefore displace
iron ions in iron (II) sulphate
Equation Zn (s) + FeSO4 (aq) ZnSO4 (aq) + Fe (s)
Ionic equation Zn (s) + Fe2+ (aq) Zn2+ (aq) + Fe (s)
Iron + Zinc sulphate No reaction iron is lower in the electrochemical series and cannot
displace the zinc ions in zinc sulphate
56
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
Answer
X displaces lead from an aqueous solution of its salts
X (s) + Pb2+ (aq) Xn+ (aq) + Pb (s)
rarr X is more reactive than Pb
X did not react with iron salts
rarr X is less reactive than Fe
Y burns very easily
Y is more reactive than Fe and Pb (both forming their corresponding oxide at a slower rate)
From electrochemical series Fe is higher and therefore more reactive than Pb
Order of reactivity
Y (most reactive) gt Fe gt X gt Pb (least reactive)
57
WEEK 5 LESSON 2 WORKSHEET ANSWERS
1
Metal Reactivity with acid
Copper X
Magnesium
Aluminium
Silver X
Zinc
58
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
Answer
Y and Z are the most reactive since they can react with dilute acid
Z is more reactive than Y since a reaction occurs with Z is added to an aqueous solution of Y
X is less reactive than W since it does not occur in nature as compounds
Order of reactivity Z (most reactive) gt Y gt W gt X
59
WEEK 5 LESSON 3 WORKSHEET ANSWERS
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
Answer
Ease of decomposition (from easiest to decompose to most difficult to decompose)
B rarrD rarrArarr C
Reactivity (most reactive to least reactive)
C (most reactive) gt A gt D gt B (least reactive)
60
WEEK 6 LESSON 1 Worksheet Answers
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
Potassium Zinc Copper
Calcium Lead Gold
Magnesium Iron
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
Aluminium is extracted from its ore bauxite through the process of electrolysis
Cryolite is added to bauxite to lower the melting point to about 900 0C The melting point of
bauxite is very high (about 2040 0C) It is difficult and expensive to keep the molten aluminium
oxide at this temperature
Reaction at the cathode Al3+ (l) + 3 e- Al (l)
61
WEEK 6 LESSON 2 Worksheet Answers
(a) What are the three raw materials that are added through the top of the blast
furnace during the extraction process for iron
Coke (carbon)
iron ore (haematitie mainly iron (II) oxide)
limestone (calcium carbonate)
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
Coke ndash coke burns to produce carbon dioxide The carbon dioxide further reacts with coke to
form carbon monoxide (reducing agent in the process)
C (s) + O2 (g) CO2 (g)
C (s) + CO2 (g) 2 CO
Haematite ndash iron ore provides the iron which is reduced by the carbon monoxide to produce
iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + CO2 (g)
Limestone ndash decomposes to form calcium oxide The calcium oxide reacts with the impurity
silicon dioxide to form slag (calcium silicate)
CaCO3 (s) CaO (s) + CO2 (g)
CaO (s) + SiO2 (l) CaSiO3(l)
62
WEEK 6 LESSON 3 Worksheet Answers
(a) Define the term alloy
An alloy is a material made from a mixture of two or more metals
(b) State 3 general advantages that alloys have over the individual metals they are made
from
They are harder stronger and more resistant to corrosion
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
1 High strength
2 Low density
Uses
1 Used to make aircraft bodies
2 Used to make space satellites
63
WEEK 7 LESSON 1 WORKSHEET ANSWERS
(a) Define the term corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
The paint forms a barrier which stops contact with air or water and the iron Hence rusting
will not take place
However when the paint is scratched that part of the iron nail is exposed to air or water and
rusting will take place
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
Magnesium is higher in the electrochemical series and will be oxidised in preference to iron
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
Aluminium is partly protected from corrosion by its coat of aluminium oxide However as the
iron rust it flakes and fall off and the rusting process continues
64
WEEK 7 LESSON 2 WORKSHEET ANSWERS
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
Magnesium is the ion found in chlorophyll Chlorophyll plays a vital part in the process of
photosynthesis A deficiency in magnesium will lead to low chlorophyll level in the tomato
plants and hence reduce the process of photosynthesis There will be less food storage and
hence will lead to smaller yield of tomatoes
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Any correct harmful effect of lead on health or environment
Any correct harmful effect of mercury on health or environment
65
WEEK 7 LESSON 3 WORKSHEET ANSWERS
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
(b) Write the ionic equation for the above reaction
2 Br- (aq) + Cl2 (aq) 2 Cl- (aq) + Br2 (aq)
(c) Identify the oxidising agent in the reaction
Cl2 (aq)
(d) Justify your answer in part (c) in terms of oxidation number
There is a reduction of the oxidation number for chlorine from 0 to ndash1
hence it has been reduced Therefore chlorine is the oxidising agent
66
WEEK 8 LESSON 1 WORKSHEET ANSWERS
Describe the laboratory preparation of oxygen gas
Oxygen is prepared in the laboratory by the decomposition of hydrogen peroxide
A suitable catalyst is manganese (IV) oxide
Drying agent silica gel OR anhydrous calcium chloride OR conc sulphuric acid
The gas is collected by downward delivery since oxygen is slightly denser than air
Balanced chemical equation 2 H2O2 (aq) 2 H2O (l) + O2 (g)
67
WEEK 8 LESSON 2 WORKSHEET ANSWERS
Describe the laboratory preparation of carbon dioxide gas
Carbon dioxide is commonly prepared in the laboratory by the reacting hydrochloric acid and
marble chips (calcium carbonate)
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
The carbon dioxide gas is collected by downward delivery since it is denser than air
Balanced chemical equation
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
68
WEEK 8 LESSON 3 WORKSHEET ANSWERS
Describe the laboratory preparation of ammonia gas
An ammonium salt (ammonium chloride) and a base (sodium hydroxide) are mixed together and
heated
Calcium oxide is used as the drying agent Calcium chloride and concentrated sulphuric acid
cannot be used since ammonia can react with them
The gas is collected by upward delivery since ammonia is less dense than air
Balanced chemical equation
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
69
WEEK 9 LESSON 1 WORKSHEET ANSWERS
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Carbon dioxide Put out fires
Oxygen Welding metals
Carbon dioxide Create lsquofizzrsquo in drinks
Oxygen Used in steel production
Oxygen Aerobic respiration
70
WEEK 9 LESSON 2 WORKSHEET ANSWERS
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Chlorine Used to make sodium hypochlorite
Sulphur Used as a fungicide on plant materials
Carbon (graphite) Used for lsquoleadrsquo in pencils
Phosphorus Used in the manufacture of bronze alloys
Nitrogen Used in the manufacture of nitric acid
Silicon Used in the manufacture of computer chips
Nitrogen Phosphorus Used to make fertilisers
71
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
Green Chemistry is using principles that reduceeliminate the use of hazardous materials in
the design manufacture and application of chemical products
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
Makes the environment safer
Reduces waste
Creates new jobs
Reduces respiratory illnesses
Atom economy
72
WEEK 10 LESSON 2 WORKSHEET ANSWERS
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P Cu2+ Q Fe2+
R Fe3+ S Ca2+
Ionic equation for R + NaOH
Fe3+ (aq) + 3 OH- (aq) Fe(OH)3 (s)
73
WEEK 10 LESSON 3 WORKSHEET ANSWERS
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A Fe3+ B Ca2+ C Al3+ Pb2+
(b) State the inference after Test 2
C Pb2+
(c) Write an ionic equation to support your answer in (b) above
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
11 Qualitative Analysis
ndash Test for gases
Qualitative Analysis
ndash Identification of
anions
Qualitative Analysis
ndash Identification of
anions
12 Problem solving of
Past CSEC Chemistry Paper 2
on topics completed in the term
13
14
15
2
WEEK 11 LESSON 1
TOPIC Qualitative Analysis ndash Test for gases
Identification of gases
Gas Colour Odour Effect on moist
litmus
Method of identification
Oxygen
O2
Colourless Odourless Neutral ndash no
effect
Relights a glowing splint
Hydrogen
H2
Colourless Odourless Neutral ndash no
effect
Lighted splint lsquopopsrsquo if air is also
present
Carbon
dioxide
CO2
Colourless Odourless Weakly acidic ndash
blue to slightly
red
A white precipitate forms in
limewater
Ca(OH)2 (aq) + CO2
CaCO3 (s) + H2O (l)
Precipitate redissolves on
continued bubbling
CaCO3 (s) + H2O (l) + CO2 (g)
Ca(HCO3)2 (aq)
Ammonia
NH3
Colourless Pungent Alkaline ndash red
to blue (only
common
alkaline gas)
Turns moist red litmus blue forms
dense white fumes with hydrogen
chloride gas
NH3 (g) + HCl (g) NH4Cl (s)
Gas Colour Odour Effect on moist
litmus
Method of identification
3
Sulphur
dioxide
SO2
Colourless Choking
smell
Acidic ndash blue to
red
Turns acidified potassium
manganate (VII) solution from
purple to colourless
Turns acidified potassium
dichromate (VI) solution from
orange to green
Chlorine
Cl2
Yellow ndash
green
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Bromine
Br2
Red ndash
brown
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Nitrogen
dioxide
NO2
Red ndash
brown
Irritating
smell
Acidic blue to
red
Turns moist blue litmus red but
does not bleach it
Water
vapour
H2O
Colourless Odourless Neutral ndash no
effect
Turns anhydrous cobalt (II)
chloride from blue to pink
Turns anhydrous copper (II)
sulphate from white to blue
4
WEEK 11 LESSON 1 WORKSHEET
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless
Yellow ndash green
Red ndash brown
Gases according to their odour
Odour of gas Identity of gas
Odourless
Pungent smell
Choking smell
Irritating smell
5
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect
Red to blue
Blue to red
Blue to red then bleaches it
6
WEEK 11 LESSON 2
TOPIC Qualitative Analysis ndash Identification of anions
Effect of heating
Method Heat a sample of the solid in a dry test tube
Effect of heating
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) not
of K or Na
CO32- (s) O2- (s) + CO2 (g)
Oxygen evolved NO3- of K or Na 2 NO3
- (s) 2 NO2- (s) + O2
(g)
Oxygen and nitrogen
dioxide evolved
NO3- of Ca and below
in reactivity series
4 NO3- (s) 2 O2- (s) + 4 NO2
(g) + O2
(g)
Sulphur dioxide evolved SO32- SO3
2- O2- (s) + SO2 (g)
Effect of dilute acid
Add dilute hydrochloric acid or nitric acid to a sample of the solid Warm if no reaction occurs
when cold
Effect of dilute acid
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) CO32- (s) + 2 H+ (aq) H2O (l) + CO2 (g)
Sulphur dioxide evolved SO32- SO3
2- (s) + 2 H+ (aq) H2O (l) + SO2 (g)
7
Effect of concentrated acid
Add concentrated sulphuric acid to a sample of the solid Warm if not reaction occurs when cold
Effect of concentrated sulphuric acid
Observation Anion
Carbon dioxide evolved CO32- or HCO3
-
Sulphur dioxide evolved SO3-
Hydrogen chloride evolved Cl-
Hydrogen bromide (colourless) and bromine
vapour (brown) evolved
Br-
Black iodine present and purple iodine vapour
evolved
I-
8
WEEK 11 LESSON 2 WORKSHEET
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater
Produces a gas which relights a glowing splint as the only gas
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green
Produces a gas forms a precipitate in limewater
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia
Black iodine present and purple iodine vapour evolved
9
WEEK 11 LESSON 3
TOPIC Qualitative Analysis ndash Identification of anions
Test for the halides ndash using silver nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous silver nitrate and
observe the precipitate Add ammonia solution and observe the solubility of the precipitate
Test for halides using silver nitrate solution
Effect of silver
nitrate solution
Anion Explanation Effect of aqueous
ammonia
White precipitate ndash
turns white in
sunlight
Cl- Ag+ (aq) + Cl- AgCl (s) Precipitate soluble
Cream precipitate ndash
turns yellow ndash green
in sunlight
Br- Ag+ (aq) + Br- AgBr (s) Precipitate slightly
soluble
Pale yellow
precipitate
I- Ag+ (aq) + I- AgI (s) Precipitate insoluble
Test for the halides ndash using lead nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous lead nitrate and
observe the precipitate
Test for halides using lead nitrate solution
Effect of lead nitrate solution Anion Explanation
White precipitate Cl- Pb2+ (aq) + 2 Cl- PbCl2 (s)
Pale yellow Br- Pb2+ (aq) + 2 Br- PbBr2 (s)
Deep yellow I- Pb2+ (aq) + 2 I- PbI2 (s)
10
Effect of barium nitrate or chloride solution followed by dilute acid
Make a solution of the solid Add barium nitrate or chloride solution and observe the precipitate
Add dilute hydrochloric or nitric acid warn if necessary and observe the solubility of the
precipitate
Effect of barium nitrate or chloride solution followed by dilute acid
Effect of
Ba(NO3)2 (aq)
or BaCl2 (aq)
Effect of HCl (aq)
or HNO3 (aq)
Anion Explanation
White precipitate Precipitate insoluble SO42- Ba2+ (aq) + SO4
2- (aq) BaSO4 (s)
BaSO4 does not react with dilute acids
White precipitate Precipitate soluble ndash
CO2 evolved
CO32- Ba2+ (aq) + CO3
2- (aq) BaCO3 (s)
BaCO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + CO2 (g)
White precipitate Precipitate soluble ndash
SO2 evolved on
warming
SO32- Ba2+ (aq) + SO3
2- (aq) BaSO3 (s)
BaSO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + SO2 (g)
11
WEEK 11 LESSON 3 WORKSHEET
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
(Ionic equation required)
12
WEEK 12 LESSON 1 WORKSHEET
(a) The Caribbean islands are known for their many resources For example the ore of
aluminium is found in Jamaica and Guyana
(i) Briefly describe the extraction of aluminium from its named ore Include in your
description one ionic equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Although aluminium ore is mined in the Caribbean the extraction of aluminium usually
takes place in other countries Suggest ONE reason why it may be difficult to extract
aluminium in the Caribbean
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) An alloy can be described as a lsquomixed metal solutionrsquo Aluminium forms an alloy with
magnesium that is used to make an aircraft
13
Identify this alloy and suggest why it is better to use it rather than the pure metal in the
manufacture of aircraft
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) ldquoSome metals can be useful to man yet harmful to the environmentrdquo Comment on this
statement with reference to mercury
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 12 LESSON 2 Worksheet
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate formed
Soluble in excess
15
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate formed
Insoluble in excess
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate formed
(Ionic equation required)
16
WEEK 12 LESSON 3 Worksheet
Dry ammonia gas can be produced in a school laboratory
(a) Identify TWO reagents that are necessary for the laboratory production of ammonia
______________________________________________________________________________
______________________________________________________________________________
(b) Two common drying agents used in the laboratory are calcium oxide and concentrated
sulphuric acid However calcium oxide is the preferred choice for drying ammonia gas
Explain why concentrated sulphuric acid is now used Include in your answer a balanced
chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) When gases are prepared in the laboratory there are three main ways in which they can
be collected
- Upward delivery
- Downward delivery
- Displacement of water
(i) What TWO other factors should be considered when choosing an appropriate method for
the collection of gases in the laboratory
______________________________________________________________________________
______________________________________________________________________________
(ii) Identify ONE of the three methods that is best suited for the collection of ammonia gas in
the laboratory Explain why EACH of the other two methods would NOT have been
appropriate
______________________________________________________________________________
17
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(d) Hence draw a labelled diagram of the apparatus which could be used for the preparation
of dry ammonia in the laboratory
Be sure to identify in your diagram
- where the reagents are placed
- where the ammonia is dried and
- where the ammonia is collected
18
WEEK 13 LESSON 1 Worksheet
(a) In solution two metals A and B form A+ and B2+ ions respectively Metal A displaces Fe
from a solution containing Fe2+ ions but metal B does NOT
(i) Arrange the metals A B and Fe in order of reactivity from LEAST reactive to MOST
reactive Write a balanced chemical equation to show the reaction between metal A and
Fe2+ ions
______________________________________________________________________________
______________________________________________________________________________
(ii) Metal A is placed in a solution of copper (II) sulphate CuSO4 (aq) Write an equation for
the reaction State ONE observable change that will occur and explain why this reaction
takes place
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) For EACH metal A and B state ONE method that can be used to extract it from its
respective oxide Give a reason for EACH answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
19
______________________________________________________________________________
(b) Metal alloys are often used for making objects found in our daily lives Name an alloy of
iron and state ONE of its uses
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 13 LESSON 2 Worksheet
(a) Many important biological processes in plants and animals depend on the specific roles
of certain metal ions
(i) Farmer Jones reaped a crop of tomatoes and reported that the yield was far below what
was expected Analysis of the soil revealed that there was a deficiency of magnesium
Discuss the importance of magnesium in plant health and explain how a magnesium
deficiency can result in the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE other metal ion which is important to plant health and state the result of its
deficiency
______________________________________________________________________________
______________________________________________________________________________
21
(b) Many years ago car exhaust fumes were known to contain compounds of metals and
non ndash metals which could negatively impact both humans and the environment Identify
ONE metal and ONE non ndash metal whose compounds were present in car exhaust fumes
Discuss the effect of these compounds on human health and the environment
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) Define lsquogreen chemistryrsquo and discuss the measures that have been taken to produce a
lsquogreenerrsquo automotive fuel
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
22
WEEK 13 LESSON 3 Worksheet
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
Zn2+ ions are present
23
WEEK 14 LESSON 1 Worksheet
(a) Metal alloys are often used in place of metals because of their enhanced properties
(i) Define the term lsquoalloyrsquo
______________________________________________________________________________
______________________________________________________________________________
(ii) Name ONE alloy of aluminium and state its use based on one of its enhanced properties
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) A student conducted an experiment to investigate the reactivity of each of the following
metals (copper iron zinc and lead) by using solutionPs of their sulphate salts
The data presented in the table below shows whether a visible chemical reaction took
place when each metal was added to the four sulphate solutions
Key Visible chemical reaction took place
X No visible chemical reaction
CHEMICAL REACTION OF METALS IN SULPHATE SOLUTIONS
Sulphate solution Cu Fe Zn Pb
CuSO4 X
FeSO4 X X X
ZnSO4 X X X X
PbSO4 X X
24
(i) State which of the TWO metals is more reaction Fe or Zn Give a reason for our answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Using the data in the previous Table deduce the order of reactivity of the four metals Cu
Fe Zn and Pb from the most reactive to the least reactive metal
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The student recorded the following observations from the reaction between the iron and
copper (II) sulphate solution
Observations Reddish ndash brown solid coating formed on the iron strip
Blue colour of the solution changed to dirty green
Account for the observations made from the reaction between the iron and copper (II)
sulphate solution
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iv) Write an ionic equation including state symbols for the reaction between the iron and
copper (II) sulphate solution
______________________________________________________________________________
25
(c) Some metal compounds are health and environmental hazards
(i) Identify which of the metals used in the experiment in (b) is MOST hazardous to the
environment
______________________________________________________________________________
______________________________________________________________________________
(ii) State TWO harmful effects of continuous exposure to the metal identified in (c) (i) on
human beings
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
26
WEEK 14 LESSON 2 Worksheet
(a) Carbon is found in the form of diamond and graphite and is a main component in many
naturally occurring compounds such as organic matter and carbon dioxide gas
(i) State ONE way in which diamond differs physically from graphite
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE similarity between diamond and graphite other than they both contain carbon
______________________________________________________________________________
______________________________________________________________________________
(b) Carbon can react with a limited supply of oxygen to form carbon monoxide which can
negatively affect human health
(i) Write a balanced chemical equation including state symbols to show the formation of
carbon monoxide
______________________________________________________________________________
(ii) State TWO effects of carbon monoxide inhalation on the human body
______________________________________________________________________________
______________________________________________________________________________
(c) Jamal wants to prepare and collect a sample of carbon dioxide gas in the laboratory using
calcium carbonate
(i) Write a balanced chemical equation including state symbols for the laboratory
preparation of carbon dioxide gas from calcium carbonate
______________________________________________________________________________
______________________________________________________________________________
(ii) Draw a clearly labelled diagram to show the arrangement of the apparatus and materials
that could be used in the laboratory to prepare and collect the carbon dioxide gas
(iii) State ONE use of carbon dioxide as it relates to the beverage industry
______________________________________________________________________________
27
WEEK 14 LESSON 3 Worksheet
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
(Ionic equation required)
Suggest a possible identity of the solid R __________________________
28
WEEK 15 LESSON 1 Worksheet
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a small
portion of solid Y gently at
first and then strongly
Colourless gas evolved
with a choking odour
Turns acidified potassium
dichromate solution from
orange to green
(ii) To the remaining portion
of solid Y add 20 cm3 of
distilled water stir to dissolve
and filter Collect the filtrate
and divide into 3 equal
portions
Filtrate is pale green in
colour
(iii) To the first portion of the
filtrate from (ii) add aqueous
sodium hydroxide slowly
until in excess
A green precipitate
Insoluble in excess sodium
hydroxide
Ionic equation required
29
TEST OBSERVATIONS INFERENCES
(iv) To the second portion of
the filtrate from (ii) add
aqueous silver nitrate
followed by aqueous
ammonia
White precipitate
Soluble in aqueous
ammonia
(v) To the third portion of the
filtrate from (ii) add aqueous
barium nitrate followed by
aqueous hydrochloric acid
White precipitate formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with the
evolution of a colourless
gas with a choking smell
30
WEEK 15 LESSON 2 Worksheet
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
31
WEEK 15 LESSON 3 Worksheet
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in excess
aqueous NH3
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change
32
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
warm filter and then divide
the filtrate into two portions
Vigorous effervescence
observed upon addition of
dilute HNO3
Gas evolved turns lime water
cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Cu2+ ions present
33
ANSWERS TO WORKSHEETS
34
WEEK 11 LESSON 1 WORKSHEET ANSWERS
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless O2 H2 CO2 NH3 SO2 H2O
Yellow ndash green Cl2
Red ndash brown Br2 NO2
Gases according to their odour
Odour of gas Identity of gas
Odourless O2 H2 CO2 H2O
Pungent smell NH3
Choking smell SO2 Cl2 Br2
Irritating smell NO2
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect Neutral O2 H2 H2O
Red to blue Alkaline NH3
Blue to red Acidic CO2 SO2 NO2
Blue to red then bleaches it Acidic Cl2 Br2
35
WEEK 11 LESSON 2 WORKSHEET ANSWERS
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-) not
of K or Na
Produces a gas which relights a glowing splint as the only gas NO3- of K or Na
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green SO32-
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-)
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia Cl-
Black iodine present and purple iodine vapour evolved I-
36
WEEK 11 LESSON 3 WORKSHEET ANSWERS
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Br-
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
Cl-
Ag+ (aq) + Cl- AgCl (s)
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow Br-
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
SO42-
Ba2+ (aq) + SO42- (aq)
BaSO4 (s)
(Ionic equation required)
37
WEEK 12 LESSON 1 Worksheet Answers
(a) (i)
The ore bauxite is purified
The purified bauxite is dissolved in molten cryolite
The aluminium oxidecryolite solution is then eletrolysed
Equation at the cathode Al3+ (l) + 3 e- Al (l)
Equation at the anode 2 O2- (l) ndash 4 e- O2 (g)
(ii) The process is too expensive mainly because too much electricity or energy is needed
(b) The alloy of Al and Mg is magnalium It is less dense than the pure metals and hence allow
aircraft to be lighter It is also stronger than the pure metals and hence allows aircraft to last
longer since it is not easily destroyed
(c) Your answer should cater for the following aspects
Benefits of mercury to humans for example in thermometers barometers in dentistry
and gold mining
Entry of mercury to the environment For example this could have been through broken
thermometers barometers or lightbulbs or improper disposal of them or batteries and
indiscriminate use in gold mining in Guyana
The identification of a negative impact on the environment such as poisoned fish and the
persons who eat the fish death mood swings and psychosis
38
WEEK 12 LESSON 2 Worksheet Answers
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas
evolved
NO2 evolved OR nitrates
present OR
Br2 gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate
formed
Soluble in excess
Pb2+ Zn2+ Al3+ or Ca2+
present
Pb2+ Zn2+ Al3+ or present
39
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate
formed
Insoluble in excess
Pb2+ Zn2+ Al3+ or present
Pb2+ or Al3+ present
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate
formed
Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
40
WEEK 12 LESSON 3 Worksheet Answers
(a) an ammonium salt and a strong alkali
(b) Ammonia is basic and it will react with H2SO4
Equation 2 NH3 (aq) + H2SO4 (aq) (NH4)2SO4 (aq)
(c) (i) ndash Density of the gas relative to air ndash The solubility of the gas in water
(ii) Ammonia is collected by upward delivery
It cannot be collected by downward delivery since ammonia is less dense than air
It cannot be collected by displacement of water since it is soluble in water
(d)
41
WEEK 13 LESSON 1 Worksheet Answer
a) i) B ˂ Fe ˂ A
2A (s) + Fe 2+ (aq) rarr 2A+ (aq) + Fe (s)
ii) 2A (s) + CuSO4 (aq) rarr A2SO4 (aq) + Cu (s)
Observation blue colour fades gets lighter OR brown solid forms is deposited OR metal A
decreases in size dissolves
Explanation Metal A is higher (than Fe which is higher) than Cu in the reactivity series OR
Metal A is more reactive (than Fe which is more reactive) than Cu so Metal A can displace Cu
iii) Metal A can be extracted by electrolysis (of its molten oxide) because Metal A is a very
reactive metal is high in the reactivity series forms stable oxides needs a lot of energy to be
extracted and very reactive metals are extracted by electrolysis
Metal B can be extracted by heating with carbon carbon monoxide OR by chemical reduction
of the oxide because Metal B is less reactive than Fe is low in the reactivity series forms less
stable oxides does not need a lot of energy to be extracted and oxides of less reactive metals are
easily reduced
b) Alloy of iron steel
Use of alloy making buildings bridges ships motor vehicles furniture utensils
42
WEEK 13 LESSON 2 Worksheet Answer
(a) (i)
Magensium is the metal ion found in chlorophyll
Chlorophyll is essential for photosynthesis
A deficiency in magnesium will result in low chlorophyll yellow leaves and a reduction in
photosynthesis
Hence there will be low carbohydrates or energy production
Hence small fruits stunted growth and lower yield will result
(ii)
Metal ion Results of deficiency
Potassium Stunted growth premature loss of leaves yellowing of leaves curling of leaf tips
Calcium Growth abnormalities in tips of roots and shoots curling of leaves
Iron Yellowing of leaves
Zinc Low chlorophyll content yellowing of leaves
Manganese Yellowing of leaves poor flavors in some crops for example potato
(b)
Metal Lead is present in some types of gasoline Upon combustion lead compounds escape into
the atmosphere It accumulates in body tissues and slowly poisons the person It causes mental
illness
Non ndash metal SulphurSulphur dioxide or NitrogenNitrogen dioxide
Dissolves in rain water to form acid rain or cause respiratory illnessproblems Acid rain can
cause corrosion damage in buildings
(c)
Green chemistry is the utilisation of a set of principles that reduces or eliminates the use or
generation of hazardous substances
43
Automotive fuels are now produced without lead so as to eliminate the release of lead
compounds into the atmosphere
Low sulphur fuel is being produced with much reduced sulphur content which causes a reduction
of sulphur dioxide release into the atmosphere
44
WEEK 13 LESSON 3 Worksheet Answer
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
gas turns litmus blue
red
brown gas
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
white precipitate
precipitate soluble in
excess
Zn2+ ions are present
45
WEEK 14 LESSON 1 Worksheet Answers
(a)(i) An alloy is a material made from a mixture of two or more metals
(ii) Any suitable answer chosen from below
Alloy Enhance Property Use
Duralumin High strength
Low density
Light
Hard
Used to make aircraft bodies
space satellites
Magnalium Light
Hard
Easier to weld
Corrosion resistant
Strong
High ductability
Used in pyrotechnics
(fireworks)
Mirrors
Aircraft parts
To make scientific
instruments
Used to make marine castings
Alchlad Strong
Corrosion resistant
Cladding for buildings
(b) (i) Zinc is more reactive than iron
Zinc displaces iron from iron (II) sulphate
Zinc is higher in the reactivity series than iron
Iron does not displace zinc from zinc sulphate
(ii) Order of reactivity Zn gt Fe gt Pb gt Cu
(iii) Reddish brown solid ndash copper metal formed
46
Dirty green solution ndash presence of Fe2+ ion
(iv) Fe (s) + Cu2+ (aq) Fe2+ (aq) + Cu (s)
(c) (i) Lead
(ii) Any two correct harmful effects of lead on the body
Impedes brain development (in young children)
Affectimpede development of the immune system in humans
Affecthamper development of nervous system in humans
Long term exposure can result in kidney and liver damage
Mental retardation
Anaemia
Death
47
WEEK 14 LESSON 2 Worksheet Answers
a) i) Diamond is transparent clear Graphite is opaque black
OR hard OR brittle
OR does not conduct electricity OR conducts electricity
a) ii) Both have a macromolecular giant molecular giant covalent structure (lattice)
OR Both have high melting point boiling point
OR Both are insoluble in water organic solvent
b) i) 2C (s) + O2 (g) rarr 2CO (g)
ii) CO reduction in amount of oxygen carried by (the haemoglobin in the red blood
cells of) the blood
Headache OR dizziness OR nausea OR fatigue OR loss of consciousness OR
death
c) i) CaCO3 (s) + 2HCl (aq) rarr CaCl2 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) + H2SO4 (aq) rarr CaSO4 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) rarr CaO (s) + CO2 (g)
48
ii)
OR
OR
Entirely closed system thistle funnel below the level of the liquid OR tap that could be
closed
Two reagents labelled CaCO3marble chips and HCl H2SO4 or heat source
collection of CO2 upward displacement of air OR over watersulphuric acid OR in gas
syringe
iii) CO2 use put in aerated drinks carbonated beverages
OR put in carbon dioxide fire extinguishers
49
WEEK 14 LESSON 3 Worksheet Answers
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
NH4+
NH4+ confirmed OR
NH3 (g) produced
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
Cl- ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation required)
Suggest a possible identity of the solid R NH4Cl (ammonium chloride)
50
WEEK 15 LESSON 1 Worksheet Answers
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a
small portion of solid Y
gently at first and then
strongly
Colourless gas
evolved with a
choking odour
Turns acidified
potassium dichromate
solution from orange
to green
SO2 evolved
Presence of a sulphite
(ii) To the remaining
portion of solid Y add 20
cm3 of distilled water stir
to dissolve and filter
Collect the filtrate and
divide into 3 equal portions
Filtrate is pale green
in colour
Fe2+ ions present
(iii) To the first portion of
the filtrate from (ii) add
aqueous sodium hydroxide
slowly until in excess
A green precipitate
Insoluble in excess
sodium hydroxide
Fe2+ ions present
Fe2+ (aq) + 2 OH- (aq) Fe(OH)2 (s)
Ionic equation required
TEST OBSERVATIONS INFERENCES
(iv) To the second portion
of the filtrate from (ii) add
aqueous silver nitrate
White precipitate
Soluble in aqueous
ammonia
Cl- ions present
51
followed by aqueous
ammonia
(v) To the third portion of
the filtrate from (ii) add
aqueous barium nitrate
followed by aqueous
hydrochloric acid
White precipitate
formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with
the evolution of a
colourless gas with a
choking smell
SO32- CO3
2- SO42- ions present
SO32- ions present
52
WEEK 15 LESSON 2 Worksheet Answers
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
Chloride ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
Cu2+ ions present
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
X contains a reducing agent
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
SO32- SO4
2- or CO32- ions are
present
SO32- ions are present
53
WEEK 15 LESSON 3 Worksheet Answers
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
White ppt
Ppt soluble in excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in
excess aqueous NH3
Al3+ Pb2+ Zn2+ present
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change Cl- Br- I- absent
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
Vigorous effervescence
observed upon addition of
dilute HNO3
CO2 evolved OR
Carbonate present
54
warm filter and then divide
the filtrate into two portions
Gas evolved turns lime
water cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
Cu2+ (aq) + OH- (aq)
Cu(OH)2 (s)
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Blue ppt
ppt dissolves in excess
NH3 to give a deep blue
solution
Cu2+ ions present
55
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
REFERENCES
Hunte-King J Maragh P Nagir F amp Norris R (2013) Chemistry for CSEC United
Kingdom Nelson Thornes Ltd
Remy C Mason L Lambert N amp Mohammed M (2007) Chemistry for CSEC England and
Wales Pearson Education Limited
Taylor M amp Chung-Harris T (2010) CXC Chemistry England Macmillan Publishers
Limited
Tindale A (2016) Chemistry A Concise Revision for CXC London HarperCollins Publishers
Limited
8
WEEK 1 LESSON 2 WORKSHEET
A group of students carried out an experiment to find the density of three different metals
aluminium calcium and an unknown metal X They measured the mass of each metal sample
using a balance The volumes of the metals were determined by displacement of oil The results
of their experiment are as follows
Aluminium Calcium Metal X
Mass (g) 100 100 100
Final volume (cm3) 335 365 310
Initial volume (cm3 300 300 300
Volume of metal (cm3)
Density (gcm-3)
Complete the table using the following formulae
Volume of metal = Final volume ndash Initial volume
Density = 119872119886119904119904
119881119900119897119906119898119890
Arrange the metals in order of increasing density _____________________________________
9
WEEK 1 LESSON 3
TOPIC Chemical properties of metals
Action of oxygen
Most metals react with oxygen or air to form the corresponding oxide These oxides are basic
oxides with the exception of aluminium zinc and lead which form amphoteric oxides Metals
lower in the electrochemical series do not react
Metal Reaction with air or oxygen
Potassium K
Burn very easily forming oxide
eg 4 Na (s) + O2 (g) 2 Na2O (s)
Sodium Na
Calcium Ca
Magnesium Mg
Aluminium Al
Burn especially if powered forming oxide
eg 4 Al (s) + 3 O2 (g) 2 Al2O3 (s)
Zinc Zn
Iron Fe
Lead Pb Do not burn form oxide when heated strongly
Copper Cu
Silver Ag No reaction
10
WEEK 1 LESSON 3 WORKSHEET
Write balanced chemical equations for the reaction of the named metals and air or oxygen
State the nature of the oxide formed (basic or amphoteric)
Potassium + Oxygen
______________________________________________________________________________
Sodium + Oxygen
______________________________________________________________________________
Calcium + Oxygen
______________________________________________________________________________
Magnesium + Oxygen
______________________________________________________________________________
Aluminium + Oxygen
______________________________________________________________________________
Zinc + Oxygen
______________________________________________________________________________
11
Iron + Oxygen
______________________________________________________________________________
Lead + Oxygen
______________________________________________________________________________
Copper + Oxygen
______________________________________________________________________________
Silver + Oxygen
______________________________________________________________________________
12
WEEK 2 LESSON 1
TOPIC Chemical properties of metals
Action of water
Metals high in the electrochemical series react with cold water to produce the metal hydroxide
and hydrogen
Reactive metals slightly lower in the electrochemical series react very slowly or not at all with
water However they may react with hot water or steam to produce the corresponding metal
oxide and hydrogen
Metals lower than hydrogen in the electrochemical series do not react with water
Metal Reaction with water or steam
Potassium K React with cold water forming metal hydroxide and hydrogen
eg Ca (s) + 2 H2O (l) Ca(OH))2 (aq) + H2 (g) Sodium Na
Calcium Ca
Magnesium Mg React with steam forming metal oxide and hydrogen
eg Zn (s) + H2O (g) ZnO (s) + H2 (g) Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
13
WEEK 2 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with water (or
steam if reaction does not occur with water)
Potassium + WaterSteam
______________________________________________________________________________
Sodium + WaterSteam
______________________________________________________________________________
Calcium + WaterSteam
______________________________________________________________________________
Magnesium + WaterSteam
______________________________________________________________________________
Aluminium + WaterSteam
______________________________________________________________________________
Zinc + WaterSteam
______________________________________________________________________________
14
Iron + WaterSteam
______________________________________________________________________________
Copper + WaterSteam
______________________________________________________________________________
Silver + WaterSteam
______________________________________________________________________________
15
WEEK 2 LESSON 2
TOPIC Chemical properties of metals
Action of dilute acids
Metals above hydrogen in the electrochemical series react with dilute acids to form a salt and
hydrogen gas They react with hydrochloric acid to form the metal chloride (a salt) and hydrogen
gas They also react with dilute suphuric acid to form the metal sulphate (a salt) and hydrogen
gas
Metal Reaction dilute hydrochloric or sulphuric acid
Potassium K Violent reaction forming a salt and hydrogen gas
eg 2 Na (s) + 2 HCl (aq) 2 NaCl (aq) + H2 (g) Sodium Na
Calcium Ca Vigorous reaction forming a salt and hydrogen gas
eg Mg (s) + 2 HCl (aq) MgCl2 (aq) + H2 (g) Magnesium Mg
Aluminium Al React forming a salt and hydrogen gas
eg Fe (s) + 2 HCl (aq) FeCl2 (aq) + H2 (g) Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
16
WEEK 2 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with
hydrochloric acid
Metal Balanced equation for reaction with hydrochloric acid
Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Copper
Silver
17
WEEK 2 LESSON 3
TOPIC Reactions of metal compounds
Reactions of metallic oxides with dilute acid
Metal oxides react with dilute hydrochloric acid or sulphuric acid to produce a salt and water
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
Some of these reactions may be slow and can be speeded up by adding heat
For example
zinc oxide + hydrochloric acid zinc chloride + water
ZnO (s) + 2 HCl (aq) ZnCl2 (aq) + H2O (l)
magnesium oxide + hydrochloric acid magnesium chloride + water
MgO (s) + 2 HCl (aq) MgCl2 (aq) + H2O (l)
aluminium oxide + sulphuric acid aluminium sulphate + water
Al2O3 3 H2SO4 (aq) Al2(SO4)3 (aq) + 3 H2O (l)
calcium oxide + sulphuric acid calcium sulphate + water
CaO H2SO4 (aq) CaSO4 (aq) + H2O (l)
18
WEEK 2 LESSON 3 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal oxides with the
corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium oxide Hydrochloric acid
Sodium oxide Sulphuric acid
Calcium oxide Hydrochloric acid
Magnesium oxide Sulphuric acid
Aluminium oxide Hydrochloric acid
Zinc oxide Sulphuric acid
19
WEEK 3 LESSON 1
TOPIC Reactions of metal compounds
Reactions of metallic hydroxides with dilute acid
Metal hydroxides react with dilute acids to form a salt and water in a neutralisation reaction
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
For example
magnesium hydroxide + hydrochloric acid magnesium chloride + water
Mg(OH)2 (aq) + 2 HCl (aq) MgCl2 (aq) + 2 H2O (l)
sodium hydroxide + hydrochloric acid sodium chloride + water
NaOH (aq) + HCl (aq) NaCl (aq) + H2O (l)
potassium hydroxide + sulphuric acid potassium sulphate + water
2 KOH + H2SO4 (aq) K2SO4 (aq) + 2 H2O (l)
calcium hydroxide + sulphuric acid calcium sulphate + water
Ca(OH)2 (aq) + H2SO4 (aq) CaSO4 (aq) + 2 H2O (l)
20
WEEK 3 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal hydroxides with
the corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium hydroxide Hydrochloric acid
Sodium hydroxide Sulphuric acid
Calcium hydroxide Hydrochloric acid
Magnesium hydroxide Sulphuric acid
Aluminium hydroxide Hydrochloric acid
Zinc hydroxide Sulphuric acid
21
WEEK 3 LESSON 2
TOPIC Reactions of metal compounds
Reactions of metallic carbonates with dilute acid
Metal carbonates react with dilute acid to form a salt carbon dioxide and water When
hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric acid is
used the corresponding sulphate salt is formed
For example
sodium carbonate + hydrochloric acid sodium chloride + carbon dioxide + water
Na2CO3 (s) + 2 HCl (aq) 2 NaCl (aq) + CO2 (g) + H2O (aq)
calcium carbonate + hydrochloric acid calcium chloride + carbon dioxide + water
CaCO3 (s) + 2 HCl (aq) CaCl2 (aq) + CO2 (g) + H2O (aq)
zinc carbonate + sulphuric acid zinc sulphate + carbon dioxide + water
ZnCO3 (s) + H2SO4 (aq) ZnSO4 (aq) CO2 (g) + H2O (aq)
potassium carbonate + sulphuric acid potassium sulphate + carbon dioxide + water
K2CO3 (s) H2SO4 (aq) K2SO4 (aq) CO2 (g) + 2 H2O (aq)
22
WEEK 3 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal carbonates with
the corresponding acid
Metallic
carbonate
Acid Balanced chemical equation
Potassium
carbonate
Hydrochloric
acid
Sodium
carbonate
Sulphuric acid
Zinc
carbonate
Hydrochloric
acid
Magnesium
carbonate
Sulphuric acid
Aluminium
carbonate
Hydrochloric
acid
Calcium
carbonate
Sulphuric acid
23
WEEK 3 LESSON 3
TOPIC Action of heat on metal compounds
Action of heat on nitrates
All nitrates decompose when heated The reactivity of the metal in the metal nitrate influences
the products of the decomposition
The nitrates of the alkali metals (Group I) with the exception of lithium nitrate decompose to
form the metal nitrite and oxygen
The nitrates of most other metals decompose to form the metal oxide nitrogen dioxide and
oxygen
The nitrates of the very unreactive metals decompose to form the meal nitrogen dioxide and
oxygen
Metal Nitrate Decomposition
Potassium K Products metal nitrite + oxygen
eg 2 NaNO3 (s) Heatrarr 2 NaNO2 (s) + O2 (g)
Sodium Na
Calcium Ca
Products metal oxide + nitrogen dioxide + oxygen
eg 2 Pb(NO3)2 (s)
Heatrarr 2 PbO (s) + 4 NO2 (g) + O2 (g)
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Products metal + nitrogen dioxide + oxygen
eg 2 AgNO3 (s) Heatrarr 2 Ag (s) + 2 NO2 (g) + O2 (g)
24
WEEK 3 LESSON 3 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
nitrates
Metal Balanced chemical equation
Potassium nitrate
Sodium nitrate
Calcium nitrate
Magnesium nitrate
Aluminium nitrate
Zinc nitrate
Lead nitrate
Copper nitrate
Silver nitrate
25
WEEK 4 LESSON 1
TOPIC Action of heat on metal compounds
Action of heat on carbonates
Upon application of heat many carbonates decompose to form the metal oxide and carbon
dioxide
Group I carbonates do not decompose on heating with the exception of lithium carbonate
Metal Carbonate decomposition
Potassium K
Stable not decomposed by heat Sodium Na
Calcium Ca
Decompose forming metal oxide and carbon dioxide
eg CaCO3 (s) Heatrarr CaO (s) + CO2 (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Unstable
26
WEEK 4 LESSON 1 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
carbonates
Metal Balanced chemical equation
Potassium carbonate
Sodium carbonate
Calcium carbonate
Magnesium carbonate
Aluminium carbonate
Zinc carbonate
Iron carbonate
Lead carbonate
Copper carbonate
27
WEEK 4 LESSON 2
TOPIC Action of heat on metal compounds
Action of heat on the metal hydroxides
Most metal hydroxides decompose on heating A metal oxide and water are formed
Group I hydroxides do not decompose on heating with the exception of lithium hydroxide
Metal Hydroxide decomposition
Potassium K Stable not decomposed by heat
Sodium Na
Calcium Ca Decompose forming metal oxide and water (as steam)
eg Zn(OH)2 (s) Heatrarr ZnO (s) + H2O (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag No hydroxide exist
28
WEEK 4 LESSON 2 WORKSHEET
Write the balanced chemical equations for the thermal decomposition of the following
metal hydroxides
Metal hydroxide Balanced chemical equation
Potassium hydroxide
Sodium hydroxide
Calcium hydroxide
Magnesium hydroxide
Aluminium hydroxide
Zinc hydroxide
Lead hydroxide
Copper hydroxide
29
WEEK 4 LESSON 3
TOPIC Reactivity of metals ndash The Reactivity Series
The reactivity series of metals is a list of metals arranged in order of their reactivity based on
Displacement reactions
Reactions with oxygen dilute acids and water
Relative ease of decomposition of their compounds
Metals at the top of the series are the most electropositive They lose electrons very easily and
readily form cations These ions are very stable and are not easily discharged to form atoms Due
to this fact they are the most reactive metals
Metals at the bottom of the series are the least electropositive They do not lose electrons easily
and do not readily form ions Their ions are very unstable and are easily discharged to form
atoms They are the least reactive metals
The reactivity series of metals
Mnemonic Metal Symbol Reactivity
People Potassium K Most reactive
Least reactive
Sometimes Sodium Na
Collect Calcium Ca
Magazines Magnesium Mg
About Aluminium Al
Zoos Zinc Zn
In Iron Fe
London Lead Pb
Having (Hydrogen) H
Cute Copper Cu
Monkeys and Mercury Hg
Small Silver Ag
Gorillas Gold Au
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
5 Reactivity of metals Reactivity of metals Reactivity of metals
6 Extraction of metals Extraction of metals Alloys
7 Corrosion Importance of metals
and their compounds
on living systems and
environment
Chemical properties
of non ndash metals
8 Laboratory
preparation of gases
Laboratory
preparation of gases
Laboratory
preparation of gases
9 Uses of gases Uses of non ndash metals
and their compounds
Harmful effects of
non ndash metals and
their compounds on
living systems and
the environment
10 Green Chemistry Qualitative Analysis
ndash Identification of
cations
Qualitative Analysis
ndash Identification of
cations
2
WEEK 5 LESSON 1
TOPIC Reactivity of metals
Reactivity based on displacement reactions between metals and metal ions
A metal will displace a metal which is lower than itself in the reactivity series from a solution of
the metal salt
Reaction of zinc and copper (II) sulphate
Expected observations
Explanation
The size of the zinc metal decreases
The zinc metal is reacting and forming the
salt zinc sulphate
The solution becomes lighter eventually
colourless
The Cu2+ (aq) ions (responsible for the blue
colour) is reduced to Cu (s)
A brown solid is deposited at the bottom of
the container
Copper metal is formed
Equation Zn (s) + CuSO4 (aq) ZnSO4 (aq) + Cu (s)
Ionic equation
Zn (s) + Cu2+ (aq) Zn2+ (aq) + Cu (s)
Zinc is higher in the reactivity series than copper Therefore it will displace the copper ions in
the reaction above
3
Examples of other displacement reactions
Magnesium will displace Zn2+ ions in zinc sulphate since it is higher in the series than zinc
Mg (s) + Zn2+(aq) Mg2+ (aq) + Zn (s)
Silver will not displace Cu2+ ions in copper (II) sulphate [Cu is higher in the series than Ag]
Using the information above we can arrange the metals in order of their reactivity with
magnesium being the most reactive and silver the least reactive metal among the four metals
Mg gt Zn gt Cu gt Ag
Reactivity based on reaction with oxygen
The reactivity of metals can also be deduced from their reaction with oxygen
The table below gives the observations for the reaction with oxygen with the selected metals
Reaction of metal with oxygen
Metal Observation
Copper The surface turns black upon heating
Magnesium Ribbon burns very rapidly
Sodium Burns vigorously
Gold No reaction
Based on the observations for the 4 metals the metal with highest reactivity is sodium and the
metal with the least reactivity is gold
The 4 metals can be arranged in terms of reactivity as follows
Na gt Mg gt Cu gt Au
4
WEEK 5 LESSON 1 WORKSHEET
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
5
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
6
WEEK 5 LESSON 2
TOPIC Reactivity of metals
Reactivity based on reactivity with acids
The metals that are higher than hydrogen in the electrochemical series react with non ndash oxidizing
acids to produce a salt and hydrogen gas
By using the same concentration of acid and same mass and size of the metals the order of
reactivity of the metals can be deduced
The table below shows the results for an experiment with the reaction of the named metals and
1 mol dm-3 hydrochloric acid
Reaction of metals with acid
Metal Observations
Silver No reaction
Magnesium Bubbles produced steadily
Calcium Bubbles produced very rapidly
Iron Bubbles produced slowly
Based on the above data the most reactive metal will be calcium with the least reactive being
silver The order of reactivity will be Ca gt Mg gt Fe gt Ag
By comparing this to the electrochemical series it can be seen that the reactivity of the metals
decrease as we go down the series
7
WEEK 5 LESSON 2 WORKSHEET
1 Place a next to the metals that will react with dilute acid and an X next to the metals
that will not react with dilute acid
Metal Reactivity with acid
Copper
Magnesium
Aluminium
Silver
Zinc
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
8
WEEK 5 LESSON 3
TOPIC Reactivity of metals
Reactivity based on ease of decomposition of the metal nitrates carbonates oxides and
hydroxides
The more reactive a metal the more difficult it is to decompose its nitrate carbonate oxide or
hydroxide on heating
For example Decomposition of carbonates
Procedure
1 Put a large spatula measure of the carbonate to be tested in a test tube
2 Fit a delivery tube and then clamp the test tube so that the delivery tube dips into a second test
tube containing 2ndash3 cm3 limewater
3 Heat the solid gently at first then more strongly
4 Lift the delivery tube from the limewater before or as soon as the heating is stopped This is to
avoid suck-back
5 Write down all observations Notice what happens to the limewater and how long it takes to turn
milky (if at all) Notice whether any melting occurs in the heated test tube and any colour
changes taking place Write your results in tabular form
6 Repeat the experiment with the other metal carbonates supplied and in each case write down
your observations
7 Wash your hands thoroughly at the end of these experiments since some of the metal carbonates
are toxic
9
Results
Metal Formula Gas evolved Ease of decomposition
Zinc ZnCO3 Carbon dioxide Fairly easy
Copper CuCO3 Carbon dioxide Easy
Sodium Na2CO3 None Very difficult
Using the results of the above activity the reactivity of the metals can be determined
Ease of decomposition Copper gt Zinc gt Sodium
The order of reactivity is the opposite for the ease of decomposition
Order of reactivity Sodium (most reactive) gt Zinc gt Copper (least reactive)
10
WEEK 5 LESSON 3 WORKSHEET
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
11
WEEK 6 LESSON 1
TOPIC Extraction of metals
Elements exist all over the earth Some are found as free elements eg copper silver and gold
Others are found combined with other elements in compounds To get the elements the
compounds have to be broken up These compounds are generally called ores the most
convenient sources of which are rocks sea and air
The extraction of a metal from its ore is a reduction process where the metals ions gain electrons
to form atoms
The general equation is Mn+ + n e- M
The choice of the extraction method depends on the position of the metal in the reactivity series
As we go down the series the metals become more stable and the metal ions (in the ores)
become less stable
The very reactive metals that are high in the series K Na Ca Mg Al have very stable ores
Therefore they require a powerful method of reduction namely electrolysis During the process
the cathode provides the electrons and acts as the reducing agent
The metals in the middle of the series (Zn Fe Pb) do not have stable ores and can be extracted
by reduction with carbon in the case of zinc and with carbon monoxide in the case of iron and
lead
Metals low in the reactivity series if present as ores can be extracted simply by heating the ores
in air at high temperatures
12
Extraction of Aluminium from purified bauxite
Pure bauxite is pure alumina (Al2O3) Aluminium is obtained from bauxite by electrolysis
Aluminium oxide has a very high melting point approximately 2050 0C so it is first dissolved in
molten cryolite (Na2AlF6) The addition of cryolite lowers the melting point to approximately
900 0C
The electrolyte is a molten mixture of alumina and molten cryolite The cathode is the graphite
lining of the cell The anodes are blocks of graphite or titanium alloys
Reaction at the cathode
Al3+ (l) + 3 e- Al (l)
Reaction at the anode
2 O2- (l) ndash 4 e- O2 (g)
Aluminium (melting point 660 0C) is a liquid at the temperature at which electrolysis is carried
out and is collected at the bottom of the cell and tapped off Oxygen gas which is given off in the
main cathode reaction together with the heat causes the anodes to burn away The anodes have
to be replaced from time to time The use of anodes from titanium alloys reduce the number of
times that the anodes have to be replaced
13
WEEK 6 LESSON 1 Worksheet
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 6 LESSON 2
TOPIC Extraction of metals
Extraction of Iron
The traditional method of production of iron is by reduction of haematite by carbon monoxide in
a blast furnace
Ores Haematite ndash Fe2O3 Magnetite ndash Fe3O4 Siderite ndash FeCO3 Magnetite and Siderite are
converted to Haematite
A mixture of haematite limestone (CaCO3) and coke (C) called the charge is placed into the top
of the furnace
Hot air is blown into the bottom of the furnace
Coke burns in air forming carbon dioxide
C (s) + O2(g) CO2 (g) ΔH -ve
The heat produced keeps the temperature at about 1900 0C
The carbon dioxide is reduced to carbon monoxide by the hot coke
CO2 (g) + C (s) 2 CO(g) Δ +ve
Heat absorbed reduces the temperature to about 1100 0C
The carbon monoxide reduces the hot iron ore to molten iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + 3 CO2(g)
The temperature at this part of the furnace is about 700 0C The iron runs to the bottom of the
furnace
The impurities are removed by the addition of limestone (CaCO3) The limestone at the
temperature of the furnace breaks down
CaCO3 (s) CaO (s) + CO2 (g)
15
The calcium oxide formed combines with silicon dioxide (sand) the main impurity in the iron
ore to form molten slag
CaO (s) + SiO2 (s) CaSiO3 (l)
The slag does not mix with the molten iron but floats on it The molten iron and slag are run off
separately
The iron formed in a blast furnace is an impure form of the metal Because the molten metal is
allowed to solidify in shallow trays known as casts the iron is called lsquocast ironrsquo or lsquopigrsquo iron
Cast iron is quite brittle and contains 2 - 4 carbon and other impurities Most of the cast iron is
converted to steel
A blast furnace used for extracting iron
16
WEEK 6 LESSON 2 Worksheet
(a) What are the three raw materials that are added through the top of the blast furnace
during the extraction process for iron
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______________________________________________________________________________
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
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17
WEEK 6 LESSON 3
TOPIC Alloys
An alloy is a mixture of two or more metals Alloys are made by melting the individual metals
mixing them and allowing the molten mixture to solidify
In general alloys are harder stronger and more resistant to corrosion than the actual metals they
are made up from
Alloy Use Properties
ALUMINIUM
-Duralumin
(AlMgCu)
-Magnalium (AlMg)
Alloys used in the
construction of
aircraft and ships
buses
Aluminium is used in
making cooking
utensils electrical
cables paint for fuel
storage tanks bottle
caps foil and utensils
for handling nitric
acid
The alloys have a low
density They are as
light as aluminium
and more resistant to
corrosion than
aluminium
LEAD
-Solder (PbSn)
Alloy is used in
joining metals
(soldering)
Lead is used in
underground cables
plates in
The alloy has a lower
melting point than
lead and is harder
than lead
18
Alloy Use Properties
accumulators shield
against x ndash rays
IRON
- Stainless Steel
(FeCONiC)
-Tungsten steel
(FeWC)
-Invar steel (FeNi)
Manganese steel
(FeMnC)
Iron is the main metal
of a variety of
constructions
Steel is used in
cutlery rock drills
electromagnets
vehicle body and
engine parts fences
pipes etc
Steel resists
corrosion is usually
harder than iron and
may be tough though
malleable and ductile
19
WEEK 6 LESSON 3 Worksheet
(a) Define the term alloy
______________________________________________________________________________
(b) State 3 general advantages that alloys have over the individual metals they are made
from
______________________________________________________________________________
______________________________________________________________________________
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
______________________________________________________________________________
______________________________________________________________________________
Uses
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 7 LESSON 1
TOPIC Corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
Familiar examples of corrosion are
- the formation of a green powder on copper sheeting
- the eating away of iron (rusting)
- the development by aluminum of a thin compact layer of oxide which protects the
underlying metal from further corrosion
When corrosion occurs in water ndash free environment it is called dry oxidation When it occurs in
aerated aqueous environments it is called wet corrosion Wet corrosion is the most common and
troublesome form of corrosion
The most familiar corrosion is the rusting of iron and steel On exposure to the atmosphere iron
and steel corrode to form rust which is hydrated iron (III) oxide Fe2O3xH2O Iron and steel
corrode easily and the rust formed flakes off easily thus exposing fresh surface for attack
When iron rust it loses electrons
Fe (s) ndash 2e- Fe 2+ (aq)
The iron (II) ions pass into solution and then combine with the hydroxyl (OH-) ions in the
aerated aqueous environment to form iron (II) hydroxide The oxygen present oxidises the iron
(II) hydroxide to hydrated iron (III) oxide or rust
Fe(OH)2 + O2 Fe2O3xH2O
21
Methods of preventing rusting
1 Coating the object with paint grease plastic or rubber which prevent contact with air or
water
2 Galvanising ndash coating the object with zinc The zinc forms an adherent oxide layer which
protects against further corrosion If damaged the zinc is oxidized in preference to the
iron since it is higher in the electrochemical series
3 Coating with tin lsquoTinrsquo cans are made of steel plated with tin However if scratched
rusting occurs since iron is more reactive than tin
4 Attaching a sacrificial anode to the object A piece of metal higher in the electrochemical
series such as magnesium is attached The magnesium will be oxidized in preference
since it is higher in the electrochemical series than iron
22
WEEK 7 LESSON 1 WORKSHEET
(a) Define the term corrosion
______________________________________________________________________________
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
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______________________________________________________________________________
______________________________________________________________________________
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
______________________________________________________________________________
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______________________________________________________________________________
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
23
WEEK 7 LESSON 2
TOPIC Importance of metals and their compounds on living systems and environment
Some metals are an integral part of different structures of living things
Metal Presence and Function
Potassium Main cation in fluid or animal cells essential for healthy plant growth
Calcium Necessary for strong bones teeth and shells needed by some enzymes Present
in dairy produce eggs nuts and cereals
Magnesium Central atom of chlorophyll needed for some enzyme action Involved in energy
and calcium metabolism
Zinc Present in many enzymes Needed for protein metabolism Essential for growth
of animals
Iron Present in haemoglobin Needed for protein metabolism Essential for growth of
animals
Chromium Needed for glucose uptake by cells and thus linked to the action of insulin
Manganese Needed for bone development and amino acid metabolism Present in several
enzymes Needed for plant growth
Cobalt Present in Vitamin B12 Needed for plant growth
Copper Involved in formation of haemoglobin and melanin Present in enzymes
controlling oxidation Needed for plant growth
24
Harmful effects of metals and their compounds to living systems and the environment
There are some metals and metal compounds which may cause harm to living systems and the
environment
Lead
Lead is a heavy metal poison that is widely encountered It may occur in food beverages paint
water formed from ndash sealed pipes in air polluted by combustion by fuels containing lead
compounds Lead is also used in some car batteries If these are paints or batteries are not
disposed of correctly lead may get into groundwater or air Lead and lead compounds harm the
nervous system including the brain especially young children
Arsenic
Arsenic compounds are poisonous They can get into the groundwater from mining waste and
from disposal of some electrical components
Cadmium
Cadmium compounds are poisonous They can get into the ground by improper disposal of
nickel ndash cadmium batteries Persons can get cadmium poisoning if they eat food grown in
contaminated soil
Mercury
Mercury can be spilled from broken thermometers in hospitals and laboratories Mercury and its
compounds are particularly poisonous to fish and it can accumulate in the food chain and
eventually poison humans
Problems of disposal of solid waste
Metals may react with water andor air and corrode to form soluble compounds that are
poisonous These toxic compounds diffuse into the soil and eventually enter rivers
Rust from iron may form unsightly pools of waste that reduce plant growth
Waste from aluminium extraction may react with water and form flammable gases
25
WEEK 7 LESSON 2 WORKSHEET
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Lead
______________________________________________________________________________
Mercury
______________________________________________________________________________
26
WEEK 7 LESSON 3
TOPIC Chemical properties of non ndash metals
Reaction with oxygen
Many non ndash metals burn in excess oxygen or air to form oxides For example
S (s) + O2 (g) SO2 (g)
C (s) + O2 (g) CO2 (g)
Reactions with metals
Some non ndash metals react with metals high in the electrochemical series when heated
For example
Sodium burns in chlorine to form sodium chloride
Na (s) + Cl2 (g) NaCl (s)
Magnesium burns in oxygen to form magnesium oxide
Mg (s) + O2 (g) MgO (s)
When heated iron combines with molten sulphur to form iron (II) sulphide
Fe (s) + S (l) FeS (s)
When heated reactive metals such as sodium and aluminium react with hydrogen to form metal
hydrides
2 Na (s) + H2 (g) 2 NaH (s)
Oxidising and Reducing properties
Hydrogen and Carbon are very good reducing agents
At high temperatures hydrogen reduces metal oxides below zinc in the electrochemical series to
form the metal For example PbO (s) + H2 (g) Pb (s) + H2O (g)
Under suitable conditions hydrogen reduces nitrogen to ammonia
N2(g) + 3 H2 (g) 2 NH3 (g)
27
At high temperatures carbon reduces metal oxides below aluminium in the reactivity series to
the metal For example
ZnO (s) + C (s) Zn (s) + CO (g)
Oxygen and Chlorine are very good oxidizing agents
Oxygen oxidized most metals to form metal oxides and some non ndash metals to non ndash metal oxides
For example
2 Mg (s) + O2(g) 2 MgO (s)
4 P (s) + 5 O2 (g) P4O10 (s)
Chlorine acts as an oxidizing agent either as a gas or as an aqueous solution For example
H2 (g) + Cl2 (g) 2 HCl (g)
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
28
WEEK 7 LESSON 3 WORKSHEET
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
______________________________________________________________________________
(b) Write the ionic equation for the above reaction
______________________________________________________________________________
(c) Identify the oxidising agent in the reaction
______________________________________________________________________________
(d) Justify your answer in part (c) in terms of oxidation number
______________________________________________________________________________
29
WEEK 8 LESSON 1
TOPIC Laboratory preparation of gases
Preparation of oxygen
Oxygen can be prepared by the decomposition of hydrogen peroxide potassium chlorate (V) or
potassium nitrate The safest method is the decomposition of hydrogen peroxide
Manganese (IV) oxide catalyses the decomposition of hydrogen peroxide
Silica gel anhydrous calcium chloride or concentrated sulphuric acid can be used as a drying
agent
The gas is collected by downward delivery since it is slightly denser than air
Equation
2 H2O2 (aq) 2 H2O (l) + O2 (g)
Apparatus used for laboratory preparation of oxygen
30
WEEK 8 LESSON 1 WORKSHEET
Describe the laboratory preparation of oxygen gas
In your answer include
The starting material
A suitable catalyst
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
31
WEEK 8 LESSON 2
TOPIC Laboratory preparation of gases
Preparation of carbon dioxide
Carbon dioxide can be prepared by the action of dilute acid on carbonates Marble chips (calcium
carbonate) and dilute hydrochloric acid are the common reagents The gas is collected by
downward delivery since it is denser than air
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
Apparatus used for laboratory preparation of carbon dioxide
32
WEEK 8 LESSON 2 WORKSHEET
Describe the laboratory preparation of carbon dioxide gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
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______________________________________________________________________________
______________________________________________________________________________
33
WEEK 8 LESSON 3
TOPIC Laboratory preparation of gases
Preparation of ammonia
Ammonia may be prepared by heating a mixture of ammonium salt and a hydroxide The
ammonia gas is collected by upward delivery since it is less dense than air
For example
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
Calcium oxide is the only suitable drying agent since ammonia reacts with conc H2SO4 and
CaCl2
Apparatus used for laboratory preparation of dry ammonia
34
11
WEEK 8 LESSON 3 WORKSHEET
Describe the laboratory preparation of ammonia gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
35
WEEK 9 LESSON 1
TOPIC Uses of gases
Carbon dioxide
Used in fire extinguishers to put out fires Carbon dioxide is denser than air and lsquoblanketsrsquo the
fire preventing oxygen from reaching it Carbon dioxide extinguishers are especially useful for
dealing with fires involving flammable liquids and electrical equipment
Carbonation in soda is created when carbon dioxide is pumped into the soda can or bottle then
held under pressure As long as the can or bottle is sealed the carbon dioxide remains mostly
stable However if the drink gets shaken up or the top is opened the tiny carbon dioxide bubbles
react by bursting
Oxygen
Oxygen is needed for aerobic respiration We need a constant supply of oxygen for this process
Oxygen is used in hospitals to improve the respiration of patients with poor blood flow blood
poisoning and heart disease
Oxygen in used in welding (joining) metals In an oxyacetylene welding torch acetylene or
ethyne (C2H2) burns in oxygen and produces a very hot flame This flame is capable of melting
most metals
Oxygen is used in steel production A blast of oxygen is blown through the molten iron The
oxygen oxidises many of the impurities of the iron and the impurities are then removed
36
WEEK 9 LESSON 1 WORKSHEET
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Put out fires
Welding metals
Create lsquofizzrsquo in drinks
Used in steel production
Aerobic respiration
37
WEEK 9 LESSON 2
TOPIC Uses of non ndash metals and their compounds
Carbon (allotrophes carbon dioxide)
Carbon is used as a reducing agent in extraction of some metals
Carbon as graphite is used as electrodes lubricants and lsquoleadrsquo for pencils
Carbon in the form of diamond is used for jewellery (because of its lustre) and in drill tips for
high ndash speed drills (because of its hardness)
Carbon dioxide is used as refrigerant (as dry ice) for carbonated beverages
Sodium hydrogen carbonate and sodium carbonate are used for water softening and raising
agent
Sulphur
Sulphur is used in the manufacture of sulphuric acid Sulphur is also used in the manufacture of
tyres to make the rubber harder (vulcanisation)
Sulphur powder is used as fungicide on plant materials
Phosphorus
Phosphorus is used in the manufacture of fertilizers
Phosphorus is used to make phosphor bronze alloys
Phosphorus sulphide is used to make the heads of lsquostrike anywherersquo matches
38
Chlorine
Chlorine is used to make sodium hypochlorite which is present in bleach It is also used in
sterilizing swimming pools and in water treatment
Chlorine is used to make the monomer vinyl chloride which is used to make the plastic PVC
Nitrogen
Nitrogen is used to make fertilisers ammonia dyes and nitric acid
Nitrogen is used as an inert atmosphere to prevent substances being oxidised and as a coolant
Silicon
Silicon is used for making silicon chips for computers
Silicon (V) oxide is present in sand Glass is made by heating sand with lime (calcium oxide) and
sodium carbonate
Silicon in the form of silicates is used in jewellery
Silica gel is used as a drying agent
39
WEEK 9 LESSON 2 WORKSHEET
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Used to make sodium hypochlorite
Used as a fungicide on plant materials
Used for lsquoleadrsquo in pencils
Used in the manufacture of bronze alloys
Used in the manufacture of nitric acid
Used in the manufacture of computer chips
Used to make fertilisers
40
WEEK 9 LESSON 3
TOPIC Harmful effects of non ndash metals and their compounds on living systems and the
environment
Sulphur dioxide
Sulphur dioxide can cause a disease of the lungs Sulphur dioxide also poisons plants in two
main ways It may enter the stomata of leaves and react with the tissue fluids to form sulphites
with the on ndash going water loss the concentration of sulphites could build up killing the cells
The second adverse effect on plants occurs when sulphur dioxide dissolves in rain thereby
increasing soil acidity A prolonged acid soil situation may lead to plasmolysis and the death of
vegetation in an area
Carbon monoxide
Carbon monoxide combines much more readily than oxygen with haemoglobin When carbon
monoxide is inhaled it prevents the haemoglobin from taking oxygen to the bodyrsquos cells
Continued breathing of air containing carbon monoxide eventually causes death
Hydrogen sulphide
Hydrogen sulphide reacts readily with many cations forming insoluble sulphides Many cations
contribute to good health by contributing to enzyme activity and to the formation of bone
pigment and haemoglobin Although these cations are required in extremely small
concentrations they are removed by being precipitated as sulphides and thus not available for
regular function Careless dumping of refuse contributes to atmospheric pollution by hydrogen
sulphide
Oxides of nitrogen
In the presence of hydrocarbons from car exhausts ozone and sunlight nitrogen oxides react to
form photochemical smog which contains many harmful chemicals
Nitrogen dioxide can harm the lungs and irritate the nose throat and eyes The other compounds
present in photochemical smog are even more harmful irritants and can cause asthma
41
Carbon dioxide
Carbon dioxide water vapour and ozone referred to as ldquogreenhouse gasesrdquo acting as a blanket
readily absorb some of the radiated heat energy and in turn warms the earthrsquos atmosphere This is
called the ldquogreenhouse effectrdquo Scientists have found direct correlation between carbon dioxide
concentration and global warming An increase in carbon dioxide concentration resulted in an
increase global temperatures Global warming is a major potential problem that the world faces
Chloroflourocarbons (CFCs)
It is believed that CFCs might be responsible for destroying the ozone layer which prevents
harmful ultraviolet (UV) radiation from reaching the earth The carbon ndash chlorine bond in CFC
molecule is easily broken by a UV photon producing an active chlorine atom This atom
combines with an ozone molecule forming a chlorine oxide radical and oxygen The radicle
reacts with more ozone producing the chlorine atom again This kind of reaction is repeated
thousands of times This type of reaction is thought to account for about eighty percent of the
loss of ozone observed
Nitrates and phospates
Nitrates and phosphates cause eutrophication The process leading to eutrophication are
Nitrates and phosphates from fertilisers spread on fields may dissolve in groundwater and
get into lakes and rivers
Nitrates and phosphates cause excessive growth of algae so that they cover the surface of
the water
Water plants including algae die because of lack of sunlight Aerobic bacteria feed on
the plant remains The bacteria multiply
The aerobic bacteria use up the oxygen in the water so aquatic animals die
42
Solid waste
The main sources of pollution from non ndash metals is from glass paper and plastics
Broken glass can cause injury to animals It can also cause fires by acting as lens focusing the
sunrsquos rays on flammable materials
Printing inks from paper dumped in the ground may contain toxic elements such as arsenic and
cadmium Bleaches and chlorine compounds from paper are also harmful
43
WEEK 9 LESSON 3 WORKSHEET
Describe ONE harmful effect of the following non ndash metals andor their compounds on
living systems and the environment
Sulphur dioxide
______________________________________________________________________________
______________________________________________________________________________
Carbon monoxide
______________________________________________________________________________
______________________________________________________________________________
Carbon dioxide
______________________________________________________________________________
______________________________________________________________________________
Oxides of nitrogen
______________________________________________________________________________
______________________________________________________________________________
Hydrogen sulphide
______________________________________________________________________________
______________________________________________________________________________
44
Chloroflourocarbons (CFCs)
______________________________________________________________________________
______________________________________________________________________________
Nitrates and phospates
______________________________________________________________________________
______________________________________________________________________________
45
WEEK 10 LESSON 1
TOPIC Green Chemistry
Green Chemistry is defined as the utilisation of a set of principles that reduces or eliminates the
use and generation of hazardous substances
There are twelve principles of green chemistry as proposed by Paul T Anastas and John C
Warner These twelve principles are
1 Prevention ndash It is better to prevent waste than to treat or clean up waste after it has been
created
2 Atom economy - Synthetic methods should be designed to maximize the incorporation of
all materials used in the process into the final product
3 Less hazardous chemical synthesis - Wherever practicable synthetic methods should be
designed to use and generate substances that possess little or no toxicity to human health
and the environment
4 Safer chemical products - Chemical products should be designed to affect their desired
function while minimizing their toxicity
5 Safer solvents and other agents - The use of auxiliary substances (eg solvents
separation agents etc) should be made unnecessary wherever possible and harmless
when used
6 Minimum energy requirements - Energy requirements of chemical processes should be
recognized for their environmental and economic impacts and should be minimized If
possible synthetic methods should be conducted at ambient temperature and pressure
7 Use of renewable raw materials - A raw material or feedstock should be renewable rather
than depleting whenever technically and economically practicable
8 Reduce use of additional chemicals or additional steps - Unnecessary derivatization (use
of blocking groups protection deprotection temporary modification of
physicalchemical processes) should be minimized or avoided if possible because such
steps require additional reagents and can generate waste
46
9 Use of catalysts ndash The use of catalysts reduce energy costs because the reactions take
place at lower temperatures The more specific the catalyst for a particular reaction is the
less it the likelihood of getting additional unwanted products
10 Nature of breakdown of products - Chemical products should be designed so that at the
end of their function they break down into innocuous degradation products and do not
persist in the environment
11 Monitoring to prevent pollution - Analytical methodologies need to be further developed
to allow for real-time in-process monitoring and control prior to the formation of
hazardous substances
12 Minimise chemical accidents - Substances and the form of a substance used in a chemical
process should be chosen to minimize the potential for chemical accidents including
releases explosions and fires
47
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
48
WEEK 10 LESSON 2
TOPIC Qualitative Analysis ndash Identification of cations
Qualitative Analysis involves identifying the constituents of single substances or mixture of
substances
Appearance
An examination of the appearance of a substance can indicate which ion it contains
Appearances of substances
Observation Indication
Blue or blue ndash green Cu2+ salt
Pale green Fe2+ salt
Yellow ndash brown Fe3+ salt
Ammonia smell NH4+ salt
49
Test for cation using sodium hydroxide
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
(d) If no precipitate forms in step b warm gently and test for ammonia
Effect of dilute sodium hydroxide solution
Effect of dilute sodium hydroxide solution Cation
Dropwise Excess
White precipitate Precipitate soluble Ca2+
White precipitate Precipitate insoluble Al3+ Pb2+ Zn2+
Blue precipitate Precipitate insoluble Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
No precipitate ndash ammonia gas
evolved on heating
ndash NH4+
The metal cations all form insoluble hydroxides with sodium hydroxide solution
For example Ca2+ (aq) + 2 OH- (aq) Ca(OH)2 (s)
Ca(OH)2 Cu(OH)2 Fe(OH)2 and Fe(OH)3 are basic and therefore do not react with excess
sodium hydroxide solution Therefore the precipitate does not dissolve in excess sodium
hydroxide solution
Al(OH)3 Pb(OH)2 and Zn(OH)2 are amphoteric Therefore the precipitates react with the excess
sodium hydroxide solution forming soluble salts and the precipitate disappears in excess sodium
hydroxide solution
The NH4+ ion forms a soluble hydroxide However on heating it reacts with the hydroxide ion to
form ammonia and water
NH4+ (aq) + OH- (aq) NH3 (g) + H2O (l)
50
WEEK 10 LESSON 2 WORKSHEET
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P _____________ Q ___________________
R _____________ S ___________________
R + NaOH
______________________________________________________________________________
51
WEEK 10 LESSON 3
TOPIC Qualitative Analysis ndash Identification of cations
Test for cation using ammonia solution (ammonium hydroxide solution)
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
Effect of dilute ammonia (ammonium hydroxide) solution
Effect of dilute ammonia solution Cation
Dropwise Excess
No precipitate ndash Ca2+
White precipitate Precipitate soluble
(forming colourless solution)
Zn2+
White precipitate Precipitate insoluble Al3+ Pb2+
Blue precipitate Precipitate soluble
(forming deep blue solution)
Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
52
Ammonia solution is a weak alkali Metal cations except Ca2+ form insoluble hydroxides with
ammonia solution as with the sodium hydroxide solution
The amphoteric hydroxides Al(OH)3 and Pb(OH)2 and the basic hydroxides Fe(OH)2 and
Fe(OH)3 do not react with excess ammonia solution Therefore the precipitates remain
However Zn(OH)2 and Cu(OH)2 do react with excess ammonia solution to form complex
soluble hydroxides each Hence their precipitates disappear on the addition of excess ammonia
solution
Confirmatory test
After carrying out test for cations using sodium hydroxide solution and ammonia solution the
only cations which cannot be distinguished are Al3+ and Pb2+ A confirmatory test is carried out
to distinguish between the two cations
Confirmatory test
Test Observation Cation Ionic equation
Add potassium
or sodium
iodide solution
Bright yellow precipitate
No precipitate
Pb2+
Al3+
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
53
WEEK 10 LESSON 3 WORKSHEET
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A __________ B ________________ C ________________________
(b) State the inference after Test 2
C _______________________
(c) Write an ionic equation to support your answer in (b) above
___________________________________________________________________________
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
54
ANSWERS TO WORKSHEETS
55
WEEK 5 LESSON 1 WORKSHEET ANSWERS
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
Answer
Zinc + Iron (II) sulphate Zinc is higher in the electrochemical series and therefore displace
iron ions in iron (II) sulphate
Equation Zn (s) + FeSO4 (aq) ZnSO4 (aq) + Fe (s)
Ionic equation Zn (s) + Fe2+ (aq) Zn2+ (aq) + Fe (s)
Iron + Zinc sulphate No reaction iron is lower in the electrochemical series and cannot
displace the zinc ions in zinc sulphate
56
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
Answer
X displaces lead from an aqueous solution of its salts
X (s) + Pb2+ (aq) Xn+ (aq) + Pb (s)
rarr X is more reactive than Pb
X did not react with iron salts
rarr X is less reactive than Fe
Y burns very easily
Y is more reactive than Fe and Pb (both forming their corresponding oxide at a slower rate)
From electrochemical series Fe is higher and therefore more reactive than Pb
Order of reactivity
Y (most reactive) gt Fe gt X gt Pb (least reactive)
57
WEEK 5 LESSON 2 WORKSHEET ANSWERS
1
Metal Reactivity with acid
Copper X
Magnesium
Aluminium
Silver X
Zinc
58
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
Answer
Y and Z are the most reactive since they can react with dilute acid
Z is more reactive than Y since a reaction occurs with Z is added to an aqueous solution of Y
X is less reactive than W since it does not occur in nature as compounds
Order of reactivity Z (most reactive) gt Y gt W gt X
59
WEEK 5 LESSON 3 WORKSHEET ANSWERS
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
Answer
Ease of decomposition (from easiest to decompose to most difficult to decompose)
B rarrD rarrArarr C
Reactivity (most reactive to least reactive)
C (most reactive) gt A gt D gt B (least reactive)
60
WEEK 6 LESSON 1 Worksheet Answers
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
Potassium Zinc Copper
Calcium Lead Gold
Magnesium Iron
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
Aluminium is extracted from its ore bauxite through the process of electrolysis
Cryolite is added to bauxite to lower the melting point to about 900 0C The melting point of
bauxite is very high (about 2040 0C) It is difficult and expensive to keep the molten aluminium
oxide at this temperature
Reaction at the cathode Al3+ (l) + 3 e- Al (l)
61
WEEK 6 LESSON 2 Worksheet Answers
(a) What are the three raw materials that are added through the top of the blast
furnace during the extraction process for iron
Coke (carbon)
iron ore (haematitie mainly iron (II) oxide)
limestone (calcium carbonate)
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
Coke ndash coke burns to produce carbon dioxide The carbon dioxide further reacts with coke to
form carbon monoxide (reducing agent in the process)
C (s) + O2 (g) CO2 (g)
C (s) + CO2 (g) 2 CO
Haematite ndash iron ore provides the iron which is reduced by the carbon monoxide to produce
iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + CO2 (g)
Limestone ndash decomposes to form calcium oxide The calcium oxide reacts with the impurity
silicon dioxide to form slag (calcium silicate)
CaCO3 (s) CaO (s) + CO2 (g)
CaO (s) + SiO2 (l) CaSiO3(l)
62
WEEK 6 LESSON 3 Worksheet Answers
(a) Define the term alloy
An alloy is a material made from a mixture of two or more metals
(b) State 3 general advantages that alloys have over the individual metals they are made
from
They are harder stronger and more resistant to corrosion
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
1 High strength
2 Low density
Uses
1 Used to make aircraft bodies
2 Used to make space satellites
63
WEEK 7 LESSON 1 WORKSHEET ANSWERS
(a) Define the term corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
The paint forms a barrier which stops contact with air or water and the iron Hence rusting
will not take place
However when the paint is scratched that part of the iron nail is exposed to air or water and
rusting will take place
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
Magnesium is higher in the electrochemical series and will be oxidised in preference to iron
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
Aluminium is partly protected from corrosion by its coat of aluminium oxide However as the
iron rust it flakes and fall off and the rusting process continues
64
WEEK 7 LESSON 2 WORKSHEET ANSWERS
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
Magnesium is the ion found in chlorophyll Chlorophyll plays a vital part in the process of
photosynthesis A deficiency in magnesium will lead to low chlorophyll level in the tomato
plants and hence reduce the process of photosynthesis There will be less food storage and
hence will lead to smaller yield of tomatoes
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Any correct harmful effect of lead on health or environment
Any correct harmful effect of mercury on health or environment
65
WEEK 7 LESSON 3 WORKSHEET ANSWERS
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
(b) Write the ionic equation for the above reaction
2 Br- (aq) + Cl2 (aq) 2 Cl- (aq) + Br2 (aq)
(c) Identify the oxidising agent in the reaction
Cl2 (aq)
(d) Justify your answer in part (c) in terms of oxidation number
There is a reduction of the oxidation number for chlorine from 0 to ndash1
hence it has been reduced Therefore chlorine is the oxidising agent
66
WEEK 8 LESSON 1 WORKSHEET ANSWERS
Describe the laboratory preparation of oxygen gas
Oxygen is prepared in the laboratory by the decomposition of hydrogen peroxide
A suitable catalyst is manganese (IV) oxide
Drying agent silica gel OR anhydrous calcium chloride OR conc sulphuric acid
The gas is collected by downward delivery since oxygen is slightly denser than air
Balanced chemical equation 2 H2O2 (aq) 2 H2O (l) + O2 (g)
67
WEEK 8 LESSON 2 WORKSHEET ANSWERS
Describe the laboratory preparation of carbon dioxide gas
Carbon dioxide is commonly prepared in the laboratory by the reacting hydrochloric acid and
marble chips (calcium carbonate)
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
The carbon dioxide gas is collected by downward delivery since it is denser than air
Balanced chemical equation
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
68
WEEK 8 LESSON 3 WORKSHEET ANSWERS
Describe the laboratory preparation of ammonia gas
An ammonium salt (ammonium chloride) and a base (sodium hydroxide) are mixed together and
heated
Calcium oxide is used as the drying agent Calcium chloride and concentrated sulphuric acid
cannot be used since ammonia can react with them
The gas is collected by upward delivery since ammonia is less dense than air
Balanced chemical equation
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
69
WEEK 9 LESSON 1 WORKSHEET ANSWERS
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Carbon dioxide Put out fires
Oxygen Welding metals
Carbon dioxide Create lsquofizzrsquo in drinks
Oxygen Used in steel production
Oxygen Aerobic respiration
70
WEEK 9 LESSON 2 WORKSHEET ANSWERS
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Chlorine Used to make sodium hypochlorite
Sulphur Used as a fungicide on plant materials
Carbon (graphite) Used for lsquoleadrsquo in pencils
Phosphorus Used in the manufacture of bronze alloys
Nitrogen Used in the manufacture of nitric acid
Silicon Used in the manufacture of computer chips
Nitrogen Phosphorus Used to make fertilisers
71
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
Green Chemistry is using principles that reduceeliminate the use of hazardous materials in
the design manufacture and application of chemical products
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
Makes the environment safer
Reduces waste
Creates new jobs
Reduces respiratory illnesses
Atom economy
72
WEEK 10 LESSON 2 WORKSHEET ANSWERS
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P Cu2+ Q Fe2+
R Fe3+ S Ca2+
Ionic equation for R + NaOH
Fe3+ (aq) + 3 OH- (aq) Fe(OH)3 (s)
73
WEEK 10 LESSON 3 WORKSHEET ANSWERS
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A Fe3+ B Ca2+ C Al3+ Pb2+
(b) State the inference after Test 2
C Pb2+
(c) Write an ionic equation to support your answer in (b) above
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
11 Qualitative Analysis
ndash Test for gases
Qualitative Analysis
ndash Identification of
anions
Qualitative Analysis
ndash Identification of
anions
12 Problem solving of
Past CSEC Chemistry Paper 2
on topics completed in the term
13
14
15
2
WEEK 11 LESSON 1
TOPIC Qualitative Analysis ndash Test for gases
Identification of gases
Gas Colour Odour Effect on moist
litmus
Method of identification
Oxygen
O2
Colourless Odourless Neutral ndash no
effect
Relights a glowing splint
Hydrogen
H2
Colourless Odourless Neutral ndash no
effect
Lighted splint lsquopopsrsquo if air is also
present
Carbon
dioxide
CO2
Colourless Odourless Weakly acidic ndash
blue to slightly
red
A white precipitate forms in
limewater
Ca(OH)2 (aq) + CO2
CaCO3 (s) + H2O (l)
Precipitate redissolves on
continued bubbling
CaCO3 (s) + H2O (l) + CO2 (g)
Ca(HCO3)2 (aq)
Ammonia
NH3
Colourless Pungent Alkaline ndash red
to blue (only
common
alkaline gas)
Turns moist red litmus blue forms
dense white fumes with hydrogen
chloride gas
NH3 (g) + HCl (g) NH4Cl (s)
Gas Colour Odour Effect on moist
litmus
Method of identification
3
Sulphur
dioxide
SO2
Colourless Choking
smell
Acidic ndash blue to
red
Turns acidified potassium
manganate (VII) solution from
purple to colourless
Turns acidified potassium
dichromate (VI) solution from
orange to green
Chlorine
Cl2
Yellow ndash
green
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Bromine
Br2
Red ndash
brown
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Nitrogen
dioxide
NO2
Red ndash
brown
Irritating
smell
Acidic blue to
red
Turns moist blue litmus red but
does not bleach it
Water
vapour
H2O
Colourless Odourless Neutral ndash no
effect
Turns anhydrous cobalt (II)
chloride from blue to pink
Turns anhydrous copper (II)
sulphate from white to blue
4
WEEK 11 LESSON 1 WORKSHEET
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless
Yellow ndash green
Red ndash brown
Gases according to their odour
Odour of gas Identity of gas
Odourless
Pungent smell
Choking smell
Irritating smell
5
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect
Red to blue
Blue to red
Blue to red then bleaches it
6
WEEK 11 LESSON 2
TOPIC Qualitative Analysis ndash Identification of anions
Effect of heating
Method Heat a sample of the solid in a dry test tube
Effect of heating
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) not
of K or Na
CO32- (s) O2- (s) + CO2 (g)
Oxygen evolved NO3- of K or Na 2 NO3
- (s) 2 NO2- (s) + O2
(g)
Oxygen and nitrogen
dioxide evolved
NO3- of Ca and below
in reactivity series
4 NO3- (s) 2 O2- (s) + 4 NO2
(g) + O2
(g)
Sulphur dioxide evolved SO32- SO3
2- O2- (s) + SO2 (g)
Effect of dilute acid
Add dilute hydrochloric acid or nitric acid to a sample of the solid Warm if no reaction occurs
when cold
Effect of dilute acid
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) CO32- (s) + 2 H+ (aq) H2O (l) + CO2 (g)
Sulphur dioxide evolved SO32- SO3
2- (s) + 2 H+ (aq) H2O (l) + SO2 (g)
7
Effect of concentrated acid
Add concentrated sulphuric acid to a sample of the solid Warm if not reaction occurs when cold
Effect of concentrated sulphuric acid
Observation Anion
Carbon dioxide evolved CO32- or HCO3
-
Sulphur dioxide evolved SO3-
Hydrogen chloride evolved Cl-
Hydrogen bromide (colourless) and bromine
vapour (brown) evolved
Br-
Black iodine present and purple iodine vapour
evolved
I-
8
WEEK 11 LESSON 2 WORKSHEET
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater
Produces a gas which relights a glowing splint as the only gas
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green
Produces a gas forms a precipitate in limewater
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia
Black iodine present and purple iodine vapour evolved
9
WEEK 11 LESSON 3
TOPIC Qualitative Analysis ndash Identification of anions
Test for the halides ndash using silver nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous silver nitrate and
observe the precipitate Add ammonia solution and observe the solubility of the precipitate
Test for halides using silver nitrate solution
Effect of silver
nitrate solution
Anion Explanation Effect of aqueous
ammonia
White precipitate ndash
turns white in
sunlight
Cl- Ag+ (aq) + Cl- AgCl (s) Precipitate soluble
Cream precipitate ndash
turns yellow ndash green
in sunlight
Br- Ag+ (aq) + Br- AgBr (s) Precipitate slightly
soluble
Pale yellow
precipitate
I- Ag+ (aq) + I- AgI (s) Precipitate insoluble
Test for the halides ndash using lead nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous lead nitrate and
observe the precipitate
Test for halides using lead nitrate solution
Effect of lead nitrate solution Anion Explanation
White precipitate Cl- Pb2+ (aq) + 2 Cl- PbCl2 (s)
Pale yellow Br- Pb2+ (aq) + 2 Br- PbBr2 (s)
Deep yellow I- Pb2+ (aq) + 2 I- PbI2 (s)
10
Effect of barium nitrate or chloride solution followed by dilute acid
Make a solution of the solid Add barium nitrate or chloride solution and observe the precipitate
Add dilute hydrochloric or nitric acid warn if necessary and observe the solubility of the
precipitate
Effect of barium nitrate or chloride solution followed by dilute acid
Effect of
Ba(NO3)2 (aq)
or BaCl2 (aq)
Effect of HCl (aq)
or HNO3 (aq)
Anion Explanation
White precipitate Precipitate insoluble SO42- Ba2+ (aq) + SO4
2- (aq) BaSO4 (s)
BaSO4 does not react with dilute acids
White precipitate Precipitate soluble ndash
CO2 evolved
CO32- Ba2+ (aq) + CO3
2- (aq) BaCO3 (s)
BaCO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + CO2 (g)
White precipitate Precipitate soluble ndash
SO2 evolved on
warming
SO32- Ba2+ (aq) + SO3
2- (aq) BaSO3 (s)
BaSO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + SO2 (g)
11
WEEK 11 LESSON 3 WORKSHEET
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
(Ionic equation required)
12
WEEK 12 LESSON 1 WORKSHEET
(a) The Caribbean islands are known for their many resources For example the ore of
aluminium is found in Jamaica and Guyana
(i) Briefly describe the extraction of aluminium from its named ore Include in your
description one ionic equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Although aluminium ore is mined in the Caribbean the extraction of aluminium usually
takes place in other countries Suggest ONE reason why it may be difficult to extract
aluminium in the Caribbean
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) An alloy can be described as a lsquomixed metal solutionrsquo Aluminium forms an alloy with
magnesium that is used to make an aircraft
13
Identify this alloy and suggest why it is better to use it rather than the pure metal in the
manufacture of aircraft
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) ldquoSome metals can be useful to man yet harmful to the environmentrdquo Comment on this
statement with reference to mercury
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 12 LESSON 2 Worksheet
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate formed
Soluble in excess
15
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate formed
Insoluble in excess
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate formed
(Ionic equation required)
16
WEEK 12 LESSON 3 Worksheet
Dry ammonia gas can be produced in a school laboratory
(a) Identify TWO reagents that are necessary for the laboratory production of ammonia
______________________________________________________________________________
______________________________________________________________________________
(b) Two common drying agents used in the laboratory are calcium oxide and concentrated
sulphuric acid However calcium oxide is the preferred choice for drying ammonia gas
Explain why concentrated sulphuric acid is now used Include in your answer a balanced
chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) When gases are prepared in the laboratory there are three main ways in which they can
be collected
- Upward delivery
- Downward delivery
- Displacement of water
(i) What TWO other factors should be considered when choosing an appropriate method for
the collection of gases in the laboratory
______________________________________________________________________________
______________________________________________________________________________
(ii) Identify ONE of the three methods that is best suited for the collection of ammonia gas in
the laboratory Explain why EACH of the other two methods would NOT have been
appropriate
______________________________________________________________________________
17
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(d) Hence draw a labelled diagram of the apparatus which could be used for the preparation
of dry ammonia in the laboratory
Be sure to identify in your diagram
- where the reagents are placed
- where the ammonia is dried and
- where the ammonia is collected
18
WEEK 13 LESSON 1 Worksheet
(a) In solution two metals A and B form A+ and B2+ ions respectively Metal A displaces Fe
from a solution containing Fe2+ ions but metal B does NOT
(i) Arrange the metals A B and Fe in order of reactivity from LEAST reactive to MOST
reactive Write a balanced chemical equation to show the reaction between metal A and
Fe2+ ions
______________________________________________________________________________
______________________________________________________________________________
(ii) Metal A is placed in a solution of copper (II) sulphate CuSO4 (aq) Write an equation for
the reaction State ONE observable change that will occur and explain why this reaction
takes place
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) For EACH metal A and B state ONE method that can be used to extract it from its
respective oxide Give a reason for EACH answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
19
______________________________________________________________________________
(b) Metal alloys are often used for making objects found in our daily lives Name an alloy of
iron and state ONE of its uses
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 13 LESSON 2 Worksheet
(a) Many important biological processes in plants and animals depend on the specific roles
of certain metal ions
(i) Farmer Jones reaped a crop of tomatoes and reported that the yield was far below what
was expected Analysis of the soil revealed that there was a deficiency of magnesium
Discuss the importance of magnesium in plant health and explain how a magnesium
deficiency can result in the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE other metal ion which is important to plant health and state the result of its
deficiency
______________________________________________________________________________
______________________________________________________________________________
21
(b) Many years ago car exhaust fumes were known to contain compounds of metals and
non ndash metals which could negatively impact both humans and the environment Identify
ONE metal and ONE non ndash metal whose compounds were present in car exhaust fumes
Discuss the effect of these compounds on human health and the environment
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) Define lsquogreen chemistryrsquo and discuss the measures that have been taken to produce a
lsquogreenerrsquo automotive fuel
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
22
WEEK 13 LESSON 3 Worksheet
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
Zn2+ ions are present
23
WEEK 14 LESSON 1 Worksheet
(a) Metal alloys are often used in place of metals because of their enhanced properties
(i) Define the term lsquoalloyrsquo
______________________________________________________________________________
______________________________________________________________________________
(ii) Name ONE alloy of aluminium and state its use based on one of its enhanced properties
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) A student conducted an experiment to investigate the reactivity of each of the following
metals (copper iron zinc and lead) by using solutionPs of their sulphate salts
The data presented in the table below shows whether a visible chemical reaction took
place when each metal was added to the four sulphate solutions
Key Visible chemical reaction took place
X No visible chemical reaction
CHEMICAL REACTION OF METALS IN SULPHATE SOLUTIONS
Sulphate solution Cu Fe Zn Pb
CuSO4 X
FeSO4 X X X
ZnSO4 X X X X
PbSO4 X X
24
(i) State which of the TWO metals is more reaction Fe or Zn Give a reason for our answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Using the data in the previous Table deduce the order of reactivity of the four metals Cu
Fe Zn and Pb from the most reactive to the least reactive metal
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The student recorded the following observations from the reaction between the iron and
copper (II) sulphate solution
Observations Reddish ndash brown solid coating formed on the iron strip
Blue colour of the solution changed to dirty green
Account for the observations made from the reaction between the iron and copper (II)
sulphate solution
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iv) Write an ionic equation including state symbols for the reaction between the iron and
copper (II) sulphate solution
______________________________________________________________________________
25
(c) Some metal compounds are health and environmental hazards
(i) Identify which of the metals used in the experiment in (b) is MOST hazardous to the
environment
______________________________________________________________________________
______________________________________________________________________________
(ii) State TWO harmful effects of continuous exposure to the metal identified in (c) (i) on
human beings
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
26
WEEK 14 LESSON 2 Worksheet
(a) Carbon is found in the form of diamond and graphite and is a main component in many
naturally occurring compounds such as organic matter and carbon dioxide gas
(i) State ONE way in which diamond differs physically from graphite
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE similarity between diamond and graphite other than they both contain carbon
______________________________________________________________________________
______________________________________________________________________________
(b) Carbon can react with a limited supply of oxygen to form carbon monoxide which can
negatively affect human health
(i) Write a balanced chemical equation including state symbols to show the formation of
carbon monoxide
______________________________________________________________________________
(ii) State TWO effects of carbon monoxide inhalation on the human body
______________________________________________________________________________
______________________________________________________________________________
(c) Jamal wants to prepare and collect a sample of carbon dioxide gas in the laboratory using
calcium carbonate
(i) Write a balanced chemical equation including state symbols for the laboratory
preparation of carbon dioxide gas from calcium carbonate
______________________________________________________________________________
______________________________________________________________________________
(ii) Draw a clearly labelled diagram to show the arrangement of the apparatus and materials
that could be used in the laboratory to prepare and collect the carbon dioxide gas
(iii) State ONE use of carbon dioxide as it relates to the beverage industry
______________________________________________________________________________
27
WEEK 14 LESSON 3 Worksheet
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
(Ionic equation required)
Suggest a possible identity of the solid R __________________________
28
WEEK 15 LESSON 1 Worksheet
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a small
portion of solid Y gently at
first and then strongly
Colourless gas evolved
with a choking odour
Turns acidified potassium
dichromate solution from
orange to green
(ii) To the remaining portion
of solid Y add 20 cm3 of
distilled water stir to dissolve
and filter Collect the filtrate
and divide into 3 equal
portions
Filtrate is pale green in
colour
(iii) To the first portion of the
filtrate from (ii) add aqueous
sodium hydroxide slowly
until in excess
A green precipitate
Insoluble in excess sodium
hydroxide
Ionic equation required
29
TEST OBSERVATIONS INFERENCES
(iv) To the second portion of
the filtrate from (ii) add
aqueous silver nitrate
followed by aqueous
ammonia
White precipitate
Soluble in aqueous
ammonia
(v) To the third portion of the
filtrate from (ii) add aqueous
barium nitrate followed by
aqueous hydrochloric acid
White precipitate formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with the
evolution of a colourless
gas with a choking smell
30
WEEK 15 LESSON 2 Worksheet
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
31
WEEK 15 LESSON 3 Worksheet
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in excess
aqueous NH3
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change
32
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
warm filter and then divide
the filtrate into two portions
Vigorous effervescence
observed upon addition of
dilute HNO3
Gas evolved turns lime water
cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Cu2+ ions present
33
ANSWERS TO WORKSHEETS
34
WEEK 11 LESSON 1 WORKSHEET ANSWERS
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless O2 H2 CO2 NH3 SO2 H2O
Yellow ndash green Cl2
Red ndash brown Br2 NO2
Gases according to their odour
Odour of gas Identity of gas
Odourless O2 H2 CO2 H2O
Pungent smell NH3
Choking smell SO2 Cl2 Br2
Irritating smell NO2
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect Neutral O2 H2 H2O
Red to blue Alkaline NH3
Blue to red Acidic CO2 SO2 NO2
Blue to red then bleaches it Acidic Cl2 Br2
35
WEEK 11 LESSON 2 WORKSHEET ANSWERS
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-) not
of K or Na
Produces a gas which relights a glowing splint as the only gas NO3- of K or Na
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green SO32-
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-)
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia Cl-
Black iodine present and purple iodine vapour evolved I-
36
WEEK 11 LESSON 3 WORKSHEET ANSWERS
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Br-
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
Cl-
Ag+ (aq) + Cl- AgCl (s)
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow Br-
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
SO42-
Ba2+ (aq) + SO42- (aq)
BaSO4 (s)
(Ionic equation required)
37
WEEK 12 LESSON 1 Worksheet Answers
(a) (i)
The ore bauxite is purified
The purified bauxite is dissolved in molten cryolite
The aluminium oxidecryolite solution is then eletrolysed
Equation at the cathode Al3+ (l) + 3 e- Al (l)
Equation at the anode 2 O2- (l) ndash 4 e- O2 (g)
(ii) The process is too expensive mainly because too much electricity or energy is needed
(b) The alloy of Al and Mg is magnalium It is less dense than the pure metals and hence allow
aircraft to be lighter It is also stronger than the pure metals and hence allows aircraft to last
longer since it is not easily destroyed
(c) Your answer should cater for the following aspects
Benefits of mercury to humans for example in thermometers barometers in dentistry
and gold mining
Entry of mercury to the environment For example this could have been through broken
thermometers barometers or lightbulbs or improper disposal of them or batteries and
indiscriminate use in gold mining in Guyana
The identification of a negative impact on the environment such as poisoned fish and the
persons who eat the fish death mood swings and psychosis
38
WEEK 12 LESSON 2 Worksheet Answers
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas
evolved
NO2 evolved OR nitrates
present OR
Br2 gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate
formed
Soluble in excess
Pb2+ Zn2+ Al3+ or Ca2+
present
Pb2+ Zn2+ Al3+ or present
39
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate
formed
Insoluble in excess
Pb2+ Zn2+ Al3+ or present
Pb2+ or Al3+ present
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate
formed
Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
40
WEEK 12 LESSON 3 Worksheet Answers
(a) an ammonium salt and a strong alkali
(b) Ammonia is basic and it will react with H2SO4
Equation 2 NH3 (aq) + H2SO4 (aq) (NH4)2SO4 (aq)
(c) (i) ndash Density of the gas relative to air ndash The solubility of the gas in water
(ii) Ammonia is collected by upward delivery
It cannot be collected by downward delivery since ammonia is less dense than air
It cannot be collected by displacement of water since it is soluble in water
(d)
41
WEEK 13 LESSON 1 Worksheet Answer
a) i) B ˂ Fe ˂ A
2A (s) + Fe 2+ (aq) rarr 2A+ (aq) + Fe (s)
ii) 2A (s) + CuSO4 (aq) rarr A2SO4 (aq) + Cu (s)
Observation blue colour fades gets lighter OR brown solid forms is deposited OR metal A
decreases in size dissolves
Explanation Metal A is higher (than Fe which is higher) than Cu in the reactivity series OR
Metal A is more reactive (than Fe which is more reactive) than Cu so Metal A can displace Cu
iii) Metal A can be extracted by electrolysis (of its molten oxide) because Metal A is a very
reactive metal is high in the reactivity series forms stable oxides needs a lot of energy to be
extracted and very reactive metals are extracted by electrolysis
Metal B can be extracted by heating with carbon carbon monoxide OR by chemical reduction
of the oxide because Metal B is less reactive than Fe is low in the reactivity series forms less
stable oxides does not need a lot of energy to be extracted and oxides of less reactive metals are
easily reduced
b) Alloy of iron steel
Use of alloy making buildings bridges ships motor vehicles furniture utensils
42
WEEK 13 LESSON 2 Worksheet Answer
(a) (i)
Magensium is the metal ion found in chlorophyll
Chlorophyll is essential for photosynthesis
A deficiency in magnesium will result in low chlorophyll yellow leaves and a reduction in
photosynthesis
Hence there will be low carbohydrates or energy production
Hence small fruits stunted growth and lower yield will result
(ii)
Metal ion Results of deficiency
Potassium Stunted growth premature loss of leaves yellowing of leaves curling of leaf tips
Calcium Growth abnormalities in tips of roots and shoots curling of leaves
Iron Yellowing of leaves
Zinc Low chlorophyll content yellowing of leaves
Manganese Yellowing of leaves poor flavors in some crops for example potato
(b)
Metal Lead is present in some types of gasoline Upon combustion lead compounds escape into
the atmosphere It accumulates in body tissues and slowly poisons the person It causes mental
illness
Non ndash metal SulphurSulphur dioxide or NitrogenNitrogen dioxide
Dissolves in rain water to form acid rain or cause respiratory illnessproblems Acid rain can
cause corrosion damage in buildings
(c)
Green chemistry is the utilisation of a set of principles that reduces or eliminates the use or
generation of hazardous substances
43
Automotive fuels are now produced without lead so as to eliminate the release of lead
compounds into the atmosphere
Low sulphur fuel is being produced with much reduced sulphur content which causes a reduction
of sulphur dioxide release into the atmosphere
44
WEEK 13 LESSON 3 Worksheet Answer
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
gas turns litmus blue
red
brown gas
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
white precipitate
precipitate soluble in
excess
Zn2+ ions are present
45
WEEK 14 LESSON 1 Worksheet Answers
(a)(i) An alloy is a material made from a mixture of two or more metals
(ii) Any suitable answer chosen from below
Alloy Enhance Property Use
Duralumin High strength
Low density
Light
Hard
Used to make aircraft bodies
space satellites
Magnalium Light
Hard
Easier to weld
Corrosion resistant
Strong
High ductability
Used in pyrotechnics
(fireworks)
Mirrors
Aircraft parts
To make scientific
instruments
Used to make marine castings
Alchlad Strong
Corrosion resistant
Cladding for buildings
(b) (i) Zinc is more reactive than iron
Zinc displaces iron from iron (II) sulphate
Zinc is higher in the reactivity series than iron
Iron does not displace zinc from zinc sulphate
(ii) Order of reactivity Zn gt Fe gt Pb gt Cu
(iii) Reddish brown solid ndash copper metal formed
46
Dirty green solution ndash presence of Fe2+ ion
(iv) Fe (s) + Cu2+ (aq) Fe2+ (aq) + Cu (s)
(c) (i) Lead
(ii) Any two correct harmful effects of lead on the body
Impedes brain development (in young children)
Affectimpede development of the immune system in humans
Affecthamper development of nervous system in humans
Long term exposure can result in kidney and liver damage
Mental retardation
Anaemia
Death
47
WEEK 14 LESSON 2 Worksheet Answers
a) i) Diamond is transparent clear Graphite is opaque black
OR hard OR brittle
OR does not conduct electricity OR conducts electricity
a) ii) Both have a macromolecular giant molecular giant covalent structure (lattice)
OR Both have high melting point boiling point
OR Both are insoluble in water organic solvent
b) i) 2C (s) + O2 (g) rarr 2CO (g)
ii) CO reduction in amount of oxygen carried by (the haemoglobin in the red blood
cells of) the blood
Headache OR dizziness OR nausea OR fatigue OR loss of consciousness OR
death
c) i) CaCO3 (s) + 2HCl (aq) rarr CaCl2 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) + H2SO4 (aq) rarr CaSO4 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) rarr CaO (s) + CO2 (g)
48
ii)
OR
OR
Entirely closed system thistle funnel below the level of the liquid OR tap that could be
closed
Two reagents labelled CaCO3marble chips and HCl H2SO4 or heat source
collection of CO2 upward displacement of air OR over watersulphuric acid OR in gas
syringe
iii) CO2 use put in aerated drinks carbonated beverages
OR put in carbon dioxide fire extinguishers
49
WEEK 14 LESSON 3 Worksheet Answers
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
NH4+
NH4+ confirmed OR
NH3 (g) produced
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
Cl- ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation required)
Suggest a possible identity of the solid R NH4Cl (ammonium chloride)
50
WEEK 15 LESSON 1 Worksheet Answers
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a
small portion of solid Y
gently at first and then
strongly
Colourless gas
evolved with a
choking odour
Turns acidified
potassium dichromate
solution from orange
to green
SO2 evolved
Presence of a sulphite
(ii) To the remaining
portion of solid Y add 20
cm3 of distilled water stir
to dissolve and filter
Collect the filtrate and
divide into 3 equal portions
Filtrate is pale green
in colour
Fe2+ ions present
(iii) To the first portion of
the filtrate from (ii) add
aqueous sodium hydroxide
slowly until in excess
A green precipitate
Insoluble in excess
sodium hydroxide
Fe2+ ions present
Fe2+ (aq) + 2 OH- (aq) Fe(OH)2 (s)
Ionic equation required
TEST OBSERVATIONS INFERENCES
(iv) To the second portion
of the filtrate from (ii) add
aqueous silver nitrate
White precipitate
Soluble in aqueous
ammonia
Cl- ions present
51
followed by aqueous
ammonia
(v) To the third portion of
the filtrate from (ii) add
aqueous barium nitrate
followed by aqueous
hydrochloric acid
White precipitate
formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with
the evolution of a
colourless gas with a
choking smell
SO32- CO3
2- SO42- ions present
SO32- ions present
52
WEEK 15 LESSON 2 Worksheet Answers
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
Chloride ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
Cu2+ ions present
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
X contains a reducing agent
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
SO32- SO4
2- or CO32- ions are
present
SO32- ions are present
53
WEEK 15 LESSON 3 Worksheet Answers
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
White ppt
Ppt soluble in excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in
excess aqueous NH3
Al3+ Pb2+ Zn2+ present
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change Cl- Br- I- absent
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
Vigorous effervescence
observed upon addition of
dilute HNO3
CO2 evolved OR
Carbonate present
54
warm filter and then divide
the filtrate into two portions
Gas evolved turns lime
water cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
Cu2+ (aq) + OH- (aq)
Cu(OH)2 (s)
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Blue ppt
ppt dissolves in excess
NH3 to give a deep blue
solution
Cu2+ ions present
55
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
REFERENCES
Hunte-King J Maragh P Nagir F amp Norris R (2013) Chemistry for CSEC United
Kingdom Nelson Thornes Ltd
Remy C Mason L Lambert N amp Mohammed M (2007) Chemistry for CSEC England and
Wales Pearson Education Limited
Taylor M amp Chung-Harris T (2010) CXC Chemistry England Macmillan Publishers
Limited
Tindale A (2016) Chemistry A Concise Revision for CXC London HarperCollins Publishers
Limited
9
WEEK 1 LESSON 3
TOPIC Chemical properties of metals
Action of oxygen
Most metals react with oxygen or air to form the corresponding oxide These oxides are basic
oxides with the exception of aluminium zinc and lead which form amphoteric oxides Metals
lower in the electrochemical series do not react
Metal Reaction with air or oxygen
Potassium K
Burn very easily forming oxide
eg 4 Na (s) + O2 (g) 2 Na2O (s)
Sodium Na
Calcium Ca
Magnesium Mg
Aluminium Al
Burn especially if powered forming oxide
eg 4 Al (s) + 3 O2 (g) 2 Al2O3 (s)
Zinc Zn
Iron Fe
Lead Pb Do not burn form oxide when heated strongly
Copper Cu
Silver Ag No reaction
10
WEEK 1 LESSON 3 WORKSHEET
Write balanced chemical equations for the reaction of the named metals and air or oxygen
State the nature of the oxide formed (basic or amphoteric)
Potassium + Oxygen
______________________________________________________________________________
Sodium + Oxygen
______________________________________________________________________________
Calcium + Oxygen
______________________________________________________________________________
Magnesium + Oxygen
______________________________________________________________________________
Aluminium + Oxygen
______________________________________________________________________________
Zinc + Oxygen
______________________________________________________________________________
11
Iron + Oxygen
______________________________________________________________________________
Lead + Oxygen
______________________________________________________________________________
Copper + Oxygen
______________________________________________________________________________
Silver + Oxygen
______________________________________________________________________________
12
WEEK 2 LESSON 1
TOPIC Chemical properties of metals
Action of water
Metals high in the electrochemical series react with cold water to produce the metal hydroxide
and hydrogen
Reactive metals slightly lower in the electrochemical series react very slowly or not at all with
water However they may react with hot water or steam to produce the corresponding metal
oxide and hydrogen
Metals lower than hydrogen in the electrochemical series do not react with water
Metal Reaction with water or steam
Potassium K React with cold water forming metal hydroxide and hydrogen
eg Ca (s) + 2 H2O (l) Ca(OH))2 (aq) + H2 (g) Sodium Na
Calcium Ca
Magnesium Mg React with steam forming metal oxide and hydrogen
eg Zn (s) + H2O (g) ZnO (s) + H2 (g) Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
13
WEEK 2 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with water (or
steam if reaction does not occur with water)
Potassium + WaterSteam
______________________________________________________________________________
Sodium + WaterSteam
______________________________________________________________________________
Calcium + WaterSteam
______________________________________________________________________________
Magnesium + WaterSteam
______________________________________________________________________________
Aluminium + WaterSteam
______________________________________________________________________________
Zinc + WaterSteam
______________________________________________________________________________
14
Iron + WaterSteam
______________________________________________________________________________
Copper + WaterSteam
______________________________________________________________________________
Silver + WaterSteam
______________________________________________________________________________
15
WEEK 2 LESSON 2
TOPIC Chemical properties of metals
Action of dilute acids
Metals above hydrogen in the electrochemical series react with dilute acids to form a salt and
hydrogen gas They react with hydrochloric acid to form the metal chloride (a salt) and hydrogen
gas They also react with dilute suphuric acid to form the metal sulphate (a salt) and hydrogen
gas
Metal Reaction dilute hydrochloric or sulphuric acid
Potassium K Violent reaction forming a salt and hydrogen gas
eg 2 Na (s) + 2 HCl (aq) 2 NaCl (aq) + H2 (g) Sodium Na
Calcium Ca Vigorous reaction forming a salt and hydrogen gas
eg Mg (s) + 2 HCl (aq) MgCl2 (aq) + H2 (g) Magnesium Mg
Aluminium Al React forming a salt and hydrogen gas
eg Fe (s) + 2 HCl (aq) FeCl2 (aq) + H2 (g) Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
16
WEEK 2 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with
hydrochloric acid
Metal Balanced equation for reaction with hydrochloric acid
Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Copper
Silver
17
WEEK 2 LESSON 3
TOPIC Reactions of metal compounds
Reactions of metallic oxides with dilute acid
Metal oxides react with dilute hydrochloric acid or sulphuric acid to produce a salt and water
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
Some of these reactions may be slow and can be speeded up by adding heat
For example
zinc oxide + hydrochloric acid zinc chloride + water
ZnO (s) + 2 HCl (aq) ZnCl2 (aq) + H2O (l)
magnesium oxide + hydrochloric acid magnesium chloride + water
MgO (s) + 2 HCl (aq) MgCl2 (aq) + H2O (l)
aluminium oxide + sulphuric acid aluminium sulphate + water
Al2O3 3 H2SO4 (aq) Al2(SO4)3 (aq) + 3 H2O (l)
calcium oxide + sulphuric acid calcium sulphate + water
CaO H2SO4 (aq) CaSO4 (aq) + H2O (l)
18
WEEK 2 LESSON 3 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal oxides with the
corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium oxide Hydrochloric acid
Sodium oxide Sulphuric acid
Calcium oxide Hydrochloric acid
Magnesium oxide Sulphuric acid
Aluminium oxide Hydrochloric acid
Zinc oxide Sulphuric acid
19
WEEK 3 LESSON 1
TOPIC Reactions of metal compounds
Reactions of metallic hydroxides with dilute acid
Metal hydroxides react with dilute acids to form a salt and water in a neutralisation reaction
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
For example
magnesium hydroxide + hydrochloric acid magnesium chloride + water
Mg(OH)2 (aq) + 2 HCl (aq) MgCl2 (aq) + 2 H2O (l)
sodium hydroxide + hydrochloric acid sodium chloride + water
NaOH (aq) + HCl (aq) NaCl (aq) + H2O (l)
potassium hydroxide + sulphuric acid potassium sulphate + water
2 KOH + H2SO4 (aq) K2SO4 (aq) + 2 H2O (l)
calcium hydroxide + sulphuric acid calcium sulphate + water
Ca(OH)2 (aq) + H2SO4 (aq) CaSO4 (aq) + 2 H2O (l)
20
WEEK 3 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal hydroxides with
the corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium hydroxide Hydrochloric acid
Sodium hydroxide Sulphuric acid
Calcium hydroxide Hydrochloric acid
Magnesium hydroxide Sulphuric acid
Aluminium hydroxide Hydrochloric acid
Zinc hydroxide Sulphuric acid
21
WEEK 3 LESSON 2
TOPIC Reactions of metal compounds
Reactions of metallic carbonates with dilute acid
Metal carbonates react with dilute acid to form a salt carbon dioxide and water When
hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric acid is
used the corresponding sulphate salt is formed
For example
sodium carbonate + hydrochloric acid sodium chloride + carbon dioxide + water
Na2CO3 (s) + 2 HCl (aq) 2 NaCl (aq) + CO2 (g) + H2O (aq)
calcium carbonate + hydrochloric acid calcium chloride + carbon dioxide + water
CaCO3 (s) + 2 HCl (aq) CaCl2 (aq) + CO2 (g) + H2O (aq)
zinc carbonate + sulphuric acid zinc sulphate + carbon dioxide + water
ZnCO3 (s) + H2SO4 (aq) ZnSO4 (aq) CO2 (g) + H2O (aq)
potassium carbonate + sulphuric acid potassium sulphate + carbon dioxide + water
K2CO3 (s) H2SO4 (aq) K2SO4 (aq) CO2 (g) + 2 H2O (aq)
22
WEEK 3 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal carbonates with
the corresponding acid
Metallic
carbonate
Acid Balanced chemical equation
Potassium
carbonate
Hydrochloric
acid
Sodium
carbonate
Sulphuric acid
Zinc
carbonate
Hydrochloric
acid
Magnesium
carbonate
Sulphuric acid
Aluminium
carbonate
Hydrochloric
acid
Calcium
carbonate
Sulphuric acid
23
WEEK 3 LESSON 3
TOPIC Action of heat on metal compounds
Action of heat on nitrates
All nitrates decompose when heated The reactivity of the metal in the metal nitrate influences
the products of the decomposition
The nitrates of the alkali metals (Group I) with the exception of lithium nitrate decompose to
form the metal nitrite and oxygen
The nitrates of most other metals decompose to form the metal oxide nitrogen dioxide and
oxygen
The nitrates of the very unreactive metals decompose to form the meal nitrogen dioxide and
oxygen
Metal Nitrate Decomposition
Potassium K Products metal nitrite + oxygen
eg 2 NaNO3 (s) Heatrarr 2 NaNO2 (s) + O2 (g)
Sodium Na
Calcium Ca
Products metal oxide + nitrogen dioxide + oxygen
eg 2 Pb(NO3)2 (s)
Heatrarr 2 PbO (s) + 4 NO2 (g) + O2 (g)
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Products metal + nitrogen dioxide + oxygen
eg 2 AgNO3 (s) Heatrarr 2 Ag (s) + 2 NO2 (g) + O2 (g)
24
WEEK 3 LESSON 3 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
nitrates
Metal Balanced chemical equation
Potassium nitrate
Sodium nitrate
Calcium nitrate
Magnesium nitrate
Aluminium nitrate
Zinc nitrate
Lead nitrate
Copper nitrate
Silver nitrate
25
WEEK 4 LESSON 1
TOPIC Action of heat on metal compounds
Action of heat on carbonates
Upon application of heat many carbonates decompose to form the metal oxide and carbon
dioxide
Group I carbonates do not decompose on heating with the exception of lithium carbonate
Metal Carbonate decomposition
Potassium K
Stable not decomposed by heat Sodium Na
Calcium Ca
Decompose forming metal oxide and carbon dioxide
eg CaCO3 (s) Heatrarr CaO (s) + CO2 (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Unstable
26
WEEK 4 LESSON 1 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
carbonates
Metal Balanced chemical equation
Potassium carbonate
Sodium carbonate
Calcium carbonate
Magnesium carbonate
Aluminium carbonate
Zinc carbonate
Iron carbonate
Lead carbonate
Copper carbonate
27
WEEK 4 LESSON 2
TOPIC Action of heat on metal compounds
Action of heat on the metal hydroxides
Most metal hydroxides decompose on heating A metal oxide and water are formed
Group I hydroxides do not decompose on heating with the exception of lithium hydroxide
Metal Hydroxide decomposition
Potassium K Stable not decomposed by heat
Sodium Na
Calcium Ca Decompose forming metal oxide and water (as steam)
eg Zn(OH)2 (s) Heatrarr ZnO (s) + H2O (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag No hydroxide exist
28
WEEK 4 LESSON 2 WORKSHEET
Write the balanced chemical equations for the thermal decomposition of the following
metal hydroxides
Metal hydroxide Balanced chemical equation
Potassium hydroxide
Sodium hydroxide
Calcium hydroxide
Magnesium hydroxide
Aluminium hydroxide
Zinc hydroxide
Lead hydroxide
Copper hydroxide
29
WEEK 4 LESSON 3
TOPIC Reactivity of metals ndash The Reactivity Series
The reactivity series of metals is a list of metals arranged in order of their reactivity based on
Displacement reactions
Reactions with oxygen dilute acids and water
Relative ease of decomposition of their compounds
Metals at the top of the series are the most electropositive They lose electrons very easily and
readily form cations These ions are very stable and are not easily discharged to form atoms Due
to this fact they are the most reactive metals
Metals at the bottom of the series are the least electropositive They do not lose electrons easily
and do not readily form ions Their ions are very unstable and are easily discharged to form
atoms They are the least reactive metals
The reactivity series of metals
Mnemonic Metal Symbol Reactivity
People Potassium K Most reactive
Least reactive
Sometimes Sodium Na
Collect Calcium Ca
Magazines Magnesium Mg
About Aluminium Al
Zoos Zinc Zn
In Iron Fe
London Lead Pb
Having (Hydrogen) H
Cute Copper Cu
Monkeys and Mercury Hg
Small Silver Ag
Gorillas Gold Au
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
5 Reactivity of metals Reactivity of metals Reactivity of metals
6 Extraction of metals Extraction of metals Alloys
7 Corrosion Importance of metals
and their compounds
on living systems and
environment
Chemical properties
of non ndash metals
8 Laboratory
preparation of gases
Laboratory
preparation of gases
Laboratory
preparation of gases
9 Uses of gases Uses of non ndash metals
and their compounds
Harmful effects of
non ndash metals and
their compounds on
living systems and
the environment
10 Green Chemistry Qualitative Analysis
ndash Identification of
cations
Qualitative Analysis
ndash Identification of
cations
2
WEEK 5 LESSON 1
TOPIC Reactivity of metals
Reactivity based on displacement reactions between metals and metal ions
A metal will displace a metal which is lower than itself in the reactivity series from a solution of
the metal salt
Reaction of zinc and copper (II) sulphate
Expected observations
Explanation
The size of the zinc metal decreases
The zinc metal is reacting and forming the
salt zinc sulphate
The solution becomes lighter eventually
colourless
The Cu2+ (aq) ions (responsible for the blue
colour) is reduced to Cu (s)
A brown solid is deposited at the bottom of
the container
Copper metal is formed
Equation Zn (s) + CuSO4 (aq) ZnSO4 (aq) + Cu (s)
Ionic equation
Zn (s) + Cu2+ (aq) Zn2+ (aq) + Cu (s)
Zinc is higher in the reactivity series than copper Therefore it will displace the copper ions in
the reaction above
3
Examples of other displacement reactions
Magnesium will displace Zn2+ ions in zinc sulphate since it is higher in the series than zinc
Mg (s) + Zn2+(aq) Mg2+ (aq) + Zn (s)
Silver will not displace Cu2+ ions in copper (II) sulphate [Cu is higher in the series than Ag]
Using the information above we can arrange the metals in order of their reactivity with
magnesium being the most reactive and silver the least reactive metal among the four metals
Mg gt Zn gt Cu gt Ag
Reactivity based on reaction with oxygen
The reactivity of metals can also be deduced from their reaction with oxygen
The table below gives the observations for the reaction with oxygen with the selected metals
Reaction of metal with oxygen
Metal Observation
Copper The surface turns black upon heating
Magnesium Ribbon burns very rapidly
Sodium Burns vigorously
Gold No reaction
Based on the observations for the 4 metals the metal with highest reactivity is sodium and the
metal with the least reactivity is gold
The 4 metals can be arranged in terms of reactivity as follows
Na gt Mg gt Cu gt Au
4
WEEK 5 LESSON 1 WORKSHEET
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
5
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
6
WEEK 5 LESSON 2
TOPIC Reactivity of metals
Reactivity based on reactivity with acids
The metals that are higher than hydrogen in the electrochemical series react with non ndash oxidizing
acids to produce a salt and hydrogen gas
By using the same concentration of acid and same mass and size of the metals the order of
reactivity of the metals can be deduced
The table below shows the results for an experiment with the reaction of the named metals and
1 mol dm-3 hydrochloric acid
Reaction of metals with acid
Metal Observations
Silver No reaction
Magnesium Bubbles produced steadily
Calcium Bubbles produced very rapidly
Iron Bubbles produced slowly
Based on the above data the most reactive metal will be calcium with the least reactive being
silver The order of reactivity will be Ca gt Mg gt Fe gt Ag
By comparing this to the electrochemical series it can be seen that the reactivity of the metals
decrease as we go down the series
7
WEEK 5 LESSON 2 WORKSHEET
1 Place a next to the metals that will react with dilute acid and an X next to the metals
that will not react with dilute acid
Metal Reactivity with acid
Copper
Magnesium
Aluminium
Silver
Zinc
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
8
WEEK 5 LESSON 3
TOPIC Reactivity of metals
Reactivity based on ease of decomposition of the metal nitrates carbonates oxides and
hydroxides
The more reactive a metal the more difficult it is to decompose its nitrate carbonate oxide or
hydroxide on heating
For example Decomposition of carbonates
Procedure
1 Put a large spatula measure of the carbonate to be tested in a test tube
2 Fit a delivery tube and then clamp the test tube so that the delivery tube dips into a second test
tube containing 2ndash3 cm3 limewater
3 Heat the solid gently at first then more strongly
4 Lift the delivery tube from the limewater before or as soon as the heating is stopped This is to
avoid suck-back
5 Write down all observations Notice what happens to the limewater and how long it takes to turn
milky (if at all) Notice whether any melting occurs in the heated test tube and any colour
changes taking place Write your results in tabular form
6 Repeat the experiment with the other metal carbonates supplied and in each case write down
your observations
7 Wash your hands thoroughly at the end of these experiments since some of the metal carbonates
are toxic
9
Results
Metal Formula Gas evolved Ease of decomposition
Zinc ZnCO3 Carbon dioxide Fairly easy
Copper CuCO3 Carbon dioxide Easy
Sodium Na2CO3 None Very difficult
Using the results of the above activity the reactivity of the metals can be determined
Ease of decomposition Copper gt Zinc gt Sodium
The order of reactivity is the opposite for the ease of decomposition
Order of reactivity Sodium (most reactive) gt Zinc gt Copper (least reactive)
10
WEEK 5 LESSON 3 WORKSHEET
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
11
WEEK 6 LESSON 1
TOPIC Extraction of metals
Elements exist all over the earth Some are found as free elements eg copper silver and gold
Others are found combined with other elements in compounds To get the elements the
compounds have to be broken up These compounds are generally called ores the most
convenient sources of which are rocks sea and air
The extraction of a metal from its ore is a reduction process where the metals ions gain electrons
to form atoms
The general equation is Mn+ + n e- M
The choice of the extraction method depends on the position of the metal in the reactivity series
As we go down the series the metals become more stable and the metal ions (in the ores)
become less stable
The very reactive metals that are high in the series K Na Ca Mg Al have very stable ores
Therefore they require a powerful method of reduction namely electrolysis During the process
the cathode provides the electrons and acts as the reducing agent
The metals in the middle of the series (Zn Fe Pb) do not have stable ores and can be extracted
by reduction with carbon in the case of zinc and with carbon monoxide in the case of iron and
lead
Metals low in the reactivity series if present as ores can be extracted simply by heating the ores
in air at high temperatures
12
Extraction of Aluminium from purified bauxite
Pure bauxite is pure alumina (Al2O3) Aluminium is obtained from bauxite by electrolysis
Aluminium oxide has a very high melting point approximately 2050 0C so it is first dissolved in
molten cryolite (Na2AlF6) The addition of cryolite lowers the melting point to approximately
900 0C
The electrolyte is a molten mixture of alumina and molten cryolite The cathode is the graphite
lining of the cell The anodes are blocks of graphite or titanium alloys
Reaction at the cathode
Al3+ (l) + 3 e- Al (l)
Reaction at the anode
2 O2- (l) ndash 4 e- O2 (g)
Aluminium (melting point 660 0C) is a liquid at the temperature at which electrolysis is carried
out and is collected at the bottom of the cell and tapped off Oxygen gas which is given off in the
main cathode reaction together with the heat causes the anodes to burn away The anodes have
to be replaced from time to time The use of anodes from titanium alloys reduce the number of
times that the anodes have to be replaced
13
WEEK 6 LESSON 1 Worksheet
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 6 LESSON 2
TOPIC Extraction of metals
Extraction of Iron
The traditional method of production of iron is by reduction of haematite by carbon monoxide in
a blast furnace
Ores Haematite ndash Fe2O3 Magnetite ndash Fe3O4 Siderite ndash FeCO3 Magnetite and Siderite are
converted to Haematite
A mixture of haematite limestone (CaCO3) and coke (C) called the charge is placed into the top
of the furnace
Hot air is blown into the bottom of the furnace
Coke burns in air forming carbon dioxide
C (s) + O2(g) CO2 (g) ΔH -ve
The heat produced keeps the temperature at about 1900 0C
The carbon dioxide is reduced to carbon monoxide by the hot coke
CO2 (g) + C (s) 2 CO(g) Δ +ve
Heat absorbed reduces the temperature to about 1100 0C
The carbon monoxide reduces the hot iron ore to molten iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + 3 CO2(g)
The temperature at this part of the furnace is about 700 0C The iron runs to the bottom of the
furnace
The impurities are removed by the addition of limestone (CaCO3) The limestone at the
temperature of the furnace breaks down
CaCO3 (s) CaO (s) + CO2 (g)
15
The calcium oxide formed combines with silicon dioxide (sand) the main impurity in the iron
ore to form molten slag
CaO (s) + SiO2 (s) CaSiO3 (l)
The slag does not mix with the molten iron but floats on it The molten iron and slag are run off
separately
The iron formed in a blast furnace is an impure form of the metal Because the molten metal is
allowed to solidify in shallow trays known as casts the iron is called lsquocast ironrsquo or lsquopigrsquo iron
Cast iron is quite brittle and contains 2 - 4 carbon and other impurities Most of the cast iron is
converted to steel
A blast furnace used for extracting iron
16
WEEK 6 LESSON 2 Worksheet
(a) What are the three raw materials that are added through the top of the blast furnace
during the extraction process for iron
______________________________________________________________________________
______________________________________________________________________________
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
17
WEEK 6 LESSON 3
TOPIC Alloys
An alloy is a mixture of two or more metals Alloys are made by melting the individual metals
mixing them and allowing the molten mixture to solidify
In general alloys are harder stronger and more resistant to corrosion than the actual metals they
are made up from
Alloy Use Properties
ALUMINIUM
-Duralumin
(AlMgCu)
-Magnalium (AlMg)
Alloys used in the
construction of
aircraft and ships
buses
Aluminium is used in
making cooking
utensils electrical
cables paint for fuel
storage tanks bottle
caps foil and utensils
for handling nitric
acid
The alloys have a low
density They are as
light as aluminium
and more resistant to
corrosion than
aluminium
LEAD
-Solder (PbSn)
Alloy is used in
joining metals
(soldering)
Lead is used in
underground cables
plates in
The alloy has a lower
melting point than
lead and is harder
than lead
18
Alloy Use Properties
accumulators shield
against x ndash rays
IRON
- Stainless Steel
(FeCONiC)
-Tungsten steel
(FeWC)
-Invar steel (FeNi)
Manganese steel
(FeMnC)
Iron is the main metal
of a variety of
constructions
Steel is used in
cutlery rock drills
electromagnets
vehicle body and
engine parts fences
pipes etc
Steel resists
corrosion is usually
harder than iron and
may be tough though
malleable and ductile
19
WEEK 6 LESSON 3 Worksheet
(a) Define the term alloy
______________________________________________________________________________
(b) State 3 general advantages that alloys have over the individual metals they are made
from
______________________________________________________________________________
______________________________________________________________________________
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
______________________________________________________________________________
______________________________________________________________________________
Uses
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 7 LESSON 1
TOPIC Corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
Familiar examples of corrosion are
- the formation of a green powder on copper sheeting
- the eating away of iron (rusting)
- the development by aluminum of a thin compact layer of oxide which protects the
underlying metal from further corrosion
When corrosion occurs in water ndash free environment it is called dry oxidation When it occurs in
aerated aqueous environments it is called wet corrosion Wet corrosion is the most common and
troublesome form of corrosion
The most familiar corrosion is the rusting of iron and steel On exposure to the atmosphere iron
and steel corrode to form rust which is hydrated iron (III) oxide Fe2O3xH2O Iron and steel
corrode easily and the rust formed flakes off easily thus exposing fresh surface for attack
When iron rust it loses electrons
Fe (s) ndash 2e- Fe 2+ (aq)
The iron (II) ions pass into solution and then combine with the hydroxyl (OH-) ions in the
aerated aqueous environment to form iron (II) hydroxide The oxygen present oxidises the iron
(II) hydroxide to hydrated iron (III) oxide or rust
Fe(OH)2 + O2 Fe2O3xH2O
21
Methods of preventing rusting
1 Coating the object with paint grease plastic or rubber which prevent contact with air or
water
2 Galvanising ndash coating the object with zinc The zinc forms an adherent oxide layer which
protects against further corrosion If damaged the zinc is oxidized in preference to the
iron since it is higher in the electrochemical series
3 Coating with tin lsquoTinrsquo cans are made of steel plated with tin However if scratched
rusting occurs since iron is more reactive than tin
4 Attaching a sacrificial anode to the object A piece of metal higher in the electrochemical
series such as magnesium is attached The magnesium will be oxidized in preference
since it is higher in the electrochemical series than iron
22
WEEK 7 LESSON 1 WORKSHEET
(a) Define the term corrosion
______________________________________________________________________________
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
23
WEEK 7 LESSON 2
TOPIC Importance of metals and their compounds on living systems and environment
Some metals are an integral part of different structures of living things
Metal Presence and Function
Potassium Main cation in fluid or animal cells essential for healthy plant growth
Calcium Necessary for strong bones teeth and shells needed by some enzymes Present
in dairy produce eggs nuts and cereals
Magnesium Central atom of chlorophyll needed for some enzyme action Involved in energy
and calcium metabolism
Zinc Present in many enzymes Needed for protein metabolism Essential for growth
of animals
Iron Present in haemoglobin Needed for protein metabolism Essential for growth of
animals
Chromium Needed for glucose uptake by cells and thus linked to the action of insulin
Manganese Needed for bone development and amino acid metabolism Present in several
enzymes Needed for plant growth
Cobalt Present in Vitamin B12 Needed for plant growth
Copper Involved in formation of haemoglobin and melanin Present in enzymes
controlling oxidation Needed for plant growth
24
Harmful effects of metals and their compounds to living systems and the environment
There are some metals and metal compounds which may cause harm to living systems and the
environment
Lead
Lead is a heavy metal poison that is widely encountered It may occur in food beverages paint
water formed from ndash sealed pipes in air polluted by combustion by fuels containing lead
compounds Lead is also used in some car batteries If these are paints or batteries are not
disposed of correctly lead may get into groundwater or air Lead and lead compounds harm the
nervous system including the brain especially young children
Arsenic
Arsenic compounds are poisonous They can get into the groundwater from mining waste and
from disposal of some electrical components
Cadmium
Cadmium compounds are poisonous They can get into the ground by improper disposal of
nickel ndash cadmium batteries Persons can get cadmium poisoning if they eat food grown in
contaminated soil
Mercury
Mercury can be spilled from broken thermometers in hospitals and laboratories Mercury and its
compounds are particularly poisonous to fish and it can accumulate in the food chain and
eventually poison humans
Problems of disposal of solid waste
Metals may react with water andor air and corrode to form soluble compounds that are
poisonous These toxic compounds diffuse into the soil and eventually enter rivers
Rust from iron may form unsightly pools of waste that reduce plant growth
Waste from aluminium extraction may react with water and form flammable gases
25
WEEK 7 LESSON 2 WORKSHEET
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Lead
______________________________________________________________________________
Mercury
______________________________________________________________________________
26
WEEK 7 LESSON 3
TOPIC Chemical properties of non ndash metals
Reaction with oxygen
Many non ndash metals burn in excess oxygen or air to form oxides For example
S (s) + O2 (g) SO2 (g)
C (s) + O2 (g) CO2 (g)
Reactions with metals
Some non ndash metals react with metals high in the electrochemical series when heated
For example
Sodium burns in chlorine to form sodium chloride
Na (s) + Cl2 (g) NaCl (s)
Magnesium burns in oxygen to form magnesium oxide
Mg (s) + O2 (g) MgO (s)
When heated iron combines with molten sulphur to form iron (II) sulphide
Fe (s) + S (l) FeS (s)
When heated reactive metals such as sodium and aluminium react with hydrogen to form metal
hydrides
2 Na (s) + H2 (g) 2 NaH (s)
Oxidising and Reducing properties
Hydrogen and Carbon are very good reducing agents
At high temperatures hydrogen reduces metal oxides below zinc in the electrochemical series to
form the metal For example PbO (s) + H2 (g) Pb (s) + H2O (g)
Under suitable conditions hydrogen reduces nitrogen to ammonia
N2(g) + 3 H2 (g) 2 NH3 (g)
27
At high temperatures carbon reduces metal oxides below aluminium in the reactivity series to
the metal For example
ZnO (s) + C (s) Zn (s) + CO (g)
Oxygen and Chlorine are very good oxidizing agents
Oxygen oxidized most metals to form metal oxides and some non ndash metals to non ndash metal oxides
For example
2 Mg (s) + O2(g) 2 MgO (s)
4 P (s) + 5 O2 (g) P4O10 (s)
Chlorine acts as an oxidizing agent either as a gas or as an aqueous solution For example
H2 (g) + Cl2 (g) 2 HCl (g)
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
28
WEEK 7 LESSON 3 WORKSHEET
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
______________________________________________________________________________
(b) Write the ionic equation for the above reaction
______________________________________________________________________________
(c) Identify the oxidising agent in the reaction
______________________________________________________________________________
(d) Justify your answer in part (c) in terms of oxidation number
______________________________________________________________________________
29
WEEK 8 LESSON 1
TOPIC Laboratory preparation of gases
Preparation of oxygen
Oxygen can be prepared by the decomposition of hydrogen peroxide potassium chlorate (V) or
potassium nitrate The safest method is the decomposition of hydrogen peroxide
Manganese (IV) oxide catalyses the decomposition of hydrogen peroxide
Silica gel anhydrous calcium chloride or concentrated sulphuric acid can be used as a drying
agent
The gas is collected by downward delivery since it is slightly denser than air
Equation
2 H2O2 (aq) 2 H2O (l) + O2 (g)
Apparatus used for laboratory preparation of oxygen
30
WEEK 8 LESSON 1 WORKSHEET
Describe the laboratory preparation of oxygen gas
In your answer include
The starting material
A suitable catalyst
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
31
WEEK 8 LESSON 2
TOPIC Laboratory preparation of gases
Preparation of carbon dioxide
Carbon dioxide can be prepared by the action of dilute acid on carbonates Marble chips (calcium
carbonate) and dilute hydrochloric acid are the common reagents The gas is collected by
downward delivery since it is denser than air
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
Apparatus used for laboratory preparation of carbon dioxide
32
WEEK 8 LESSON 2 WORKSHEET
Describe the laboratory preparation of carbon dioxide gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
33
WEEK 8 LESSON 3
TOPIC Laboratory preparation of gases
Preparation of ammonia
Ammonia may be prepared by heating a mixture of ammonium salt and a hydroxide The
ammonia gas is collected by upward delivery since it is less dense than air
For example
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
Calcium oxide is the only suitable drying agent since ammonia reacts with conc H2SO4 and
CaCl2
Apparatus used for laboratory preparation of dry ammonia
34
11
WEEK 8 LESSON 3 WORKSHEET
Describe the laboratory preparation of ammonia gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
35
WEEK 9 LESSON 1
TOPIC Uses of gases
Carbon dioxide
Used in fire extinguishers to put out fires Carbon dioxide is denser than air and lsquoblanketsrsquo the
fire preventing oxygen from reaching it Carbon dioxide extinguishers are especially useful for
dealing with fires involving flammable liquids and electrical equipment
Carbonation in soda is created when carbon dioxide is pumped into the soda can or bottle then
held under pressure As long as the can or bottle is sealed the carbon dioxide remains mostly
stable However if the drink gets shaken up or the top is opened the tiny carbon dioxide bubbles
react by bursting
Oxygen
Oxygen is needed for aerobic respiration We need a constant supply of oxygen for this process
Oxygen is used in hospitals to improve the respiration of patients with poor blood flow blood
poisoning and heart disease
Oxygen in used in welding (joining) metals In an oxyacetylene welding torch acetylene or
ethyne (C2H2) burns in oxygen and produces a very hot flame This flame is capable of melting
most metals
Oxygen is used in steel production A blast of oxygen is blown through the molten iron The
oxygen oxidises many of the impurities of the iron and the impurities are then removed
36
WEEK 9 LESSON 1 WORKSHEET
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Put out fires
Welding metals
Create lsquofizzrsquo in drinks
Used in steel production
Aerobic respiration
37
WEEK 9 LESSON 2
TOPIC Uses of non ndash metals and their compounds
Carbon (allotrophes carbon dioxide)
Carbon is used as a reducing agent in extraction of some metals
Carbon as graphite is used as electrodes lubricants and lsquoleadrsquo for pencils
Carbon in the form of diamond is used for jewellery (because of its lustre) and in drill tips for
high ndash speed drills (because of its hardness)
Carbon dioxide is used as refrigerant (as dry ice) for carbonated beverages
Sodium hydrogen carbonate and sodium carbonate are used for water softening and raising
agent
Sulphur
Sulphur is used in the manufacture of sulphuric acid Sulphur is also used in the manufacture of
tyres to make the rubber harder (vulcanisation)
Sulphur powder is used as fungicide on plant materials
Phosphorus
Phosphorus is used in the manufacture of fertilizers
Phosphorus is used to make phosphor bronze alloys
Phosphorus sulphide is used to make the heads of lsquostrike anywherersquo matches
38
Chlorine
Chlorine is used to make sodium hypochlorite which is present in bleach It is also used in
sterilizing swimming pools and in water treatment
Chlorine is used to make the monomer vinyl chloride which is used to make the plastic PVC
Nitrogen
Nitrogen is used to make fertilisers ammonia dyes and nitric acid
Nitrogen is used as an inert atmosphere to prevent substances being oxidised and as a coolant
Silicon
Silicon is used for making silicon chips for computers
Silicon (V) oxide is present in sand Glass is made by heating sand with lime (calcium oxide) and
sodium carbonate
Silicon in the form of silicates is used in jewellery
Silica gel is used as a drying agent
39
WEEK 9 LESSON 2 WORKSHEET
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Used to make sodium hypochlorite
Used as a fungicide on plant materials
Used for lsquoleadrsquo in pencils
Used in the manufacture of bronze alloys
Used in the manufacture of nitric acid
Used in the manufacture of computer chips
Used to make fertilisers
40
WEEK 9 LESSON 3
TOPIC Harmful effects of non ndash metals and their compounds on living systems and the
environment
Sulphur dioxide
Sulphur dioxide can cause a disease of the lungs Sulphur dioxide also poisons plants in two
main ways It may enter the stomata of leaves and react with the tissue fluids to form sulphites
with the on ndash going water loss the concentration of sulphites could build up killing the cells
The second adverse effect on plants occurs when sulphur dioxide dissolves in rain thereby
increasing soil acidity A prolonged acid soil situation may lead to plasmolysis and the death of
vegetation in an area
Carbon monoxide
Carbon monoxide combines much more readily than oxygen with haemoglobin When carbon
monoxide is inhaled it prevents the haemoglobin from taking oxygen to the bodyrsquos cells
Continued breathing of air containing carbon monoxide eventually causes death
Hydrogen sulphide
Hydrogen sulphide reacts readily with many cations forming insoluble sulphides Many cations
contribute to good health by contributing to enzyme activity and to the formation of bone
pigment and haemoglobin Although these cations are required in extremely small
concentrations they are removed by being precipitated as sulphides and thus not available for
regular function Careless dumping of refuse contributes to atmospheric pollution by hydrogen
sulphide
Oxides of nitrogen
In the presence of hydrocarbons from car exhausts ozone and sunlight nitrogen oxides react to
form photochemical smog which contains many harmful chemicals
Nitrogen dioxide can harm the lungs and irritate the nose throat and eyes The other compounds
present in photochemical smog are even more harmful irritants and can cause asthma
41
Carbon dioxide
Carbon dioxide water vapour and ozone referred to as ldquogreenhouse gasesrdquo acting as a blanket
readily absorb some of the radiated heat energy and in turn warms the earthrsquos atmosphere This is
called the ldquogreenhouse effectrdquo Scientists have found direct correlation between carbon dioxide
concentration and global warming An increase in carbon dioxide concentration resulted in an
increase global temperatures Global warming is a major potential problem that the world faces
Chloroflourocarbons (CFCs)
It is believed that CFCs might be responsible for destroying the ozone layer which prevents
harmful ultraviolet (UV) radiation from reaching the earth The carbon ndash chlorine bond in CFC
molecule is easily broken by a UV photon producing an active chlorine atom This atom
combines with an ozone molecule forming a chlorine oxide radical and oxygen The radicle
reacts with more ozone producing the chlorine atom again This kind of reaction is repeated
thousands of times This type of reaction is thought to account for about eighty percent of the
loss of ozone observed
Nitrates and phospates
Nitrates and phosphates cause eutrophication The process leading to eutrophication are
Nitrates and phosphates from fertilisers spread on fields may dissolve in groundwater and
get into lakes and rivers
Nitrates and phosphates cause excessive growth of algae so that they cover the surface of
the water
Water plants including algae die because of lack of sunlight Aerobic bacteria feed on
the plant remains The bacteria multiply
The aerobic bacteria use up the oxygen in the water so aquatic animals die
42
Solid waste
The main sources of pollution from non ndash metals is from glass paper and plastics
Broken glass can cause injury to animals It can also cause fires by acting as lens focusing the
sunrsquos rays on flammable materials
Printing inks from paper dumped in the ground may contain toxic elements such as arsenic and
cadmium Bleaches and chlorine compounds from paper are also harmful
43
WEEK 9 LESSON 3 WORKSHEET
Describe ONE harmful effect of the following non ndash metals andor their compounds on
living systems and the environment
Sulphur dioxide
______________________________________________________________________________
______________________________________________________________________________
Carbon monoxide
______________________________________________________________________________
______________________________________________________________________________
Carbon dioxide
______________________________________________________________________________
______________________________________________________________________________
Oxides of nitrogen
______________________________________________________________________________
______________________________________________________________________________
Hydrogen sulphide
______________________________________________________________________________
______________________________________________________________________________
44
Chloroflourocarbons (CFCs)
______________________________________________________________________________
______________________________________________________________________________
Nitrates and phospates
______________________________________________________________________________
______________________________________________________________________________
45
WEEK 10 LESSON 1
TOPIC Green Chemistry
Green Chemistry is defined as the utilisation of a set of principles that reduces or eliminates the
use and generation of hazardous substances
There are twelve principles of green chemistry as proposed by Paul T Anastas and John C
Warner These twelve principles are
1 Prevention ndash It is better to prevent waste than to treat or clean up waste after it has been
created
2 Atom economy - Synthetic methods should be designed to maximize the incorporation of
all materials used in the process into the final product
3 Less hazardous chemical synthesis - Wherever practicable synthetic methods should be
designed to use and generate substances that possess little or no toxicity to human health
and the environment
4 Safer chemical products - Chemical products should be designed to affect their desired
function while minimizing their toxicity
5 Safer solvents and other agents - The use of auxiliary substances (eg solvents
separation agents etc) should be made unnecessary wherever possible and harmless
when used
6 Minimum energy requirements - Energy requirements of chemical processes should be
recognized for their environmental and economic impacts and should be minimized If
possible synthetic methods should be conducted at ambient temperature and pressure
7 Use of renewable raw materials - A raw material or feedstock should be renewable rather
than depleting whenever technically and economically practicable
8 Reduce use of additional chemicals or additional steps - Unnecessary derivatization (use
of blocking groups protection deprotection temporary modification of
physicalchemical processes) should be minimized or avoided if possible because such
steps require additional reagents and can generate waste
46
9 Use of catalysts ndash The use of catalysts reduce energy costs because the reactions take
place at lower temperatures The more specific the catalyst for a particular reaction is the
less it the likelihood of getting additional unwanted products
10 Nature of breakdown of products - Chemical products should be designed so that at the
end of their function they break down into innocuous degradation products and do not
persist in the environment
11 Monitoring to prevent pollution - Analytical methodologies need to be further developed
to allow for real-time in-process monitoring and control prior to the formation of
hazardous substances
12 Minimise chemical accidents - Substances and the form of a substance used in a chemical
process should be chosen to minimize the potential for chemical accidents including
releases explosions and fires
47
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
48
WEEK 10 LESSON 2
TOPIC Qualitative Analysis ndash Identification of cations
Qualitative Analysis involves identifying the constituents of single substances or mixture of
substances
Appearance
An examination of the appearance of a substance can indicate which ion it contains
Appearances of substances
Observation Indication
Blue or blue ndash green Cu2+ salt
Pale green Fe2+ salt
Yellow ndash brown Fe3+ salt
Ammonia smell NH4+ salt
49
Test for cation using sodium hydroxide
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
(d) If no precipitate forms in step b warm gently and test for ammonia
Effect of dilute sodium hydroxide solution
Effect of dilute sodium hydroxide solution Cation
Dropwise Excess
White precipitate Precipitate soluble Ca2+
White precipitate Precipitate insoluble Al3+ Pb2+ Zn2+
Blue precipitate Precipitate insoluble Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
No precipitate ndash ammonia gas
evolved on heating
ndash NH4+
The metal cations all form insoluble hydroxides with sodium hydroxide solution
For example Ca2+ (aq) + 2 OH- (aq) Ca(OH)2 (s)
Ca(OH)2 Cu(OH)2 Fe(OH)2 and Fe(OH)3 are basic and therefore do not react with excess
sodium hydroxide solution Therefore the precipitate does not dissolve in excess sodium
hydroxide solution
Al(OH)3 Pb(OH)2 and Zn(OH)2 are amphoteric Therefore the precipitates react with the excess
sodium hydroxide solution forming soluble salts and the precipitate disappears in excess sodium
hydroxide solution
The NH4+ ion forms a soluble hydroxide However on heating it reacts with the hydroxide ion to
form ammonia and water
NH4+ (aq) + OH- (aq) NH3 (g) + H2O (l)
50
WEEK 10 LESSON 2 WORKSHEET
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P _____________ Q ___________________
R _____________ S ___________________
R + NaOH
______________________________________________________________________________
51
WEEK 10 LESSON 3
TOPIC Qualitative Analysis ndash Identification of cations
Test for cation using ammonia solution (ammonium hydroxide solution)
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
Effect of dilute ammonia (ammonium hydroxide) solution
Effect of dilute ammonia solution Cation
Dropwise Excess
No precipitate ndash Ca2+
White precipitate Precipitate soluble
(forming colourless solution)
Zn2+
White precipitate Precipitate insoluble Al3+ Pb2+
Blue precipitate Precipitate soluble
(forming deep blue solution)
Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
52
Ammonia solution is a weak alkali Metal cations except Ca2+ form insoluble hydroxides with
ammonia solution as with the sodium hydroxide solution
The amphoteric hydroxides Al(OH)3 and Pb(OH)2 and the basic hydroxides Fe(OH)2 and
Fe(OH)3 do not react with excess ammonia solution Therefore the precipitates remain
However Zn(OH)2 and Cu(OH)2 do react with excess ammonia solution to form complex
soluble hydroxides each Hence their precipitates disappear on the addition of excess ammonia
solution
Confirmatory test
After carrying out test for cations using sodium hydroxide solution and ammonia solution the
only cations which cannot be distinguished are Al3+ and Pb2+ A confirmatory test is carried out
to distinguish between the two cations
Confirmatory test
Test Observation Cation Ionic equation
Add potassium
or sodium
iodide solution
Bright yellow precipitate
No precipitate
Pb2+
Al3+
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
53
WEEK 10 LESSON 3 WORKSHEET
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A __________ B ________________ C ________________________
(b) State the inference after Test 2
C _______________________
(c) Write an ionic equation to support your answer in (b) above
___________________________________________________________________________
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
54
ANSWERS TO WORKSHEETS
55
WEEK 5 LESSON 1 WORKSHEET ANSWERS
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
Answer
Zinc + Iron (II) sulphate Zinc is higher in the electrochemical series and therefore displace
iron ions in iron (II) sulphate
Equation Zn (s) + FeSO4 (aq) ZnSO4 (aq) + Fe (s)
Ionic equation Zn (s) + Fe2+ (aq) Zn2+ (aq) + Fe (s)
Iron + Zinc sulphate No reaction iron is lower in the electrochemical series and cannot
displace the zinc ions in zinc sulphate
56
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
Answer
X displaces lead from an aqueous solution of its salts
X (s) + Pb2+ (aq) Xn+ (aq) + Pb (s)
rarr X is more reactive than Pb
X did not react with iron salts
rarr X is less reactive than Fe
Y burns very easily
Y is more reactive than Fe and Pb (both forming their corresponding oxide at a slower rate)
From electrochemical series Fe is higher and therefore more reactive than Pb
Order of reactivity
Y (most reactive) gt Fe gt X gt Pb (least reactive)
57
WEEK 5 LESSON 2 WORKSHEET ANSWERS
1
Metal Reactivity with acid
Copper X
Magnesium
Aluminium
Silver X
Zinc
58
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
Answer
Y and Z are the most reactive since they can react with dilute acid
Z is more reactive than Y since a reaction occurs with Z is added to an aqueous solution of Y
X is less reactive than W since it does not occur in nature as compounds
Order of reactivity Z (most reactive) gt Y gt W gt X
59
WEEK 5 LESSON 3 WORKSHEET ANSWERS
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
Answer
Ease of decomposition (from easiest to decompose to most difficult to decompose)
B rarrD rarrArarr C
Reactivity (most reactive to least reactive)
C (most reactive) gt A gt D gt B (least reactive)
60
WEEK 6 LESSON 1 Worksheet Answers
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
Potassium Zinc Copper
Calcium Lead Gold
Magnesium Iron
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
Aluminium is extracted from its ore bauxite through the process of electrolysis
Cryolite is added to bauxite to lower the melting point to about 900 0C The melting point of
bauxite is very high (about 2040 0C) It is difficult and expensive to keep the molten aluminium
oxide at this temperature
Reaction at the cathode Al3+ (l) + 3 e- Al (l)
61
WEEK 6 LESSON 2 Worksheet Answers
(a) What are the three raw materials that are added through the top of the blast
furnace during the extraction process for iron
Coke (carbon)
iron ore (haematitie mainly iron (II) oxide)
limestone (calcium carbonate)
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
Coke ndash coke burns to produce carbon dioxide The carbon dioxide further reacts with coke to
form carbon monoxide (reducing agent in the process)
C (s) + O2 (g) CO2 (g)
C (s) + CO2 (g) 2 CO
Haematite ndash iron ore provides the iron which is reduced by the carbon monoxide to produce
iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + CO2 (g)
Limestone ndash decomposes to form calcium oxide The calcium oxide reacts with the impurity
silicon dioxide to form slag (calcium silicate)
CaCO3 (s) CaO (s) + CO2 (g)
CaO (s) + SiO2 (l) CaSiO3(l)
62
WEEK 6 LESSON 3 Worksheet Answers
(a) Define the term alloy
An alloy is a material made from a mixture of two or more metals
(b) State 3 general advantages that alloys have over the individual metals they are made
from
They are harder stronger and more resistant to corrosion
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
1 High strength
2 Low density
Uses
1 Used to make aircraft bodies
2 Used to make space satellites
63
WEEK 7 LESSON 1 WORKSHEET ANSWERS
(a) Define the term corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
The paint forms a barrier which stops contact with air or water and the iron Hence rusting
will not take place
However when the paint is scratched that part of the iron nail is exposed to air or water and
rusting will take place
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
Magnesium is higher in the electrochemical series and will be oxidised in preference to iron
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
Aluminium is partly protected from corrosion by its coat of aluminium oxide However as the
iron rust it flakes and fall off and the rusting process continues
64
WEEK 7 LESSON 2 WORKSHEET ANSWERS
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
Magnesium is the ion found in chlorophyll Chlorophyll plays a vital part in the process of
photosynthesis A deficiency in magnesium will lead to low chlorophyll level in the tomato
plants and hence reduce the process of photosynthesis There will be less food storage and
hence will lead to smaller yield of tomatoes
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Any correct harmful effect of lead on health or environment
Any correct harmful effect of mercury on health or environment
65
WEEK 7 LESSON 3 WORKSHEET ANSWERS
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
(b) Write the ionic equation for the above reaction
2 Br- (aq) + Cl2 (aq) 2 Cl- (aq) + Br2 (aq)
(c) Identify the oxidising agent in the reaction
Cl2 (aq)
(d) Justify your answer in part (c) in terms of oxidation number
There is a reduction of the oxidation number for chlorine from 0 to ndash1
hence it has been reduced Therefore chlorine is the oxidising agent
66
WEEK 8 LESSON 1 WORKSHEET ANSWERS
Describe the laboratory preparation of oxygen gas
Oxygen is prepared in the laboratory by the decomposition of hydrogen peroxide
A suitable catalyst is manganese (IV) oxide
Drying agent silica gel OR anhydrous calcium chloride OR conc sulphuric acid
The gas is collected by downward delivery since oxygen is slightly denser than air
Balanced chemical equation 2 H2O2 (aq) 2 H2O (l) + O2 (g)
67
WEEK 8 LESSON 2 WORKSHEET ANSWERS
Describe the laboratory preparation of carbon dioxide gas
Carbon dioxide is commonly prepared in the laboratory by the reacting hydrochloric acid and
marble chips (calcium carbonate)
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
The carbon dioxide gas is collected by downward delivery since it is denser than air
Balanced chemical equation
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
68
WEEK 8 LESSON 3 WORKSHEET ANSWERS
Describe the laboratory preparation of ammonia gas
An ammonium salt (ammonium chloride) and a base (sodium hydroxide) are mixed together and
heated
Calcium oxide is used as the drying agent Calcium chloride and concentrated sulphuric acid
cannot be used since ammonia can react with them
The gas is collected by upward delivery since ammonia is less dense than air
Balanced chemical equation
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
69
WEEK 9 LESSON 1 WORKSHEET ANSWERS
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Carbon dioxide Put out fires
Oxygen Welding metals
Carbon dioxide Create lsquofizzrsquo in drinks
Oxygen Used in steel production
Oxygen Aerobic respiration
70
WEEK 9 LESSON 2 WORKSHEET ANSWERS
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Chlorine Used to make sodium hypochlorite
Sulphur Used as a fungicide on plant materials
Carbon (graphite) Used for lsquoleadrsquo in pencils
Phosphorus Used in the manufacture of bronze alloys
Nitrogen Used in the manufacture of nitric acid
Silicon Used in the manufacture of computer chips
Nitrogen Phosphorus Used to make fertilisers
71
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
Green Chemistry is using principles that reduceeliminate the use of hazardous materials in
the design manufacture and application of chemical products
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
Makes the environment safer
Reduces waste
Creates new jobs
Reduces respiratory illnesses
Atom economy
72
WEEK 10 LESSON 2 WORKSHEET ANSWERS
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P Cu2+ Q Fe2+
R Fe3+ S Ca2+
Ionic equation for R + NaOH
Fe3+ (aq) + 3 OH- (aq) Fe(OH)3 (s)
73
WEEK 10 LESSON 3 WORKSHEET ANSWERS
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A Fe3+ B Ca2+ C Al3+ Pb2+
(b) State the inference after Test 2
C Pb2+
(c) Write an ionic equation to support your answer in (b) above
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
11 Qualitative Analysis
ndash Test for gases
Qualitative Analysis
ndash Identification of
anions
Qualitative Analysis
ndash Identification of
anions
12 Problem solving of
Past CSEC Chemistry Paper 2
on topics completed in the term
13
14
15
2
WEEK 11 LESSON 1
TOPIC Qualitative Analysis ndash Test for gases
Identification of gases
Gas Colour Odour Effect on moist
litmus
Method of identification
Oxygen
O2
Colourless Odourless Neutral ndash no
effect
Relights a glowing splint
Hydrogen
H2
Colourless Odourless Neutral ndash no
effect
Lighted splint lsquopopsrsquo if air is also
present
Carbon
dioxide
CO2
Colourless Odourless Weakly acidic ndash
blue to slightly
red
A white precipitate forms in
limewater
Ca(OH)2 (aq) + CO2
CaCO3 (s) + H2O (l)
Precipitate redissolves on
continued bubbling
CaCO3 (s) + H2O (l) + CO2 (g)
Ca(HCO3)2 (aq)
Ammonia
NH3
Colourless Pungent Alkaline ndash red
to blue (only
common
alkaline gas)
Turns moist red litmus blue forms
dense white fumes with hydrogen
chloride gas
NH3 (g) + HCl (g) NH4Cl (s)
Gas Colour Odour Effect on moist
litmus
Method of identification
3
Sulphur
dioxide
SO2
Colourless Choking
smell
Acidic ndash blue to
red
Turns acidified potassium
manganate (VII) solution from
purple to colourless
Turns acidified potassium
dichromate (VI) solution from
orange to green
Chlorine
Cl2
Yellow ndash
green
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Bromine
Br2
Red ndash
brown
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Nitrogen
dioxide
NO2
Red ndash
brown
Irritating
smell
Acidic blue to
red
Turns moist blue litmus red but
does not bleach it
Water
vapour
H2O
Colourless Odourless Neutral ndash no
effect
Turns anhydrous cobalt (II)
chloride from blue to pink
Turns anhydrous copper (II)
sulphate from white to blue
4
WEEK 11 LESSON 1 WORKSHEET
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless
Yellow ndash green
Red ndash brown
Gases according to their odour
Odour of gas Identity of gas
Odourless
Pungent smell
Choking smell
Irritating smell
5
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect
Red to blue
Blue to red
Blue to red then bleaches it
6
WEEK 11 LESSON 2
TOPIC Qualitative Analysis ndash Identification of anions
Effect of heating
Method Heat a sample of the solid in a dry test tube
Effect of heating
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) not
of K or Na
CO32- (s) O2- (s) + CO2 (g)
Oxygen evolved NO3- of K or Na 2 NO3
- (s) 2 NO2- (s) + O2
(g)
Oxygen and nitrogen
dioxide evolved
NO3- of Ca and below
in reactivity series
4 NO3- (s) 2 O2- (s) + 4 NO2
(g) + O2
(g)
Sulphur dioxide evolved SO32- SO3
2- O2- (s) + SO2 (g)
Effect of dilute acid
Add dilute hydrochloric acid or nitric acid to a sample of the solid Warm if no reaction occurs
when cold
Effect of dilute acid
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) CO32- (s) + 2 H+ (aq) H2O (l) + CO2 (g)
Sulphur dioxide evolved SO32- SO3
2- (s) + 2 H+ (aq) H2O (l) + SO2 (g)
7
Effect of concentrated acid
Add concentrated sulphuric acid to a sample of the solid Warm if not reaction occurs when cold
Effect of concentrated sulphuric acid
Observation Anion
Carbon dioxide evolved CO32- or HCO3
-
Sulphur dioxide evolved SO3-
Hydrogen chloride evolved Cl-
Hydrogen bromide (colourless) and bromine
vapour (brown) evolved
Br-
Black iodine present and purple iodine vapour
evolved
I-
8
WEEK 11 LESSON 2 WORKSHEET
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater
Produces a gas which relights a glowing splint as the only gas
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green
Produces a gas forms a precipitate in limewater
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia
Black iodine present and purple iodine vapour evolved
9
WEEK 11 LESSON 3
TOPIC Qualitative Analysis ndash Identification of anions
Test for the halides ndash using silver nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous silver nitrate and
observe the precipitate Add ammonia solution and observe the solubility of the precipitate
Test for halides using silver nitrate solution
Effect of silver
nitrate solution
Anion Explanation Effect of aqueous
ammonia
White precipitate ndash
turns white in
sunlight
Cl- Ag+ (aq) + Cl- AgCl (s) Precipitate soluble
Cream precipitate ndash
turns yellow ndash green
in sunlight
Br- Ag+ (aq) + Br- AgBr (s) Precipitate slightly
soluble
Pale yellow
precipitate
I- Ag+ (aq) + I- AgI (s) Precipitate insoluble
Test for the halides ndash using lead nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous lead nitrate and
observe the precipitate
Test for halides using lead nitrate solution
Effect of lead nitrate solution Anion Explanation
White precipitate Cl- Pb2+ (aq) + 2 Cl- PbCl2 (s)
Pale yellow Br- Pb2+ (aq) + 2 Br- PbBr2 (s)
Deep yellow I- Pb2+ (aq) + 2 I- PbI2 (s)
10
Effect of barium nitrate or chloride solution followed by dilute acid
Make a solution of the solid Add barium nitrate or chloride solution and observe the precipitate
Add dilute hydrochloric or nitric acid warn if necessary and observe the solubility of the
precipitate
Effect of barium nitrate or chloride solution followed by dilute acid
Effect of
Ba(NO3)2 (aq)
or BaCl2 (aq)
Effect of HCl (aq)
or HNO3 (aq)
Anion Explanation
White precipitate Precipitate insoluble SO42- Ba2+ (aq) + SO4
2- (aq) BaSO4 (s)
BaSO4 does not react with dilute acids
White precipitate Precipitate soluble ndash
CO2 evolved
CO32- Ba2+ (aq) + CO3
2- (aq) BaCO3 (s)
BaCO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + CO2 (g)
White precipitate Precipitate soluble ndash
SO2 evolved on
warming
SO32- Ba2+ (aq) + SO3
2- (aq) BaSO3 (s)
BaSO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + SO2 (g)
11
WEEK 11 LESSON 3 WORKSHEET
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
(Ionic equation required)
12
WEEK 12 LESSON 1 WORKSHEET
(a) The Caribbean islands are known for their many resources For example the ore of
aluminium is found in Jamaica and Guyana
(i) Briefly describe the extraction of aluminium from its named ore Include in your
description one ionic equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Although aluminium ore is mined in the Caribbean the extraction of aluminium usually
takes place in other countries Suggest ONE reason why it may be difficult to extract
aluminium in the Caribbean
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) An alloy can be described as a lsquomixed metal solutionrsquo Aluminium forms an alloy with
magnesium that is used to make an aircraft
13
Identify this alloy and suggest why it is better to use it rather than the pure metal in the
manufacture of aircraft
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) ldquoSome metals can be useful to man yet harmful to the environmentrdquo Comment on this
statement with reference to mercury
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 12 LESSON 2 Worksheet
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate formed
Soluble in excess
15
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate formed
Insoluble in excess
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate formed
(Ionic equation required)
16
WEEK 12 LESSON 3 Worksheet
Dry ammonia gas can be produced in a school laboratory
(a) Identify TWO reagents that are necessary for the laboratory production of ammonia
______________________________________________________________________________
______________________________________________________________________________
(b) Two common drying agents used in the laboratory are calcium oxide and concentrated
sulphuric acid However calcium oxide is the preferred choice for drying ammonia gas
Explain why concentrated sulphuric acid is now used Include in your answer a balanced
chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) When gases are prepared in the laboratory there are three main ways in which they can
be collected
- Upward delivery
- Downward delivery
- Displacement of water
(i) What TWO other factors should be considered when choosing an appropriate method for
the collection of gases in the laboratory
______________________________________________________________________________
______________________________________________________________________________
(ii) Identify ONE of the three methods that is best suited for the collection of ammonia gas in
the laboratory Explain why EACH of the other two methods would NOT have been
appropriate
______________________________________________________________________________
17
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(d) Hence draw a labelled diagram of the apparatus which could be used for the preparation
of dry ammonia in the laboratory
Be sure to identify in your diagram
- where the reagents are placed
- where the ammonia is dried and
- where the ammonia is collected
18
WEEK 13 LESSON 1 Worksheet
(a) In solution two metals A and B form A+ and B2+ ions respectively Metal A displaces Fe
from a solution containing Fe2+ ions but metal B does NOT
(i) Arrange the metals A B and Fe in order of reactivity from LEAST reactive to MOST
reactive Write a balanced chemical equation to show the reaction between metal A and
Fe2+ ions
______________________________________________________________________________
______________________________________________________________________________
(ii) Metal A is placed in a solution of copper (II) sulphate CuSO4 (aq) Write an equation for
the reaction State ONE observable change that will occur and explain why this reaction
takes place
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) For EACH metal A and B state ONE method that can be used to extract it from its
respective oxide Give a reason for EACH answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
19
______________________________________________________________________________
(b) Metal alloys are often used for making objects found in our daily lives Name an alloy of
iron and state ONE of its uses
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 13 LESSON 2 Worksheet
(a) Many important biological processes in plants and animals depend on the specific roles
of certain metal ions
(i) Farmer Jones reaped a crop of tomatoes and reported that the yield was far below what
was expected Analysis of the soil revealed that there was a deficiency of magnesium
Discuss the importance of magnesium in plant health and explain how a magnesium
deficiency can result in the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE other metal ion which is important to plant health and state the result of its
deficiency
______________________________________________________________________________
______________________________________________________________________________
21
(b) Many years ago car exhaust fumes were known to contain compounds of metals and
non ndash metals which could negatively impact both humans and the environment Identify
ONE metal and ONE non ndash metal whose compounds were present in car exhaust fumes
Discuss the effect of these compounds on human health and the environment
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) Define lsquogreen chemistryrsquo and discuss the measures that have been taken to produce a
lsquogreenerrsquo automotive fuel
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
22
WEEK 13 LESSON 3 Worksheet
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
Zn2+ ions are present
23
WEEK 14 LESSON 1 Worksheet
(a) Metal alloys are often used in place of metals because of their enhanced properties
(i) Define the term lsquoalloyrsquo
______________________________________________________________________________
______________________________________________________________________________
(ii) Name ONE alloy of aluminium and state its use based on one of its enhanced properties
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) A student conducted an experiment to investigate the reactivity of each of the following
metals (copper iron zinc and lead) by using solutionPs of their sulphate salts
The data presented in the table below shows whether a visible chemical reaction took
place when each metal was added to the four sulphate solutions
Key Visible chemical reaction took place
X No visible chemical reaction
CHEMICAL REACTION OF METALS IN SULPHATE SOLUTIONS
Sulphate solution Cu Fe Zn Pb
CuSO4 X
FeSO4 X X X
ZnSO4 X X X X
PbSO4 X X
24
(i) State which of the TWO metals is more reaction Fe or Zn Give a reason for our answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Using the data in the previous Table deduce the order of reactivity of the four metals Cu
Fe Zn and Pb from the most reactive to the least reactive metal
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The student recorded the following observations from the reaction between the iron and
copper (II) sulphate solution
Observations Reddish ndash brown solid coating formed on the iron strip
Blue colour of the solution changed to dirty green
Account for the observations made from the reaction between the iron and copper (II)
sulphate solution
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iv) Write an ionic equation including state symbols for the reaction between the iron and
copper (II) sulphate solution
______________________________________________________________________________
25
(c) Some metal compounds are health and environmental hazards
(i) Identify which of the metals used in the experiment in (b) is MOST hazardous to the
environment
______________________________________________________________________________
______________________________________________________________________________
(ii) State TWO harmful effects of continuous exposure to the metal identified in (c) (i) on
human beings
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
26
WEEK 14 LESSON 2 Worksheet
(a) Carbon is found in the form of diamond and graphite and is a main component in many
naturally occurring compounds such as organic matter and carbon dioxide gas
(i) State ONE way in which diamond differs physically from graphite
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE similarity between diamond and graphite other than they both contain carbon
______________________________________________________________________________
______________________________________________________________________________
(b) Carbon can react with a limited supply of oxygen to form carbon monoxide which can
negatively affect human health
(i) Write a balanced chemical equation including state symbols to show the formation of
carbon monoxide
______________________________________________________________________________
(ii) State TWO effects of carbon monoxide inhalation on the human body
______________________________________________________________________________
______________________________________________________________________________
(c) Jamal wants to prepare and collect a sample of carbon dioxide gas in the laboratory using
calcium carbonate
(i) Write a balanced chemical equation including state symbols for the laboratory
preparation of carbon dioxide gas from calcium carbonate
______________________________________________________________________________
______________________________________________________________________________
(ii) Draw a clearly labelled diagram to show the arrangement of the apparatus and materials
that could be used in the laboratory to prepare and collect the carbon dioxide gas
(iii) State ONE use of carbon dioxide as it relates to the beverage industry
______________________________________________________________________________
27
WEEK 14 LESSON 3 Worksheet
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
(Ionic equation required)
Suggest a possible identity of the solid R __________________________
28
WEEK 15 LESSON 1 Worksheet
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a small
portion of solid Y gently at
first and then strongly
Colourless gas evolved
with a choking odour
Turns acidified potassium
dichromate solution from
orange to green
(ii) To the remaining portion
of solid Y add 20 cm3 of
distilled water stir to dissolve
and filter Collect the filtrate
and divide into 3 equal
portions
Filtrate is pale green in
colour
(iii) To the first portion of the
filtrate from (ii) add aqueous
sodium hydroxide slowly
until in excess
A green precipitate
Insoluble in excess sodium
hydroxide
Ionic equation required
29
TEST OBSERVATIONS INFERENCES
(iv) To the second portion of
the filtrate from (ii) add
aqueous silver nitrate
followed by aqueous
ammonia
White precipitate
Soluble in aqueous
ammonia
(v) To the third portion of the
filtrate from (ii) add aqueous
barium nitrate followed by
aqueous hydrochloric acid
White precipitate formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with the
evolution of a colourless
gas with a choking smell
30
WEEK 15 LESSON 2 Worksheet
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
31
WEEK 15 LESSON 3 Worksheet
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in excess
aqueous NH3
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change
32
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
warm filter and then divide
the filtrate into two portions
Vigorous effervescence
observed upon addition of
dilute HNO3
Gas evolved turns lime water
cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Cu2+ ions present
33
ANSWERS TO WORKSHEETS
34
WEEK 11 LESSON 1 WORKSHEET ANSWERS
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless O2 H2 CO2 NH3 SO2 H2O
Yellow ndash green Cl2
Red ndash brown Br2 NO2
Gases according to their odour
Odour of gas Identity of gas
Odourless O2 H2 CO2 H2O
Pungent smell NH3
Choking smell SO2 Cl2 Br2
Irritating smell NO2
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect Neutral O2 H2 H2O
Red to blue Alkaline NH3
Blue to red Acidic CO2 SO2 NO2
Blue to red then bleaches it Acidic Cl2 Br2
35
WEEK 11 LESSON 2 WORKSHEET ANSWERS
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-) not
of K or Na
Produces a gas which relights a glowing splint as the only gas NO3- of K or Na
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green SO32-
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-)
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia Cl-
Black iodine present and purple iodine vapour evolved I-
36
WEEK 11 LESSON 3 WORKSHEET ANSWERS
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Br-
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
Cl-
Ag+ (aq) + Cl- AgCl (s)
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow Br-
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
SO42-
Ba2+ (aq) + SO42- (aq)
BaSO4 (s)
(Ionic equation required)
37
WEEK 12 LESSON 1 Worksheet Answers
(a) (i)
The ore bauxite is purified
The purified bauxite is dissolved in molten cryolite
The aluminium oxidecryolite solution is then eletrolysed
Equation at the cathode Al3+ (l) + 3 e- Al (l)
Equation at the anode 2 O2- (l) ndash 4 e- O2 (g)
(ii) The process is too expensive mainly because too much electricity or energy is needed
(b) The alloy of Al and Mg is magnalium It is less dense than the pure metals and hence allow
aircraft to be lighter It is also stronger than the pure metals and hence allows aircraft to last
longer since it is not easily destroyed
(c) Your answer should cater for the following aspects
Benefits of mercury to humans for example in thermometers barometers in dentistry
and gold mining
Entry of mercury to the environment For example this could have been through broken
thermometers barometers or lightbulbs or improper disposal of them or batteries and
indiscriminate use in gold mining in Guyana
The identification of a negative impact on the environment such as poisoned fish and the
persons who eat the fish death mood swings and psychosis
38
WEEK 12 LESSON 2 Worksheet Answers
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas
evolved
NO2 evolved OR nitrates
present OR
Br2 gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate
formed
Soluble in excess
Pb2+ Zn2+ Al3+ or Ca2+
present
Pb2+ Zn2+ Al3+ or present
39
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate
formed
Insoluble in excess
Pb2+ Zn2+ Al3+ or present
Pb2+ or Al3+ present
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate
formed
Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
40
WEEK 12 LESSON 3 Worksheet Answers
(a) an ammonium salt and a strong alkali
(b) Ammonia is basic and it will react with H2SO4
Equation 2 NH3 (aq) + H2SO4 (aq) (NH4)2SO4 (aq)
(c) (i) ndash Density of the gas relative to air ndash The solubility of the gas in water
(ii) Ammonia is collected by upward delivery
It cannot be collected by downward delivery since ammonia is less dense than air
It cannot be collected by displacement of water since it is soluble in water
(d)
41
WEEK 13 LESSON 1 Worksheet Answer
a) i) B ˂ Fe ˂ A
2A (s) + Fe 2+ (aq) rarr 2A+ (aq) + Fe (s)
ii) 2A (s) + CuSO4 (aq) rarr A2SO4 (aq) + Cu (s)
Observation blue colour fades gets lighter OR brown solid forms is deposited OR metal A
decreases in size dissolves
Explanation Metal A is higher (than Fe which is higher) than Cu in the reactivity series OR
Metal A is more reactive (than Fe which is more reactive) than Cu so Metal A can displace Cu
iii) Metal A can be extracted by electrolysis (of its molten oxide) because Metal A is a very
reactive metal is high in the reactivity series forms stable oxides needs a lot of energy to be
extracted and very reactive metals are extracted by electrolysis
Metal B can be extracted by heating with carbon carbon monoxide OR by chemical reduction
of the oxide because Metal B is less reactive than Fe is low in the reactivity series forms less
stable oxides does not need a lot of energy to be extracted and oxides of less reactive metals are
easily reduced
b) Alloy of iron steel
Use of alloy making buildings bridges ships motor vehicles furniture utensils
42
WEEK 13 LESSON 2 Worksheet Answer
(a) (i)
Magensium is the metal ion found in chlorophyll
Chlorophyll is essential for photosynthesis
A deficiency in magnesium will result in low chlorophyll yellow leaves and a reduction in
photosynthesis
Hence there will be low carbohydrates or energy production
Hence small fruits stunted growth and lower yield will result
(ii)
Metal ion Results of deficiency
Potassium Stunted growth premature loss of leaves yellowing of leaves curling of leaf tips
Calcium Growth abnormalities in tips of roots and shoots curling of leaves
Iron Yellowing of leaves
Zinc Low chlorophyll content yellowing of leaves
Manganese Yellowing of leaves poor flavors in some crops for example potato
(b)
Metal Lead is present in some types of gasoline Upon combustion lead compounds escape into
the atmosphere It accumulates in body tissues and slowly poisons the person It causes mental
illness
Non ndash metal SulphurSulphur dioxide or NitrogenNitrogen dioxide
Dissolves in rain water to form acid rain or cause respiratory illnessproblems Acid rain can
cause corrosion damage in buildings
(c)
Green chemistry is the utilisation of a set of principles that reduces or eliminates the use or
generation of hazardous substances
43
Automotive fuels are now produced without lead so as to eliminate the release of lead
compounds into the atmosphere
Low sulphur fuel is being produced with much reduced sulphur content which causes a reduction
of sulphur dioxide release into the atmosphere
44
WEEK 13 LESSON 3 Worksheet Answer
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
gas turns litmus blue
red
brown gas
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
white precipitate
precipitate soluble in
excess
Zn2+ ions are present
45
WEEK 14 LESSON 1 Worksheet Answers
(a)(i) An alloy is a material made from a mixture of two or more metals
(ii) Any suitable answer chosen from below
Alloy Enhance Property Use
Duralumin High strength
Low density
Light
Hard
Used to make aircraft bodies
space satellites
Magnalium Light
Hard
Easier to weld
Corrosion resistant
Strong
High ductability
Used in pyrotechnics
(fireworks)
Mirrors
Aircraft parts
To make scientific
instruments
Used to make marine castings
Alchlad Strong
Corrosion resistant
Cladding for buildings
(b) (i) Zinc is more reactive than iron
Zinc displaces iron from iron (II) sulphate
Zinc is higher in the reactivity series than iron
Iron does not displace zinc from zinc sulphate
(ii) Order of reactivity Zn gt Fe gt Pb gt Cu
(iii) Reddish brown solid ndash copper metal formed
46
Dirty green solution ndash presence of Fe2+ ion
(iv) Fe (s) + Cu2+ (aq) Fe2+ (aq) + Cu (s)
(c) (i) Lead
(ii) Any two correct harmful effects of lead on the body
Impedes brain development (in young children)
Affectimpede development of the immune system in humans
Affecthamper development of nervous system in humans
Long term exposure can result in kidney and liver damage
Mental retardation
Anaemia
Death
47
WEEK 14 LESSON 2 Worksheet Answers
a) i) Diamond is transparent clear Graphite is opaque black
OR hard OR brittle
OR does not conduct electricity OR conducts electricity
a) ii) Both have a macromolecular giant molecular giant covalent structure (lattice)
OR Both have high melting point boiling point
OR Both are insoluble in water organic solvent
b) i) 2C (s) + O2 (g) rarr 2CO (g)
ii) CO reduction in amount of oxygen carried by (the haemoglobin in the red blood
cells of) the blood
Headache OR dizziness OR nausea OR fatigue OR loss of consciousness OR
death
c) i) CaCO3 (s) + 2HCl (aq) rarr CaCl2 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) + H2SO4 (aq) rarr CaSO4 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) rarr CaO (s) + CO2 (g)
48
ii)
OR
OR
Entirely closed system thistle funnel below the level of the liquid OR tap that could be
closed
Two reagents labelled CaCO3marble chips and HCl H2SO4 or heat source
collection of CO2 upward displacement of air OR over watersulphuric acid OR in gas
syringe
iii) CO2 use put in aerated drinks carbonated beverages
OR put in carbon dioxide fire extinguishers
49
WEEK 14 LESSON 3 Worksheet Answers
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
NH4+
NH4+ confirmed OR
NH3 (g) produced
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
Cl- ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation required)
Suggest a possible identity of the solid R NH4Cl (ammonium chloride)
50
WEEK 15 LESSON 1 Worksheet Answers
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a
small portion of solid Y
gently at first and then
strongly
Colourless gas
evolved with a
choking odour
Turns acidified
potassium dichromate
solution from orange
to green
SO2 evolved
Presence of a sulphite
(ii) To the remaining
portion of solid Y add 20
cm3 of distilled water stir
to dissolve and filter
Collect the filtrate and
divide into 3 equal portions
Filtrate is pale green
in colour
Fe2+ ions present
(iii) To the first portion of
the filtrate from (ii) add
aqueous sodium hydroxide
slowly until in excess
A green precipitate
Insoluble in excess
sodium hydroxide
Fe2+ ions present
Fe2+ (aq) + 2 OH- (aq) Fe(OH)2 (s)
Ionic equation required
TEST OBSERVATIONS INFERENCES
(iv) To the second portion
of the filtrate from (ii) add
aqueous silver nitrate
White precipitate
Soluble in aqueous
ammonia
Cl- ions present
51
followed by aqueous
ammonia
(v) To the third portion of
the filtrate from (ii) add
aqueous barium nitrate
followed by aqueous
hydrochloric acid
White precipitate
formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with
the evolution of a
colourless gas with a
choking smell
SO32- CO3
2- SO42- ions present
SO32- ions present
52
WEEK 15 LESSON 2 Worksheet Answers
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
Chloride ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
Cu2+ ions present
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
X contains a reducing agent
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
SO32- SO4
2- or CO32- ions are
present
SO32- ions are present
53
WEEK 15 LESSON 3 Worksheet Answers
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
White ppt
Ppt soluble in excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in
excess aqueous NH3
Al3+ Pb2+ Zn2+ present
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change Cl- Br- I- absent
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
Vigorous effervescence
observed upon addition of
dilute HNO3
CO2 evolved OR
Carbonate present
54
warm filter and then divide
the filtrate into two portions
Gas evolved turns lime
water cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
Cu2+ (aq) + OH- (aq)
Cu(OH)2 (s)
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Blue ppt
ppt dissolves in excess
NH3 to give a deep blue
solution
Cu2+ ions present
55
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
REFERENCES
Hunte-King J Maragh P Nagir F amp Norris R (2013) Chemistry for CSEC United
Kingdom Nelson Thornes Ltd
Remy C Mason L Lambert N amp Mohammed M (2007) Chemistry for CSEC England and
Wales Pearson Education Limited
Taylor M amp Chung-Harris T (2010) CXC Chemistry England Macmillan Publishers
Limited
Tindale A (2016) Chemistry A Concise Revision for CXC London HarperCollins Publishers
Limited
10
WEEK 1 LESSON 3 WORKSHEET
Write balanced chemical equations for the reaction of the named metals and air or oxygen
State the nature of the oxide formed (basic or amphoteric)
Potassium + Oxygen
______________________________________________________________________________
Sodium + Oxygen
______________________________________________________________________________
Calcium + Oxygen
______________________________________________________________________________
Magnesium + Oxygen
______________________________________________________________________________
Aluminium + Oxygen
______________________________________________________________________________
Zinc + Oxygen
______________________________________________________________________________
11
Iron + Oxygen
______________________________________________________________________________
Lead + Oxygen
______________________________________________________________________________
Copper + Oxygen
______________________________________________________________________________
Silver + Oxygen
______________________________________________________________________________
12
WEEK 2 LESSON 1
TOPIC Chemical properties of metals
Action of water
Metals high in the electrochemical series react with cold water to produce the metal hydroxide
and hydrogen
Reactive metals slightly lower in the electrochemical series react very slowly or not at all with
water However they may react with hot water or steam to produce the corresponding metal
oxide and hydrogen
Metals lower than hydrogen in the electrochemical series do not react with water
Metal Reaction with water or steam
Potassium K React with cold water forming metal hydroxide and hydrogen
eg Ca (s) + 2 H2O (l) Ca(OH))2 (aq) + H2 (g) Sodium Na
Calcium Ca
Magnesium Mg React with steam forming metal oxide and hydrogen
eg Zn (s) + H2O (g) ZnO (s) + H2 (g) Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
13
WEEK 2 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with water (or
steam if reaction does not occur with water)
Potassium + WaterSteam
______________________________________________________________________________
Sodium + WaterSteam
______________________________________________________________________________
Calcium + WaterSteam
______________________________________________________________________________
Magnesium + WaterSteam
______________________________________________________________________________
Aluminium + WaterSteam
______________________________________________________________________________
Zinc + WaterSteam
______________________________________________________________________________
14
Iron + WaterSteam
______________________________________________________________________________
Copper + WaterSteam
______________________________________________________________________________
Silver + WaterSteam
______________________________________________________________________________
15
WEEK 2 LESSON 2
TOPIC Chemical properties of metals
Action of dilute acids
Metals above hydrogen in the electrochemical series react with dilute acids to form a salt and
hydrogen gas They react with hydrochloric acid to form the metal chloride (a salt) and hydrogen
gas They also react with dilute suphuric acid to form the metal sulphate (a salt) and hydrogen
gas
Metal Reaction dilute hydrochloric or sulphuric acid
Potassium K Violent reaction forming a salt and hydrogen gas
eg 2 Na (s) + 2 HCl (aq) 2 NaCl (aq) + H2 (g) Sodium Na
Calcium Ca Vigorous reaction forming a salt and hydrogen gas
eg Mg (s) + 2 HCl (aq) MgCl2 (aq) + H2 (g) Magnesium Mg
Aluminium Al React forming a salt and hydrogen gas
eg Fe (s) + 2 HCl (aq) FeCl2 (aq) + H2 (g) Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
16
WEEK 2 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with
hydrochloric acid
Metal Balanced equation for reaction with hydrochloric acid
Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Copper
Silver
17
WEEK 2 LESSON 3
TOPIC Reactions of metal compounds
Reactions of metallic oxides with dilute acid
Metal oxides react with dilute hydrochloric acid or sulphuric acid to produce a salt and water
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
Some of these reactions may be slow and can be speeded up by adding heat
For example
zinc oxide + hydrochloric acid zinc chloride + water
ZnO (s) + 2 HCl (aq) ZnCl2 (aq) + H2O (l)
magnesium oxide + hydrochloric acid magnesium chloride + water
MgO (s) + 2 HCl (aq) MgCl2 (aq) + H2O (l)
aluminium oxide + sulphuric acid aluminium sulphate + water
Al2O3 3 H2SO4 (aq) Al2(SO4)3 (aq) + 3 H2O (l)
calcium oxide + sulphuric acid calcium sulphate + water
CaO H2SO4 (aq) CaSO4 (aq) + H2O (l)
18
WEEK 2 LESSON 3 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal oxides with the
corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium oxide Hydrochloric acid
Sodium oxide Sulphuric acid
Calcium oxide Hydrochloric acid
Magnesium oxide Sulphuric acid
Aluminium oxide Hydrochloric acid
Zinc oxide Sulphuric acid
19
WEEK 3 LESSON 1
TOPIC Reactions of metal compounds
Reactions of metallic hydroxides with dilute acid
Metal hydroxides react with dilute acids to form a salt and water in a neutralisation reaction
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
For example
magnesium hydroxide + hydrochloric acid magnesium chloride + water
Mg(OH)2 (aq) + 2 HCl (aq) MgCl2 (aq) + 2 H2O (l)
sodium hydroxide + hydrochloric acid sodium chloride + water
NaOH (aq) + HCl (aq) NaCl (aq) + H2O (l)
potassium hydroxide + sulphuric acid potassium sulphate + water
2 KOH + H2SO4 (aq) K2SO4 (aq) + 2 H2O (l)
calcium hydroxide + sulphuric acid calcium sulphate + water
Ca(OH)2 (aq) + H2SO4 (aq) CaSO4 (aq) + 2 H2O (l)
20
WEEK 3 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal hydroxides with
the corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium hydroxide Hydrochloric acid
Sodium hydroxide Sulphuric acid
Calcium hydroxide Hydrochloric acid
Magnesium hydroxide Sulphuric acid
Aluminium hydroxide Hydrochloric acid
Zinc hydroxide Sulphuric acid
21
WEEK 3 LESSON 2
TOPIC Reactions of metal compounds
Reactions of metallic carbonates with dilute acid
Metal carbonates react with dilute acid to form a salt carbon dioxide and water When
hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric acid is
used the corresponding sulphate salt is formed
For example
sodium carbonate + hydrochloric acid sodium chloride + carbon dioxide + water
Na2CO3 (s) + 2 HCl (aq) 2 NaCl (aq) + CO2 (g) + H2O (aq)
calcium carbonate + hydrochloric acid calcium chloride + carbon dioxide + water
CaCO3 (s) + 2 HCl (aq) CaCl2 (aq) + CO2 (g) + H2O (aq)
zinc carbonate + sulphuric acid zinc sulphate + carbon dioxide + water
ZnCO3 (s) + H2SO4 (aq) ZnSO4 (aq) CO2 (g) + H2O (aq)
potassium carbonate + sulphuric acid potassium sulphate + carbon dioxide + water
K2CO3 (s) H2SO4 (aq) K2SO4 (aq) CO2 (g) + 2 H2O (aq)
22
WEEK 3 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal carbonates with
the corresponding acid
Metallic
carbonate
Acid Balanced chemical equation
Potassium
carbonate
Hydrochloric
acid
Sodium
carbonate
Sulphuric acid
Zinc
carbonate
Hydrochloric
acid
Magnesium
carbonate
Sulphuric acid
Aluminium
carbonate
Hydrochloric
acid
Calcium
carbonate
Sulphuric acid
23
WEEK 3 LESSON 3
TOPIC Action of heat on metal compounds
Action of heat on nitrates
All nitrates decompose when heated The reactivity of the metal in the metal nitrate influences
the products of the decomposition
The nitrates of the alkali metals (Group I) with the exception of lithium nitrate decompose to
form the metal nitrite and oxygen
The nitrates of most other metals decompose to form the metal oxide nitrogen dioxide and
oxygen
The nitrates of the very unreactive metals decompose to form the meal nitrogen dioxide and
oxygen
Metal Nitrate Decomposition
Potassium K Products metal nitrite + oxygen
eg 2 NaNO3 (s) Heatrarr 2 NaNO2 (s) + O2 (g)
Sodium Na
Calcium Ca
Products metal oxide + nitrogen dioxide + oxygen
eg 2 Pb(NO3)2 (s)
Heatrarr 2 PbO (s) + 4 NO2 (g) + O2 (g)
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Products metal + nitrogen dioxide + oxygen
eg 2 AgNO3 (s) Heatrarr 2 Ag (s) + 2 NO2 (g) + O2 (g)
24
WEEK 3 LESSON 3 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
nitrates
Metal Balanced chemical equation
Potassium nitrate
Sodium nitrate
Calcium nitrate
Magnesium nitrate
Aluminium nitrate
Zinc nitrate
Lead nitrate
Copper nitrate
Silver nitrate
25
WEEK 4 LESSON 1
TOPIC Action of heat on metal compounds
Action of heat on carbonates
Upon application of heat many carbonates decompose to form the metal oxide and carbon
dioxide
Group I carbonates do not decompose on heating with the exception of lithium carbonate
Metal Carbonate decomposition
Potassium K
Stable not decomposed by heat Sodium Na
Calcium Ca
Decompose forming metal oxide and carbon dioxide
eg CaCO3 (s) Heatrarr CaO (s) + CO2 (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Unstable
26
WEEK 4 LESSON 1 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
carbonates
Metal Balanced chemical equation
Potassium carbonate
Sodium carbonate
Calcium carbonate
Magnesium carbonate
Aluminium carbonate
Zinc carbonate
Iron carbonate
Lead carbonate
Copper carbonate
27
WEEK 4 LESSON 2
TOPIC Action of heat on metal compounds
Action of heat on the metal hydroxides
Most metal hydroxides decompose on heating A metal oxide and water are formed
Group I hydroxides do not decompose on heating with the exception of lithium hydroxide
Metal Hydroxide decomposition
Potassium K Stable not decomposed by heat
Sodium Na
Calcium Ca Decompose forming metal oxide and water (as steam)
eg Zn(OH)2 (s) Heatrarr ZnO (s) + H2O (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag No hydroxide exist
28
WEEK 4 LESSON 2 WORKSHEET
Write the balanced chemical equations for the thermal decomposition of the following
metal hydroxides
Metal hydroxide Balanced chemical equation
Potassium hydroxide
Sodium hydroxide
Calcium hydroxide
Magnesium hydroxide
Aluminium hydroxide
Zinc hydroxide
Lead hydroxide
Copper hydroxide
29
WEEK 4 LESSON 3
TOPIC Reactivity of metals ndash The Reactivity Series
The reactivity series of metals is a list of metals arranged in order of their reactivity based on
Displacement reactions
Reactions with oxygen dilute acids and water
Relative ease of decomposition of their compounds
Metals at the top of the series are the most electropositive They lose electrons very easily and
readily form cations These ions are very stable and are not easily discharged to form atoms Due
to this fact they are the most reactive metals
Metals at the bottom of the series are the least electropositive They do not lose electrons easily
and do not readily form ions Their ions are very unstable and are easily discharged to form
atoms They are the least reactive metals
The reactivity series of metals
Mnemonic Metal Symbol Reactivity
People Potassium K Most reactive
Least reactive
Sometimes Sodium Na
Collect Calcium Ca
Magazines Magnesium Mg
About Aluminium Al
Zoos Zinc Zn
In Iron Fe
London Lead Pb
Having (Hydrogen) H
Cute Copper Cu
Monkeys and Mercury Hg
Small Silver Ag
Gorillas Gold Au
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
5 Reactivity of metals Reactivity of metals Reactivity of metals
6 Extraction of metals Extraction of metals Alloys
7 Corrosion Importance of metals
and their compounds
on living systems and
environment
Chemical properties
of non ndash metals
8 Laboratory
preparation of gases
Laboratory
preparation of gases
Laboratory
preparation of gases
9 Uses of gases Uses of non ndash metals
and their compounds
Harmful effects of
non ndash metals and
their compounds on
living systems and
the environment
10 Green Chemistry Qualitative Analysis
ndash Identification of
cations
Qualitative Analysis
ndash Identification of
cations
2
WEEK 5 LESSON 1
TOPIC Reactivity of metals
Reactivity based on displacement reactions between metals and metal ions
A metal will displace a metal which is lower than itself in the reactivity series from a solution of
the metal salt
Reaction of zinc and copper (II) sulphate
Expected observations
Explanation
The size of the zinc metal decreases
The zinc metal is reacting and forming the
salt zinc sulphate
The solution becomes lighter eventually
colourless
The Cu2+ (aq) ions (responsible for the blue
colour) is reduced to Cu (s)
A brown solid is deposited at the bottom of
the container
Copper metal is formed
Equation Zn (s) + CuSO4 (aq) ZnSO4 (aq) + Cu (s)
Ionic equation
Zn (s) + Cu2+ (aq) Zn2+ (aq) + Cu (s)
Zinc is higher in the reactivity series than copper Therefore it will displace the copper ions in
the reaction above
3
Examples of other displacement reactions
Magnesium will displace Zn2+ ions in zinc sulphate since it is higher in the series than zinc
Mg (s) + Zn2+(aq) Mg2+ (aq) + Zn (s)
Silver will not displace Cu2+ ions in copper (II) sulphate [Cu is higher in the series than Ag]
Using the information above we can arrange the metals in order of their reactivity with
magnesium being the most reactive and silver the least reactive metal among the four metals
Mg gt Zn gt Cu gt Ag
Reactivity based on reaction with oxygen
The reactivity of metals can also be deduced from their reaction with oxygen
The table below gives the observations for the reaction with oxygen with the selected metals
Reaction of metal with oxygen
Metal Observation
Copper The surface turns black upon heating
Magnesium Ribbon burns very rapidly
Sodium Burns vigorously
Gold No reaction
Based on the observations for the 4 metals the metal with highest reactivity is sodium and the
metal with the least reactivity is gold
The 4 metals can be arranged in terms of reactivity as follows
Na gt Mg gt Cu gt Au
4
WEEK 5 LESSON 1 WORKSHEET
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
5
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
6
WEEK 5 LESSON 2
TOPIC Reactivity of metals
Reactivity based on reactivity with acids
The metals that are higher than hydrogen in the electrochemical series react with non ndash oxidizing
acids to produce a salt and hydrogen gas
By using the same concentration of acid and same mass and size of the metals the order of
reactivity of the metals can be deduced
The table below shows the results for an experiment with the reaction of the named metals and
1 mol dm-3 hydrochloric acid
Reaction of metals with acid
Metal Observations
Silver No reaction
Magnesium Bubbles produced steadily
Calcium Bubbles produced very rapidly
Iron Bubbles produced slowly
Based on the above data the most reactive metal will be calcium with the least reactive being
silver The order of reactivity will be Ca gt Mg gt Fe gt Ag
By comparing this to the electrochemical series it can be seen that the reactivity of the metals
decrease as we go down the series
7
WEEK 5 LESSON 2 WORKSHEET
1 Place a next to the metals that will react with dilute acid and an X next to the metals
that will not react with dilute acid
Metal Reactivity with acid
Copper
Magnesium
Aluminium
Silver
Zinc
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
8
WEEK 5 LESSON 3
TOPIC Reactivity of metals
Reactivity based on ease of decomposition of the metal nitrates carbonates oxides and
hydroxides
The more reactive a metal the more difficult it is to decompose its nitrate carbonate oxide or
hydroxide on heating
For example Decomposition of carbonates
Procedure
1 Put a large spatula measure of the carbonate to be tested in a test tube
2 Fit a delivery tube and then clamp the test tube so that the delivery tube dips into a second test
tube containing 2ndash3 cm3 limewater
3 Heat the solid gently at first then more strongly
4 Lift the delivery tube from the limewater before or as soon as the heating is stopped This is to
avoid suck-back
5 Write down all observations Notice what happens to the limewater and how long it takes to turn
milky (if at all) Notice whether any melting occurs in the heated test tube and any colour
changes taking place Write your results in tabular form
6 Repeat the experiment with the other metal carbonates supplied and in each case write down
your observations
7 Wash your hands thoroughly at the end of these experiments since some of the metal carbonates
are toxic
9
Results
Metal Formula Gas evolved Ease of decomposition
Zinc ZnCO3 Carbon dioxide Fairly easy
Copper CuCO3 Carbon dioxide Easy
Sodium Na2CO3 None Very difficult
Using the results of the above activity the reactivity of the metals can be determined
Ease of decomposition Copper gt Zinc gt Sodium
The order of reactivity is the opposite for the ease of decomposition
Order of reactivity Sodium (most reactive) gt Zinc gt Copper (least reactive)
10
WEEK 5 LESSON 3 WORKSHEET
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
11
WEEK 6 LESSON 1
TOPIC Extraction of metals
Elements exist all over the earth Some are found as free elements eg copper silver and gold
Others are found combined with other elements in compounds To get the elements the
compounds have to be broken up These compounds are generally called ores the most
convenient sources of which are rocks sea and air
The extraction of a metal from its ore is a reduction process where the metals ions gain electrons
to form atoms
The general equation is Mn+ + n e- M
The choice of the extraction method depends on the position of the metal in the reactivity series
As we go down the series the metals become more stable and the metal ions (in the ores)
become less stable
The very reactive metals that are high in the series K Na Ca Mg Al have very stable ores
Therefore they require a powerful method of reduction namely electrolysis During the process
the cathode provides the electrons and acts as the reducing agent
The metals in the middle of the series (Zn Fe Pb) do not have stable ores and can be extracted
by reduction with carbon in the case of zinc and with carbon monoxide in the case of iron and
lead
Metals low in the reactivity series if present as ores can be extracted simply by heating the ores
in air at high temperatures
12
Extraction of Aluminium from purified bauxite
Pure bauxite is pure alumina (Al2O3) Aluminium is obtained from bauxite by electrolysis
Aluminium oxide has a very high melting point approximately 2050 0C so it is first dissolved in
molten cryolite (Na2AlF6) The addition of cryolite lowers the melting point to approximately
900 0C
The electrolyte is a molten mixture of alumina and molten cryolite The cathode is the graphite
lining of the cell The anodes are blocks of graphite or titanium alloys
Reaction at the cathode
Al3+ (l) + 3 e- Al (l)
Reaction at the anode
2 O2- (l) ndash 4 e- O2 (g)
Aluminium (melting point 660 0C) is a liquid at the temperature at which electrolysis is carried
out and is collected at the bottom of the cell and tapped off Oxygen gas which is given off in the
main cathode reaction together with the heat causes the anodes to burn away The anodes have
to be replaced from time to time The use of anodes from titanium alloys reduce the number of
times that the anodes have to be replaced
13
WEEK 6 LESSON 1 Worksheet
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 6 LESSON 2
TOPIC Extraction of metals
Extraction of Iron
The traditional method of production of iron is by reduction of haematite by carbon monoxide in
a blast furnace
Ores Haematite ndash Fe2O3 Magnetite ndash Fe3O4 Siderite ndash FeCO3 Magnetite and Siderite are
converted to Haematite
A mixture of haematite limestone (CaCO3) and coke (C) called the charge is placed into the top
of the furnace
Hot air is blown into the bottom of the furnace
Coke burns in air forming carbon dioxide
C (s) + O2(g) CO2 (g) ΔH -ve
The heat produced keeps the temperature at about 1900 0C
The carbon dioxide is reduced to carbon monoxide by the hot coke
CO2 (g) + C (s) 2 CO(g) Δ +ve
Heat absorbed reduces the temperature to about 1100 0C
The carbon monoxide reduces the hot iron ore to molten iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + 3 CO2(g)
The temperature at this part of the furnace is about 700 0C The iron runs to the bottom of the
furnace
The impurities are removed by the addition of limestone (CaCO3) The limestone at the
temperature of the furnace breaks down
CaCO3 (s) CaO (s) + CO2 (g)
15
The calcium oxide formed combines with silicon dioxide (sand) the main impurity in the iron
ore to form molten slag
CaO (s) + SiO2 (s) CaSiO3 (l)
The slag does not mix with the molten iron but floats on it The molten iron and slag are run off
separately
The iron formed in a blast furnace is an impure form of the metal Because the molten metal is
allowed to solidify in shallow trays known as casts the iron is called lsquocast ironrsquo or lsquopigrsquo iron
Cast iron is quite brittle and contains 2 - 4 carbon and other impurities Most of the cast iron is
converted to steel
A blast furnace used for extracting iron
16
WEEK 6 LESSON 2 Worksheet
(a) What are the three raw materials that are added through the top of the blast furnace
during the extraction process for iron
______________________________________________________________________________
______________________________________________________________________________
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
______________________________________________________________________________
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______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
17
WEEK 6 LESSON 3
TOPIC Alloys
An alloy is a mixture of two or more metals Alloys are made by melting the individual metals
mixing them and allowing the molten mixture to solidify
In general alloys are harder stronger and more resistant to corrosion than the actual metals they
are made up from
Alloy Use Properties
ALUMINIUM
-Duralumin
(AlMgCu)
-Magnalium (AlMg)
Alloys used in the
construction of
aircraft and ships
buses
Aluminium is used in
making cooking
utensils electrical
cables paint for fuel
storage tanks bottle
caps foil and utensils
for handling nitric
acid
The alloys have a low
density They are as
light as aluminium
and more resistant to
corrosion than
aluminium
LEAD
-Solder (PbSn)
Alloy is used in
joining metals
(soldering)
Lead is used in
underground cables
plates in
The alloy has a lower
melting point than
lead and is harder
than lead
18
Alloy Use Properties
accumulators shield
against x ndash rays
IRON
- Stainless Steel
(FeCONiC)
-Tungsten steel
(FeWC)
-Invar steel (FeNi)
Manganese steel
(FeMnC)
Iron is the main metal
of a variety of
constructions
Steel is used in
cutlery rock drills
electromagnets
vehicle body and
engine parts fences
pipes etc
Steel resists
corrosion is usually
harder than iron and
may be tough though
malleable and ductile
19
WEEK 6 LESSON 3 Worksheet
(a) Define the term alloy
______________________________________________________________________________
(b) State 3 general advantages that alloys have over the individual metals they are made
from
______________________________________________________________________________
______________________________________________________________________________
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
______________________________________________________________________________
______________________________________________________________________________
Uses
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 7 LESSON 1
TOPIC Corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
Familiar examples of corrosion are
- the formation of a green powder on copper sheeting
- the eating away of iron (rusting)
- the development by aluminum of a thin compact layer of oxide which protects the
underlying metal from further corrosion
When corrosion occurs in water ndash free environment it is called dry oxidation When it occurs in
aerated aqueous environments it is called wet corrosion Wet corrosion is the most common and
troublesome form of corrosion
The most familiar corrosion is the rusting of iron and steel On exposure to the atmosphere iron
and steel corrode to form rust which is hydrated iron (III) oxide Fe2O3xH2O Iron and steel
corrode easily and the rust formed flakes off easily thus exposing fresh surface for attack
When iron rust it loses electrons
Fe (s) ndash 2e- Fe 2+ (aq)
The iron (II) ions pass into solution and then combine with the hydroxyl (OH-) ions in the
aerated aqueous environment to form iron (II) hydroxide The oxygen present oxidises the iron
(II) hydroxide to hydrated iron (III) oxide or rust
Fe(OH)2 + O2 Fe2O3xH2O
21
Methods of preventing rusting
1 Coating the object with paint grease plastic or rubber which prevent contact with air or
water
2 Galvanising ndash coating the object with zinc The zinc forms an adherent oxide layer which
protects against further corrosion If damaged the zinc is oxidized in preference to the
iron since it is higher in the electrochemical series
3 Coating with tin lsquoTinrsquo cans are made of steel plated with tin However if scratched
rusting occurs since iron is more reactive than tin
4 Attaching a sacrificial anode to the object A piece of metal higher in the electrochemical
series such as magnesium is attached The magnesium will be oxidized in preference
since it is higher in the electrochemical series than iron
22
WEEK 7 LESSON 1 WORKSHEET
(a) Define the term corrosion
______________________________________________________________________________
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
23
WEEK 7 LESSON 2
TOPIC Importance of metals and their compounds on living systems and environment
Some metals are an integral part of different structures of living things
Metal Presence and Function
Potassium Main cation in fluid or animal cells essential for healthy plant growth
Calcium Necessary for strong bones teeth and shells needed by some enzymes Present
in dairy produce eggs nuts and cereals
Magnesium Central atom of chlorophyll needed for some enzyme action Involved in energy
and calcium metabolism
Zinc Present in many enzymes Needed for protein metabolism Essential for growth
of animals
Iron Present in haemoglobin Needed for protein metabolism Essential for growth of
animals
Chromium Needed for glucose uptake by cells and thus linked to the action of insulin
Manganese Needed for bone development and amino acid metabolism Present in several
enzymes Needed for plant growth
Cobalt Present in Vitamin B12 Needed for plant growth
Copper Involved in formation of haemoglobin and melanin Present in enzymes
controlling oxidation Needed for plant growth
24
Harmful effects of metals and their compounds to living systems and the environment
There are some metals and metal compounds which may cause harm to living systems and the
environment
Lead
Lead is a heavy metal poison that is widely encountered It may occur in food beverages paint
water formed from ndash sealed pipes in air polluted by combustion by fuels containing lead
compounds Lead is also used in some car batteries If these are paints or batteries are not
disposed of correctly lead may get into groundwater or air Lead and lead compounds harm the
nervous system including the brain especially young children
Arsenic
Arsenic compounds are poisonous They can get into the groundwater from mining waste and
from disposal of some electrical components
Cadmium
Cadmium compounds are poisonous They can get into the ground by improper disposal of
nickel ndash cadmium batteries Persons can get cadmium poisoning if they eat food grown in
contaminated soil
Mercury
Mercury can be spilled from broken thermometers in hospitals and laboratories Mercury and its
compounds are particularly poisonous to fish and it can accumulate in the food chain and
eventually poison humans
Problems of disposal of solid waste
Metals may react with water andor air and corrode to form soluble compounds that are
poisonous These toxic compounds diffuse into the soil and eventually enter rivers
Rust from iron may form unsightly pools of waste that reduce plant growth
Waste from aluminium extraction may react with water and form flammable gases
25
WEEK 7 LESSON 2 WORKSHEET
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Lead
______________________________________________________________________________
Mercury
______________________________________________________________________________
26
WEEK 7 LESSON 3
TOPIC Chemical properties of non ndash metals
Reaction with oxygen
Many non ndash metals burn in excess oxygen or air to form oxides For example
S (s) + O2 (g) SO2 (g)
C (s) + O2 (g) CO2 (g)
Reactions with metals
Some non ndash metals react with metals high in the electrochemical series when heated
For example
Sodium burns in chlorine to form sodium chloride
Na (s) + Cl2 (g) NaCl (s)
Magnesium burns in oxygen to form magnesium oxide
Mg (s) + O2 (g) MgO (s)
When heated iron combines with molten sulphur to form iron (II) sulphide
Fe (s) + S (l) FeS (s)
When heated reactive metals such as sodium and aluminium react with hydrogen to form metal
hydrides
2 Na (s) + H2 (g) 2 NaH (s)
Oxidising and Reducing properties
Hydrogen and Carbon are very good reducing agents
At high temperatures hydrogen reduces metal oxides below zinc in the electrochemical series to
form the metal For example PbO (s) + H2 (g) Pb (s) + H2O (g)
Under suitable conditions hydrogen reduces nitrogen to ammonia
N2(g) + 3 H2 (g) 2 NH3 (g)
27
At high temperatures carbon reduces metal oxides below aluminium in the reactivity series to
the metal For example
ZnO (s) + C (s) Zn (s) + CO (g)
Oxygen and Chlorine are very good oxidizing agents
Oxygen oxidized most metals to form metal oxides and some non ndash metals to non ndash metal oxides
For example
2 Mg (s) + O2(g) 2 MgO (s)
4 P (s) + 5 O2 (g) P4O10 (s)
Chlorine acts as an oxidizing agent either as a gas or as an aqueous solution For example
H2 (g) + Cl2 (g) 2 HCl (g)
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
28
WEEK 7 LESSON 3 WORKSHEET
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
______________________________________________________________________________
(b) Write the ionic equation for the above reaction
______________________________________________________________________________
(c) Identify the oxidising agent in the reaction
______________________________________________________________________________
(d) Justify your answer in part (c) in terms of oxidation number
______________________________________________________________________________
29
WEEK 8 LESSON 1
TOPIC Laboratory preparation of gases
Preparation of oxygen
Oxygen can be prepared by the decomposition of hydrogen peroxide potassium chlorate (V) or
potassium nitrate The safest method is the decomposition of hydrogen peroxide
Manganese (IV) oxide catalyses the decomposition of hydrogen peroxide
Silica gel anhydrous calcium chloride or concentrated sulphuric acid can be used as a drying
agent
The gas is collected by downward delivery since it is slightly denser than air
Equation
2 H2O2 (aq) 2 H2O (l) + O2 (g)
Apparatus used for laboratory preparation of oxygen
30
WEEK 8 LESSON 1 WORKSHEET
Describe the laboratory preparation of oxygen gas
In your answer include
The starting material
A suitable catalyst
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
31
WEEK 8 LESSON 2
TOPIC Laboratory preparation of gases
Preparation of carbon dioxide
Carbon dioxide can be prepared by the action of dilute acid on carbonates Marble chips (calcium
carbonate) and dilute hydrochloric acid are the common reagents The gas is collected by
downward delivery since it is denser than air
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
Apparatus used for laboratory preparation of carbon dioxide
32
WEEK 8 LESSON 2 WORKSHEET
Describe the laboratory preparation of carbon dioxide gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
33
WEEK 8 LESSON 3
TOPIC Laboratory preparation of gases
Preparation of ammonia
Ammonia may be prepared by heating a mixture of ammonium salt and a hydroxide The
ammonia gas is collected by upward delivery since it is less dense than air
For example
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
Calcium oxide is the only suitable drying agent since ammonia reacts with conc H2SO4 and
CaCl2
Apparatus used for laboratory preparation of dry ammonia
34
11
WEEK 8 LESSON 3 WORKSHEET
Describe the laboratory preparation of ammonia gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
35
WEEK 9 LESSON 1
TOPIC Uses of gases
Carbon dioxide
Used in fire extinguishers to put out fires Carbon dioxide is denser than air and lsquoblanketsrsquo the
fire preventing oxygen from reaching it Carbon dioxide extinguishers are especially useful for
dealing with fires involving flammable liquids and electrical equipment
Carbonation in soda is created when carbon dioxide is pumped into the soda can or bottle then
held under pressure As long as the can or bottle is sealed the carbon dioxide remains mostly
stable However if the drink gets shaken up or the top is opened the tiny carbon dioxide bubbles
react by bursting
Oxygen
Oxygen is needed for aerobic respiration We need a constant supply of oxygen for this process
Oxygen is used in hospitals to improve the respiration of patients with poor blood flow blood
poisoning and heart disease
Oxygen in used in welding (joining) metals In an oxyacetylene welding torch acetylene or
ethyne (C2H2) burns in oxygen and produces a very hot flame This flame is capable of melting
most metals
Oxygen is used in steel production A blast of oxygen is blown through the molten iron The
oxygen oxidises many of the impurities of the iron and the impurities are then removed
36
WEEK 9 LESSON 1 WORKSHEET
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Put out fires
Welding metals
Create lsquofizzrsquo in drinks
Used in steel production
Aerobic respiration
37
WEEK 9 LESSON 2
TOPIC Uses of non ndash metals and their compounds
Carbon (allotrophes carbon dioxide)
Carbon is used as a reducing agent in extraction of some metals
Carbon as graphite is used as electrodes lubricants and lsquoleadrsquo for pencils
Carbon in the form of diamond is used for jewellery (because of its lustre) and in drill tips for
high ndash speed drills (because of its hardness)
Carbon dioxide is used as refrigerant (as dry ice) for carbonated beverages
Sodium hydrogen carbonate and sodium carbonate are used for water softening and raising
agent
Sulphur
Sulphur is used in the manufacture of sulphuric acid Sulphur is also used in the manufacture of
tyres to make the rubber harder (vulcanisation)
Sulphur powder is used as fungicide on plant materials
Phosphorus
Phosphorus is used in the manufacture of fertilizers
Phosphorus is used to make phosphor bronze alloys
Phosphorus sulphide is used to make the heads of lsquostrike anywherersquo matches
38
Chlorine
Chlorine is used to make sodium hypochlorite which is present in bleach It is also used in
sterilizing swimming pools and in water treatment
Chlorine is used to make the monomer vinyl chloride which is used to make the plastic PVC
Nitrogen
Nitrogen is used to make fertilisers ammonia dyes and nitric acid
Nitrogen is used as an inert atmosphere to prevent substances being oxidised and as a coolant
Silicon
Silicon is used for making silicon chips for computers
Silicon (V) oxide is present in sand Glass is made by heating sand with lime (calcium oxide) and
sodium carbonate
Silicon in the form of silicates is used in jewellery
Silica gel is used as a drying agent
39
WEEK 9 LESSON 2 WORKSHEET
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Used to make sodium hypochlorite
Used as a fungicide on plant materials
Used for lsquoleadrsquo in pencils
Used in the manufacture of bronze alloys
Used in the manufacture of nitric acid
Used in the manufacture of computer chips
Used to make fertilisers
40
WEEK 9 LESSON 3
TOPIC Harmful effects of non ndash metals and their compounds on living systems and the
environment
Sulphur dioxide
Sulphur dioxide can cause a disease of the lungs Sulphur dioxide also poisons plants in two
main ways It may enter the stomata of leaves and react with the tissue fluids to form sulphites
with the on ndash going water loss the concentration of sulphites could build up killing the cells
The second adverse effect on plants occurs when sulphur dioxide dissolves in rain thereby
increasing soil acidity A prolonged acid soil situation may lead to plasmolysis and the death of
vegetation in an area
Carbon monoxide
Carbon monoxide combines much more readily than oxygen with haemoglobin When carbon
monoxide is inhaled it prevents the haemoglobin from taking oxygen to the bodyrsquos cells
Continued breathing of air containing carbon monoxide eventually causes death
Hydrogen sulphide
Hydrogen sulphide reacts readily with many cations forming insoluble sulphides Many cations
contribute to good health by contributing to enzyme activity and to the formation of bone
pigment and haemoglobin Although these cations are required in extremely small
concentrations they are removed by being precipitated as sulphides and thus not available for
regular function Careless dumping of refuse contributes to atmospheric pollution by hydrogen
sulphide
Oxides of nitrogen
In the presence of hydrocarbons from car exhausts ozone and sunlight nitrogen oxides react to
form photochemical smog which contains many harmful chemicals
Nitrogen dioxide can harm the lungs and irritate the nose throat and eyes The other compounds
present in photochemical smog are even more harmful irritants and can cause asthma
41
Carbon dioxide
Carbon dioxide water vapour and ozone referred to as ldquogreenhouse gasesrdquo acting as a blanket
readily absorb some of the radiated heat energy and in turn warms the earthrsquos atmosphere This is
called the ldquogreenhouse effectrdquo Scientists have found direct correlation between carbon dioxide
concentration and global warming An increase in carbon dioxide concentration resulted in an
increase global temperatures Global warming is a major potential problem that the world faces
Chloroflourocarbons (CFCs)
It is believed that CFCs might be responsible for destroying the ozone layer which prevents
harmful ultraviolet (UV) radiation from reaching the earth The carbon ndash chlorine bond in CFC
molecule is easily broken by a UV photon producing an active chlorine atom This atom
combines with an ozone molecule forming a chlorine oxide radical and oxygen The radicle
reacts with more ozone producing the chlorine atom again This kind of reaction is repeated
thousands of times This type of reaction is thought to account for about eighty percent of the
loss of ozone observed
Nitrates and phospates
Nitrates and phosphates cause eutrophication The process leading to eutrophication are
Nitrates and phosphates from fertilisers spread on fields may dissolve in groundwater and
get into lakes and rivers
Nitrates and phosphates cause excessive growth of algae so that they cover the surface of
the water
Water plants including algae die because of lack of sunlight Aerobic bacteria feed on
the plant remains The bacteria multiply
The aerobic bacteria use up the oxygen in the water so aquatic animals die
42
Solid waste
The main sources of pollution from non ndash metals is from glass paper and plastics
Broken glass can cause injury to animals It can also cause fires by acting as lens focusing the
sunrsquos rays on flammable materials
Printing inks from paper dumped in the ground may contain toxic elements such as arsenic and
cadmium Bleaches and chlorine compounds from paper are also harmful
43
WEEK 9 LESSON 3 WORKSHEET
Describe ONE harmful effect of the following non ndash metals andor their compounds on
living systems and the environment
Sulphur dioxide
______________________________________________________________________________
______________________________________________________________________________
Carbon monoxide
______________________________________________________________________________
______________________________________________________________________________
Carbon dioxide
______________________________________________________________________________
______________________________________________________________________________
Oxides of nitrogen
______________________________________________________________________________
______________________________________________________________________________
Hydrogen sulphide
______________________________________________________________________________
______________________________________________________________________________
44
Chloroflourocarbons (CFCs)
______________________________________________________________________________
______________________________________________________________________________
Nitrates and phospates
______________________________________________________________________________
______________________________________________________________________________
45
WEEK 10 LESSON 1
TOPIC Green Chemistry
Green Chemistry is defined as the utilisation of a set of principles that reduces or eliminates the
use and generation of hazardous substances
There are twelve principles of green chemistry as proposed by Paul T Anastas and John C
Warner These twelve principles are
1 Prevention ndash It is better to prevent waste than to treat or clean up waste after it has been
created
2 Atom economy - Synthetic methods should be designed to maximize the incorporation of
all materials used in the process into the final product
3 Less hazardous chemical synthesis - Wherever practicable synthetic methods should be
designed to use and generate substances that possess little or no toxicity to human health
and the environment
4 Safer chemical products - Chemical products should be designed to affect their desired
function while minimizing their toxicity
5 Safer solvents and other agents - The use of auxiliary substances (eg solvents
separation agents etc) should be made unnecessary wherever possible and harmless
when used
6 Minimum energy requirements - Energy requirements of chemical processes should be
recognized for their environmental and economic impacts and should be minimized If
possible synthetic methods should be conducted at ambient temperature and pressure
7 Use of renewable raw materials - A raw material or feedstock should be renewable rather
than depleting whenever technically and economically practicable
8 Reduce use of additional chemicals or additional steps - Unnecessary derivatization (use
of blocking groups protection deprotection temporary modification of
physicalchemical processes) should be minimized or avoided if possible because such
steps require additional reagents and can generate waste
46
9 Use of catalysts ndash The use of catalysts reduce energy costs because the reactions take
place at lower temperatures The more specific the catalyst for a particular reaction is the
less it the likelihood of getting additional unwanted products
10 Nature of breakdown of products - Chemical products should be designed so that at the
end of their function they break down into innocuous degradation products and do not
persist in the environment
11 Monitoring to prevent pollution - Analytical methodologies need to be further developed
to allow for real-time in-process monitoring and control prior to the formation of
hazardous substances
12 Minimise chemical accidents - Substances and the form of a substance used in a chemical
process should be chosen to minimize the potential for chemical accidents including
releases explosions and fires
47
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
48
WEEK 10 LESSON 2
TOPIC Qualitative Analysis ndash Identification of cations
Qualitative Analysis involves identifying the constituents of single substances or mixture of
substances
Appearance
An examination of the appearance of a substance can indicate which ion it contains
Appearances of substances
Observation Indication
Blue or blue ndash green Cu2+ salt
Pale green Fe2+ salt
Yellow ndash brown Fe3+ salt
Ammonia smell NH4+ salt
49
Test for cation using sodium hydroxide
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
(d) If no precipitate forms in step b warm gently and test for ammonia
Effect of dilute sodium hydroxide solution
Effect of dilute sodium hydroxide solution Cation
Dropwise Excess
White precipitate Precipitate soluble Ca2+
White precipitate Precipitate insoluble Al3+ Pb2+ Zn2+
Blue precipitate Precipitate insoluble Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
No precipitate ndash ammonia gas
evolved on heating
ndash NH4+
The metal cations all form insoluble hydroxides with sodium hydroxide solution
For example Ca2+ (aq) + 2 OH- (aq) Ca(OH)2 (s)
Ca(OH)2 Cu(OH)2 Fe(OH)2 and Fe(OH)3 are basic and therefore do not react with excess
sodium hydroxide solution Therefore the precipitate does not dissolve in excess sodium
hydroxide solution
Al(OH)3 Pb(OH)2 and Zn(OH)2 are amphoteric Therefore the precipitates react with the excess
sodium hydroxide solution forming soluble salts and the precipitate disappears in excess sodium
hydroxide solution
The NH4+ ion forms a soluble hydroxide However on heating it reacts with the hydroxide ion to
form ammonia and water
NH4+ (aq) + OH- (aq) NH3 (g) + H2O (l)
50
WEEK 10 LESSON 2 WORKSHEET
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P _____________ Q ___________________
R _____________ S ___________________
R + NaOH
______________________________________________________________________________
51
WEEK 10 LESSON 3
TOPIC Qualitative Analysis ndash Identification of cations
Test for cation using ammonia solution (ammonium hydroxide solution)
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
Effect of dilute ammonia (ammonium hydroxide) solution
Effect of dilute ammonia solution Cation
Dropwise Excess
No precipitate ndash Ca2+
White precipitate Precipitate soluble
(forming colourless solution)
Zn2+
White precipitate Precipitate insoluble Al3+ Pb2+
Blue precipitate Precipitate soluble
(forming deep blue solution)
Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
52
Ammonia solution is a weak alkali Metal cations except Ca2+ form insoluble hydroxides with
ammonia solution as with the sodium hydroxide solution
The amphoteric hydroxides Al(OH)3 and Pb(OH)2 and the basic hydroxides Fe(OH)2 and
Fe(OH)3 do not react with excess ammonia solution Therefore the precipitates remain
However Zn(OH)2 and Cu(OH)2 do react with excess ammonia solution to form complex
soluble hydroxides each Hence their precipitates disappear on the addition of excess ammonia
solution
Confirmatory test
After carrying out test for cations using sodium hydroxide solution and ammonia solution the
only cations which cannot be distinguished are Al3+ and Pb2+ A confirmatory test is carried out
to distinguish between the two cations
Confirmatory test
Test Observation Cation Ionic equation
Add potassium
or sodium
iodide solution
Bright yellow precipitate
No precipitate
Pb2+
Al3+
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
53
WEEK 10 LESSON 3 WORKSHEET
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A __________ B ________________ C ________________________
(b) State the inference after Test 2
C _______________________
(c) Write an ionic equation to support your answer in (b) above
___________________________________________________________________________
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
54
ANSWERS TO WORKSHEETS
55
WEEK 5 LESSON 1 WORKSHEET ANSWERS
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
Answer
Zinc + Iron (II) sulphate Zinc is higher in the electrochemical series and therefore displace
iron ions in iron (II) sulphate
Equation Zn (s) + FeSO4 (aq) ZnSO4 (aq) + Fe (s)
Ionic equation Zn (s) + Fe2+ (aq) Zn2+ (aq) + Fe (s)
Iron + Zinc sulphate No reaction iron is lower in the electrochemical series and cannot
displace the zinc ions in zinc sulphate
56
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
Answer
X displaces lead from an aqueous solution of its salts
X (s) + Pb2+ (aq) Xn+ (aq) + Pb (s)
rarr X is more reactive than Pb
X did not react with iron salts
rarr X is less reactive than Fe
Y burns very easily
Y is more reactive than Fe and Pb (both forming their corresponding oxide at a slower rate)
From electrochemical series Fe is higher and therefore more reactive than Pb
Order of reactivity
Y (most reactive) gt Fe gt X gt Pb (least reactive)
57
WEEK 5 LESSON 2 WORKSHEET ANSWERS
1
Metal Reactivity with acid
Copper X
Magnesium
Aluminium
Silver X
Zinc
58
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
Answer
Y and Z are the most reactive since they can react with dilute acid
Z is more reactive than Y since a reaction occurs with Z is added to an aqueous solution of Y
X is less reactive than W since it does not occur in nature as compounds
Order of reactivity Z (most reactive) gt Y gt W gt X
59
WEEK 5 LESSON 3 WORKSHEET ANSWERS
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
Answer
Ease of decomposition (from easiest to decompose to most difficult to decompose)
B rarrD rarrArarr C
Reactivity (most reactive to least reactive)
C (most reactive) gt A gt D gt B (least reactive)
60
WEEK 6 LESSON 1 Worksheet Answers
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
Potassium Zinc Copper
Calcium Lead Gold
Magnesium Iron
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
Aluminium is extracted from its ore bauxite through the process of electrolysis
Cryolite is added to bauxite to lower the melting point to about 900 0C The melting point of
bauxite is very high (about 2040 0C) It is difficult and expensive to keep the molten aluminium
oxide at this temperature
Reaction at the cathode Al3+ (l) + 3 e- Al (l)
61
WEEK 6 LESSON 2 Worksheet Answers
(a) What are the three raw materials that are added through the top of the blast
furnace during the extraction process for iron
Coke (carbon)
iron ore (haematitie mainly iron (II) oxide)
limestone (calcium carbonate)
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
Coke ndash coke burns to produce carbon dioxide The carbon dioxide further reacts with coke to
form carbon monoxide (reducing agent in the process)
C (s) + O2 (g) CO2 (g)
C (s) + CO2 (g) 2 CO
Haematite ndash iron ore provides the iron which is reduced by the carbon monoxide to produce
iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + CO2 (g)
Limestone ndash decomposes to form calcium oxide The calcium oxide reacts with the impurity
silicon dioxide to form slag (calcium silicate)
CaCO3 (s) CaO (s) + CO2 (g)
CaO (s) + SiO2 (l) CaSiO3(l)
62
WEEK 6 LESSON 3 Worksheet Answers
(a) Define the term alloy
An alloy is a material made from a mixture of two or more metals
(b) State 3 general advantages that alloys have over the individual metals they are made
from
They are harder stronger and more resistant to corrosion
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
1 High strength
2 Low density
Uses
1 Used to make aircraft bodies
2 Used to make space satellites
63
WEEK 7 LESSON 1 WORKSHEET ANSWERS
(a) Define the term corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
The paint forms a barrier which stops contact with air or water and the iron Hence rusting
will not take place
However when the paint is scratched that part of the iron nail is exposed to air or water and
rusting will take place
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
Magnesium is higher in the electrochemical series and will be oxidised in preference to iron
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
Aluminium is partly protected from corrosion by its coat of aluminium oxide However as the
iron rust it flakes and fall off and the rusting process continues
64
WEEK 7 LESSON 2 WORKSHEET ANSWERS
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
Magnesium is the ion found in chlorophyll Chlorophyll plays a vital part in the process of
photosynthesis A deficiency in magnesium will lead to low chlorophyll level in the tomato
plants and hence reduce the process of photosynthesis There will be less food storage and
hence will lead to smaller yield of tomatoes
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Any correct harmful effect of lead on health or environment
Any correct harmful effect of mercury on health or environment
65
WEEK 7 LESSON 3 WORKSHEET ANSWERS
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
(b) Write the ionic equation for the above reaction
2 Br- (aq) + Cl2 (aq) 2 Cl- (aq) + Br2 (aq)
(c) Identify the oxidising agent in the reaction
Cl2 (aq)
(d) Justify your answer in part (c) in terms of oxidation number
There is a reduction of the oxidation number for chlorine from 0 to ndash1
hence it has been reduced Therefore chlorine is the oxidising agent
66
WEEK 8 LESSON 1 WORKSHEET ANSWERS
Describe the laboratory preparation of oxygen gas
Oxygen is prepared in the laboratory by the decomposition of hydrogen peroxide
A suitable catalyst is manganese (IV) oxide
Drying agent silica gel OR anhydrous calcium chloride OR conc sulphuric acid
The gas is collected by downward delivery since oxygen is slightly denser than air
Balanced chemical equation 2 H2O2 (aq) 2 H2O (l) + O2 (g)
67
WEEK 8 LESSON 2 WORKSHEET ANSWERS
Describe the laboratory preparation of carbon dioxide gas
Carbon dioxide is commonly prepared in the laboratory by the reacting hydrochloric acid and
marble chips (calcium carbonate)
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
The carbon dioxide gas is collected by downward delivery since it is denser than air
Balanced chemical equation
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
68
WEEK 8 LESSON 3 WORKSHEET ANSWERS
Describe the laboratory preparation of ammonia gas
An ammonium salt (ammonium chloride) and a base (sodium hydroxide) are mixed together and
heated
Calcium oxide is used as the drying agent Calcium chloride and concentrated sulphuric acid
cannot be used since ammonia can react with them
The gas is collected by upward delivery since ammonia is less dense than air
Balanced chemical equation
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
69
WEEK 9 LESSON 1 WORKSHEET ANSWERS
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Carbon dioxide Put out fires
Oxygen Welding metals
Carbon dioxide Create lsquofizzrsquo in drinks
Oxygen Used in steel production
Oxygen Aerobic respiration
70
WEEK 9 LESSON 2 WORKSHEET ANSWERS
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Chlorine Used to make sodium hypochlorite
Sulphur Used as a fungicide on plant materials
Carbon (graphite) Used for lsquoleadrsquo in pencils
Phosphorus Used in the manufacture of bronze alloys
Nitrogen Used in the manufacture of nitric acid
Silicon Used in the manufacture of computer chips
Nitrogen Phosphorus Used to make fertilisers
71
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
Green Chemistry is using principles that reduceeliminate the use of hazardous materials in
the design manufacture and application of chemical products
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
Makes the environment safer
Reduces waste
Creates new jobs
Reduces respiratory illnesses
Atom economy
72
WEEK 10 LESSON 2 WORKSHEET ANSWERS
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P Cu2+ Q Fe2+
R Fe3+ S Ca2+
Ionic equation for R + NaOH
Fe3+ (aq) + 3 OH- (aq) Fe(OH)3 (s)
73
WEEK 10 LESSON 3 WORKSHEET ANSWERS
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A Fe3+ B Ca2+ C Al3+ Pb2+
(b) State the inference after Test 2
C Pb2+
(c) Write an ionic equation to support your answer in (b) above
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
11 Qualitative Analysis
ndash Test for gases
Qualitative Analysis
ndash Identification of
anions
Qualitative Analysis
ndash Identification of
anions
12 Problem solving of
Past CSEC Chemistry Paper 2
on topics completed in the term
13
14
15
2
WEEK 11 LESSON 1
TOPIC Qualitative Analysis ndash Test for gases
Identification of gases
Gas Colour Odour Effect on moist
litmus
Method of identification
Oxygen
O2
Colourless Odourless Neutral ndash no
effect
Relights a glowing splint
Hydrogen
H2
Colourless Odourless Neutral ndash no
effect
Lighted splint lsquopopsrsquo if air is also
present
Carbon
dioxide
CO2
Colourless Odourless Weakly acidic ndash
blue to slightly
red
A white precipitate forms in
limewater
Ca(OH)2 (aq) + CO2
CaCO3 (s) + H2O (l)
Precipitate redissolves on
continued bubbling
CaCO3 (s) + H2O (l) + CO2 (g)
Ca(HCO3)2 (aq)
Ammonia
NH3
Colourless Pungent Alkaline ndash red
to blue (only
common
alkaline gas)
Turns moist red litmus blue forms
dense white fumes with hydrogen
chloride gas
NH3 (g) + HCl (g) NH4Cl (s)
Gas Colour Odour Effect on moist
litmus
Method of identification
3
Sulphur
dioxide
SO2
Colourless Choking
smell
Acidic ndash blue to
red
Turns acidified potassium
manganate (VII) solution from
purple to colourless
Turns acidified potassium
dichromate (VI) solution from
orange to green
Chlorine
Cl2
Yellow ndash
green
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Bromine
Br2
Red ndash
brown
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Nitrogen
dioxide
NO2
Red ndash
brown
Irritating
smell
Acidic blue to
red
Turns moist blue litmus red but
does not bleach it
Water
vapour
H2O
Colourless Odourless Neutral ndash no
effect
Turns anhydrous cobalt (II)
chloride from blue to pink
Turns anhydrous copper (II)
sulphate from white to blue
4
WEEK 11 LESSON 1 WORKSHEET
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless
Yellow ndash green
Red ndash brown
Gases according to their odour
Odour of gas Identity of gas
Odourless
Pungent smell
Choking smell
Irritating smell
5
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect
Red to blue
Blue to red
Blue to red then bleaches it
6
WEEK 11 LESSON 2
TOPIC Qualitative Analysis ndash Identification of anions
Effect of heating
Method Heat a sample of the solid in a dry test tube
Effect of heating
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) not
of K or Na
CO32- (s) O2- (s) + CO2 (g)
Oxygen evolved NO3- of K or Na 2 NO3
- (s) 2 NO2- (s) + O2
(g)
Oxygen and nitrogen
dioxide evolved
NO3- of Ca and below
in reactivity series
4 NO3- (s) 2 O2- (s) + 4 NO2
(g) + O2
(g)
Sulphur dioxide evolved SO32- SO3
2- O2- (s) + SO2 (g)
Effect of dilute acid
Add dilute hydrochloric acid or nitric acid to a sample of the solid Warm if no reaction occurs
when cold
Effect of dilute acid
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) CO32- (s) + 2 H+ (aq) H2O (l) + CO2 (g)
Sulphur dioxide evolved SO32- SO3
2- (s) + 2 H+ (aq) H2O (l) + SO2 (g)
7
Effect of concentrated acid
Add concentrated sulphuric acid to a sample of the solid Warm if not reaction occurs when cold
Effect of concentrated sulphuric acid
Observation Anion
Carbon dioxide evolved CO32- or HCO3
-
Sulphur dioxide evolved SO3-
Hydrogen chloride evolved Cl-
Hydrogen bromide (colourless) and bromine
vapour (brown) evolved
Br-
Black iodine present and purple iodine vapour
evolved
I-
8
WEEK 11 LESSON 2 WORKSHEET
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater
Produces a gas which relights a glowing splint as the only gas
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green
Produces a gas forms a precipitate in limewater
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia
Black iodine present and purple iodine vapour evolved
9
WEEK 11 LESSON 3
TOPIC Qualitative Analysis ndash Identification of anions
Test for the halides ndash using silver nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous silver nitrate and
observe the precipitate Add ammonia solution and observe the solubility of the precipitate
Test for halides using silver nitrate solution
Effect of silver
nitrate solution
Anion Explanation Effect of aqueous
ammonia
White precipitate ndash
turns white in
sunlight
Cl- Ag+ (aq) + Cl- AgCl (s) Precipitate soluble
Cream precipitate ndash
turns yellow ndash green
in sunlight
Br- Ag+ (aq) + Br- AgBr (s) Precipitate slightly
soluble
Pale yellow
precipitate
I- Ag+ (aq) + I- AgI (s) Precipitate insoluble
Test for the halides ndash using lead nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous lead nitrate and
observe the precipitate
Test for halides using lead nitrate solution
Effect of lead nitrate solution Anion Explanation
White precipitate Cl- Pb2+ (aq) + 2 Cl- PbCl2 (s)
Pale yellow Br- Pb2+ (aq) + 2 Br- PbBr2 (s)
Deep yellow I- Pb2+ (aq) + 2 I- PbI2 (s)
10
Effect of barium nitrate or chloride solution followed by dilute acid
Make a solution of the solid Add barium nitrate or chloride solution and observe the precipitate
Add dilute hydrochloric or nitric acid warn if necessary and observe the solubility of the
precipitate
Effect of barium nitrate or chloride solution followed by dilute acid
Effect of
Ba(NO3)2 (aq)
or BaCl2 (aq)
Effect of HCl (aq)
or HNO3 (aq)
Anion Explanation
White precipitate Precipitate insoluble SO42- Ba2+ (aq) + SO4
2- (aq) BaSO4 (s)
BaSO4 does not react with dilute acids
White precipitate Precipitate soluble ndash
CO2 evolved
CO32- Ba2+ (aq) + CO3
2- (aq) BaCO3 (s)
BaCO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + CO2 (g)
White precipitate Precipitate soluble ndash
SO2 evolved on
warming
SO32- Ba2+ (aq) + SO3
2- (aq) BaSO3 (s)
BaSO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + SO2 (g)
11
WEEK 11 LESSON 3 WORKSHEET
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
(Ionic equation required)
12
WEEK 12 LESSON 1 WORKSHEET
(a) The Caribbean islands are known for their many resources For example the ore of
aluminium is found in Jamaica and Guyana
(i) Briefly describe the extraction of aluminium from its named ore Include in your
description one ionic equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Although aluminium ore is mined in the Caribbean the extraction of aluminium usually
takes place in other countries Suggest ONE reason why it may be difficult to extract
aluminium in the Caribbean
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) An alloy can be described as a lsquomixed metal solutionrsquo Aluminium forms an alloy with
magnesium that is used to make an aircraft
13
Identify this alloy and suggest why it is better to use it rather than the pure metal in the
manufacture of aircraft
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) ldquoSome metals can be useful to man yet harmful to the environmentrdquo Comment on this
statement with reference to mercury
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 12 LESSON 2 Worksheet
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate formed
Soluble in excess
15
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate formed
Insoluble in excess
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate formed
(Ionic equation required)
16
WEEK 12 LESSON 3 Worksheet
Dry ammonia gas can be produced in a school laboratory
(a) Identify TWO reagents that are necessary for the laboratory production of ammonia
______________________________________________________________________________
______________________________________________________________________________
(b) Two common drying agents used in the laboratory are calcium oxide and concentrated
sulphuric acid However calcium oxide is the preferred choice for drying ammonia gas
Explain why concentrated sulphuric acid is now used Include in your answer a balanced
chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) When gases are prepared in the laboratory there are three main ways in which they can
be collected
- Upward delivery
- Downward delivery
- Displacement of water
(i) What TWO other factors should be considered when choosing an appropriate method for
the collection of gases in the laboratory
______________________________________________________________________________
______________________________________________________________________________
(ii) Identify ONE of the three methods that is best suited for the collection of ammonia gas in
the laboratory Explain why EACH of the other two methods would NOT have been
appropriate
______________________________________________________________________________
17
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(d) Hence draw a labelled diagram of the apparatus which could be used for the preparation
of dry ammonia in the laboratory
Be sure to identify in your diagram
- where the reagents are placed
- where the ammonia is dried and
- where the ammonia is collected
18
WEEK 13 LESSON 1 Worksheet
(a) In solution two metals A and B form A+ and B2+ ions respectively Metal A displaces Fe
from a solution containing Fe2+ ions but metal B does NOT
(i) Arrange the metals A B and Fe in order of reactivity from LEAST reactive to MOST
reactive Write a balanced chemical equation to show the reaction between metal A and
Fe2+ ions
______________________________________________________________________________
______________________________________________________________________________
(ii) Metal A is placed in a solution of copper (II) sulphate CuSO4 (aq) Write an equation for
the reaction State ONE observable change that will occur and explain why this reaction
takes place
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) For EACH metal A and B state ONE method that can be used to extract it from its
respective oxide Give a reason for EACH answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
19
______________________________________________________________________________
(b) Metal alloys are often used for making objects found in our daily lives Name an alloy of
iron and state ONE of its uses
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 13 LESSON 2 Worksheet
(a) Many important biological processes in plants and animals depend on the specific roles
of certain metal ions
(i) Farmer Jones reaped a crop of tomatoes and reported that the yield was far below what
was expected Analysis of the soil revealed that there was a deficiency of magnesium
Discuss the importance of magnesium in plant health and explain how a magnesium
deficiency can result in the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE other metal ion which is important to plant health and state the result of its
deficiency
______________________________________________________________________________
______________________________________________________________________________
21
(b) Many years ago car exhaust fumes were known to contain compounds of metals and
non ndash metals which could negatively impact both humans and the environment Identify
ONE metal and ONE non ndash metal whose compounds were present in car exhaust fumes
Discuss the effect of these compounds on human health and the environment
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) Define lsquogreen chemistryrsquo and discuss the measures that have been taken to produce a
lsquogreenerrsquo automotive fuel
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
22
WEEK 13 LESSON 3 Worksheet
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
Zn2+ ions are present
23
WEEK 14 LESSON 1 Worksheet
(a) Metal alloys are often used in place of metals because of their enhanced properties
(i) Define the term lsquoalloyrsquo
______________________________________________________________________________
______________________________________________________________________________
(ii) Name ONE alloy of aluminium and state its use based on one of its enhanced properties
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) A student conducted an experiment to investigate the reactivity of each of the following
metals (copper iron zinc and lead) by using solutionPs of their sulphate salts
The data presented in the table below shows whether a visible chemical reaction took
place when each metal was added to the four sulphate solutions
Key Visible chemical reaction took place
X No visible chemical reaction
CHEMICAL REACTION OF METALS IN SULPHATE SOLUTIONS
Sulphate solution Cu Fe Zn Pb
CuSO4 X
FeSO4 X X X
ZnSO4 X X X X
PbSO4 X X
24
(i) State which of the TWO metals is more reaction Fe or Zn Give a reason for our answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Using the data in the previous Table deduce the order of reactivity of the four metals Cu
Fe Zn and Pb from the most reactive to the least reactive metal
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The student recorded the following observations from the reaction between the iron and
copper (II) sulphate solution
Observations Reddish ndash brown solid coating formed on the iron strip
Blue colour of the solution changed to dirty green
Account for the observations made from the reaction between the iron and copper (II)
sulphate solution
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iv) Write an ionic equation including state symbols for the reaction between the iron and
copper (II) sulphate solution
______________________________________________________________________________
25
(c) Some metal compounds are health and environmental hazards
(i) Identify which of the metals used in the experiment in (b) is MOST hazardous to the
environment
______________________________________________________________________________
______________________________________________________________________________
(ii) State TWO harmful effects of continuous exposure to the metal identified in (c) (i) on
human beings
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
26
WEEK 14 LESSON 2 Worksheet
(a) Carbon is found in the form of diamond and graphite and is a main component in many
naturally occurring compounds such as organic matter and carbon dioxide gas
(i) State ONE way in which diamond differs physically from graphite
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE similarity between diamond and graphite other than they both contain carbon
______________________________________________________________________________
______________________________________________________________________________
(b) Carbon can react with a limited supply of oxygen to form carbon monoxide which can
negatively affect human health
(i) Write a balanced chemical equation including state symbols to show the formation of
carbon monoxide
______________________________________________________________________________
(ii) State TWO effects of carbon monoxide inhalation on the human body
______________________________________________________________________________
______________________________________________________________________________
(c) Jamal wants to prepare and collect a sample of carbon dioxide gas in the laboratory using
calcium carbonate
(i) Write a balanced chemical equation including state symbols for the laboratory
preparation of carbon dioxide gas from calcium carbonate
______________________________________________________________________________
______________________________________________________________________________
(ii) Draw a clearly labelled diagram to show the arrangement of the apparatus and materials
that could be used in the laboratory to prepare and collect the carbon dioxide gas
(iii) State ONE use of carbon dioxide as it relates to the beverage industry
______________________________________________________________________________
27
WEEK 14 LESSON 3 Worksheet
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
(Ionic equation required)
Suggest a possible identity of the solid R __________________________
28
WEEK 15 LESSON 1 Worksheet
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a small
portion of solid Y gently at
first and then strongly
Colourless gas evolved
with a choking odour
Turns acidified potassium
dichromate solution from
orange to green
(ii) To the remaining portion
of solid Y add 20 cm3 of
distilled water stir to dissolve
and filter Collect the filtrate
and divide into 3 equal
portions
Filtrate is pale green in
colour
(iii) To the first portion of the
filtrate from (ii) add aqueous
sodium hydroxide slowly
until in excess
A green precipitate
Insoluble in excess sodium
hydroxide
Ionic equation required
29
TEST OBSERVATIONS INFERENCES
(iv) To the second portion of
the filtrate from (ii) add
aqueous silver nitrate
followed by aqueous
ammonia
White precipitate
Soluble in aqueous
ammonia
(v) To the third portion of the
filtrate from (ii) add aqueous
barium nitrate followed by
aqueous hydrochloric acid
White precipitate formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with the
evolution of a colourless
gas with a choking smell
30
WEEK 15 LESSON 2 Worksheet
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
31
WEEK 15 LESSON 3 Worksheet
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in excess
aqueous NH3
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change
32
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
warm filter and then divide
the filtrate into two portions
Vigorous effervescence
observed upon addition of
dilute HNO3
Gas evolved turns lime water
cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Cu2+ ions present
33
ANSWERS TO WORKSHEETS
34
WEEK 11 LESSON 1 WORKSHEET ANSWERS
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless O2 H2 CO2 NH3 SO2 H2O
Yellow ndash green Cl2
Red ndash brown Br2 NO2
Gases according to their odour
Odour of gas Identity of gas
Odourless O2 H2 CO2 H2O
Pungent smell NH3
Choking smell SO2 Cl2 Br2
Irritating smell NO2
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect Neutral O2 H2 H2O
Red to blue Alkaline NH3
Blue to red Acidic CO2 SO2 NO2
Blue to red then bleaches it Acidic Cl2 Br2
35
WEEK 11 LESSON 2 WORKSHEET ANSWERS
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-) not
of K or Na
Produces a gas which relights a glowing splint as the only gas NO3- of K or Na
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green SO32-
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-)
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia Cl-
Black iodine present and purple iodine vapour evolved I-
36
WEEK 11 LESSON 3 WORKSHEET ANSWERS
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Br-
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
Cl-
Ag+ (aq) + Cl- AgCl (s)
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow Br-
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
SO42-
Ba2+ (aq) + SO42- (aq)
BaSO4 (s)
(Ionic equation required)
37
WEEK 12 LESSON 1 Worksheet Answers
(a) (i)
The ore bauxite is purified
The purified bauxite is dissolved in molten cryolite
The aluminium oxidecryolite solution is then eletrolysed
Equation at the cathode Al3+ (l) + 3 e- Al (l)
Equation at the anode 2 O2- (l) ndash 4 e- O2 (g)
(ii) The process is too expensive mainly because too much electricity or energy is needed
(b) The alloy of Al and Mg is magnalium It is less dense than the pure metals and hence allow
aircraft to be lighter It is also stronger than the pure metals and hence allows aircraft to last
longer since it is not easily destroyed
(c) Your answer should cater for the following aspects
Benefits of mercury to humans for example in thermometers barometers in dentistry
and gold mining
Entry of mercury to the environment For example this could have been through broken
thermometers barometers or lightbulbs or improper disposal of them or batteries and
indiscriminate use in gold mining in Guyana
The identification of a negative impact on the environment such as poisoned fish and the
persons who eat the fish death mood swings and psychosis
38
WEEK 12 LESSON 2 Worksheet Answers
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas
evolved
NO2 evolved OR nitrates
present OR
Br2 gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate
formed
Soluble in excess
Pb2+ Zn2+ Al3+ or Ca2+
present
Pb2+ Zn2+ Al3+ or present
39
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate
formed
Insoluble in excess
Pb2+ Zn2+ Al3+ or present
Pb2+ or Al3+ present
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate
formed
Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
40
WEEK 12 LESSON 3 Worksheet Answers
(a) an ammonium salt and a strong alkali
(b) Ammonia is basic and it will react with H2SO4
Equation 2 NH3 (aq) + H2SO4 (aq) (NH4)2SO4 (aq)
(c) (i) ndash Density of the gas relative to air ndash The solubility of the gas in water
(ii) Ammonia is collected by upward delivery
It cannot be collected by downward delivery since ammonia is less dense than air
It cannot be collected by displacement of water since it is soluble in water
(d)
41
WEEK 13 LESSON 1 Worksheet Answer
a) i) B ˂ Fe ˂ A
2A (s) + Fe 2+ (aq) rarr 2A+ (aq) + Fe (s)
ii) 2A (s) + CuSO4 (aq) rarr A2SO4 (aq) + Cu (s)
Observation blue colour fades gets lighter OR brown solid forms is deposited OR metal A
decreases in size dissolves
Explanation Metal A is higher (than Fe which is higher) than Cu in the reactivity series OR
Metal A is more reactive (than Fe which is more reactive) than Cu so Metal A can displace Cu
iii) Metal A can be extracted by electrolysis (of its molten oxide) because Metal A is a very
reactive metal is high in the reactivity series forms stable oxides needs a lot of energy to be
extracted and very reactive metals are extracted by electrolysis
Metal B can be extracted by heating with carbon carbon monoxide OR by chemical reduction
of the oxide because Metal B is less reactive than Fe is low in the reactivity series forms less
stable oxides does not need a lot of energy to be extracted and oxides of less reactive metals are
easily reduced
b) Alloy of iron steel
Use of alloy making buildings bridges ships motor vehicles furniture utensils
42
WEEK 13 LESSON 2 Worksheet Answer
(a) (i)
Magensium is the metal ion found in chlorophyll
Chlorophyll is essential for photosynthesis
A deficiency in magnesium will result in low chlorophyll yellow leaves and a reduction in
photosynthesis
Hence there will be low carbohydrates or energy production
Hence small fruits stunted growth and lower yield will result
(ii)
Metal ion Results of deficiency
Potassium Stunted growth premature loss of leaves yellowing of leaves curling of leaf tips
Calcium Growth abnormalities in tips of roots and shoots curling of leaves
Iron Yellowing of leaves
Zinc Low chlorophyll content yellowing of leaves
Manganese Yellowing of leaves poor flavors in some crops for example potato
(b)
Metal Lead is present in some types of gasoline Upon combustion lead compounds escape into
the atmosphere It accumulates in body tissues and slowly poisons the person It causes mental
illness
Non ndash metal SulphurSulphur dioxide or NitrogenNitrogen dioxide
Dissolves in rain water to form acid rain or cause respiratory illnessproblems Acid rain can
cause corrosion damage in buildings
(c)
Green chemistry is the utilisation of a set of principles that reduces or eliminates the use or
generation of hazardous substances
43
Automotive fuels are now produced without lead so as to eliminate the release of lead
compounds into the atmosphere
Low sulphur fuel is being produced with much reduced sulphur content which causes a reduction
of sulphur dioxide release into the atmosphere
44
WEEK 13 LESSON 3 Worksheet Answer
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
gas turns litmus blue
red
brown gas
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
white precipitate
precipitate soluble in
excess
Zn2+ ions are present
45
WEEK 14 LESSON 1 Worksheet Answers
(a)(i) An alloy is a material made from a mixture of two or more metals
(ii) Any suitable answer chosen from below
Alloy Enhance Property Use
Duralumin High strength
Low density
Light
Hard
Used to make aircraft bodies
space satellites
Magnalium Light
Hard
Easier to weld
Corrosion resistant
Strong
High ductability
Used in pyrotechnics
(fireworks)
Mirrors
Aircraft parts
To make scientific
instruments
Used to make marine castings
Alchlad Strong
Corrosion resistant
Cladding for buildings
(b) (i) Zinc is more reactive than iron
Zinc displaces iron from iron (II) sulphate
Zinc is higher in the reactivity series than iron
Iron does not displace zinc from zinc sulphate
(ii) Order of reactivity Zn gt Fe gt Pb gt Cu
(iii) Reddish brown solid ndash copper metal formed
46
Dirty green solution ndash presence of Fe2+ ion
(iv) Fe (s) + Cu2+ (aq) Fe2+ (aq) + Cu (s)
(c) (i) Lead
(ii) Any two correct harmful effects of lead on the body
Impedes brain development (in young children)
Affectimpede development of the immune system in humans
Affecthamper development of nervous system in humans
Long term exposure can result in kidney and liver damage
Mental retardation
Anaemia
Death
47
WEEK 14 LESSON 2 Worksheet Answers
a) i) Diamond is transparent clear Graphite is opaque black
OR hard OR brittle
OR does not conduct electricity OR conducts electricity
a) ii) Both have a macromolecular giant molecular giant covalent structure (lattice)
OR Both have high melting point boiling point
OR Both are insoluble in water organic solvent
b) i) 2C (s) + O2 (g) rarr 2CO (g)
ii) CO reduction in amount of oxygen carried by (the haemoglobin in the red blood
cells of) the blood
Headache OR dizziness OR nausea OR fatigue OR loss of consciousness OR
death
c) i) CaCO3 (s) + 2HCl (aq) rarr CaCl2 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) + H2SO4 (aq) rarr CaSO4 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) rarr CaO (s) + CO2 (g)
48
ii)
OR
OR
Entirely closed system thistle funnel below the level of the liquid OR tap that could be
closed
Two reagents labelled CaCO3marble chips and HCl H2SO4 or heat source
collection of CO2 upward displacement of air OR over watersulphuric acid OR in gas
syringe
iii) CO2 use put in aerated drinks carbonated beverages
OR put in carbon dioxide fire extinguishers
49
WEEK 14 LESSON 3 Worksheet Answers
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
NH4+
NH4+ confirmed OR
NH3 (g) produced
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
Cl- ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation required)
Suggest a possible identity of the solid R NH4Cl (ammonium chloride)
50
WEEK 15 LESSON 1 Worksheet Answers
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a
small portion of solid Y
gently at first and then
strongly
Colourless gas
evolved with a
choking odour
Turns acidified
potassium dichromate
solution from orange
to green
SO2 evolved
Presence of a sulphite
(ii) To the remaining
portion of solid Y add 20
cm3 of distilled water stir
to dissolve and filter
Collect the filtrate and
divide into 3 equal portions
Filtrate is pale green
in colour
Fe2+ ions present
(iii) To the first portion of
the filtrate from (ii) add
aqueous sodium hydroxide
slowly until in excess
A green precipitate
Insoluble in excess
sodium hydroxide
Fe2+ ions present
Fe2+ (aq) + 2 OH- (aq) Fe(OH)2 (s)
Ionic equation required
TEST OBSERVATIONS INFERENCES
(iv) To the second portion
of the filtrate from (ii) add
aqueous silver nitrate
White precipitate
Soluble in aqueous
ammonia
Cl- ions present
51
followed by aqueous
ammonia
(v) To the third portion of
the filtrate from (ii) add
aqueous barium nitrate
followed by aqueous
hydrochloric acid
White precipitate
formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with
the evolution of a
colourless gas with a
choking smell
SO32- CO3
2- SO42- ions present
SO32- ions present
52
WEEK 15 LESSON 2 Worksheet Answers
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
Chloride ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
Cu2+ ions present
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
X contains a reducing agent
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
SO32- SO4
2- or CO32- ions are
present
SO32- ions are present
53
WEEK 15 LESSON 3 Worksheet Answers
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
White ppt
Ppt soluble in excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in
excess aqueous NH3
Al3+ Pb2+ Zn2+ present
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change Cl- Br- I- absent
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
Vigorous effervescence
observed upon addition of
dilute HNO3
CO2 evolved OR
Carbonate present
54
warm filter and then divide
the filtrate into two portions
Gas evolved turns lime
water cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
Cu2+ (aq) + OH- (aq)
Cu(OH)2 (s)
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Blue ppt
ppt dissolves in excess
NH3 to give a deep blue
solution
Cu2+ ions present
55
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
REFERENCES
Hunte-King J Maragh P Nagir F amp Norris R (2013) Chemistry for CSEC United
Kingdom Nelson Thornes Ltd
Remy C Mason L Lambert N amp Mohammed M (2007) Chemistry for CSEC England and
Wales Pearson Education Limited
Taylor M amp Chung-Harris T (2010) CXC Chemistry England Macmillan Publishers
Limited
Tindale A (2016) Chemistry A Concise Revision for CXC London HarperCollins Publishers
Limited
11
Iron + Oxygen
______________________________________________________________________________
Lead + Oxygen
______________________________________________________________________________
Copper + Oxygen
______________________________________________________________________________
Silver + Oxygen
______________________________________________________________________________
12
WEEK 2 LESSON 1
TOPIC Chemical properties of metals
Action of water
Metals high in the electrochemical series react with cold water to produce the metal hydroxide
and hydrogen
Reactive metals slightly lower in the electrochemical series react very slowly or not at all with
water However they may react with hot water or steam to produce the corresponding metal
oxide and hydrogen
Metals lower than hydrogen in the electrochemical series do not react with water
Metal Reaction with water or steam
Potassium K React with cold water forming metal hydroxide and hydrogen
eg Ca (s) + 2 H2O (l) Ca(OH))2 (aq) + H2 (g) Sodium Na
Calcium Ca
Magnesium Mg React with steam forming metal oxide and hydrogen
eg Zn (s) + H2O (g) ZnO (s) + H2 (g) Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
13
WEEK 2 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with water (or
steam if reaction does not occur with water)
Potassium + WaterSteam
______________________________________________________________________________
Sodium + WaterSteam
______________________________________________________________________________
Calcium + WaterSteam
______________________________________________________________________________
Magnesium + WaterSteam
______________________________________________________________________________
Aluminium + WaterSteam
______________________________________________________________________________
Zinc + WaterSteam
______________________________________________________________________________
14
Iron + WaterSteam
______________________________________________________________________________
Copper + WaterSteam
______________________________________________________________________________
Silver + WaterSteam
______________________________________________________________________________
15
WEEK 2 LESSON 2
TOPIC Chemical properties of metals
Action of dilute acids
Metals above hydrogen in the electrochemical series react with dilute acids to form a salt and
hydrogen gas They react with hydrochloric acid to form the metal chloride (a salt) and hydrogen
gas They also react with dilute suphuric acid to form the metal sulphate (a salt) and hydrogen
gas
Metal Reaction dilute hydrochloric or sulphuric acid
Potassium K Violent reaction forming a salt and hydrogen gas
eg 2 Na (s) + 2 HCl (aq) 2 NaCl (aq) + H2 (g) Sodium Na
Calcium Ca Vigorous reaction forming a salt and hydrogen gas
eg Mg (s) + 2 HCl (aq) MgCl2 (aq) + H2 (g) Magnesium Mg
Aluminium Al React forming a salt and hydrogen gas
eg Fe (s) + 2 HCl (aq) FeCl2 (aq) + H2 (g) Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
16
WEEK 2 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with
hydrochloric acid
Metal Balanced equation for reaction with hydrochloric acid
Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Copper
Silver
17
WEEK 2 LESSON 3
TOPIC Reactions of metal compounds
Reactions of metallic oxides with dilute acid
Metal oxides react with dilute hydrochloric acid or sulphuric acid to produce a salt and water
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
Some of these reactions may be slow and can be speeded up by adding heat
For example
zinc oxide + hydrochloric acid zinc chloride + water
ZnO (s) + 2 HCl (aq) ZnCl2 (aq) + H2O (l)
magnesium oxide + hydrochloric acid magnesium chloride + water
MgO (s) + 2 HCl (aq) MgCl2 (aq) + H2O (l)
aluminium oxide + sulphuric acid aluminium sulphate + water
Al2O3 3 H2SO4 (aq) Al2(SO4)3 (aq) + 3 H2O (l)
calcium oxide + sulphuric acid calcium sulphate + water
CaO H2SO4 (aq) CaSO4 (aq) + H2O (l)
18
WEEK 2 LESSON 3 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal oxides with the
corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium oxide Hydrochloric acid
Sodium oxide Sulphuric acid
Calcium oxide Hydrochloric acid
Magnesium oxide Sulphuric acid
Aluminium oxide Hydrochloric acid
Zinc oxide Sulphuric acid
19
WEEK 3 LESSON 1
TOPIC Reactions of metal compounds
Reactions of metallic hydroxides with dilute acid
Metal hydroxides react with dilute acids to form a salt and water in a neutralisation reaction
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
For example
magnesium hydroxide + hydrochloric acid magnesium chloride + water
Mg(OH)2 (aq) + 2 HCl (aq) MgCl2 (aq) + 2 H2O (l)
sodium hydroxide + hydrochloric acid sodium chloride + water
NaOH (aq) + HCl (aq) NaCl (aq) + H2O (l)
potassium hydroxide + sulphuric acid potassium sulphate + water
2 KOH + H2SO4 (aq) K2SO4 (aq) + 2 H2O (l)
calcium hydroxide + sulphuric acid calcium sulphate + water
Ca(OH)2 (aq) + H2SO4 (aq) CaSO4 (aq) + 2 H2O (l)
20
WEEK 3 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal hydroxides with
the corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium hydroxide Hydrochloric acid
Sodium hydroxide Sulphuric acid
Calcium hydroxide Hydrochloric acid
Magnesium hydroxide Sulphuric acid
Aluminium hydroxide Hydrochloric acid
Zinc hydroxide Sulphuric acid
21
WEEK 3 LESSON 2
TOPIC Reactions of metal compounds
Reactions of metallic carbonates with dilute acid
Metal carbonates react with dilute acid to form a salt carbon dioxide and water When
hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric acid is
used the corresponding sulphate salt is formed
For example
sodium carbonate + hydrochloric acid sodium chloride + carbon dioxide + water
Na2CO3 (s) + 2 HCl (aq) 2 NaCl (aq) + CO2 (g) + H2O (aq)
calcium carbonate + hydrochloric acid calcium chloride + carbon dioxide + water
CaCO3 (s) + 2 HCl (aq) CaCl2 (aq) + CO2 (g) + H2O (aq)
zinc carbonate + sulphuric acid zinc sulphate + carbon dioxide + water
ZnCO3 (s) + H2SO4 (aq) ZnSO4 (aq) CO2 (g) + H2O (aq)
potassium carbonate + sulphuric acid potassium sulphate + carbon dioxide + water
K2CO3 (s) H2SO4 (aq) K2SO4 (aq) CO2 (g) + 2 H2O (aq)
22
WEEK 3 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal carbonates with
the corresponding acid
Metallic
carbonate
Acid Balanced chemical equation
Potassium
carbonate
Hydrochloric
acid
Sodium
carbonate
Sulphuric acid
Zinc
carbonate
Hydrochloric
acid
Magnesium
carbonate
Sulphuric acid
Aluminium
carbonate
Hydrochloric
acid
Calcium
carbonate
Sulphuric acid
23
WEEK 3 LESSON 3
TOPIC Action of heat on metal compounds
Action of heat on nitrates
All nitrates decompose when heated The reactivity of the metal in the metal nitrate influences
the products of the decomposition
The nitrates of the alkali metals (Group I) with the exception of lithium nitrate decompose to
form the metal nitrite and oxygen
The nitrates of most other metals decompose to form the metal oxide nitrogen dioxide and
oxygen
The nitrates of the very unreactive metals decompose to form the meal nitrogen dioxide and
oxygen
Metal Nitrate Decomposition
Potassium K Products metal nitrite + oxygen
eg 2 NaNO3 (s) Heatrarr 2 NaNO2 (s) + O2 (g)
Sodium Na
Calcium Ca
Products metal oxide + nitrogen dioxide + oxygen
eg 2 Pb(NO3)2 (s)
Heatrarr 2 PbO (s) + 4 NO2 (g) + O2 (g)
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Products metal + nitrogen dioxide + oxygen
eg 2 AgNO3 (s) Heatrarr 2 Ag (s) + 2 NO2 (g) + O2 (g)
24
WEEK 3 LESSON 3 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
nitrates
Metal Balanced chemical equation
Potassium nitrate
Sodium nitrate
Calcium nitrate
Magnesium nitrate
Aluminium nitrate
Zinc nitrate
Lead nitrate
Copper nitrate
Silver nitrate
25
WEEK 4 LESSON 1
TOPIC Action of heat on metal compounds
Action of heat on carbonates
Upon application of heat many carbonates decompose to form the metal oxide and carbon
dioxide
Group I carbonates do not decompose on heating with the exception of lithium carbonate
Metal Carbonate decomposition
Potassium K
Stable not decomposed by heat Sodium Na
Calcium Ca
Decompose forming metal oxide and carbon dioxide
eg CaCO3 (s) Heatrarr CaO (s) + CO2 (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Unstable
26
WEEK 4 LESSON 1 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
carbonates
Metal Balanced chemical equation
Potassium carbonate
Sodium carbonate
Calcium carbonate
Magnesium carbonate
Aluminium carbonate
Zinc carbonate
Iron carbonate
Lead carbonate
Copper carbonate
27
WEEK 4 LESSON 2
TOPIC Action of heat on metal compounds
Action of heat on the metal hydroxides
Most metal hydroxides decompose on heating A metal oxide and water are formed
Group I hydroxides do not decompose on heating with the exception of lithium hydroxide
Metal Hydroxide decomposition
Potassium K Stable not decomposed by heat
Sodium Na
Calcium Ca Decompose forming metal oxide and water (as steam)
eg Zn(OH)2 (s) Heatrarr ZnO (s) + H2O (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag No hydroxide exist
28
WEEK 4 LESSON 2 WORKSHEET
Write the balanced chemical equations for the thermal decomposition of the following
metal hydroxides
Metal hydroxide Balanced chemical equation
Potassium hydroxide
Sodium hydroxide
Calcium hydroxide
Magnesium hydroxide
Aluminium hydroxide
Zinc hydroxide
Lead hydroxide
Copper hydroxide
29
WEEK 4 LESSON 3
TOPIC Reactivity of metals ndash The Reactivity Series
The reactivity series of metals is a list of metals arranged in order of their reactivity based on
Displacement reactions
Reactions with oxygen dilute acids and water
Relative ease of decomposition of their compounds
Metals at the top of the series are the most electropositive They lose electrons very easily and
readily form cations These ions are very stable and are not easily discharged to form atoms Due
to this fact they are the most reactive metals
Metals at the bottom of the series are the least electropositive They do not lose electrons easily
and do not readily form ions Their ions are very unstable and are easily discharged to form
atoms They are the least reactive metals
The reactivity series of metals
Mnemonic Metal Symbol Reactivity
People Potassium K Most reactive
Least reactive
Sometimes Sodium Na
Collect Calcium Ca
Magazines Magnesium Mg
About Aluminium Al
Zoos Zinc Zn
In Iron Fe
London Lead Pb
Having (Hydrogen) H
Cute Copper Cu
Monkeys and Mercury Hg
Small Silver Ag
Gorillas Gold Au
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
5 Reactivity of metals Reactivity of metals Reactivity of metals
6 Extraction of metals Extraction of metals Alloys
7 Corrosion Importance of metals
and their compounds
on living systems and
environment
Chemical properties
of non ndash metals
8 Laboratory
preparation of gases
Laboratory
preparation of gases
Laboratory
preparation of gases
9 Uses of gases Uses of non ndash metals
and their compounds
Harmful effects of
non ndash metals and
their compounds on
living systems and
the environment
10 Green Chemistry Qualitative Analysis
ndash Identification of
cations
Qualitative Analysis
ndash Identification of
cations
2
WEEK 5 LESSON 1
TOPIC Reactivity of metals
Reactivity based on displacement reactions between metals and metal ions
A metal will displace a metal which is lower than itself in the reactivity series from a solution of
the metal salt
Reaction of zinc and copper (II) sulphate
Expected observations
Explanation
The size of the zinc metal decreases
The zinc metal is reacting and forming the
salt zinc sulphate
The solution becomes lighter eventually
colourless
The Cu2+ (aq) ions (responsible for the blue
colour) is reduced to Cu (s)
A brown solid is deposited at the bottom of
the container
Copper metal is formed
Equation Zn (s) + CuSO4 (aq) ZnSO4 (aq) + Cu (s)
Ionic equation
Zn (s) + Cu2+ (aq) Zn2+ (aq) + Cu (s)
Zinc is higher in the reactivity series than copper Therefore it will displace the copper ions in
the reaction above
3
Examples of other displacement reactions
Magnesium will displace Zn2+ ions in zinc sulphate since it is higher in the series than zinc
Mg (s) + Zn2+(aq) Mg2+ (aq) + Zn (s)
Silver will not displace Cu2+ ions in copper (II) sulphate [Cu is higher in the series than Ag]
Using the information above we can arrange the metals in order of their reactivity with
magnesium being the most reactive and silver the least reactive metal among the four metals
Mg gt Zn gt Cu gt Ag
Reactivity based on reaction with oxygen
The reactivity of metals can also be deduced from their reaction with oxygen
The table below gives the observations for the reaction with oxygen with the selected metals
Reaction of metal with oxygen
Metal Observation
Copper The surface turns black upon heating
Magnesium Ribbon burns very rapidly
Sodium Burns vigorously
Gold No reaction
Based on the observations for the 4 metals the metal with highest reactivity is sodium and the
metal with the least reactivity is gold
The 4 metals can be arranged in terms of reactivity as follows
Na gt Mg gt Cu gt Au
4
WEEK 5 LESSON 1 WORKSHEET
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
5
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
6
WEEK 5 LESSON 2
TOPIC Reactivity of metals
Reactivity based on reactivity with acids
The metals that are higher than hydrogen in the electrochemical series react with non ndash oxidizing
acids to produce a salt and hydrogen gas
By using the same concentration of acid and same mass and size of the metals the order of
reactivity of the metals can be deduced
The table below shows the results for an experiment with the reaction of the named metals and
1 mol dm-3 hydrochloric acid
Reaction of metals with acid
Metal Observations
Silver No reaction
Magnesium Bubbles produced steadily
Calcium Bubbles produced very rapidly
Iron Bubbles produced slowly
Based on the above data the most reactive metal will be calcium with the least reactive being
silver The order of reactivity will be Ca gt Mg gt Fe gt Ag
By comparing this to the electrochemical series it can be seen that the reactivity of the metals
decrease as we go down the series
7
WEEK 5 LESSON 2 WORKSHEET
1 Place a next to the metals that will react with dilute acid and an X next to the metals
that will not react with dilute acid
Metal Reactivity with acid
Copper
Magnesium
Aluminium
Silver
Zinc
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
8
WEEK 5 LESSON 3
TOPIC Reactivity of metals
Reactivity based on ease of decomposition of the metal nitrates carbonates oxides and
hydroxides
The more reactive a metal the more difficult it is to decompose its nitrate carbonate oxide or
hydroxide on heating
For example Decomposition of carbonates
Procedure
1 Put a large spatula measure of the carbonate to be tested in a test tube
2 Fit a delivery tube and then clamp the test tube so that the delivery tube dips into a second test
tube containing 2ndash3 cm3 limewater
3 Heat the solid gently at first then more strongly
4 Lift the delivery tube from the limewater before or as soon as the heating is stopped This is to
avoid suck-back
5 Write down all observations Notice what happens to the limewater and how long it takes to turn
milky (if at all) Notice whether any melting occurs in the heated test tube and any colour
changes taking place Write your results in tabular form
6 Repeat the experiment with the other metal carbonates supplied and in each case write down
your observations
7 Wash your hands thoroughly at the end of these experiments since some of the metal carbonates
are toxic
9
Results
Metal Formula Gas evolved Ease of decomposition
Zinc ZnCO3 Carbon dioxide Fairly easy
Copper CuCO3 Carbon dioxide Easy
Sodium Na2CO3 None Very difficult
Using the results of the above activity the reactivity of the metals can be determined
Ease of decomposition Copper gt Zinc gt Sodium
The order of reactivity is the opposite for the ease of decomposition
Order of reactivity Sodium (most reactive) gt Zinc gt Copper (least reactive)
10
WEEK 5 LESSON 3 WORKSHEET
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
11
WEEK 6 LESSON 1
TOPIC Extraction of metals
Elements exist all over the earth Some are found as free elements eg copper silver and gold
Others are found combined with other elements in compounds To get the elements the
compounds have to be broken up These compounds are generally called ores the most
convenient sources of which are rocks sea and air
The extraction of a metal from its ore is a reduction process where the metals ions gain electrons
to form atoms
The general equation is Mn+ + n e- M
The choice of the extraction method depends on the position of the metal in the reactivity series
As we go down the series the metals become more stable and the metal ions (in the ores)
become less stable
The very reactive metals that are high in the series K Na Ca Mg Al have very stable ores
Therefore they require a powerful method of reduction namely electrolysis During the process
the cathode provides the electrons and acts as the reducing agent
The metals in the middle of the series (Zn Fe Pb) do not have stable ores and can be extracted
by reduction with carbon in the case of zinc and with carbon monoxide in the case of iron and
lead
Metals low in the reactivity series if present as ores can be extracted simply by heating the ores
in air at high temperatures
12
Extraction of Aluminium from purified bauxite
Pure bauxite is pure alumina (Al2O3) Aluminium is obtained from bauxite by electrolysis
Aluminium oxide has a very high melting point approximately 2050 0C so it is first dissolved in
molten cryolite (Na2AlF6) The addition of cryolite lowers the melting point to approximately
900 0C
The electrolyte is a molten mixture of alumina and molten cryolite The cathode is the graphite
lining of the cell The anodes are blocks of graphite or titanium alloys
Reaction at the cathode
Al3+ (l) + 3 e- Al (l)
Reaction at the anode
2 O2- (l) ndash 4 e- O2 (g)
Aluminium (melting point 660 0C) is a liquid at the temperature at which electrolysis is carried
out and is collected at the bottom of the cell and tapped off Oxygen gas which is given off in the
main cathode reaction together with the heat causes the anodes to burn away The anodes have
to be replaced from time to time The use of anodes from titanium alloys reduce the number of
times that the anodes have to be replaced
13
WEEK 6 LESSON 1 Worksheet
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 6 LESSON 2
TOPIC Extraction of metals
Extraction of Iron
The traditional method of production of iron is by reduction of haematite by carbon monoxide in
a blast furnace
Ores Haematite ndash Fe2O3 Magnetite ndash Fe3O4 Siderite ndash FeCO3 Magnetite and Siderite are
converted to Haematite
A mixture of haematite limestone (CaCO3) and coke (C) called the charge is placed into the top
of the furnace
Hot air is blown into the bottom of the furnace
Coke burns in air forming carbon dioxide
C (s) + O2(g) CO2 (g) ΔH -ve
The heat produced keeps the temperature at about 1900 0C
The carbon dioxide is reduced to carbon monoxide by the hot coke
CO2 (g) + C (s) 2 CO(g) Δ +ve
Heat absorbed reduces the temperature to about 1100 0C
The carbon monoxide reduces the hot iron ore to molten iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + 3 CO2(g)
The temperature at this part of the furnace is about 700 0C The iron runs to the bottom of the
furnace
The impurities are removed by the addition of limestone (CaCO3) The limestone at the
temperature of the furnace breaks down
CaCO3 (s) CaO (s) + CO2 (g)
15
The calcium oxide formed combines with silicon dioxide (sand) the main impurity in the iron
ore to form molten slag
CaO (s) + SiO2 (s) CaSiO3 (l)
The slag does not mix with the molten iron but floats on it The molten iron and slag are run off
separately
The iron formed in a blast furnace is an impure form of the metal Because the molten metal is
allowed to solidify in shallow trays known as casts the iron is called lsquocast ironrsquo or lsquopigrsquo iron
Cast iron is quite brittle and contains 2 - 4 carbon and other impurities Most of the cast iron is
converted to steel
A blast furnace used for extracting iron
16
WEEK 6 LESSON 2 Worksheet
(a) What are the three raw materials that are added through the top of the blast furnace
during the extraction process for iron
______________________________________________________________________________
______________________________________________________________________________
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
17
WEEK 6 LESSON 3
TOPIC Alloys
An alloy is a mixture of two or more metals Alloys are made by melting the individual metals
mixing them and allowing the molten mixture to solidify
In general alloys are harder stronger and more resistant to corrosion than the actual metals they
are made up from
Alloy Use Properties
ALUMINIUM
-Duralumin
(AlMgCu)
-Magnalium (AlMg)
Alloys used in the
construction of
aircraft and ships
buses
Aluminium is used in
making cooking
utensils electrical
cables paint for fuel
storage tanks bottle
caps foil and utensils
for handling nitric
acid
The alloys have a low
density They are as
light as aluminium
and more resistant to
corrosion than
aluminium
LEAD
-Solder (PbSn)
Alloy is used in
joining metals
(soldering)
Lead is used in
underground cables
plates in
The alloy has a lower
melting point than
lead and is harder
than lead
18
Alloy Use Properties
accumulators shield
against x ndash rays
IRON
- Stainless Steel
(FeCONiC)
-Tungsten steel
(FeWC)
-Invar steel (FeNi)
Manganese steel
(FeMnC)
Iron is the main metal
of a variety of
constructions
Steel is used in
cutlery rock drills
electromagnets
vehicle body and
engine parts fences
pipes etc
Steel resists
corrosion is usually
harder than iron and
may be tough though
malleable and ductile
19
WEEK 6 LESSON 3 Worksheet
(a) Define the term alloy
______________________________________________________________________________
(b) State 3 general advantages that alloys have over the individual metals they are made
from
______________________________________________________________________________
______________________________________________________________________________
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
______________________________________________________________________________
______________________________________________________________________________
Uses
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 7 LESSON 1
TOPIC Corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
Familiar examples of corrosion are
- the formation of a green powder on copper sheeting
- the eating away of iron (rusting)
- the development by aluminum of a thin compact layer of oxide which protects the
underlying metal from further corrosion
When corrosion occurs in water ndash free environment it is called dry oxidation When it occurs in
aerated aqueous environments it is called wet corrosion Wet corrosion is the most common and
troublesome form of corrosion
The most familiar corrosion is the rusting of iron and steel On exposure to the atmosphere iron
and steel corrode to form rust which is hydrated iron (III) oxide Fe2O3xH2O Iron and steel
corrode easily and the rust formed flakes off easily thus exposing fresh surface for attack
When iron rust it loses electrons
Fe (s) ndash 2e- Fe 2+ (aq)
The iron (II) ions pass into solution and then combine with the hydroxyl (OH-) ions in the
aerated aqueous environment to form iron (II) hydroxide The oxygen present oxidises the iron
(II) hydroxide to hydrated iron (III) oxide or rust
Fe(OH)2 + O2 Fe2O3xH2O
21
Methods of preventing rusting
1 Coating the object with paint grease plastic or rubber which prevent contact with air or
water
2 Galvanising ndash coating the object with zinc The zinc forms an adherent oxide layer which
protects against further corrosion If damaged the zinc is oxidized in preference to the
iron since it is higher in the electrochemical series
3 Coating with tin lsquoTinrsquo cans are made of steel plated with tin However if scratched
rusting occurs since iron is more reactive than tin
4 Attaching a sacrificial anode to the object A piece of metal higher in the electrochemical
series such as magnesium is attached The magnesium will be oxidized in preference
since it is higher in the electrochemical series than iron
22
WEEK 7 LESSON 1 WORKSHEET
(a) Define the term corrosion
______________________________________________________________________________
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
23
WEEK 7 LESSON 2
TOPIC Importance of metals and their compounds on living systems and environment
Some metals are an integral part of different structures of living things
Metal Presence and Function
Potassium Main cation in fluid or animal cells essential for healthy plant growth
Calcium Necessary for strong bones teeth and shells needed by some enzymes Present
in dairy produce eggs nuts and cereals
Magnesium Central atom of chlorophyll needed for some enzyme action Involved in energy
and calcium metabolism
Zinc Present in many enzymes Needed for protein metabolism Essential for growth
of animals
Iron Present in haemoglobin Needed for protein metabolism Essential for growth of
animals
Chromium Needed for glucose uptake by cells and thus linked to the action of insulin
Manganese Needed for bone development and amino acid metabolism Present in several
enzymes Needed for plant growth
Cobalt Present in Vitamin B12 Needed for plant growth
Copper Involved in formation of haemoglobin and melanin Present in enzymes
controlling oxidation Needed for plant growth
24
Harmful effects of metals and their compounds to living systems and the environment
There are some metals and metal compounds which may cause harm to living systems and the
environment
Lead
Lead is a heavy metal poison that is widely encountered It may occur in food beverages paint
water formed from ndash sealed pipes in air polluted by combustion by fuels containing lead
compounds Lead is also used in some car batteries If these are paints or batteries are not
disposed of correctly lead may get into groundwater or air Lead and lead compounds harm the
nervous system including the brain especially young children
Arsenic
Arsenic compounds are poisonous They can get into the groundwater from mining waste and
from disposal of some electrical components
Cadmium
Cadmium compounds are poisonous They can get into the ground by improper disposal of
nickel ndash cadmium batteries Persons can get cadmium poisoning if they eat food grown in
contaminated soil
Mercury
Mercury can be spilled from broken thermometers in hospitals and laboratories Mercury and its
compounds are particularly poisonous to fish and it can accumulate in the food chain and
eventually poison humans
Problems of disposal of solid waste
Metals may react with water andor air and corrode to form soluble compounds that are
poisonous These toxic compounds diffuse into the soil and eventually enter rivers
Rust from iron may form unsightly pools of waste that reduce plant growth
Waste from aluminium extraction may react with water and form flammable gases
25
WEEK 7 LESSON 2 WORKSHEET
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Lead
______________________________________________________________________________
Mercury
______________________________________________________________________________
26
WEEK 7 LESSON 3
TOPIC Chemical properties of non ndash metals
Reaction with oxygen
Many non ndash metals burn in excess oxygen or air to form oxides For example
S (s) + O2 (g) SO2 (g)
C (s) + O2 (g) CO2 (g)
Reactions with metals
Some non ndash metals react with metals high in the electrochemical series when heated
For example
Sodium burns in chlorine to form sodium chloride
Na (s) + Cl2 (g) NaCl (s)
Magnesium burns in oxygen to form magnesium oxide
Mg (s) + O2 (g) MgO (s)
When heated iron combines with molten sulphur to form iron (II) sulphide
Fe (s) + S (l) FeS (s)
When heated reactive metals such as sodium and aluminium react with hydrogen to form metal
hydrides
2 Na (s) + H2 (g) 2 NaH (s)
Oxidising and Reducing properties
Hydrogen and Carbon are very good reducing agents
At high temperatures hydrogen reduces metal oxides below zinc in the electrochemical series to
form the metal For example PbO (s) + H2 (g) Pb (s) + H2O (g)
Under suitable conditions hydrogen reduces nitrogen to ammonia
N2(g) + 3 H2 (g) 2 NH3 (g)
27
At high temperatures carbon reduces metal oxides below aluminium in the reactivity series to
the metal For example
ZnO (s) + C (s) Zn (s) + CO (g)
Oxygen and Chlorine are very good oxidizing agents
Oxygen oxidized most metals to form metal oxides and some non ndash metals to non ndash metal oxides
For example
2 Mg (s) + O2(g) 2 MgO (s)
4 P (s) + 5 O2 (g) P4O10 (s)
Chlorine acts as an oxidizing agent either as a gas or as an aqueous solution For example
H2 (g) + Cl2 (g) 2 HCl (g)
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
28
WEEK 7 LESSON 3 WORKSHEET
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
______________________________________________________________________________
(b) Write the ionic equation for the above reaction
______________________________________________________________________________
(c) Identify the oxidising agent in the reaction
______________________________________________________________________________
(d) Justify your answer in part (c) in terms of oxidation number
______________________________________________________________________________
29
WEEK 8 LESSON 1
TOPIC Laboratory preparation of gases
Preparation of oxygen
Oxygen can be prepared by the decomposition of hydrogen peroxide potassium chlorate (V) or
potassium nitrate The safest method is the decomposition of hydrogen peroxide
Manganese (IV) oxide catalyses the decomposition of hydrogen peroxide
Silica gel anhydrous calcium chloride or concentrated sulphuric acid can be used as a drying
agent
The gas is collected by downward delivery since it is slightly denser than air
Equation
2 H2O2 (aq) 2 H2O (l) + O2 (g)
Apparatus used for laboratory preparation of oxygen
30
WEEK 8 LESSON 1 WORKSHEET
Describe the laboratory preparation of oxygen gas
In your answer include
The starting material
A suitable catalyst
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
31
WEEK 8 LESSON 2
TOPIC Laboratory preparation of gases
Preparation of carbon dioxide
Carbon dioxide can be prepared by the action of dilute acid on carbonates Marble chips (calcium
carbonate) and dilute hydrochloric acid are the common reagents The gas is collected by
downward delivery since it is denser than air
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
Apparatus used for laboratory preparation of carbon dioxide
32
WEEK 8 LESSON 2 WORKSHEET
Describe the laboratory preparation of carbon dioxide gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
33
WEEK 8 LESSON 3
TOPIC Laboratory preparation of gases
Preparation of ammonia
Ammonia may be prepared by heating a mixture of ammonium salt and a hydroxide The
ammonia gas is collected by upward delivery since it is less dense than air
For example
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
Calcium oxide is the only suitable drying agent since ammonia reacts with conc H2SO4 and
CaCl2
Apparatus used for laboratory preparation of dry ammonia
34
11
WEEK 8 LESSON 3 WORKSHEET
Describe the laboratory preparation of ammonia gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
35
WEEK 9 LESSON 1
TOPIC Uses of gases
Carbon dioxide
Used in fire extinguishers to put out fires Carbon dioxide is denser than air and lsquoblanketsrsquo the
fire preventing oxygen from reaching it Carbon dioxide extinguishers are especially useful for
dealing with fires involving flammable liquids and electrical equipment
Carbonation in soda is created when carbon dioxide is pumped into the soda can or bottle then
held under pressure As long as the can or bottle is sealed the carbon dioxide remains mostly
stable However if the drink gets shaken up or the top is opened the tiny carbon dioxide bubbles
react by bursting
Oxygen
Oxygen is needed for aerobic respiration We need a constant supply of oxygen for this process
Oxygen is used in hospitals to improve the respiration of patients with poor blood flow blood
poisoning and heart disease
Oxygen in used in welding (joining) metals In an oxyacetylene welding torch acetylene or
ethyne (C2H2) burns in oxygen and produces a very hot flame This flame is capable of melting
most metals
Oxygen is used in steel production A blast of oxygen is blown through the molten iron The
oxygen oxidises many of the impurities of the iron and the impurities are then removed
36
WEEK 9 LESSON 1 WORKSHEET
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Put out fires
Welding metals
Create lsquofizzrsquo in drinks
Used in steel production
Aerobic respiration
37
WEEK 9 LESSON 2
TOPIC Uses of non ndash metals and their compounds
Carbon (allotrophes carbon dioxide)
Carbon is used as a reducing agent in extraction of some metals
Carbon as graphite is used as electrodes lubricants and lsquoleadrsquo for pencils
Carbon in the form of diamond is used for jewellery (because of its lustre) and in drill tips for
high ndash speed drills (because of its hardness)
Carbon dioxide is used as refrigerant (as dry ice) for carbonated beverages
Sodium hydrogen carbonate and sodium carbonate are used for water softening and raising
agent
Sulphur
Sulphur is used in the manufacture of sulphuric acid Sulphur is also used in the manufacture of
tyres to make the rubber harder (vulcanisation)
Sulphur powder is used as fungicide on plant materials
Phosphorus
Phosphorus is used in the manufacture of fertilizers
Phosphorus is used to make phosphor bronze alloys
Phosphorus sulphide is used to make the heads of lsquostrike anywherersquo matches
38
Chlorine
Chlorine is used to make sodium hypochlorite which is present in bleach It is also used in
sterilizing swimming pools and in water treatment
Chlorine is used to make the monomer vinyl chloride which is used to make the plastic PVC
Nitrogen
Nitrogen is used to make fertilisers ammonia dyes and nitric acid
Nitrogen is used as an inert atmosphere to prevent substances being oxidised and as a coolant
Silicon
Silicon is used for making silicon chips for computers
Silicon (V) oxide is present in sand Glass is made by heating sand with lime (calcium oxide) and
sodium carbonate
Silicon in the form of silicates is used in jewellery
Silica gel is used as a drying agent
39
WEEK 9 LESSON 2 WORKSHEET
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Used to make sodium hypochlorite
Used as a fungicide on plant materials
Used for lsquoleadrsquo in pencils
Used in the manufacture of bronze alloys
Used in the manufacture of nitric acid
Used in the manufacture of computer chips
Used to make fertilisers
40
WEEK 9 LESSON 3
TOPIC Harmful effects of non ndash metals and their compounds on living systems and the
environment
Sulphur dioxide
Sulphur dioxide can cause a disease of the lungs Sulphur dioxide also poisons plants in two
main ways It may enter the stomata of leaves and react with the tissue fluids to form sulphites
with the on ndash going water loss the concentration of sulphites could build up killing the cells
The second adverse effect on plants occurs when sulphur dioxide dissolves in rain thereby
increasing soil acidity A prolonged acid soil situation may lead to plasmolysis and the death of
vegetation in an area
Carbon monoxide
Carbon monoxide combines much more readily than oxygen with haemoglobin When carbon
monoxide is inhaled it prevents the haemoglobin from taking oxygen to the bodyrsquos cells
Continued breathing of air containing carbon monoxide eventually causes death
Hydrogen sulphide
Hydrogen sulphide reacts readily with many cations forming insoluble sulphides Many cations
contribute to good health by contributing to enzyme activity and to the formation of bone
pigment and haemoglobin Although these cations are required in extremely small
concentrations they are removed by being precipitated as sulphides and thus not available for
regular function Careless dumping of refuse contributes to atmospheric pollution by hydrogen
sulphide
Oxides of nitrogen
In the presence of hydrocarbons from car exhausts ozone and sunlight nitrogen oxides react to
form photochemical smog which contains many harmful chemicals
Nitrogen dioxide can harm the lungs and irritate the nose throat and eyes The other compounds
present in photochemical smog are even more harmful irritants and can cause asthma
41
Carbon dioxide
Carbon dioxide water vapour and ozone referred to as ldquogreenhouse gasesrdquo acting as a blanket
readily absorb some of the radiated heat energy and in turn warms the earthrsquos atmosphere This is
called the ldquogreenhouse effectrdquo Scientists have found direct correlation between carbon dioxide
concentration and global warming An increase in carbon dioxide concentration resulted in an
increase global temperatures Global warming is a major potential problem that the world faces
Chloroflourocarbons (CFCs)
It is believed that CFCs might be responsible for destroying the ozone layer which prevents
harmful ultraviolet (UV) radiation from reaching the earth The carbon ndash chlorine bond in CFC
molecule is easily broken by a UV photon producing an active chlorine atom This atom
combines with an ozone molecule forming a chlorine oxide radical and oxygen The radicle
reacts with more ozone producing the chlorine atom again This kind of reaction is repeated
thousands of times This type of reaction is thought to account for about eighty percent of the
loss of ozone observed
Nitrates and phospates
Nitrates and phosphates cause eutrophication The process leading to eutrophication are
Nitrates and phosphates from fertilisers spread on fields may dissolve in groundwater and
get into lakes and rivers
Nitrates and phosphates cause excessive growth of algae so that they cover the surface of
the water
Water plants including algae die because of lack of sunlight Aerobic bacteria feed on
the plant remains The bacteria multiply
The aerobic bacteria use up the oxygen in the water so aquatic animals die
42
Solid waste
The main sources of pollution from non ndash metals is from glass paper and plastics
Broken glass can cause injury to animals It can also cause fires by acting as lens focusing the
sunrsquos rays on flammable materials
Printing inks from paper dumped in the ground may contain toxic elements such as arsenic and
cadmium Bleaches and chlorine compounds from paper are also harmful
43
WEEK 9 LESSON 3 WORKSHEET
Describe ONE harmful effect of the following non ndash metals andor their compounds on
living systems and the environment
Sulphur dioxide
______________________________________________________________________________
______________________________________________________________________________
Carbon monoxide
______________________________________________________________________________
______________________________________________________________________________
Carbon dioxide
______________________________________________________________________________
______________________________________________________________________________
Oxides of nitrogen
______________________________________________________________________________
______________________________________________________________________________
Hydrogen sulphide
______________________________________________________________________________
______________________________________________________________________________
44
Chloroflourocarbons (CFCs)
______________________________________________________________________________
______________________________________________________________________________
Nitrates and phospates
______________________________________________________________________________
______________________________________________________________________________
45
WEEK 10 LESSON 1
TOPIC Green Chemistry
Green Chemistry is defined as the utilisation of a set of principles that reduces or eliminates the
use and generation of hazardous substances
There are twelve principles of green chemistry as proposed by Paul T Anastas and John C
Warner These twelve principles are
1 Prevention ndash It is better to prevent waste than to treat or clean up waste after it has been
created
2 Atom economy - Synthetic methods should be designed to maximize the incorporation of
all materials used in the process into the final product
3 Less hazardous chemical synthesis - Wherever practicable synthetic methods should be
designed to use and generate substances that possess little or no toxicity to human health
and the environment
4 Safer chemical products - Chemical products should be designed to affect their desired
function while minimizing their toxicity
5 Safer solvents and other agents - The use of auxiliary substances (eg solvents
separation agents etc) should be made unnecessary wherever possible and harmless
when used
6 Minimum energy requirements - Energy requirements of chemical processes should be
recognized for their environmental and economic impacts and should be minimized If
possible synthetic methods should be conducted at ambient temperature and pressure
7 Use of renewable raw materials - A raw material or feedstock should be renewable rather
than depleting whenever technically and economically practicable
8 Reduce use of additional chemicals or additional steps - Unnecessary derivatization (use
of blocking groups protection deprotection temporary modification of
physicalchemical processes) should be minimized or avoided if possible because such
steps require additional reagents and can generate waste
46
9 Use of catalysts ndash The use of catalysts reduce energy costs because the reactions take
place at lower temperatures The more specific the catalyst for a particular reaction is the
less it the likelihood of getting additional unwanted products
10 Nature of breakdown of products - Chemical products should be designed so that at the
end of their function they break down into innocuous degradation products and do not
persist in the environment
11 Monitoring to prevent pollution - Analytical methodologies need to be further developed
to allow for real-time in-process monitoring and control prior to the formation of
hazardous substances
12 Minimise chemical accidents - Substances and the form of a substance used in a chemical
process should be chosen to minimize the potential for chemical accidents including
releases explosions and fires
47
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
48
WEEK 10 LESSON 2
TOPIC Qualitative Analysis ndash Identification of cations
Qualitative Analysis involves identifying the constituents of single substances or mixture of
substances
Appearance
An examination of the appearance of a substance can indicate which ion it contains
Appearances of substances
Observation Indication
Blue or blue ndash green Cu2+ salt
Pale green Fe2+ salt
Yellow ndash brown Fe3+ salt
Ammonia smell NH4+ salt
49
Test for cation using sodium hydroxide
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
(d) If no precipitate forms in step b warm gently and test for ammonia
Effect of dilute sodium hydroxide solution
Effect of dilute sodium hydroxide solution Cation
Dropwise Excess
White precipitate Precipitate soluble Ca2+
White precipitate Precipitate insoluble Al3+ Pb2+ Zn2+
Blue precipitate Precipitate insoluble Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
No precipitate ndash ammonia gas
evolved on heating
ndash NH4+
The metal cations all form insoluble hydroxides with sodium hydroxide solution
For example Ca2+ (aq) + 2 OH- (aq) Ca(OH)2 (s)
Ca(OH)2 Cu(OH)2 Fe(OH)2 and Fe(OH)3 are basic and therefore do not react with excess
sodium hydroxide solution Therefore the precipitate does not dissolve in excess sodium
hydroxide solution
Al(OH)3 Pb(OH)2 and Zn(OH)2 are amphoteric Therefore the precipitates react with the excess
sodium hydroxide solution forming soluble salts and the precipitate disappears in excess sodium
hydroxide solution
The NH4+ ion forms a soluble hydroxide However on heating it reacts with the hydroxide ion to
form ammonia and water
NH4+ (aq) + OH- (aq) NH3 (g) + H2O (l)
50
WEEK 10 LESSON 2 WORKSHEET
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P _____________ Q ___________________
R _____________ S ___________________
R + NaOH
______________________________________________________________________________
51
WEEK 10 LESSON 3
TOPIC Qualitative Analysis ndash Identification of cations
Test for cation using ammonia solution (ammonium hydroxide solution)
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
Effect of dilute ammonia (ammonium hydroxide) solution
Effect of dilute ammonia solution Cation
Dropwise Excess
No precipitate ndash Ca2+
White precipitate Precipitate soluble
(forming colourless solution)
Zn2+
White precipitate Precipitate insoluble Al3+ Pb2+
Blue precipitate Precipitate soluble
(forming deep blue solution)
Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
52
Ammonia solution is a weak alkali Metal cations except Ca2+ form insoluble hydroxides with
ammonia solution as with the sodium hydroxide solution
The amphoteric hydroxides Al(OH)3 and Pb(OH)2 and the basic hydroxides Fe(OH)2 and
Fe(OH)3 do not react with excess ammonia solution Therefore the precipitates remain
However Zn(OH)2 and Cu(OH)2 do react with excess ammonia solution to form complex
soluble hydroxides each Hence their precipitates disappear on the addition of excess ammonia
solution
Confirmatory test
After carrying out test for cations using sodium hydroxide solution and ammonia solution the
only cations which cannot be distinguished are Al3+ and Pb2+ A confirmatory test is carried out
to distinguish between the two cations
Confirmatory test
Test Observation Cation Ionic equation
Add potassium
or sodium
iodide solution
Bright yellow precipitate
No precipitate
Pb2+
Al3+
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
53
WEEK 10 LESSON 3 WORKSHEET
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A __________ B ________________ C ________________________
(b) State the inference after Test 2
C _______________________
(c) Write an ionic equation to support your answer in (b) above
___________________________________________________________________________
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
54
ANSWERS TO WORKSHEETS
55
WEEK 5 LESSON 1 WORKSHEET ANSWERS
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
Answer
Zinc + Iron (II) sulphate Zinc is higher in the electrochemical series and therefore displace
iron ions in iron (II) sulphate
Equation Zn (s) + FeSO4 (aq) ZnSO4 (aq) + Fe (s)
Ionic equation Zn (s) + Fe2+ (aq) Zn2+ (aq) + Fe (s)
Iron + Zinc sulphate No reaction iron is lower in the electrochemical series and cannot
displace the zinc ions in zinc sulphate
56
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
Answer
X displaces lead from an aqueous solution of its salts
X (s) + Pb2+ (aq) Xn+ (aq) + Pb (s)
rarr X is more reactive than Pb
X did not react with iron salts
rarr X is less reactive than Fe
Y burns very easily
Y is more reactive than Fe and Pb (both forming their corresponding oxide at a slower rate)
From electrochemical series Fe is higher and therefore more reactive than Pb
Order of reactivity
Y (most reactive) gt Fe gt X gt Pb (least reactive)
57
WEEK 5 LESSON 2 WORKSHEET ANSWERS
1
Metal Reactivity with acid
Copper X
Magnesium
Aluminium
Silver X
Zinc
58
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
Answer
Y and Z are the most reactive since they can react with dilute acid
Z is more reactive than Y since a reaction occurs with Z is added to an aqueous solution of Y
X is less reactive than W since it does not occur in nature as compounds
Order of reactivity Z (most reactive) gt Y gt W gt X
59
WEEK 5 LESSON 3 WORKSHEET ANSWERS
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
Answer
Ease of decomposition (from easiest to decompose to most difficult to decompose)
B rarrD rarrArarr C
Reactivity (most reactive to least reactive)
C (most reactive) gt A gt D gt B (least reactive)
60
WEEK 6 LESSON 1 Worksheet Answers
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
Potassium Zinc Copper
Calcium Lead Gold
Magnesium Iron
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
Aluminium is extracted from its ore bauxite through the process of electrolysis
Cryolite is added to bauxite to lower the melting point to about 900 0C The melting point of
bauxite is very high (about 2040 0C) It is difficult and expensive to keep the molten aluminium
oxide at this temperature
Reaction at the cathode Al3+ (l) + 3 e- Al (l)
61
WEEK 6 LESSON 2 Worksheet Answers
(a) What are the three raw materials that are added through the top of the blast
furnace during the extraction process for iron
Coke (carbon)
iron ore (haematitie mainly iron (II) oxide)
limestone (calcium carbonate)
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
Coke ndash coke burns to produce carbon dioxide The carbon dioxide further reacts with coke to
form carbon monoxide (reducing agent in the process)
C (s) + O2 (g) CO2 (g)
C (s) + CO2 (g) 2 CO
Haematite ndash iron ore provides the iron which is reduced by the carbon monoxide to produce
iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + CO2 (g)
Limestone ndash decomposes to form calcium oxide The calcium oxide reacts with the impurity
silicon dioxide to form slag (calcium silicate)
CaCO3 (s) CaO (s) + CO2 (g)
CaO (s) + SiO2 (l) CaSiO3(l)
62
WEEK 6 LESSON 3 Worksheet Answers
(a) Define the term alloy
An alloy is a material made from a mixture of two or more metals
(b) State 3 general advantages that alloys have over the individual metals they are made
from
They are harder stronger and more resistant to corrosion
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
1 High strength
2 Low density
Uses
1 Used to make aircraft bodies
2 Used to make space satellites
63
WEEK 7 LESSON 1 WORKSHEET ANSWERS
(a) Define the term corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
The paint forms a barrier which stops contact with air or water and the iron Hence rusting
will not take place
However when the paint is scratched that part of the iron nail is exposed to air or water and
rusting will take place
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
Magnesium is higher in the electrochemical series and will be oxidised in preference to iron
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
Aluminium is partly protected from corrosion by its coat of aluminium oxide However as the
iron rust it flakes and fall off and the rusting process continues
64
WEEK 7 LESSON 2 WORKSHEET ANSWERS
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
Magnesium is the ion found in chlorophyll Chlorophyll plays a vital part in the process of
photosynthesis A deficiency in magnesium will lead to low chlorophyll level in the tomato
plants and hence reduce the process of photosynthesis There will be less food storage and
hence will lead to smaller yield of tomatoes
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Any correct harmful effect of lead on health or environment
Any correct harmful effect of mercury on health or environment
65
WEEK 7 LESSON 3 WORKSHEET ANSWERS
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
(b) Write the ionic equation for the above reaction
2 Br- (aq) + Cl2 (aq) 2 Cl- (aq) + Br2 (aq)
(c) Identify the oxidising agent in the reaction
Cl2 (aq)
(d) Justify your answer in part (c) in terms of oxidation number
There is a reduction of the oxidation number for chlorine from 0 to ndash1
hence it has been reduced Therefore chlorine is the oxidising agent
66
WEEK 8 LESSON 1 WORKSHEET ANSWERS
Describe the laboratory preparation of oxygen gas
Oxygen is prepared in the laboratory by the decomposition of hydrogen peroxide
A suitable catalyst is manganese (IV) oxide
Drying agent silica gel OR anhydrous calcium chloride OR conc sulphuric acid
The gas is collected by downward delivery since oxygen is slightly denser than air
Balanced chemical equation 2 H2O2 (aq) 2 H2O (l) + O2 (g)
67
WEEK 8 LESSON 2 WORKSHEET ANSWERS
Describe the laboratory preparation of carbon dioxide gas
Carbon dioxide is commonly prepared in the laboratory by the reacting hydrochloric acid and
marble chips (calcium carbonate)
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
The carbon dioxide gas is collected by downward delivery since it is denser than air
Balanced chemical equation
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
68
WEEK 8 LESSON 3 WORKSHEET ANSWERS
Describe the laboratory preparation of ammonia gas
An ammonium salt (ammonium chloride) and a base (sodium hydroxide) are mixed together and
heated
Calcium oxide is used as the drying agent Calcium chloride and concentrated sulphuric acid
cannot be used since ammonia can react with them
The gas is collected by upward delivery since ammonia is less dense than air
Balanced chemical equation
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
69
WEEK 9 LESSON 1 WORKSHEET ANSWERS
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Carbon dioxide Put out fires
Oxygen Welding metals
Carbon dioxide Create lsquofizzrsquo in drinks
Oxygen Used in steel production
Oxygen Aerobic respiration
70
WEEK 9 LESSON 2 WORKSHEET ANSWERS
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Chlorine Used to make sodium hypochlorite
Sulphur Used as a fungicide on plant materials
Carbon (graphite) Used for lsquoleadrsquo in pencils
Phosphorus Used in the manufacture of bronze alloys
Nitrogen Used in the manufacture of nitric acid
Silicon Used in the manufacture of computer chips
Nitrogen Phosphorus Used to make fertilisers
71
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
Green Chemistry is using principles that reduceeliminate the use of hazardous materials in
the design manufacture and application of chemical products
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
Makes the environment safer
Reduces waste
Creates new jobs
Reduces respiratory illnesses
Atom economy
72
WEEK 10 LESSON 2 WORKSHEET ANSWERS
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P Cu2+ Q Fe2+
R Fe3+ S Ca2+
Ionic equation for R + NaOH
Fe3+ (aq) + 3 OH- (aq) Fe(OH)3 (s)
73
WEEK 10 LESSON 3 WORKSHEET ANSWERS
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A Fe3+ B Ca2+ C Al3+ Pb2+
(b) State the inference after Test 2
C Pb2+
(c) Write an ionic equation to support your answer in (b) above
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
11 Qualitative Analysis
ndash Test for gases
Qualitative Analysis
ndash Identification of
anions
Qualitative Analysis
ndash Identification of
anions
12 Problem solving of
Past CSEC Chemistry Paper 2
on topics completed in the term
13
14
15
2
WEEK 11 LESSON 1
TOPIC Qualitative Analysis ndash Test for gases
Identification of gases
Gas Colour Odour Effect on moist
litmus
Method of identification
Oxygen
O2
Colourless Odourless Neutral ndash no
effect
Relights a glowing splint
Hydrogen
H2
Colourless Odourless Neutral ndash no
effect
Lighted splint lsquopopsrsquo if air is also
present
Carbon
dioxide
CO2
Colourless Odourless Weakly acidic ndash
blue to slightly
red
A white precipitate forms in
limewater
Ca(OH)2 (aq) + CO2
CaCO3 (s) + H2O (l)
Precipitate redissolves on
continued bubbling
CaCO3 (s) + H2O (l) + CO2 (g)
Ca(HCO3)2 (aq)
Ammonia
NH3
Colourless Pungent Alkaline ndash red
to blue (only
common
alkaline gas)
Turns moist red litmus blue forms
dense white fumes with hydrogen
chloride gas
NH3 (g) + HCl (g) NH4Cl (s)
Gas Colour Odour Effect on moist
litmus
Method of identification
3
Sulphur
dioxide
SO2
Colourless Choking
smell
Acidic ndash blue to
red
Turns acidified potassium
manganate (VII) solution from
purple to colourless
Turns acidified potassium
dichromate (VI) solution from
orange to green
Chlorine
Cl2
Yellow ndash
green
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Bromine
Br2
Red ndash
brown
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Nitrogen
dioxide
NO2
Red ndash
brown
Irritating
smell
Acidic blue to
red
Turns moist blue litmus red but
does not bleach it
Water
vapour
H2O
Colourless Odourless Neutral ndash no
effect
Turns anhydrous cobalt (II)
chloride from blue to pink
Turns anhydrous copper (II)
sulphate from white to blue
4
WEEK 11 LESSON 1 WORKSHEET
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless
Yellow ndash green
Red ndash brown
Gases according to their odour
Odour of gas Identity of gas
Odourless
Pungent smell
Choking smell
Irritating smell
5
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect
Red to blue
Blue to red
Blue to red then bleaches it
6
WEEK 11 LESSON 2
TOPIC Qualitative Analysis ndash Identification of anions
Effect of heating
Method Heat a sample of the solid in a dry test tube
Effect of heating
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) not
of K or Na
CO32- (s) O2- (s) + CO2 (g)
Oxygen evolved NO3- of K or Na 2 NO3
- (s) 2 NO2- (s) + O2
(g)
Oxygen and nitrogen
dioxide evolved
NO3- of Ca and below
in reactivity series
4 NO3- (s) 2 O2- (s) + 4 NO2
(g) + O2
(g)
Sulphur dioxide evolved SO32- SO3
2- O2- (s) + SO2 (g)
Effect of dilute acid
Add dilute hydrochloric acid or nitric acid to a sample of the solid Warm if no reaction occurs
when cold
Effect of dilute acid
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) CO32- (s) + 2 H+ (aq) H2O (l) + CO2 (g)
Sulphur dioxide evolved SO32- SO3
2- (s) + 2 H+ (aq) H2O (l) + SO2 (g)
7
Effect of concentrated acid
Add concentrated sulphuric acid to a sample of the solid Warm if not reaction occurs when cold
Effect of concentrated sulphuric acid
Observation Anion
Carbon dioxide evolved CO32- or HCO3
-
Sulphur dioxide evolved SO3-
Hydrogen chloride evolved Cl-
Hydrogen bromide (colourless) and bromine
vapour (brown) evolved
Br-
Black iodine present and purple iodine vapour
evolved
I-
8
WEEK 11 LESSON 2 WORKSHEET
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater
Produces a gas which relights a glowing splint as the only gas
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green
Produces a gas forms a precipitate in limewater
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia
Black iodine present and purple iodine vapour evolved
9
WEEK 11 LESSON 3
TOPIC Qualitative Analysis ndash Identification of anions
Test for the halides ndash using silver nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous silver nitrate and
observe the precipitate Add ammonia solution and observe the solubility of the precipitate
Test for halides using silver nitrate solution
Effect of silver
nitrate solution
Anion Explanation Effect of aqueous
ammonia
White precipitate ndash
turns white in
sunlight
Cl- Ag+ (aq) + Cl- AgCl (s) Precipitate soluble
Cream precipitate ndash
turns yellow ndash green
in sunlight
Br- Ag+ (aq) + Br- AgBr (s) Precipitate slightly
soluble
Pale yellow
precipitate
I- Ag+ (aq) + I- AgI (s) Precipitate insoluble
Test for the halides ndash using lead nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous lead nitrate and
observe the precipitate
Test for halides using lead nitrate solution
Effect of lead nitrate solution Anion Explanation
White precipitate Cl- Pb2+ (aq) + 2 Cl- PbCl2 (s)
Pale yellow Br- Pb2+ (aq) + 2 Br- PbBr2 (s)
Deep yellow I- Pb2+ (aq) + 2 I- PbI2 (s)
10
Effect of barium nitrate or chloride solution followed by dilute acid
Make a solution of the solid Add barium nitrate or chloride solution and observe the precipitate
Add dilute hydrochloric or nitric acid warn if necessary and observe the solubility of the
precipitate
Effect of barium nitrate or chloride solution followed by dilute acid
Effect of
Ba(NO3)2 (aq)
or BaCl2 (aq)
Effect of HCl (aq)
or HNO3 (aq)
Anion Explanation
White precipitate Precipitate insoluble SO42- Ba2+ (aq) + SO4
2- (aq) BaSO4 (s)
BaSO4 does not react with dilute acids
White precipitate Precipitate soluble ndash
CO2 evolved
CO32- Ba2+ (aq) + CO3
2- (aq) BaCO3 (s)
BaCO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + CO2 (g)
White precipitate Precipitate soluble ndash
SO2 evolved on
warming
SO32- Ba2+ (aq) + SO3
2- (aq) BaSO3 (s)
BaSO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + SO2 (g)
11
WEEK 11 LESSON 3 WORKSHEET
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
(Ionic equation required)
12
WEEK 12 LESSON 1 WORKSHEET
(a) The Caribbean islands are known for their many resources For example the ore of
aluminium is found in Jamaica and Guyana
(i) Briefly describe the extraction of aluminium from its named ore Include in your
description one ionic equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Although aluminium ore is mined in the Caribbean the extraction of aluminium usually
takes place in other countries Suggest ONE reason why it may be difficult to extract
aluminium in the Caribbean
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) An alloy can be described as a lsquomixed metal solutionrsquo Aluminium forms an alloy with
magnesium that is used to make an aircraft
13
Identify this alloy and suggest why it is better to use it rather than the pure metal in the
manufacture of aircraft
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) ldquoSome metals can be useful to man yet harmful to the environmentrdquo Comment on this
statement with reference to mercury
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 12 LESSON 2 Worksheet
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate formed
Soluble in excess
15
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate formed
Insoluble in excess
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate formed
(Ionic equation required)
16
WEEK 12 LESSON 3 Worksheet
Dry ammonia gas can be produced in a school laboratory
(a) Identify TWO reagents that are necessary for the laboratory production of ammonia
______________________________________________________________________________
______________________________________________________________________________
(b) Two common drying agents used in the laboratory are calcium oxide and concentrated
sulphuric acid However calcium oxide is the preferred choice for drying ammonia gas
Explain why concentrated sulphuric acid is now used Include in your answer a balanced
chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) When gases are prepared in the laboratory there are three main ways in which they can
be collected
- Upward delivery
- Downward delivery
- Displacement of water
(i) What TWO other factors should be considered when choosing an appropriate method for
the collection of gases in the laboratory
______________________________________________________________________________
______________________________________________________________________________
(ii) Identify ONE of the three methods that is best suited for the collection of ammonia gas in
the laboratory Explain why EACH of the other two methods would NOT have been
appropriate
______________________________________________________________________________
17
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(d) Hence draw a labelled diagram of the apparatus which could be used for the preparation
of dry ammonia in the laboratory
Be sure to identify in your diagram
- where the reagents are placed
- where the ammonia is dried and
- where the ammonia is collected
18
WEEK 13 LESSON 1 Worksheet
(a) In solution two metals A and B form A+ and B2+ ions respectively Metal A displaces Fe
from a solution containing Fe2+ ions but metal B does NOT
(i) Arrange the metals A B and Fe in order of reactivity from LEAST reactive to MOST
reactive Write a balanced chemical equation to show the reaction between metal A and
Fe2+ ions
______________________________________________________________________________
______________________________________________________________________________
(ii) Metal A is placed in a solution of copper (II) sulphate CuSO4 (aq) Write an equation for
the reaction State ONE observable change that will occur and explain why this reaction
takes place
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) For EACH metal A and B state ONE method that can be used to extract it from its
respective oxide Give a reason for EACH answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
19
______________________________________________________________________________
(b) Metal alloys are often used for making objects found in our daily lives Name an alloy of
iron and state ONE of its uses
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 13 LESSON 2 Worksheet
(a) Many important biological processes in plants and animals depend on the specific roles
of certain metal ions
(i) Farmer Jones reaped a crop of tomatoes and reported that the yield was far below what
was expected Analysis of the soil revealed that there was a deficiency of magnesium
Discuss the importance of magnesium in plant health and explain how a magnesium
deficiency can result in the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE other metal ion which is important to plant health and state the result of its
deficiency
______________________________________________________________________________
______________________________________________________________________________
21
(b) Many years ago car exhaust fumes were known to contain compounds of metals and
non ndash metals which could negatively impact both humans and the environment Identify
ONE metal and ONE non ndash metal whose compounds were present in car exhaust fumes
Discuss the effect of these compounds on human health and the environment
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) Define lsquogreen chemistryrsquo and discuss the measures that have been taken to produce a
lsquogreenerrsquo automotive fuel
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
22
WEEK 13 LESSON 3 Worksheet
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
Zn2+ ions are present
23
WEEK 14 LESSON 1 Worksheet
(a) Metal alloys are often used in place of metals because of their enhanced properties
(i) Define the term lsquoalloyrsquo
______________________________________________________________________________
______________________________________________________________________________
(ii) Name ONE alloy of aluminium and state its use based on one of its enhanced properties
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) A student conducted an experiment to investigate the reactivity of each of the following
metals (copper iron zinc and lead) by using solutionPs of their sulphate salts
The data presented in the table below shows whether a visible chemical reaction took
place when each metal was added to the four sulphate solutions
Key Visible chemical reaction took place
X No visible chemical reaction
CHEMICAL REACTION OF METALS IN SULPHATE SOLUTIONS
Sulphate solution Cu Fe Zn Pb
CuSO4 X
FeSO4 X X X
ZnSO4 X X X X
PbSO4 X X
24
(i) State which of the TWO metals is more reaction Fe or Zn Give a reason for our answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Using the data in the previous Table deduce the order of reactivity of the four metals Cu
Fe Zn and Pb from the most reactive to the least reactive metal
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The student recorded the following observations from the reaction between the iron and
copper (II) sulphate solution
Observations Reddish ndash brown solid coating formed on the iron strip
Blue colour of the solution changed to dirty green
Account for the observations made from the reaction between the iron and copper (II)
sulphate solution
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iv) Write an ionic equation including state symbols for the reaction between the iron and
copper (II) sulphate solution
______________________________________________________________________________
25
(c) Some metal compounds are health and environmental hazards
(i) Identify which of the metals used in the experiment in (b) is MOST hazardous to the
environment
______________________________________________________________________________
______________________________________________________________________________
(ii) State TWO harmful effects of continuous exposure to the metal identified in (c) (i) on
human beings
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
26
WEEK 14 LESSON 2 Worksheet
(a) Carbon is found in the form of diamond and graphite and is a main component in many
naturally occurring compounds such as organic matter and carbon dioxide gas
(i) State ONE way in which diamond differs physically from graphite
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE similarity between diamond and graphite other than they both contain carbon
______________________________________________________________________________
______________________________________________________________________________
(b) Carbon can react with a limited supply of oxygen to form carbon monoxide which can
negatively affect human health
(i) Write a balanced chemical equation including state symbols to show the formation of
carbon monoxide
______________________________________________________________________________
(ii) State TWO effects of carbon monoxide inhalation on the human body
______________________________________________________________________________
______________________________________________________________________________
(c) Jamal wants to prepare and collect a sample of carbon dioxide gas in the laboratory using
calcium carbonate
(i) Write a balanced chemical equation including state symbols for the laboratory
preparation of carbon dioxide gas from calcium carbonate
______________________________________________________________________________
______________________________________________________________________________
(ii) Draw a clearly labelled diagram to show the arrangement of the apparatus and materials
that could be used in the laboratory to prepare and collect the carbon dioxide gas
(iii) State ONE use of carbon dioxide as it relates to the beverage industry
______________________________________________________________________________
27
WEEK 14 LESSON 3 Worksheet
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
(Ionic equation required)
Suggest a possible identity of the solid R __________________________
28
WEEK 15 LESSON 1 Worksheet
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a small
portion of solid Y gently at
first and then strongly
Colourless gas evolved
with a choking odour
Turns acidified potassium
dichromate solution from
orange to green
(ii) To the remaining portion
of solid Y add 20 cm3 of
distilled water stir to dissolve
and filter Collect the filtrate
and divide into 3 equal
portions
Filtrate is pale green in
colour
(iii) To the first portion of the
filtrate from (ii) add aqueous
sodium hydroxide slowly
until in excess
A green precipitate
Insoluble in excess sodium
hydroxide
Ionic equation required
29
TEST OBSERVATIONS INFERENCES
(iv) To the second portion of
the filtrate from (ii) add
aqueous silver nitrate
followed by aqueous
ammonia
White precipitate
Soluble in aqueous
ammonia
(v) To the third portion of the
filtrate from (ii) add aqueous
barium nitrate followed by
aqueous hydrochloric acid
White precipitate formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with the
evolution of a colourless
gas with a choking smell
30
WEEK 15 LESSON 2 Worksheet
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
31
WEEK 15 LESSON 3 Worksheet
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in excess
aqueous NH3
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change
32
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
warm filter and then divide
the filtrate into two portions
Vigorous effervescence
observed upon addition of
dilute HNO3
Gas evolved turns lime water
cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Cu2+ ions present
33
ANSWERS TO WORKSHEETS
34
WEEK 11 LESSON 1 WORKSHEET ANSWERS
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless O2 H2 CO2 NH3 SO2 H2O
Yellow ndash green Cl2
Red ndash brown Br2 NO2
Gases according to their odour
Odour of gas Identity of gas
Odourless O2 H2 CO2 H2O
Pungent smell NH3
Choking smell SO2 Cl2 Br2
Irritating smell NO2
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect Neutral O2 H2 H2O
Red to blue Alkaline NH3
Blue to red Acidic CO2 SO2 NO2
Blue to red then bleaches it Acidic Cl2 Br2
35
WEEK 11 LESSON 2 WORKSHEET ANSWERS
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-) not
of K or Na
Produces a gas which relights a glowing splint as the only gas NO3- of K or Na
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green SO32-
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-)
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia Cl-
Black iodine present and purple iodine vapour evolved I-
36
WEEK 11 LESSON 3 WORKSHEET ANSWERS
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Br-
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
Cl-
Ag+ (aq) + Cl- AgCl (s)
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow Br-
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
SO42-
Ba2+ (aq) + SO42- (aq)
BaSO4 (s)
(Ionic equation required)
37
WEEK 12 LESSON 1 Worksheet Answers
(a) (i)
The ore bauxite is purified
The purified bauxite is dissolved in molten cryolite
The aluminium oxidecryolite solution is then eletrolysed
Equation at the cathode Al3+ (l) + 3 e- Al (l)
Equation at the anode 2 O2- (l) ndash 4 e- O2 (g)
(ii) The process is too expensive mainly because too much electricity or energy is needed
(b) The alloy of Al and Mg is magnalium It is less dense than the pure metals and hence allow
aircraft to be lighter It is also stronger than the pure metals and hence allows aircraft to last
longer since it is not easily destroyed
(c) Your answer should cater for the following aspects
Benefits of mercury to humans for example in thermometers barometers in dentistry
and gold mining
Entry of mercury to the environment For example this could have been through broken
thermometers barometers or lightbulbs or improper disposal of them or batteries and
indiscriminate use in gold mining in Guyana
The identification of a negative impact on the environment such as poisoned fish and the
persons who eat the fish death mood swings and psychosis
38
WEEK 12 LESSON 2 Worksheet Answers
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas
evolved
NO2 evolved OR nitrates
present OR
Br2 gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate
formed
Soluble in excess
Pb2+ Zn2+ Al3+ or Ca2+
present
Pb2+ Zn2+ Al3+ or present
39
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate
formed
Insoluble in excess
Pb2+ Zn2+ Al3+ or present
Pb2+ or Al3+ present
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate
formed
Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
40
WEEK 12 LESSON 3 Worksheet Answers
(a) an ammonium salt and a strong alkali
(b) Ammonia is basic and it will react with H2SO4
Equation 2 NH3 (aq) + H2SO4 (aq) (NH4)2SO4 (aq)
(c) (i) ndash Density of the gas relative to air ndash The solubility of the gas in water
(ii) Ammonia is collected by upward delivery
It cannot be collected by downward delivery since ammonia is less dense than air
It cannot be collected by displacement of water since it is soluble in water
(d)
41
WEEK 13 LESSON 1 Worksheet Answer
a) i) B ˂ Fe ˂ A
2A (s) + Fe 2+ (aq) rarr 2A+ (aq) + Fe (s)
ii) 2A (s) + CuSO4 (aq) rarr A2SO4 (aq) + Cu (s)
Observation blue colour fades gets lighter OR brown solid forms is deposited OR metal A
decreases in size dissolves
Explanation Metal A is higher (than Fe which is higher) than Cu in the reactivity series OR
Metal A is more reactive (than Fe which is more reactive) than Cu so Metal A can displace Cu
iii) Metal A can be extracted by electrolysis (of its molten oxide) because Metal A is a very
reactive metal is high in the reactivity series forms stable oxides needs a lot of energy to be
extracted and very reactive metals are extracted by electrolysis
Metal B can be extracted by heating with carbon carbon monoxide OR by chemical reduction
of the oxide because Metal B is less reactive than Fe is low in the reactivity series forms less
stable oxides does not need a lot of energy to be extracted and oxides of less reactive metals are
easily reduced
b) Alloy of iron steel
Use of alloy making buildings bridges ships motor vehicles furniture utensils
42
WEEK 13 LESSON 2 Worksheet Answer
(a) (i)
Magensium is the metal ion found in chlorophyll
Chlorophyll is essential for photosynthesis
A deficiency in magnesium will result in low chlorophyll yellow leaves and a reduction in
photosynthesis
Hence there will be low carbohydrates or energy production
Hence small fruits stunted growth and lower yield will result
(ii)
Metal ion Results of deficiency
Potassium Stunted growth premature loss of leaves yellowing of leaves curling of leaf tips
Calcium Growth abnormalities in tips of roots and shoots curling of leaves
Iron Yellowing of leaves
Zinc Low chlorophyll content yellowing of leaves
Manganese Yellowing of leaves poor flavors in some crops for example potato
(b)
Metal Lead is present in some types of gasoline Upon combustion lead compounds escape into
the atmosphere It accumulates in body tissues and slowly poisons the person It causes mental
illness
Non ndash metal SulphurSulphur dioxide or NitrogenNitrogen dioxide
Dissolves in rain water to form acid rain or cause respiratory illnessproblems Acid rain can
cause corrosion damage in buildings
(c)
Green chemistry is the utilisation of a set of principles that reduces or eliminates the use or
generation of hazardous substances
43
Automotive fuels are now produced without lead so as to eliminate the release of lead
compounds into the atmosphere
Low sulphur fuel is being produced with much reduced sulphur content which causes a reduction
of sulphur dioxide release into the atmosphere
44
WEEK 13 LESSON 3 Worksheet Answer
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
gas turns litmus blue
red
brown gas
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
white precipitate
precipitate soluble in
excess
Zn2+ ions are present
45
WEEK 14 LESSON 1 Worksheet Answers
(a)(i) An alloy is a material made from a mixture of two or more metals
(ii) Any suitable answer chosen from below
Alloy Enhance Property Use
Duralumin High strength
Low density
Light
Hard
Used to make aircraft bodies
space satellites
Magnalium Light
Hard
Easier to weld
Corrosion resistant
Strong
High ductability
Used in pyrotechnics
(fireworks)
Mirrors
Aircraft parts
To make scientific
instruments
Used to make marine castings
Alchlad Strong
Corrosion resistant
Cladding for buildings
(b) (i) Zinc is more reactive than iron
Zinc displaces iron from iron (II) sulphate
Zinc is higher in the reactivity series than iron
Iron does not displace zinc from zinc sulphate
(ii) Order of reactivity Zn gt Fe gt Pb gt Cu
(iii) Reddish brown solid ndash copper metal formed
46
Dirty green solution ndash presence of Fe2+ ion
(iv) Fe (s) + Cu2+ (aq) Fe2+ (aq) + Cu (s)
(c) (i) Lead
(ii) Any two correct harmful effects of lead on the body
Impedes brain development (in young children)
Affectimpede development of the immune system in humans
Affecthamper development of nervous system in humans
Long term exposure can result in kidney and liver damage
Mental retardation
Anaemia
Death
47
WEEK 14 LESSON 2 Worksheet Answers
a) i) Diamond is transparent clear Graphite is opaque black
OR hard OR brittle
OR does not conduct electricity OR conducts electricity
a) ii) Both have a macromolecular giant molecular giant covalent structure (lattice)
OR Both have high melting point boiling point
OR Both are insoluble in water organic solvent
b) i) 2C (s) + O2 (g) rarr 2CO (g)
ii) CO reduction in amount of oxygen carried by (the haemoglobin in the red blood
cells of) the blood
Headache OR dizziness OR nausea OR fatigue OR loss of consciousness OR
death
c) i) CaCO3 (s) + 2HCl (aq) rarr CaCl2 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) + H2SO4 (aq) rarr CaSO4 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) rarr CaO (s) + CO2 (g)
48
ii)
OR
OR
Entirely closed system thistle funnel below the level of the liquid OR tap that could be
closed
Two reagents labelled CaCO3marble chips and HCl H2SO4 or heat source
collection of CO2 upward displacement of air OR over watersulphuric acid OR in gas
syringe
iii) CO2 use put in aerated drinks carbonated beverages
OR put in carbon dioxide fire extinguishers
49
WEEK 14 LESSON 3 Worksheet Answers
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
NH4+
NH4+ confirmed OR
NH3 (g) produced
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
Cl- ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation required)
Suggest a possible identity of the solid R NH4Cl (ammonium chloride)
50
WEEK 15 LESSON 1 Worksheet Answers
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a
small portion of solid Y
gently at first and then
strongly
Colourless gas
evolved with a
choking odour
Turns acidified
potassium dichromate
solution from orange
to green
SO2 evolved
Presence of a sulphite
(ii) To the remaining
portion of solid Y add 20
cm3 of distilled water stir
to dissolve and filter
Collect the filtrate and
divide into 3 equal portions
Filtrate is pale green
in colour
Fe2+ ions present
(iii) To the first portion of
the filtrate from (ii) add
aqueous sodium hydroxide
slowly until in excess
A green precipitate
Insoluble in excess
sodium hydroxide
Fe2+ ions present
Fe2+ (aq) + 2 OH- (aq) Fe(OH)2 (s)
Ionic equation required
TEST OBSERVATIONS INFERENCES
(iv) To the second portion
of the filtrate from (ii) add
aqueous silver nitrate
White precipitate
Soluble in aqueous
ammonia
Cl- ions present
51
followed by aqueous
ammonia
(v) To the third portion of
the filtrate from (ii) add
aqueous barium nitrate
followed by aqueous
hydrochloric acid
White precipitate
formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with
the evolution of a
colourless gas with a
choking smell
SO32- CO3
2- SO42- ions present
SO32- ions present
52
WEEK 15 LESSON 2 Worksheet Answers
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
Chloride ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
Cu2+ ions present
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
X contains a reducing agent
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
SO32- SO4
2- or CO32- ions are
present
SO32- ions are present
53
WEEK 15 LESSON 3 Worksheet Answers
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
White ppt
Ppt soluble in excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in
excess aqueous NH3
Al3+ Pb2+ Zn2+ present
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change Cl- Br- I- absent
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
Vigorous effervescence
observed upon addition of
dilute HNO3
CO2 evolved OR
Carbonate present
54
warm filter and then divide
the filtrate into two portions
Gas evolved turns lime
water cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
Cu2+ (aq) + OH- (aq)
Cu(OH)2 (s)
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Blue ppt
ppt dissolves in excess
NH3 to give a deep blue
solution
Cu2+ ions present
55
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
REFERENCES
Hunte-King J Maragh P Nagir F amp Norris R (2013) Chemistry for CSEC United
Kingdom Nelson Thornes Ltd
Remy C Mason L Lambert N amp Mohammed M (2007) Chemistry for CSEC England and
Wales Pearson Education Limited
Taylor M amp Chung-Harris T (2010) CXC Chemistry England Macmillan Publishers
Limited
Tindale A (2016) Chemistry A Concise Revision for CXC London HarperCollins Publishers
Limited
12
WEEK 2 LESSON 1
TOPIC Chemical properties of metals
Action of water
Metals high in the electrochemical series react with cold water to produce the metal hydroxide
and hydrogen
Reactive metals slightly lower in the electrochemical series react very slowly or not at all with
water However they may react with hot water or steam to produce the corresponding metal
oxide and hydrogen
Metals lower than hydrogen in the electrochemical series do not react with water
Metal Reaction with water or steam
Potassium K React with cold water forming metal hydroxide and hydrogen
eg Ca (s) + 2 H2O (l) Ca(OH))2 (aq) + H2 (g) Sodium Na
Calcium Ca
Magnesium Mg React with steam forming metal oxide and hydrogen
eg Zn (s) + H2O (g) ZnO (s) + H2 (g) Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
13
WEEK 2 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with water (or
steam if reaction does not occur with water)
Potassium + WaterSteam
______________________________________________________________________________
Sodium + WaterSteam
______________________________________________________________________________
Calcium + WaterSteam
______________________________________________________________________________
Magnesium + WaterSteam
______________________________________________________________________________
Aluminium + WaterSteam
______________________________________________________________________________
Zinc + WaterSteam
______________________________________________________________________________
14
Iron + WaterSteam
______________________________________________________________________________
Copper + WaterSteam
______________________________________________________________________________
Silver + WaterSteam
______________________________________________________________________________
15
WEEK 2 LESSON 2
TOPIC Chemical properties of metals
Action of dilute acids
Metals above hydrogen in the electrochemical series react with dilute acids to form a salt and
hydrogen gas They react with hydrochloric acid to form the metal chloride (a salt) and hydrogen
gas They also react with dilute suphuric acid to form the metal sulphate (a salt) and hydrogen
gas
Metal Reaction dilute hydrochloric or sulphuric acid
Potassium K Violent reaction forming a salt and hydrogen gas
eg 2 Na (s) + 2 HCl (aq) 2 NaCl (aq) + H2 (g) Sodium Na
Calcium Ca Vigorous reaction forming a salt and hydrogen gas
eg Mg (s) + 2 HCl (aq) MgCl2 (aq) + H2 (g) Magnesium Mg
Aluminium Al React forming a salt and hydrogen gas
eg Fe (s) + 2 HCl (aq) FeCl2 (aq) + H2 (g) Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
16
WEEK 2 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with
hydrochloric acid
Metal Balanced equation for reaction with hydrochloric acid
Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Copper
Silver
17
WEEK 2 LESSON 3
TOPIC Reactions of metal compounds
Reactions of metallic oxides with dilute acid
Metal oxides react with dilute hydrochloric acid or sulphuric acid to produce a salt and water
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
Some of these reactions may be slow and can be speeded up by adding heat
For example
zinc oxide + hydrochloric acid zinc chloride + water
ZnO (s) + 2 HCl (aq) ZnCl2 (aq) + H2O (l)
magnesium oxide + hydrochloric acid magnesium chloride + water
MgO (s) + 2 HCl (aq) MgCl2 (aq) + H2O (l)
aluminium oxide + sulphuric acid aluminium sulphate + water
Al2O3 3 H2SO4 (aq) Al2(SO4)3 (aq) + 3 H2O (l)
calcium oxide + sulphuric acid calcium sulphate + water
CaO H2SO4 (aq) CaSO4 (aq) + H2O (l)
18
WEEK 2 LESSON 3 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal oxides with the
corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium oxide Hydrochloric acid
Sodium oxide Sulphuric acid
Calcium oxide Hydrochloric acid
Magnesium oxide Sulphuric acid
Aluminium oxide Hydrochloric acid
Zinc oxide Sulphuric acid
19
WEEK 3 LESSON 1
TOPIC Reactions of metal compounds
Reactions of metallic hydroxides with dilute acid
Metal hydroxides react with dilute acids to form a salt and water in a neutralisation reaction
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
For example
magnesium hydroxide + hydrochloric acid magnesium chloride + water
Mg(OH)2 (aq) + 2 HCl (aq) MgCl2 (aq) + 2 H2O (l)
sodium hydroxide + hydrochloric acid sodium chloride + water
NaOH (aq) + HCl (aq) NaCl (aq) + H2O (l)
potassium hydroxide + sulphuric acid potassium sulphate + water
2 KOH + H2SO4 (aq) K2SO4 (aq) + 2 H2O (l)
calcium hydroxide + sulphuric acid calcium sulphate + water
Ca(OH)2 (aq) + H2SO4 (aq) CaSO4 (aq) + 2 H2O (l)
20
WEEK 3 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal hydroxides with
the corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium hydroxide Hydrochloric acid
Sodium hydroxide Sulphuric acid
Calcium hydroxide Hydrochloric acid
Magnesium hydroxide Sulphuric acid
Aluminium hydroxide Hydrochloric acid
Zinc hydroxide Sulphuric acid
21
WEEK 3 LESSON 2
TOPIC Reactions of metal compounds
Reactions of metallic carbonates with dilute acid
Metal carbonates react with dilute acid to form a salt carbon dioxide and water When
hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric acid is
used the corresponding sulphate salt is formed
For example
sodium carbonate + hydrochloric acid sodium chloride + carbon dioxide + water
Na2CO3 (s) + 2 HCl (aq) 2 NaCl (aq) + CO2 (g) + H2O (aq)
calcium carbonate + hydrochloric acid calcium chloride + carbon dioxide + water
CaCO3 (s) + 2 HCl (aq) CaCl2 (aq) + CO2 (g) + H2O (aq)
zinc carbonate + sulphuric acid zinc sulphate + carbon dioxide + water
ZnCO3 (s) + H2SO4 (aq) ZnSO4 (aq) CO2 (g) + H2O (aq)
potassium carbonate + sulphuric acid potassium sulphate + carbon dioxide + water
K2CO3 (s) H2SO4 (aq) K2SO4 (aq) CO2 (g) + 2 H2O (aq)
22
WEEK 3 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal carbonates with
the corresponding acid
Metallic
carbonate
Acid Balanced chemical equation
Potassium
carbonate
Hydrochloric
acid
Sodium
carbonate
Sulphuric acid
Zinc
carbonate
Hydrochloric
acid
Magnesium
carbonate
Sulphuric acid
Aluminium
carbonate
Hydrochloric
acid
Calcium
carbonate
Sulphuric acid
23
WEEK 3 LESSON 3
TOPIC Action of heat on metal compounds
Action of heat on nitrates
All nitrates decompose when heated The reactivity of the metal in the metal nitrate influences
the products of the decomposition
The nitrates of the alkali metals (Group I) with the exception of lithium nitrate decompose to
form the metal nitrite and oxygen
The nitrates of most other metals decompose to form the metal oxide nitrogen dioxide and
oxygen
The nitrates of the very unreactive metals decompose to form the meal nitrogen dioxide and
oxygen
Metal Nitrate Decomposition
Potassium K Products metal nitrite + oxygen
eg 2 NaNO3 (s) Heatrarr 2 NaNO2 (s) + O2 (g)
Sodium Na
Calcium Ca
Products metal oxide + nitrogen dioxide + oxygen
eg 2 Pb(NO3)2 (s)
Heatrarr 2 PbO (s) + 4 NO2 (g) + O2 (g)
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Products metal + nitrogen dioxide + oxygen
eg 2 AgNO3 (s) Heatrarr 2 Ag (s) + 2 NO2 (g) + O2 (g)
24
WEEK 3 LESSON 3 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
nitrates
Metal Balanced chemical equation
Potassium nitrate
Sodium nitrate
Calcium nitrate
Magnesium nitrate
Aluminium nitrate
Zinc nitrate
Lead nitrate
Copper nitrate
Silver nitrate
25
WEEK 4 LESSON 1
TOPIC Action of heat on metal compounds
Action of heat on carbonates
Upon application of heat many carbonates decompose to form the metal oxide and carbon
dioxide
Group I carbonates do not decompose on heating with the exception of lithium carbonate
Metal Carbonate decomposition
Potassium K
Stable not decomposed by heat Sodium Na
Calcium Ca
Decompose forming metal oxide and carbon dioxide
eg CaCO3 (s) Heatrarr CaO (s) + CO2 (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Unstable
26
WEEK 4 LESSON 1 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
carbonates
Metal Balanced chemical equation
Potassium carbonate
Sodium carbonate
Calcium carbonate
Magnesium carbonate
Aluminium carbonate
Zinc carbonate
Iron carbonate
Lead carbonate
Copper carbonate
27
WEEK 4 LESSON 2
TOPIC Action of heat on metal compounds
Action of heat on the metal hydroxides
Most metal hydroxides decompose on heating A metal oxide and water are formed
Group I hydroxides do not decompose on heating with the exception of lithium hydroxide
Metal Hydroxide decomposition
Potassium K Stable not decomposed by heat
Sodium Na
Calcium Ca Decompose forming metal oxide and water (as steam)
eg Zn(OH)2 (s) Heatrarr ZnO (s) + H2O (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag No hydroxide exist
28
WEEK 4 LESSON 2 WORKSHEET
Write the balanced chemical equations for the thermal decomposition of the following
metal hydroxides
Metal hydroxide Balanced chemical equation
Potassium hydroxide
Sodium hydroxide
Calcium hydroxide
Magnesium hydroxide
Aluminium hydroxide
Zinc hydroxide
Lead hydroxide
Copper hydroxide
29
WEEK 4 LESSON 3
TOPIC Reactivity of metals ndash The Reactivity Series
The reactivity series of metals is a list of metals arranged in order of their reactivity based on
Displacement reactions
Reactions with oxygen dilute acids and water
Relative ease of decomposition of their compounds
Metals at the top of the series are the most electropositive They lose electrons very easily and
readily form cations These ions are very stable and are not easily discharged to form atoms Due
to this fact they are the most reactive metals
Metals at the bottom of the series are the least electropositive They do not lose electrons easily
and do not readily form ions Their ions are very unstable and are easily discharged to form
atoms They are the least reactive metals
The reactivity series of metals
Mnemonic Metal Symbol Reactivity
People Potassium K Most reactive
Least reactive
Sometimes Sodium Na
Collect Calcium Ca
Magazines Magnesium Mg
About Aluminium Al
Zoos Zinc Zn
In Iron Fe
London Lead Pb
Having (Hydrogen) H
Cute Copper Cu
Monkeys and Mercury Hg
Small Silver Ag
Gorillas Gold Au
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
5 Reactivity of metals Reactivity of metals Reactivity of metals
6 Extraction of metals Extraction of metals Alloys
7 Corrosion Importance of metals
and their compounds
on living systems and
environment
Chemical properties
of non ndash metals
8 Laboratory
preparation of gases
Laboratory
preparation of gases
Laboratory
preparation of gases
9 Uses of gases Uses of non ndash metals
and their compounds
Harmful effects of
non ndash metals and
their compounds on
living systems and
the environment
10 Green Chemistry Qualitative Analysis
ndash Identification of
cations
Qualitative Analysis
ndash Identification of
cations
2
WEEK 5 LESSON 1
TOPIC Reactivity of metals
Reactivity based on displacement reactions between metals and metal ions
A metal will displace a metal which is lower than itself in the reactivity series from a solution of
the metal salt
Reaction of zinc and copper (II) sulphate
Expected observations
Explanation
The size of the zinc metal decreases
The zinc metal is reacting and forming the
salt zinc sulphate
The solution becomes lighter eventually
colourless
The Cu2+ (aq) ions (responsible for the blue
colour) is reduced to Cu (s)
A brown solid is deposited at the bottom of
the container
Copper metal is formed
Equation Zn (s) + CuSO4 (aq) ZnSO4 (aq) + Cu (s)
Ionic equation
Zn (s) + Cu2+ (aq) Zn2+ (aq) + Cu (s)
Zinc is higher in the reactivity series than copper Therefore it will displace the copper ions in
the reaction above
3
Examples of other displacement reactions
Magnesium will displace Zn2+ ions in zinc sulphate since it is higher in the series than zinc
Mg (s) + Zn2+(aq) Mg2+ (aq) + Zn (s)
Silver will not displace Cu2+ ions in copper (II) sulphate [Cu is higher in the series than Ag]
Using the information above we can arrange the metals in order of their reactivity with
magnesium being the most reactive and silver the least reactive metal among the four metals
Mg gt Zn gt Cu gt Ag
Reactivity based on reaction with oxygen
The reactivity of metals can also be deduced from their reaction with oxygen
The table below gives the observations for the reaction with oxygen with the selected metals
Reaction of metal with oxygen
Metal Observation
Copper The surface turns black upon heating
Magnesium Ribbon burns very rapidly
Sodium Burns vigorously
Gold No reaction
Based on the observations for the 4 metals the metal with highest reactivity is sodium and the
metal with the least reactivity is gold
The 4 metals can be arranged in terms of reactivity as follows
Na gt Mg gt Cu gt Au
4
WEEK 5 LESSON 1 WORKSHEET
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
5
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
6
WEEK 5 LESSON 2
TOPIC Reactivity of metals
Reactivity based on reactivity with acids
The metals that are higher than hydrogen in the electrochemical series react with non ndash oxidizing
acids to produce a salt and hydrogen gas
By using the same concentration of acid and same mass and size of the metals the order of
reactivity of the metals can be deduced
The table below shows the results for an experiment with the reaction of the named metals and
1 mol dm-3 hydrochloric acid
Reaction of metals with acid
Metal Observations
Silver No reaction
Magnesium Bubbles produced steadily
Calcium Bubbles produced very rapidly
Iron Bubbles produced slowly
Based on the above data the most reactive metal will be calcium with the least reactive being
silver The order of reactivity will be Ca gt Mg gt Fe gt Ag
By comparing this to the electrochemical series it can be seen that the reactivity of the metals
decrease as we go down the series
7
WEEK 5 LESSON 2 WORKSHEET
1 Place a next to the metals that will react with dilute acid and an X next to the metals
that will not react with dilute acid
Metal Reactivity with acid
Copper
Magnesium
Aluminium
Silver
Zinc
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
8
WEEK 5 LESSON 3
TOPIC Reactivity of metals
Reactivity based on ease of decomposition of the metal nitrates carbonates oxides and
hydroxides
The more reactive a metal the more difficult it is to decompose its nitrate carbonate oxide or
hydroxide on heating
For example Decomposition of carbonates
Procedure
1 Put a large spatula measure of the carbonate to be tested in a test tube
2 Fit a delivery tube and then clamp the test tube so that the delivery tube dips into a second test
tube containing 2ndash3 cm3 limewater
3 Heat the solid gently at first then more strongly
4 Lift the delivery tube from the limewater before or as soon as the heating is stopped This is to
avoid suck-back
5 Write down all observations Notice what happens to the limewater and how long it takes to turn
milky (if at all) Notice whether any melting occurs in the heated test tube and any colour
changes taking place Write your results in tabular form
6 Repeat the experiment with the other metal carbonates supplied and in each case write down
your observations
7 Wash your hands thoroughly at the end of these experiments since some of the metal carbonates
are toxic
9
Results
Metal Formula Gas evolved Ease of decomposition
Zinc ZnCO3 Carbon dioxide Fairly easy
Copper CuCO3 Carbon dioxide Easy
Sodium Na2CO3 None Very difficult
Using the results of the above activity the reactivity of the metals can be determined
Ease of decomposition Copper gt Zinc gt Sodium
The order of reactivity is the opposite for the ease of decomposition
Order of reactivity Sodium (most reactive) gt Zinc gt Copper (least reactive)
10
WEEK 5 LESSON 3 WORKSHEET
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
11
WEEK 6 LESSON 1
TOPIC Extraction of metals
Elements exist all over the earth Some are found as free elements eg copper silver and gold
Others are found combined with other elements in compounds To get the elements the
compounds have to be broken up These compounds are generally called ores the most
convenient sources of which are rocks sea and air
The extraction of a metal from its ore is a reduction process where the metals ions gain electrons
to form atoms
The general equation is Mn+ + n e- M
The choice of the extraction method depends on the position of the metal in the reactivity series
As we go down the series the metals become more stable and the metal ions (in the ores)
become less stable
The very reactive metals that are high in the series K Na Ca Mg Al have very stable ores
Therefore they require a powerful method of reduction namely electrolysis During the process
the cathode provides the electrons and acts as the reducing agent
The metals in the middle of the series (Zn Fe Pb) do not have stable ores and can be extracted
by reduction with carbon in the case of zinc and with carbon monoxide in the case of iron and
lead
Metals low in the reactivity series if present as ores can be extracted simply by heating the ores
in air at high temperatures
12
Extraction of Aluminium from purified bauxite
Pure bauxite is pure alumina (Al2O3) Aluminium is obtained from bauxite by electrolysis
Aluminium oxide has a very high melting point approximately 2050 0C so it is first dissolved in
molten cryolite (Na2AlF6) The addition of cryolite lowers the melting point to approximately
900 0C
The electrolyte is a molten mixture of alumina and molten cryolite The cathode is the graphite
lining of the cell The anodes are blocks of graphite or titanium alloys
Reaction at the cathode
Al3+ (l) + 3 e- Al (l)
Reaction at the anode
2 O2- (l) ndash 4 e- O2 (g)
Aluminium (melting point 660 0C) is a liquid at the temperature at which electrolysis is carried
out and is collected at the bottom of the cell and tapped off Oxygen gas which is given off in the
main cathode reaction together with the heat causes the anodes to burn away The anodes have
to be replaced from time to time The use of anodes from titanium alloys reduce the number of
times that the anodes have to be replaced
13
WEEK 6 LESSON 1 Worksheet
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 6 LESSON 2
TOPIC Extraction of metals
Extraction of Iron
The traditional method of production of iron is by reduction of haematite by carbon monoxide in
a blast furnace
Ores Haematite ndash Fe2O3 Magnetite ndash Fe3O4 Siderite ndash FeCO3 Magnetite and Siderite are
converted to Haematite
A mixture of haematite limestone (CaCO3) and coke (C) called the charge is placed into the top
of the furnace
Hot air is blown into the bottom of the furnace
Coke burns in air forming carbon dioxide
C (s) + O2(g) CO2 (g) ΔH -ve
The heat produced keeps the temperature at about 1900 0C
The carbon dioxide is reduced to carbon monoxide by the hot coke
CO2 (g) + C (s) 2 CO(g) Δ +ve
Heat absorbed reduces the temperature to about 1100 0C
The carbon monoxide reduces the hot iron ore to molten iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + 3 CO2(g)
The temperature at this part of the furnace is about 700 0C The iron runs to the bottom of the
furnace
The impurities are removed by the addition of limestone (CaCO3) The limestone at the
temperature of the furnace breaks down
CaCO3 (s) CaO (s) + CO2 (g)
15
The calcium oxide formed combines with silicon dioxide (sand) the main impurity in the iron
ore to form molten slag
CaO (s) + SiO2 (s) CaSiO3 (l)
The slag does not mix with the molten iron but floats on it The molten iron and slag are run off
separately
The iron formed in a blast furnace is an impure form of the metal Because the molten metal is
allowed to solidify in shallow trays known as casts the iron is called lsquocast ironrsquo or lsquopigrsquo iron
Cast iron is quite brittle and contains 2 - 4 carbon and other impurities Most of the cast iron is
converted to steel
A blast furnace used for extracting iron
16
WEEK 6 LESSON 2 Worksheet
(a) What are the three raw materials that are added through the top of the blast furnace
during the extraction process for iron
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______________________________________________________________________________
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
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17
WEEK 6 LESSON 3
TOPIC Alloys
An alloy is a mixture of two or more metals Alloys are made by melting the individual metals
mixing them and allowing the molten mixture to solidify
In general alloys are harder stronger and more resistant to corrosion than the actual metals they
are made up from
Alloy Use Properties
ALUMINIUM
-Duralumin
(AlMgCu)
-Magnalium (AlMg)
Alloys used in the
construction of
aircraft and ships
buses
Aluminium is used in
making cooking
utensils electrical
cables paint for fuel
storage tanks bottle
caps foil and utensils
for handling nitric
acid
The alloys have a low
density They are as
light as aluminium
and more resistant to
corrosion than
aluminium
LEAD
-Solder (PbSn)
Alloy is used in
joining metals
(soldering)
Lead is used in
underground cables
plates in
The alloy has a lower
melting point than
lead and is harder
than lead
18
Alloy Use Properties
accumulators shield
against x ndash rays
IRON
- Stainless Steel
(FeCONiC)
-Tungsten steel
(FeWC)
-Invar steel (FeNi)
Manganese steel
(FeMnC)
Iron is the main metal
of a variety of
constructions
Steel is used in
cutlery rock drills
electromagnets
vehicle body and
engine parts fences
pipes etc
Steel resists
corrosion is usually
harder than iron and
may be tough though
malleable and ductile
19
WEEK 6 LESSON 3 Worksheet
(a) Define the term alloy
______________________________________________________________________________
(b) State 3 general advantages that alloys have over the individual metals they are made
from
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______________________________________________________________________________
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
______________________________________________________________________________
______________________________________________________________________________
Uses
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 7 LESSON 1
TOPIC Corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
Familiar examples of corrosion are
- the formation of a green powder on copper sheeting
- the eating away of iron (rusting)
- the development by aluminum of a thin compact layer of oxide which protects the
underlying metal from further corrosion
When corrosion occurs in water ndash free environment it is called dry oxidation When it occurs in
aerated aqueous environments it is called wet corrosion Wet corrosion is the most common and
troublesome form of corrosion
The most familiar corrosion is the rusting of iron and steel On exposure to the atmosphere iron
and steel corrode to form rust which is hydrated iron (III) oxide Fe2O3xH2O Iron and steel
corrode easily and the rust formed flakes off easily thus exposing fresh surface for attack
When iron rust it loses electrons
Fe (s) ndash 2e- Fe 2+ (aq)
The iron (II) ions pass into solution and then combine with the hydroxyl (OH-) ions in the
aerated aqueous environment to form iron (II) hydroxide The oxygen present oxidises the iron
(II) hydroxide to hydrated iron (III) oxide or rust
Fe(OH)2 + O2 Fe2O3xH2O
21
Methods of preventing rusting
1 Coating the object with paint grease plastic or rubber which prevent contact with air or
water
2 Galvanising ndash coating the object with zinc The zinc forms an adherent oxide layer which
protects against further corrosion If damaged the zinc is oxidized in preference to the
iron since it is higher in the electrochemical series
3 Coating with tin lsquoTinrsquo cans are made of steel plated with tin However if scratched
rusting occurs since iron is more reactive than tin
4 Attaching a sacrificial anode to the object A piece of metal higher in the electrochemical
series such as magnesium is attached The magnesium will be oxidized in preference
since it is higher in the electrochemical series than iron
22
WEEK 7 LESSON 1 WORKSHEET
(a) Define the term corrosion
______________________________________________________________________________
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
23
WEEK 7 LESSON 2
TOPIC Importance of metals and their compounds on living systems and environment
Some metals are an integral part of different structures of living things
Metal Presence and Function
Potassium Main cation in fluid or animal cells essential for healthy plant growth
Calcium Necessary for strong bones teeth and shells needed by some enzymes Present
in dairy produce eggs nuts and cereals
Magnesium Central atom of chlorophyll needed for some enzyme action Involved in energy
and calcium metabolism
Zinc Present in many enzymes Needed for protein metabolism Essential for growth
of animals
Iron Present in haemoglobin Needed for protein metabolism Essential for growth of
animals
Chromium Needed for glucose uptake by cells and thus linked to the action of insulin
Manganese Needed for bone development and amino acid metabolism Present in several
enzymes Needed for plant growth
Cobalt Present in Vitamin B12 Needed for plant growth
Copper Involved in formation of haemoglobin and melanin Present in enzymes
controlling oxidation Needed for plant growth
24
Harmful effects of metals and their compounds to living systems and the environment
There are some metals and metal compounds which may cause harm to living systems and the
environment
Lead
Lead is a heavy metal poison that is widely encountered It may occur in food beverages paint
water formed from ndash sealed pipes in air polluted by combustion by fuels containing lead
compounds Lead is also used in some car batteries If these are paints or batteries are not
disposed of correctly lead may get into groundwater or air Lead and lead compounds harm the
nervous system including the brain especially young children
Arsenic
Arsenic compounds are poisonous They can get into the groundwater from mining waste and
from disposal of some electrical components
Cadmium
Cadmium compounds are poisonous They can get into the ground by improper disposal of
nickel ndash cadmium batteries Persons can get cadmium poisoning if they eat food grown in
contaminated soil
Mercury
Mercury can be spilled from broken thermometers in hospitals and laboratories Mercury and its
compounds are particularly poisonous to fish and it can accumulate in the food chain and
eventually poison humans
Problems of disposal of solid waste
Metals may react with water andor air and corrode to form soluble compounds that are
poisonous These toxic compounds diffuse into the soil and eventually enter rivers
Rust from iron may form unsightly pools of waste that reduce plant growth
Waste from aluminium extraction may react with water and form flammable gases
25
WEEK 7 LESSON 2 WORKSHEET
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Lead
______________________________________________________________________________
Mercury
______________________________________________________________________________
26
WEEK 7 LESSON 3
TOPIC Chemical properties of non ndash metals
Reaction with oxygen
Many non ndash metals burn in excess oxygen or air to form oxides For example
S (s) + O2 (g) SO2 (g)
C (s) + O2 (g) CO2 (g)
Reactions with metals
Some non ndash metals react with metals high in the electrochemical series when heated
For example
Sodium burns in chlorine to form sodium chloride
Na (s) + Cl2 (g) NaCl (s)
Magnesium burns in oxygen to form magnesium oxide
Mg (s) + O2 (g) MgO (s)
When heated iron combines with molten sulphur to form iron (II) sulphide
Fe (s) + S (l) FeS (s)
When heated reactive metals such as sodium and aluminium react with hydrogen to form metal
hydrides
2 Na (s) + H2 (g) 2 NaH (s)
Oxidising and Reducing properties
Hydrogen and Carbon are very good reducing agents
At high temperatures hydrogen reduces metal oxides below zinc in the electrochemical series to
form the metal For example PbO (s) + H2 (g) Pb (s) + H2O (g)
Under suitable conditions hydrogen reduces nitrogen to ammonia
N2(g) + 3 H2 (g) 2 NH3 (g)
27
At high temperatures carbon reduces metal oxides below aluminium in the reactivity series to
the metal For example
ZnO (s) + C (s) Zn (s) + CO (g)
Oxygen and Chlorine are very good oxidizing agents
Oxygen oxidized most metals to form metal oxides and some non ndash metals to non ndash metal oxides
For example
2 Mg (s) + O2(g) 2 MgO (s)
4 P (s) + 5 O2 (g) P4O10 (s)
Chlorine acts as an oxidizing agent either as a gas or as an aqueous solution For example
H2 (g) + Cl2 (g) 2 HCl (g)
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
28
WEEK 7 LESSON 3 WORKSHEET
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
______________________________________________________________________________
(b) Write the ionic equation for the above reaction
______________________________________________________________________________
(c) Identify the oxidising agent in the reaction
______________________________________________________________________________
(d) Justify your answer in part (c) in terms of oxidation number
______________________________________________________________________________
29
WEEK 8 LESSON 1
TOPIC Laboratory preparation of gases
Preparation of oxygen
Oxygen can be prepared by the decomposition of hydrogen peroxide potassium chlorate (V) or
potassium nitrate The safest method is the decomposition of hydrogen peroxide
Manganese (IV) oxide catalyses the decomposition of hydrogen peroxide
Silica gel anhydrous calcium chloride or concentrated sulphuric acid can be used as a drying
agent
The gas is collected by downward delivery since it is slightly denser than air
Equation
2 H2O2 (aq) 2 H2O (l) + O2 (g)
Apparatus used for laboratory preparation of oxygen
30
WEEK 8 LESSON 1 WORKSHEET
Describe the laboratory preparation of oxygen gas
In your answer include
The starting material
A suitable catalyst
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
31
WEEK 8 LESSON 2
TOPIC Laboratory preparation of gases
Preparation of carbon dioxide
Carbon dioxide can be prepared by the action of dilute acid on carbonates Marble chips (calcium
carbonate) and dilute hydrochloric acid are the common reagents The gas is collected by
downward delivery since it is denser than air
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
Apparatus used for laboratory preparation of carbon dioxide
32
WEEK 8 LESSON 2 WORKSHEET
Describe the laboratory preparation of carbon dioxide gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
33
WEEK 8 LESSON 3
TOPIC Laboratory preparation of gases
Preparation of ammonia
Ammonia may be prepared by heating a mixture of ammonium salt and a hydroxide The
ammonia gas is collected by upward delivery since it is less dense than air
For example
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
Calcium oxide is the only suitable drying agent since ammonia reacts with conc H2SO4 and
CaCl2
Apparatus used for laboratory preparation of dry ammonia
34
11
WEEK 8 LESSON 3 WORKSHEET
Describe the laboratory preparation of ammonia gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
35
WEEK 9 LESSON 1
TOPIC Uses of gases
Carbon dioxide
Used in fire extinguishers to put out fires Carbon dioxide is denser than air and lsquoblanketsrsquo the
fire preventing oxygen from reaching it Carbon dioxide extinguishers are especially useful for
dealing with fires involving flammable liquids and electrical equipment
Carbonation in soda is created when carbon dioxide is pumped into the soda can or bottle then
held under pressure As long as the can or bottle is sealed the carbon dioxide remains mostly
stable However if the drink gets shaken up or the top is opened the tiny carbon dioxide bubbles
react by bursting
Oxygen
Oxygen is needed for aerobic respiration We need a constant supply of oxygen for this process
Oxygen is used in hospitals to improve the respiration of patients with poor blood flow blood
poisoning and heart disease
Oxygen in used in welding (joining) metals In an oxyacetylene welding torch acetylene or
ethyne (C2H2) burns in oxygen and produces a very hot flame This flame is capable of melting
most metals
Oxygen is used in steel production A blast of oxygen is blown through the molten iron The
oxygen oxidises many of the impurities of the iron and the impurities are then removed
36
WEEK 9 LESSON 1 WORKSHEET
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Put out fires
Welding metals
Create lsquofizzrsquo in drinks
Used in steel production
Aerobic respiration
37
WEEK 9 LESSON 2
TOPIC Uses of non ndash metals and their compounds
Carbon (allotrophes carbon dioxide)
Carbon is used as a reducing agent in extraction of some metals
Carbon as graphite is used as electrodes lubricants and lsquoleadrsquo for pencils
Carbon in the form of diamond is used for jewellery (because of its lustre) and in drill tips for
high ndash speed drills (because of its hardness)
Carbon dioxide is used as refrigerant (as dry ice) for carbonated beverages
Sodium hydrogen carbonate and sodium carbonate are used for water softening and raising
agent
Sulphur
Sulphur is used in the manufacture of sulphuric acid Sulphur is also used in the manufacture of
tyres to make the rubber harder (vulcanisation)
Sulphur powder is used as fungicide on plant materials
Phosphorus
Phosphorus is used in the manufacture of fertilizers
Phosphorus is used to make phosphor bronze alloys
Phosphorus sulphide is used to make the heads of lsquostrike anywherersquo matches
38
Chlorine
Chlorine is used to make sodium hypochlorite which is present in bleach It is also used in
sterilizing swimming pools and in water treatment
Chlorine is used to make the monomer vinyl chloride which is used to make the plastic PVC
Nitrogen
Nitrogen is used to make fertilisers ammonia dyes and nitric acid
Nitrogen is used as an inert atmosphere to prevent substances being oxidised and as a coolant
Silicon
Silicon is used for making silicon chips for computers
Silicon (V) oxide is present in sand Glass is made by heating sand with lime (calcium oxide) and
sodium carbonate
Silicon in the form of silicates is used in jewellery
Silica gel is used as a drying agent
39
WEEK 9 LESSON 2 WORKSHEET
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Used to make sodium hypochlorite
Used as a fungicide on plant materials
Used for lsquoleadrsquo in pencils
Used in the manufacture of bronze alloys
Used in the manufacture of nitric acid
Used in the manufacture of computer chips
Used to make fertilisers
40
WEEK 9 LESSON 3
TOPIC Harmful effects of non ndash metals and their compounds on living systems and the
environment
Sulphur dioxide
Sulphur dioxide can cause a disease of the lungs Sulphur dioxide also poisons plants in two
main ways It may enter the stomata of leaves and react with the tissue fluids to form sulphites
with the on ndash going water loss the concentration of sulphites could build up killing the cells
The second adverse effect on plants occurs when sulphur dioxide dissolves in rain thereby
increasing soil acidity A prolonged acid soil situation may lead to plasmolysis and the death of
vegetation in an area
Carbon monoxide
Carbon monoxide combines much more readily than oxygen with haemoglobin When carbon
monoxide is inhaled it prevents the haemoglobin from taking oxygen to the bodyrsquos cells
Continued breathing of air containing carbon monoxide eventually causes death
Hydrogen sulphide
Hydrogen sulphide reacts readily with many cations forming insoluble sulphides Many cations
contribute to good health by contributing to enzyme activity and to the formation of bone
pigment and haemoglobin Although these cations are required in extremely small
concentrations they are removed by being precipitated as sulphides and thus not available for
regular function Careless dumping of refuse contributes to atmospheric pollution by hydrogen
sulphide
Oxides of nitrogen
In the presence of hydrocarbons from car exhausts ozone and sunlight nitrogen oxides react to
form photochemical smog which contains many harmful chemicals
Nitrogen dioxide can harm the lungs and irritate the nose throat and eyes The other compounds
present in photochemical smog are even more harmful irritants and can cause asthma
41
Carbon dioxide
Carbon dioxide water vapour and ozone referred to as ldquogreenhouse gasesrdquo acting as a blanket
readily absorb some of the radiated heat energy and in turn warms the earthrsquos atmosphere This is
called the ldquogreenhouse effectrdquo Scientists have found direct correlation between carbon dioxide
concentration and global warming An increase in carbon dioxide concentration resulted in an
increase global temperatures Global warming is a major potential problem that the world faces
Chloroflourocarbons (CFCs)
It is believed that CFCs might be responsible for destroying the ozone layer which prevents
harmful ultraviolet (UV) radiation from reaching the earth The carbon ndash chlorine bond in CFC
molecule is easily broken by a UV photon producing an active chlorine atom This atom
combines with an ozone molecule forming a chlorine oxide radical and oxygen The radicle
reacts with more ozone producing the chlorine atom again This kind of reaction is repeated
thousands of times This type of reaction is thought to account for about eighty percent of the
loss of ozone observed
Nitrates and phospates
Nitrates and phosphates cause eutrophication The process leading to eutrophication are
Nitrates and phosphates from fertilisers spread on fields may dissolve in groundwater and
get into lakes and rivers
Nitrates and phosphates cause excessive growth of algae so that they cover the surface of
the water
Water plants including algae die because of lack of sunlight Aerobic bacteria feed on
the plant remains The bacteria multiply
The aerobic bacteria use up the oxygen in the water so aquatic animals die
42
Solid waste
The main sources of pollution from non ndash metals is from glass paper and plastics
Broken glass can cause injury to animals It can also cause fires by acting as lens focusing the
sunrsquos rays on flammable materials
Printing inks from paper dumped in the ground may contain toxic elements such as arsenic and
cadmium Bleaches and chlorine compounds from paper are also harmful
43
WEEK 9 LESSON 3 WORKSHEET
Describe ONE harmful effect of the following non ndash metals andor their compounds on
living systems and the environment
Sulphur dioxide
______________________________________________________________________________
______________________________________________________________________________
Carbon monoxide
______________________________________________________________________________
______________________________________________________________________________
Carbon dioxide
______________________________________________________________________________
______________________________________________________________________________
Oxides of nitrogen
______________________________________________________________________________
______________________________________________________________________________
Hydrogen sulphide
______________________________________________________________________________
______________________________________________________________________________
44
Chloroflourocarbons (CFCs)
______________________________________________________________________________
______________________________________________________________________________
Nitrates and phospates
______________________________________________________________________________
______________________________________________________________________________
45
WEEK 10 LESSON 1
TOPIC Green Chemistry
Green Chemistry is defined as the utilisation of a set of principles that reduces or eliminates the
use and generation of hazardous substances
There are twelve principles of green chemistry as proposed by Paul T Anastas and John C
Warner These twelve principles are
1 Prevention ndash It is better to prevent waste than to treat or clean up waste after it has been
created
2 Atom economy - Synthetic methods should be designed to maximize the incorporation of
all materials used in the process into the final product
3 Less hazardous chemical synthesis - Wherever practicable synthetic methods should be
designed to use and generate substances that possess little or no toxicity to human health
and the environment
4 Safer chemical products - Chemical products should be designed to affect their desired
function while minimizing their toxicity
5 Safer solvents and other agents - The use of auxiliary substances (eg solvents
separation agents etc) should be made unnecessary wherever possible and harmless
when used
6 Minimum energy requirements - Energy requirements of chemical processes should be
recognized for their environmental and economic impacts and should be minimized If
possible synthetic methods should be conducted at ambient temperature and pressure
7 Use of renewable raw materials - A raw material or feedstock should be renewable rather
than depleting whenever technically and economically practicable
8 Reduce use of additional chemicals or additional steps - Unnecessary derivatization (use
of blocking groups protection deprotection temporary modification of
physicalchemical processes) should be minimized or avoided if possible because such
steps require additional reagents and can generate waste
46
9 Use of catalysts ndash The use of catalysts reduce energy costs because the reactions take
place at lower temperatures The more specific the catalyst for a particular reaction is the
less it the likelihood of getting additional unwanted products
10 Nature of breakdown of products - Chemical products should be designed so that at the
end of their function they break down into innocuous degradation products and do not
persist in the environment
11 Monitoring to prevent pollution - Analytical methodologies need to be further developed
to allow for real-time in-process monitoring and control prior to the formation of
hazardous substances
12 Minimise chemical accidents - Substances and the form of a substance used in a chemical
process should be chosen to minimize the potential for chemical accidents including
releases explosions and fires
47
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
48
WEEK 10 LESSON 2
TOPIC Qualitative Analysis ndash Identification of cations
Qualitative Analysis involves identifying the constituents of single substances or mixture of
substances
Appearance
An examination of the appearance of a substance can indicate which ion it contains
Appearances of substances
Observation Indication
Blue or blue ndash green Cu2+ salt
Pale green Fe2+ salt
Yellow ndash brown Fe3+ salt
Ammonia smell NH4+ salt
49
Test for cation using sodium hydroxide
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
(d) If no precipitate forms in step b warm gently and test for ammonia
Effect of dilute sodium hydroxide solution
Effect of dilute sodium hydroxide solution Cation
Dropwise Excess
White precipitate Precipitate soluble Ca2+
White precipitate Precipitate insoluble Al3+ Pb2+ Zn2+
Blue precipitate Precipitate insoluble Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
No precipitate ndash ammonia gas
evolved on heating
ndash NH4+
The metal cations all form insoluble hydroxides with sodium hydroxide solution
For example Ca2+ (aq) + 2 OH- (aq) Ca(OH)2 (s)
Ca(OH)2 Cu(OH)2 Fe(OH)2 and Fe(OH)3 are basic and therefore do not react with excess
sodium hydroxide solution Therefore the precipitate does not dissolve in excess sodium
hydroxide solution
Al(OH)3 Pb(OH)2 and Zn(OH)2 are amphoteric Therefore the precipitates react with the excess
sodium hydroxide solution forming soluble salts and the precipitate disappears in excess sodium
hydroxide solution
The NH4+ ion forms a soluble hydroxide However on heating it reacts with the hydroxide ion to
form ammonia and water
NH4+ (aq) + OH- (aq) NH3 (g) + H2O (l)
50
WEEK 10 LESSON 2 WORKSHEET
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P _____________ Q ___________________
R _____________ S ___________________
R + NaOH
______________________________________________________________________________
51
WEEK 10 LESSON 3
TOPIC Qualitative Analysis ndash Identification of cations
Test for cation using ammonia solution (ammonium hydroxide solution)
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
Effect of dilute ammonia (ammonium hydroxide) solution
Effect of dilute ammonia solution Cation
Dropwise Excess
No precipitate ndash Ca2+
White precipitate Precipitate soluble
(forming colourless solution)
Zn2+
White precipitate Precipitate insoluble Al3+ Pb2+
Blue precipitate Precipitate soluble
(forming deep blue solution)
Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
52
Ammonia solution is a weak alkali Metal cations except Ca2+ form insoluble hydroxides with
ammonia solution as with the sodium hydroxide solution
The amphoteric hydroxides Al(OH)3 and Pb(OH)2 and the basic hydroxides Fe(OH)2 and
Fe(OH)3 do not react with excess ammonia solution Therefore the precipitates remain
However Zn(OH)2 and Cu(OH)2 do react with excess ammonia solution to form complex
soluble hydroxides each Hence their precipitates disappear on the addition of excess ammonia
solution
Confirmatory test
After carrying out test for cations using sodium hydroxide solution and ammonia solution the
only cations which cannot be distinguished are Al3+ and Pb2+ A confirmatory test is carried out
to distinguish between the two cations
Confirmatory test
Test Observation Cation Ionic equation
Add potassium
or sodium
iodide solution
Bright yellow precipitate
No precipitate
Pb2+
Al3+
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
53
WEEK 10 LESSON 3 WORKSHEET
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A __________ B ________________ C ________________________
(b) State the inference after Test 2
C _______________________
(c) Write an ionic equation to support your answer in (b) above
___________________________________________________________________________
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
54
ANSWERS TO WORKSHEETS
55
WEEK 5 LESSON 1 WORKSHEET ANSWERS
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
Answer
Zinc + Iron (II) sulphate Zinc is higher in the electrochemical series and therefore displace
iron ions in iron (II) sulphate
Equation Zn (s) + FeSO4 (aq) ZnSO4 (aq) + Fe (s)
Ionic equation Zn (s) + Fe2+ (aq) Zn2+ (aq) + Fe (s)
Iron + Zinc sulphate No reaction iron is lower in the electrochemical series and cannot
displace the zinc ions in zinc sulphate
56
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
Answer
X displaces lead from an aqueous solution of its salts
X (s) + Pb2+ (aq) Xn+ (aq) + Pb (s)
rarr X is more reactive than Pb
X did not react with iron salts
rarr X is less reactive than Fe
Y burns very easily
Y is more reactive than Fe and Pb (both forming their corresponding oxide at a slower rate)
From electrochemical series Fe is higher and therefore more reactive than Pb
Order of reactivity
Y (most reactive) gt Fe gt X gt Pb (least reactive)
57
WEEK 5 LESSON 2 WORKSHEET ANSWERS
1
Metal Reactivity with acid
Copper X
Magnesium
Aluminium
Silver X
Zinc
58
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
Answer
Y and Z are the most reactive since they can react with dilute acid
Z is more reactive than Y since a reaction occurs with Z is added to an aqueous solution of Y
X is less reactive than W since it does not occur in nature as compounds
Order of reactivity Z (most reactive) gt Y gt W gt X
59
WEEK 5 LESSON 3 WORKSHEET ANSWERS
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
Answer
Ease of decomposition (from easiest to decompose to most difficult to decompose)
B rarrD rarrArarr C
Reactivity (most reactive to least reactive)
C (most reactive) gt A gt D gt B (least reactive)
60
WEEK 6 LESSON 1 Worksheet Answers
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
Potassium Zinc Copper
Calcium Lead Gold
Magnesium Iron
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
Aluminium is extracted from its ore bauxite through the process of electrolysis
Cryolite is added to bauxite to lower the melting point to about 900 0C The melting point of
bauxite is very high (about 2040 0C) It is difficult and expensive to keep the molten aluminium
oxide at this temperature
Reaction at the cathode Al3+ (l) + 3 e- Al (l)
61
WEEK 6 LESSON 2 Worksheet Answers
(a) What are the three raw materials that are added through the top of the blast
furnace during the extraction process for iron
Coke (carbon)
iron ore (haematitie mainly iron (II) oxide)
limestone (calcium carbonate)
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
Coke ndash coke burns to produce carbon dioxide The carbon dioxide further reacts with coke to
form carbon monoxide (reducing agent in the process)
C (s) + O2 (g) CO2 (g)
C (s) + CO2 (g) 2 CO
Haematite ndash iron ore provides the iron which is reduced by the carbon monoxide to produce
iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + CO2 (g)
Limestone ndash decomposes to form calcium oxide The calcium oxide reacts with the impurity
silicon dioxide to form slag (calcium silicate)
CaCO3 (s) CaO (s) + CO2 (g)
CaO (s) + SiO2 (l) CaSiO3(l)
62
WEEK 6 LESSON 3 Worksheet Answers
(a) Define the term alloy
An alloy is a material made from a mixture of two or more metals
(b) State 3 general advantages that alloys have over the individual metals they are made
from
They are harder stronger and more resistant to corrosion
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
1 High strength
2 Low density
Uses
1 Used to make aircraft bodies
2 Used to make space satellites
63
WEEK 7 LESSON 1 WORKSHEET ANSWERS
(a) Define the term corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
The paint forms a barrier which stops contact with air or water and the iron Hence rusting
will not take place
However when the paint is scratched that part of the iron nail is exposed to air or water and
rusting will take place
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
Magnesium is higher in the electrochemical series and will be oxidised in preference to iron
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
Aluminium is partly protected from corrosion by its coat of aluminium oxide However as the
iron rust it flakes and fall off and the rusting process continues
64
WEEK 7 LESSON 2 WORKSHEET ANSWERS
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
Magnesium is the ion found in chlorophyll Chlorophyll plays a vital part in the process of
photosynthesis A deficiency in magnesium will lead to low chlorophyll level in the tomato
plants and hence reduce the process of photosynthesis There will be less food storage and
hence will lead to smaller yield of tomatoes
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Any correct harmful effect of lead on health or environment
Any correct harmful effect of mercury on health or environment
65
WEEK 7 LESSON 3 WORKSHEET ANSWERS
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
(b) Write the ionic equation for the above reaction
2 Br- (aq) + Cl2 (aq) 2 Cl- (aq) + Br2 (aq)
(c) Identify the oxidising agent in the reaction
Cl2 (aq)
(d) Justify your answer in part (c) in terms of oxidation number
There is a reduction of the oxidation number for chlorine from 0 to ndash1
hence it has been reduced Therefore chlorine is the oxidising agent
66
WEEK 8 LESSON 1 WORKSHEET ANSWERS
Describe the laboratory preparation of oxygen gas
Oxygen is prepared in the laboratory by the decomposition of hydrogen peroxide
A suitable catalyst is manganese (IV) oxide
Drying agent silica gel OR anhydrous calcium chloride OR conc sulphuric acid
The gas is collected by downward delivery since oxygen is slightly denser than air
Balanced chemical equation 2 H2O2 (aq) 2 H2O (l) + O2 (g)
67
WEEK 8 LESSON 2 WORKSHEET ANSWERS
Describe the laboratory preparation of carbon dioxide gas
Carbon dioxide is commonly prepared in the laboratory by the reacting hydrochloric acid and
marble chips (calcium carbonate)
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
The carbon dioxide gas is collected by downward delivery since it is denser than air
Balanced chemical equation
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
68
WEEK 8 LESSON 3 WORKSHEET ANSWERS
Describe the laboratory preparation of ammonia gas
An ammonium salt (ammonium chloride) and a base (sodium hydroxide) are mixed together and
heated
Calcium oxide is used as the drying agent Calcium chloride and concentrated sulphuric acid
cannot be used since ammonia can react with them
The gas is collected by upward delivery since ammonia is less dense than air
Balanced chemical equation
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
69
WEEK 9 LESSON 1 WORKSHEET ANSWERS
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Carbon dioxide Put out fires
Oxygen Welding metals
Carbon dioxide Create lsquofizzrsquo in drinks
Oxygen Used in steel production
Oxygen Aerobic respiration
70
WEEK 9 LESSON 2 WORKSHEET ANSWERS
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Chlorine Used to make sodium hypochlorite
Sulphur Used as a fungicide on plant materials
Carbon (graphite) Used for lsquoleadrsquo in pencils
Phosphorus Used in the manufacture of bronze alloys
Nitrogen Used in the manufacture of nitric acid
Silicon Used in the manufacture of computer chips
Nitrogen Phosphorus Used to make fertilisers
71
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
Green Chemistry is using principles that reduceeliminate the use of hazardous materials in
the design manufacture and application of chemical products
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
Makes the environment safer
Reduces waste
Creates new jobs
Reduces respiratory illnesses
Atom economy
72
WEEK 10 LESSON 2 WORKSHEET ANSWERS
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P Cu2+ Q Fe2+
R Fe3+ S Ca2+
Ionic equation for R + NaOH
Fe3+ (aq) + 3 OH- (aq) Fe(OH)3 (s)
73
WEEK 10 LESSON 3 WORKSHEET ANSWERS
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A Fe3+ B Ca2+ C Al3+ Pb2+
(b) State the inference after Test 2
C Pb2+
(c) Write an ionic equation to support your answer in (b) above
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
11 Qualitative Analysis
ndash Test for gases
Qualitative Analysis
ndash Identification of
anions
Qualitative Analysis
ndash Identification of
anions
12 Problem solving of
Past CSEC Chemistry Paper 2
on topics completed in the term
13
14
15
2
WEEK 11 LESSON 1
TOPIC Qualitative Analysis ndash Test for gases
Identification of gases
Gas Colour Odour Effect on moist
litmus
Method of identification
Oxygen
O2
Colourless Odourless Neutral ndash no
effect
Relights a glowing splint
Hydrogen
H2
Colourless Odourless Neutral ndash no
effect
Lighted splint lsquopopsrsquo if air is also
present
Carbon
dioxide
CO2
Colourless Odourless Weakly acidic ndash
blue to slightly
red
A white precipitate forms in
limewater
Ca(OH)2 (aq) + CO2
CaCO3 (s) + H2O (l)
Precipitate redissolves on
continued bubbling
CaCO3 (s) + H2O (l) + CO2 (g)
Ca(HCO3)2 (aq)
Ammonia
NH3
Colourless Pungent Alkaline ndash red
to blue (only
common
alkaline gas)
Turns moist red litmus blue forms
dense white fumes with hydrogen
chloride gas
NH3 (g) + HCl (g) NH4Cl (s)
Gas Colour Odour Effect on moist
litmus
Method of identification
3
Sulphur
dioxide
SO2
Colourless Choking
smell
Acidic ndash blue to
red
Turns acidified potassium
manganate (VII) solution from
purple to colourless
Turns acidified potassium
dichromate (VI) solution from
orange to green
Chlorine
Cl2
Yellow ndash
green
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Bromine
Br2
Red ndash
brown
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Nitrogen
dioxide
NO2
Red ndash
brown
Irritating
smell
Acidic blue to
red
Turns moist blue litmus red but
does not bleach it
Water
vapour
H2O
Colourless Odourless Neutral ndash no
effect
Turns anhydrous cobalt (II)
chloride from blue to pink
Turns anhydrous copper (II)
sulphate from white to blue
4
WEEK 11 LESSON 1 WORKSHEET
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless
Yellow ndash green
Red ndash brown
Gases according to their odour
Odour of gas Identity of gas
Odourless
Pungent smell
Choking smell
Irritating smell
5
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect
Red to blue
Blue to red
Blue to red then bleaches it
6
WEEK 11 LESSON 2
TOPIC Qualitative Analysis ndash Identification of anions
Effect of heating
Method Heat a sample of the solid in a dry test tube
Effect of heating
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) not
of K or Na
CO32- (s) O2- (s) + CO2 (g)
Oxygen evolved NO3- of K or Na 2 NO3
- (s) 2 NO2- (s) + O2
(g)
Oxygen and nitrogen
dioxide evolved
NO3- of Ca and below
in reactivity series
4 NO3- (s) 2 O2- (s) + 4 NO2
(g) + O2
(g)
Sulphur dioxide evolved SO32- SO3
2- O2- (s) + SO2 (g)
Effect of dilute acid
Add dilute hydrochloric acid or nitric acid to a sample of the solid Warm if no reaction occurs
when cold
Effect of dilute acid
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) CO32- (s) + 2 H+ (aq) H2O (l) + CO2 (g)
Sulphur dioxide evolved SO32- SO3
2- (s) + 2 H+ (aq) H2O (l) + SO2 (g)
7
Effect of concentrated acid
Add concentrated sulphuric acid to a sample of the solid Warm if not reaction occurs when cold
Effect of concentrated sulphuric acid
Observation Anion
Carbon dioxide evolved CO32- or HCO3
-
Sulphur dioxide evolved SO3-
Hydrogen chloride evolved Cl-
Hydrogen bromide (colourless) and bromine
vapour (brown) evolved
Br-
Black iodine present and purple iodine vapour
evolved
I-
8
WEEK 11 LESSON 2 WORKSHEET
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater
Produces a gas which relights a glowing splint as the only gas
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green
Produces a gas forms a precipitate in limewater
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia
Black iodine present and purple iodine vapour evolved
9
WEEK 11 LESSON 3
TOPIC Qualitative Analysis ndash Identification of anions
Test for the halides ndash using silver nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous silver nitrate and
observe the precipitate Add ammonia solution and observe the solubility of the precipitate
Test for halides using silver nitrate solution
Effect of silver
nitrate solution
Anion Explanation Effect of aqueous
ammonia
White precipitate ndash
turns white in
sunlight
Cl- Ag+ (aq) + Cl- AgCl (s) Precipitate soluble
Cream precipitate ndash
turns yellow ndash green
in sunlight
Br- Ag+ (aq) + Br- AgBr (s) Precipitate slightly
soluble
Pale yellow
precipitate
I- Ag+ (aq) + I- AgI (s) Precipitate insoluble
Test for the halides ndash using lead nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous lead nitrate and
observe the precipitate
Test for halides using lead nitrate solution
Effect of lead nitrate solution Anion Explanation
White precipitate Cl- Pb2+ (aq) + 2 Cl- PbCl2 (s)
Pale yellow Br- Pb2+ (aq) + 2 Br- PbBr2 (s)
Deep yellow I- Pb2+ (aq) + 2 I- PbI2 (s)
10
Effect of barium nitrate or chloride solution followed by dilute acid
Make a solution of the solid Add barium nitrate or chloride solution and observe the precipitate
Add dilute hydrochloric or nitric acid warn if necessary and observe the solubility of the
precipitate
Effect of barium nitrate or chloride solution followed by dilute acid
Effect of
Ba(NO3)2 (aq)
or BaCl2 (aq)
Effect of HCl (aq)
or HNO3 (aq)
Anion Explanation
White precipitate Precipitate insoluble SO42- Ba2+ (aq) + SO4
2- (aq) BaSO4 (s)
BaSO4 does not react with dilute acids
White precipitate Precipitate soluble ndash
CO2 evolved
CO32- Ba2+ (aq) + CO3
2- (aq) BaCO3 (s)
BaCO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + CO2 (g)
White precipitate Precipitate soluble ndash
SO2 evolved on
warming
SO32- Ba2+ (aq) + SO3
2- (aq) BaSO3 (s)
BaSO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + SO2 (g)
11
WEEK 11 LESSON 3 WORKSHEET
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
(Ionic equation required)
12
WEEK 12 LESSON 1 WORKSHEET
(a) The Caribbean islands are known for their many resources For example the ore of
aluminium is found in Jamaica and Guyana
(i) Briefly describe the extraction of aluminium from its named ore Include in your
description one ionic equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Although aluminium ore is mined in the Caribbean the extraction of aluminium usually
takes place in other countries Suggest ONE reason why it may be difficult to extract
aluminium in the Caribbean
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) An alloy can be described as a lsquomixed metal solutionrsquo Aluminium forms an alloy with
magnesium that is used to make an aircraft
13
Identify this alloy and suggest why it is better to use it rather than the pure metal in the
manufacture of aircraft
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) ldquoSome metals can be useful to man yet harmful to the environmentrdquo Comment on this
statement with reference to mercury
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 12 LESSON 2 Worksheet
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate formed
Soluble in excess
15
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate formed
Insoluble in excess
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate formed
(Ionic equation required)
16
WEEK 12 LESSON 3 Worksheet
Dry ammonia gas can be produced in a school laboratory
(a) Identify TWO reagents that are necessary for the laboratory production of ammonia
______________________________________________________________________________
______________________________________________________________________________
(b) Two common drying agents used in the laboratory are calcium oxide and concentrated
sulphuric acid However calcium oxide is the preferred choice for drying ammonia gas
Explain why concentrated sulphuric acid is now used Include in your answer a balanced
chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) When gases are prepared in the laboratory there are three main ways in which they can
be collected
- Upward delivery
- Downward delivery
- Displacement of water
(i) What TWO other factors should be considered when choosing an appropriate method for
the collection of gases in the laboratory
______________________________________________________________________________
______________________________________________________________________________
(ii) Identify ONE of the three methods that is best suited for the collection of ammonia gas in
the laboratory Explain why EACH of the other two methods would NOT have been
appropriate
______________________________________________________________________________
17
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(d) Hence draw a labelled diagram of the apparatus which could be used for the preparation
of dry ammonia in the laboratory
Be sure to identify in your diagram
- where the reagents are placed
- where the ammonia is dried and
- where the ammonia is collected
18
WEEK 13 LESSON 1 Worksheet
(a) In solution two metals A and B form A+ and B2+ ions respectively Metal A displaces Fe
from a solution containing Fe2+ ions but metal B does NOT
(i) Arrange the metals A B and Fe in order of reactivity from LEAST reactive to MOST
reactive Write a balanced chemical equation to show the reaction between metal A and
Fe2+ ions
______________________________________________________________________________
______________________________________________________________________________
(ii) Metal A is placed in a solution of copper (II) sulphate CuSO4 (aq) Write an equation for
the reaction State ONE observable change that will occur and explain why this reaction
takes place
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) For EACH metal A and B state ONE method that can be used to extract it from its
respective oxide Give a reason for EACH answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
19
______________________________________________________________________________
(b) Metal alloys are often used for making objects found in our daily lives Name an alloy of
iron and state ONE of its uses
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 13 LESSON 2 Worksheet
(a) Many important biological processes in plants and animals depend on the specific roles
of certain metal ions
(i) Farmer Jones reaped a crop of tomatoes and reported that the yield was far below what
was expected Analysis of the soil revealed that there was a deficiency of magnesium
Discuss the importance of magnesium in plant health and explain how a magnesium
deficiency can result in the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE other metal ion which is important to plant health and state the result of its
deficiency
______________________________________________________________________________
______________________________________________________________________________
21
(b) Many years ago car exhaust fumes were known to contain compounds of metals and
non ndash metals which could negatively impact both humans and the environment Identify
ONE metal and ONE non ndash metal whose compounds were present in car exhaust fumes
Discuss the effect of these compounds on human health and the environment
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) Define lsquogreen chemistryrsquo and discuss the measures that have been taken to produce a
lsquogreenerrsquo automotive fuel
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
22
WEEK 13 LESSON 3 Worksheet
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
Zn2+ ions are present
23
WEEK 14 LESSON 1 Worksheet
(a) Metal alloys are often used in place of metals because of their enhanced properties
(i) Define the term lsquoalloyrsquo
______________________________________________________________________________
______________________________________________________________________________
(ii) Name ONE alloy of aluminium and state its use based on one of its enhanced properties
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) A student conducted an experiment to investigate the reactivity of each of the following
metals (copper iron zinc and lead) by using solutionPs of their sulphate salts
The data presented in the table below shows whether a visible chemical reaction took
place when each metal was added to the four sulphate solutions
Key Visible chemical reaction took place
X No visible chemical reaction
CHEMICAL REACTION OF METALS IN SULPHATE SOLUTIONS
Sulphate solution Cu Fe Zn Pb
CuSO4 X
FeSO4 X X X
ZnSO4 X X X X
PbSO4 X X
24
(i) State which of the TWO metals is more reaction Fe or Zn Give a reason for our answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Using the data in the previous Table deduce the order of reactivity of the four metals Cu
Fe Zn and Pb from the most reactive to the least reactive metal
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The student recorded the following observations from the reaction between the iron and
copper (II) sulphate solution
Observations Reddish ndash brown solid coating formed on the iron strip
Blue colour of the solution changed to dirty green
Account for the observations made from the reaction between the iron and copper (II)
sulphate solution
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iv) Write an ionic equation including state symbols for the reaction between the iron and
copper (II) sulphate solution
______________________________________________________________________________
25
(c) Some metal compounds are health and environmental hazards
(i) Identify which of the metals used in the experiment in (b) is MOST hazardous to the
environment
______________________________________________________________________________
______________________________________________________________________________
(ii) State TWO harmful effects of continuous exposure to the metal identified in (c) (i) on
human beings
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
26
WEEK 14 LESSON 2 Worksheet
(a) Carbon is found in the form of diamond and graphite and is a main component in many
naturally occurring compounds such as organic matter and carbon dioxide gas
(i) State ONE way in which diamond differs physically from graphite
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE similarity between diamond and graphite other than they both contain carbon
______________________________________________________________________________
______________________________________________________________________________
(b) Carbon can react with a limited supply of oxygen to form carbon monoxide which can
negatively affect human health
(i) Write a balanced chemical equation including state symbols to show the formation of
carbon monoxide
______________________________________________________________________________
(ii) State TWO effects of carbon monoxide inhalation on the human body
______________________________________________________________________________
______________________________________________________________________________
(c) Jamal wants to prepare and collect a sample of carbon dioxide gas in the laboratory using
calcium carbonate
(i) Write a balanced chemical equation including state symbols for the laboratory
preparation of carbon dioxide gas from calcium carbonate
______________________________________________________________________________
______________________________________________________________________________
(ii) Draw a clearly labelled diagram to show the arrangement of the apparatus and materials
that could be used in the laboratory to prepare and collect the carbon dioxide gas
(iii) State ONE use of carbon dioxide as it relates to the beverage industry
______________________________________________________________________________
27
WEEK 14 LESSON 3 Worksheet
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
(Ionic equation required)
Suggest a possible identity of the solid R __________________________
28
WEEK 15 LESSON 1 Worksheet
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a small
portion of solid Y gently at
first and then strongly
Colourless gas evolved
with a choking odour
Turns acidified potassium
dichromate solution from
orange to green
(ii) To the remaining portion
of solid Y add 20 cm3 of
distilled water stir to dissolve
and filter Collect the filtrate
and divide into 3 equal
portions
Filtrate is pale green in
colour
(iii) To the first portion of the
filtrate from (ii) add aqueous
sodium hydroxide slowly
until in excess
A green precipitate
Insoluble in excess sodium
hydroxide
Ionic equation required
29
TEST OBSERVATIONS INFERENCES
(iv) To the second portion of
the filtrate from (ii) add
aqueous silver nitrate
followed by aqueous
ammonia
White precipitate
Soluble in aqueous
ammonia
(v) To the third portion of the
filtrate from (ii) add aqueous
barium nitrate followed by
aqueous hydrochloric acid
White precipitate formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with the
evolution of a colourless
gas with a choking smell
30
WEEK 15 LESSON 2 Worksheet
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
31
WEEK 15 LESSON 3 Worksheet
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in excess
aqueous NH3
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change
32
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
warm filter and then divide
the filtrate into two portions
Vigorous effervescence
observed upon addition of
dilute HNO3
Gas evolved turns lime water
cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Cu2+ ions present
33
ANSWERS TO WORKSHEETS
34
WEEK 11 LESSON 1 WORKSHEET ANSWERS
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless O2 H2 CO2 NH3 SO2 H2O
Yellow ndash green Cl2
Red ndash brown Br2 NO2
Gases according to their odour
Odour of gas Identity of gas
Odourless O2 H2 CO2 H2O
Pungent smell NH3
Choking smell SO2 Cl2 Br2
Irritating smell NO2
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect Neutral O2 H2 H2O
Red to blue Alkaline NH3
Blue to red Acidic CO2 SO2 NO2
Blue to red then bleaches it Acidic Cl2 Br2
35
WEEK 11 LESSON 2 WORKSHEET ANSWERS
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-) not
of K or Na
Produces a gas which relights a glowing splint as the only gas NO3- of K or Na
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green SO32-
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-)
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia Cl-
Black iodine present and purple iodine vapour evolved I-
36
WEEK 11 LESSON 3 WORKSHEET ANSWERS
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Br-
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
Cl-
Ag+ (aq) + Cl- AgCl (s)
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow Br-
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
SO42-
Ba2+ (aq) + SO42- (aq)
BaSO4 (s)
(Ionic equation required)
37
WEEK 12 LESSON 1 Worksheet Answers
(a) (i)
The ore bauxite is purified
The purified bauxite is dissolved in molten cryolite
The aluminium oxidecryolite solution is then eletrolysed
Equation at the cathode Al3+ (l) + 3 e- Al (l)
Equation at the anode 2 O2- (l) ndash 4 e- O2 (g)
(ii) The process is too expensive mainly because too much electricity or energy is needed
(b) The alloy of Al and Mg is magnalium It is less dense than the pure metals and hence allow
aircraft to be lighter It is also stronger than the pure metals and hence allows aircraft to last
longer since it is not easily destroyed
(c) Your answer should cater for the following aspects
Benefits of mercury to humans for example in thermometers barometers in dentistry
and gold mining
Entry of mercury to the environment For example this could have been through broken
thermometers barometers or lightbulbs or improper disposal of them or batteries and
indiscriminate use in gold mining in Guyana
The identification of a negative impact on the environment such as poisoned fish and the
persons who eat the fish death mood swings and psychosis
38
WEEK 12 LESSON 2 Worksheet Answers
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas
evolved
NO2 evolved OR nitrates
present OR
Br2 gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate
formed
Soluble in excess
Pb2+ Zn2+ Al3+ or Ca2+
present
Pb2+ Zn2+ Al3+ or present
39
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate
formed
Insoluble in excess
Pb2+ Zn2+ Al3+ or present
Pb2+ or Al3+ present
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate
formed
Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
40
WEEK 12 LESSON 3 Worksheet Answers
(a) an ammonium salt and a strong alkali
(b) Ammonia is basic and it will react with H2SO4
Equation 2 NH3 (aq) + H2SO4 (aq) (NH4)2SO4 (aq)
(c) (i) ndash Density of the gas relative to air ndash The solubility of the gas in water
(ii) Ammonia is collected by upward delivery
It cannot be collected by downward delivery since ammonia is less dense than air
It cannot be collected by displacement of water since it is soluble in water
(d)
41
WEEK 13 LESSON 1 Worksheet Answer
a) i) B ˂ Fe ˂ A
2A (s) + Fe 2+ (aq) rarr 2A+ (aq) + Fe (s)
ii) 2A (s) + CuSO4 (aq) rarr A2SO4 (aq) + Cu (s)
Observation blue colour fades gets lighter OR brown solid forms is deposited OR metal A
decreases in size dissolves
Explanation Metal A is higher (than Fe which is higher) than Cu in the reactivity series OR
Metal A is more reactive (than Fe which is more reactive) than Cu so Metal A can displace Cu
iii) Metal A can be extracted by electrolysis (of its molten oxide) because Metal A is a very
reactive metal is high in the reactivity series forms stable oxides needs a lot of energy to be
extracted and very reactive metals are extracted by electrolysis
Metal B can be extracted by heating with carbon carbon monoxide OR by chemical reduction
of the oxide because Metal B is less reactive than Fe is low in the reactivity series forms less
stable oxides does not need a lot of energy to be extracted and oxides of less reactive metals are
easily reduced
b) Alloy of iron steel
Use of alloy making buildings bridges ships motor vehicles furniture utensils
42
WEEK 13 LESSON 2 Worksheet Answer
(a) (i)
Magensium is the metal ion found in chlorophyll
Chlorophyll is essential for photosynthesis
A deficiency in magnesium will result in low chlorophyll yellow leaves and a reduction in
photosynthesis
Hence there will be low carbohydrates or energy production
Hence small fruits stunted growth and lower yield will result
(ii)
Metal ion Results of deficiency
Potassium Stunted growth premature loss of leaves yellowing of leaves curling of leaf tips
Calcium Growth abnormalities in tips of roots and shoots curling of leaves
Iron Yellowing of leaves
Zinc Low chlorophyll content yellowing of leaves
Manganese Yellowing of leaves poor flavors in some crops for example potato
(b)
Metal Lead is present in some types of gasoline Upon combustion lead compounds escape into
the atmosphere It accumulates in body tissues and slowly poisons the person It causes mental
illness
Non ndash metal SulphurSulphur dioxide or NitrogenNitrogen dioxide
Dissolves in rain water to form acid rain or cause respiratory illnessproblems Acid rain can
cause corrosion damage in buildings
(c)
Green chemistry is the utilisation of a set of principles that reduces or eliminates the use or
generation of hazardous substances
43
Automotive fuels are now produced without lead so as to eliminate the release of lead
compounds into the atmosphere
Low sulphur fuel is being produced with much reduced sulphur content which causes a reduction
of sulphur dioxide release into the atmosphere
44
WEEK 13 LESSON 3 Worksheet Answer
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
gas turns litmus blue
red
brown gas
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
white precipitate
precipitate soluble in
excess
Zn2+ ions are present
45
WEEK 14 LESSON 1 Worksheet Answers
(a)(i) An alloy is a material made from a mixture of two or more metals
(ii) Any suitable answer chosen from below
Alloy Enhance Property Use
Duralumin High strength
Low density
Light
Hard
Used to make aircraft bodies
space satellites
Magnalium Light
Hard
Easier to weld
Corrosion resistant
Strong
High ductability
Used in pyrotechnics
(fireworks)
Mirrors
Aircraft parts
To make scientific
instruments
Used to make marine castings
Alchlad Strong
Corrosion resistant
Cladding for buildings
(b) (i) Zinc is more reactive than iron
Zinc displaces iron from iron (II) sulphate
Zinc is higher in the reactivity series than iron
Iron does not displace zinc from zinc sulphate
(ii) Order of reactivity Zn gt Fe gt Pb gt Cu
(iii) Reddish brown solid ndash copper metal formed
46
Dirty green solution ndash presence of Fe2+ ion
(iv) Fe (s) + Cu2+ (aq) Fe2+ (aq) + Cu (s)
(c) (i) Lead
(ii) Any two correct harmful effects of lead on the body
Impedes brain development (in young children)
Affectimpede development of the immune system in humans
Affecthamper development of nervous system in humans
Long term exposure can result in kidney and liver damage
Mental retardation
Anaemia
Death
47
WEEK 14 LESSON 2 Worksheet Answers
a) i) Diamond is transparent clear Graphite is opaque black
OR hard OR brittle
OR does not conduct electricity OR conducts electricity
a) ii) Both have a macromolecular giant molecular giant covalent structure (lattice)
OR Both have high melting point boiling point
OR Both are insoluble in water organic solvent
b) i) 2C (s) + O2 (g) rarr 2CO (g)
ii) CO reduction in amount of oxygen carried by (the haemoglobin in the red blood
cells of) the blood
Headache OR dizziness OR nausea OR fatigue OR loss of consciousness OR
death
c) i) CaCO3 (s) + 2HCl (aq) rarr CaCl2 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) + H2SO4 (aq) rarr CaSO4 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) rarr CaO (s) + CO2 (g)
48
ii)
OR
OR
Entirely closed system thistle funnel below the level of the liquid OR tap that could be
closed
Two reagents labelled CaCO3marble chips and HCl H2SO4 or heat source
collection of CO2 upward displacement of air OR over watersulphuric acid OR in gas
syringe
iii) CO2 use put in aerated drinks carbonated beverages
OR put in carbon dioxide fire extinguishers
49
WEEK 14 LESSON 3 Worksheet Answers
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
NH4+
NH4+ confirmed OR
NH3 (g) produced
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
Cl- ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation required)
Suggest a possible identity of the solid R NH4Cl (ammonium chloride)
50
WEEK 15 LESSON 1 Worksheet Answers
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a
small portion of solid Y
gently at first and then
strongly
Colourless gas
evolved with a
choking odour
Turns acidified
potassium dichromate
solution from orange
to green
SO2 evolved
Presence of a sulphite
(ii) To the remaining
portion of solid Y add 20
cm3 of distilled water stir
to dissolve and filter
Collect the filtrate and
divide into 3 equal portions
Filtrate is pale green
in colour
Fe2+ ions present
(iii) To the first portion of
the filtrate from (ii) add
aqueous sodium hydroxide
slowly until in excess
A green precipitate
Insoluble in excess
sodium hydroxide
Fe2+ ions present
Fe2+ (aq) + 2 OH- (aq) Fe(OH)2 (s)
Ionic equation required
TEST OBSERVATIONS INFERENCES
(iv) To the second portion
of the filtrate from (ii) add
aqueous silver nitrate
White precipitate
Soluble in aqueous
ammonia
Cl- ions present
51
followed by aqueous
ammonia
(v) To the third portion of
the filtrate from (ii) add
aqueous barium nitrate
followed by aqueous
hydrochloric acid
White precipitate
formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with
the evolution of a
colourless gas with a
choking smell
SO32- CO3
2- SO42- ions present
SO32- ions present
52
WEEK 15 LESSON 2 Worksheet Answers
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
Chloride ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
Cu2+ ions present
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
X contains a reducing agent
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
SO32- SO4
2- or CO32- ions are
present
SO32- ions are present
53
WEEK 15 LESSON 3 Worksheet Answers
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
White ppt
Ppt soluble in excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in
excess aqueous NH3
Al3+ Pb2+ Zn2+ present
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change Cl- Br- I- absent
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
Vigorous effervescence
observed upon addition of
dilute HNO3
CO2 evolved OR
Carbonate present
54
warm filter and then divide
the filtrate into two portions
Gas evolved turns lime
water cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
Cu2+ (aq) + OH- (aq)
Cu(OH)2 (s)
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Blue ppt
ppt dissolves in excess
NH3 to give a deep blue
solution
Cu2+ ions present
55
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
REFERENCES
Hunte-King J Maragh P Nagir F amp Norris R (2013) Chemistry for CSEC United
Kingdom Nelson Thornes Ltd
Remy C Mason L Lambert N amp Mohammed M (2007) Chemistry for CSEC England and
Wales Pearson Education Limited
Taylor M amp Chung-Harris T (2010) CXC Chemistry England Macmillan Publishers
Limited
Tindale A (2016) Chemistry A Concise Revision for CXC London HarperCollins Publishers
Limited
13
WEEK 2 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with water (or
steam if reaction does not occur with water)
Potassium + WaterSteam
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Sodium + WaterSteam
______________________________________________________________________________
Calcium + WaterSteam
______________________________________________________________________________
Magnesium + WaterSteam
______________________________________________________________________________
Aluminium + WaterSteam
______________________________________________________________________________
Zinc + WaterSteam
______________________________________________________________________________
14
Iron + WaterSteam
______________________________________________________________________________
Copper + WaterSteam
______________________________________________________________________________
Silver + WaterSteam
______________________________________________________________________________
15
WEEK 2 LESSON 2
TOPIC Chemical properties of metals
Action of dilute acids
Metals above hydrogen in the electrochemical series react with dilute acids to form a salt and
hydrogen gas They react with hydrochloric acid to form the metal chloride (a salt) and hydrogen
gas They also react with dilute suphuric acid to form the metal sulphate (a salt) and hydrogen
gas
Metal Reaction dilute hydrochloric or sulphuric acid
Potassium K Violent reaction forming a salt and hydrogen gas
eg 2 Na (s) + 2 HCl (aq) 2 NaCl (aq) + H2 (g) Sodium Na
Calcium Ca Vigorous reaction forming a salt and hydrogen gas
eg Mg (s) + 2 HCl (aq) MgCl2 (aq) + H2 (g) Magnesium Mg
Aluminium Al React forming a salt and hydrogen gas
eg Fe (s) + 2 HCl (aq) FeCl2 (aq) + H2 (g) Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
16
WEEK 2 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with
hydrochloric acid
Metal Balanced equation for reaction with hydrochloric acid
Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Copper
Silver
17
WEEK 2 LESSON 3
TOPIC Reactions of metal compounds
Reactions of metallic oxides with dilute acid
Metal oxides react with dilute hydrochloric acid or sulphuric acid to produce a salt and water
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
Some of these reactions may be slow and can be speeded up by adding heat
For example
zinc oxide + hydrochloric acid zinc chloride + water
ZnO (s) + 2 HCl (aq) ZnCl2 (aq) + H2O (l)
magnesium oxide + hydrochloric acid magnesium chloride + water
MgO (s) + 2 HCl (aq) MgCl2 (aq) + H2O (l)
aluminium oxide + sulphuric acid aluminium sulphate + water
Al2O3 3 H2SO4 (aq) Al2(SO4)3 (aq) + 3 H2O (l)
calcium oxide + sulphuric acid calcium sulphate + water
CaO H2SO4 (aq) CaSO4 (aq) + H2O (l)
18
WEEK 2 LESSON 3 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal oxides with the
corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium oxide Hydrochloric acid
Sodium oxide Sulphuric acid
Calcium oxide Hydrochloric acid
Magnesium oxide Sulphuric acid
Aluminium oxide Hydrochloric acid
Zinc oxide Sulphuric acid
19
WEEK 3 LESSON 1
TOPIC Reactions of metal compounds
Reactions of metallic hydroxides with dilute acid
Metal hydroxides react with dilute acids to form a salt and water in a neutralisation reaction
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
For example
magnesium hydroxide + hydrochloric acid magnesium chloride + water
Mg(OH)2 (aq) + 2 HCl (aq) MgCl2 (aq) + 2 H2O (l)
sodium hydroxide + hydrochloric acid sodium chloride + water
NaOH (aq) + HCl (aq) NaCl (aq) + H2O (l)
potassium hydroxide + sulphuric acid potassium sulphate + water
2 KOH + H2SO4 (aq) K2SO4 (aq) + 2 H2O (l)
calcium hydroxide + sulphuric acid calcium sulphate + water
Ca(OH)2 (aq) + H2SO4 (aq) CaSO4 (aq) + 2 H2O (l)
20
WEEK 3 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal hydroxides with
the corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium hydroxide Hydrochloric acid
Sodium hydroxide Sulphuric acid
Calcium hydroxide Hydrochloric acid
Magnesium hydroxide Sulphuric acid
Aluminium hydroxide Hydrochloric acid
Zinc hydroxide Sulphuric acid
21
WEEK 3 LESSON 2
TOPIC Reactions of metal compounds
Reactions of metallic carbonates with dilute acid
Metal carbonates react with dilute acid to form a salt carbon dioxide and water When
hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric acid is
used the corresponding sulphate salt is formed
For example
sodium carbonate + hydrochloric acid sodium chloride + carbon dioxide + water
Na2CO3 (s) + 2 HCl (aq) 2 NaCl (aq) + CO2 (g) + H2O (aq)
calcium carbonate + hydrochloric acid calcium chloride + carbon dioxide + water
CaCO3 (s) + 2 HCl (aq) CaCl2 (aq) + CO2 (g) + H2O (aq)
zinc carbonate + sulphuric acid zinc sulphate + carbon dioxide + water
ZnCO3 (s) + H2SO4 (aq) ZnSO4 (aq) CO2 (g) + H2O (aq)
potassium carbonate + sulphuric acid potassium sulphate + carbon dioxide + water
K2CO3 (s) H2SO4 (aq) K2SO4 (aq) CO2 (g) + 2 H2O (aq)
22
WEEK 3 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal carbonates with
the corresponding acid
Metallic
carbonate
Acid Balanced chemical equation
Potassium
carbonate
Hydrochloric
acid
Sodium
carbonate
Sulphuric acid
Zinc
carbonate
Hydrochloric
acid
Magnesium
carbonate
Sulphuric acid
Aluminium
carbonate
Hydrochloric
acid
Calcium
carbonate
Sulphuric acid
23
WEEK 3 LESSON 3
TOPIC Action of heat on metal compounds
Action of heat on nitrates
All nitrates decompose when heated The reactivity of the metal in the metal nitrate influences
the products of the decomposition
The nitrates of the alkali metals (Group I) with the exception of lithium nitrate decompose to
form the metal nitrite and oxygen
The nitrates of most other metals decompose to form the metal oxide nitrogen dioxide and
oxygen
The nitrates of the very unreactive metals decompose to form the meal nitrogen dioxide and
oxygen
Metal Nitrate Decomposition
Potassium K Products metal nitrite + oxygen
eg 2 NaNO3 (s) Heatrarr 2 NaNO2 (s) + O2 (g)
Sodium Na
Calcium Ca
Products metal oxide + nitrogen dioxide + oxygen
eg 2 Pb(NO3)2 (s)
Heatrarr 2 PbO (s) + 4 NO2 (g) + O2 (g)
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Products metal + nitrogen dioxide + oxygen
eg 2 AgNO3 (s) Heatrarr 2 Ag (s) + 2 NO2 (g) + O2 (g)
24
WEEK 3 LESSON 3 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
nitrates
Metal Balanced chemical equation
Potassium nitrate
Sodium nitrate
Calcium nitrate
Magnesium nitrate
Aluminium nitrate
Zinc nitrate
Lead nitrate
Copper nitrate
Silver nitrate
25
WEEK 4 LESSON 1
TOPIC Action of heat on metal compounds
Action of heat on carbonates
Upon application of heat many carbonates decompose to form the metal oxide and carbon
dioxide
Group I carbonates do not decompose on heating with the exception of lithium carbonate
Metal Carbonate decomposition
Potassium K
Stable not decomposed by heat Sodium Na
Calcium Ca
Decompose forming metal oxide and carbon dioxide
eg CaCO3 (s) Heatrarr CaO (s) + CO2 (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Unstable
26
WEEK 4 LESSON 1 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
carbonates
Metal Balanced chemical equation
Potassium carbonate
Sodium carbonate
Calcium carbonate
Magnesium carbonate
Aluminium carbonate
Zinc carbonate
Iron carbonate
Lead carbonate
Copper carbonate
27
WEEK 4 LESSON 2
TOPIC Action of heat on metal compounds
Action of heat on the metal hydroxides
Most metal hydroxides decompose on heating A metal oxide and water are formed
Group I hydroxides do not decompose on heating with the exception of lithium hydroxide
Metal Hydroxide decomposition
Potassium K Stable not decomposed by heat
Sodium Na
Calcium Ca Decompose forming metal oxide and water (as steam)
eg Zn(OH)2 (s) Heatrarr ZnO (s) + H2O (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag No hydroxide exist
28
WEEK 4 LESSON 2 WORKSHEET
Write the balanced chemical equations for the thermal decomposition of the following
metal hydroxides
Metal hydroxide Balanced chemical equation
Potassium hydroxide
Sodium hydroxide
Calcium hydroxide
Magnesium hydroxide
Aluminium hydroxide
Zinc hydroxide
Lead hydroxide
Copper hydroxide
29
WEEK 4 LESSON 3
TOPIC Reactivity of metals ndash The Reactivity Series
The reactivity series of metals is a list of metals arranged in order of their reactivity based on
Displacement reactions
Reactions with oxygen dilute acids and water
Relative ease of decomposition of their compounds
Metals at the top of the series are the most electropositive They lose electrons very easily and
readily form cations These ions are very stable and are not easily discharged to form atoms Due
to this fact they are the most reactive metals
Metals at the bottom of the series are the least electropositive They do not lose electrons easily
and do not readily form ions Their ions are very unstable and are easily discharged to form
atoms They are the least reactive metals
The reactivity series of metals
Mnemonic Metal Symbol Reactivity
People Potassium K Most reactive
Least reactive
Sometimes Sodium Na
Collect Calcium Ca
Magazines Magnesium Mg
About Aluminium Al
Zoos Zinc Zn
In Iron Fe
London Lead Pb
Having (Hydrogen) H
Cute Copper Cu
Monkeys and Mercury Hg
Small Silver Ag
Gorillas Gold Au
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
5 Reactivity of metals Reactivity of metals Reactivity of metals
6 Extraction of metals Extraction of metals Alloys
7 Corrosion Importance of metals
and their compounds
on living systems and
environment
Chemical properties
of non ndash metals
8 Laboratory
preparation of gases
Laboratory
preparation of gases
Laboratory
preparation of gases
9 Uses of gases Uses of non ndash metals
and their compounds
Harmful effects of
non ndash metals and
their compounds on
living systems and
the environment
10 Green Chemistry Qualitative Analysis
ndash Identification of
cations
Qualitative Analysis
ndash Identification of
cations
2
WEEK 5 LESSON 1
TOPIC Reactivity of metals
Reactivity based on displacement reactions between metals and metal ions
A metal will displace a metal which is lower than itself in the reactivity series from a solution of
the metal salt
Reaction of zinc and copper (II) sulphate
Expected observations
Explanation
The size of the zinc metal decreases
The zinc metal is reacting and forming the
salt zinc sulphate
The solution becomes lighter eventually
colourless
The Cu2+ (aq) ions (responsible for the blue
colour) is reduced to Cu (s)
A brown solid is deposited at the bottom of
the container
Copper metal is formed
Equation Zn (s) + CuSO4 (aq) ZnSO4 (aq) + Cu (s)
Ionic equation
Zn (s) + Cu2+ (aq) Zn2+ (aq) + Cu (s)
Zinc is higher in the reactivity series than copper Therefore it will displace the copper ions in
the reaction above
3
Examples of other displacement reactions
Magnesium will displace Zn2+ ions in zinc sulphate since it is higher in the series than zinc
Mg (s) + Zn2+(aq) Mg2+ (aq) + Zn (s)
Silver will not displace Cu2+ ions in copper (II) sulphate [Cu is higher in the series than Ag]
Using the information above we can arrange the metals in order of their reactivity with
magnesium being the most reactive and silver the least reactive metal among the four metals
Mg gt Zn gt Cu gt Ag
Reactivity based on reaction with oxygen
The reactivity of metals can also be deduced from their reaction with oxygen
The table below gives the observations for the reaction with oxygen with the selected metals
Reaction of metal with oxygen
Metal Observation
Copper The surface turns black upon heating
Magnesium Ribbon burns very rapidly
Sodium Burns vigorously
Gold No reaction
Based on the observations for the 4 metals the metal with highest reactivity is sodium and the
metal with the least reactivity is gold
The 4 metals can be arranged in terms of reactivity as follows
Na gt Mg gt Cu gt Au
4
WEEK 5 LESSON 1 WORKSHEET
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
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5
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
6
WEEK 5 LESSON 2
TOPIC Reactivity of metals
Reactivity based on reactivity with acids
The metals that are higher than hydrogen in the electrochemical series react with non ndash oxidizing
acids to produce a salt and hydrogen gas
By using the same concentration of acid and same mass and size of the metals the order of
reactivity of the metals can be deduced
The table below shows the results for an experiment with the reaction of the named metals and
1 mol dm-3 hydrochloric acid
Reaction of metals with acid
Metal Observations
Silver No reaction
Magnesium Bubbles produced steadily
Calcium Bubbles produced very rapidly
Iron Bubbles produced slowly
Based on the above data the most reactive metal will be calcium with the least reactive being
silver The order of reactivity will be Ca gt Mg gt Fe gt Ag
By comparing this to the electrochemical series it can be seen that the reactivity of the metals
decrease as we go down the series
7
WEEK 5 LESSON 2 WORKSHEET
1 Place a next to the metals that will react with dilute acid and an X next to the metals
that will not react with dilute acid
Metal Reactivity with acid
Copper
Magnesium
Aluminium
Silver
Zinc
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
8
WEEK 5 LESSON 3
TOPIC Reactivity of metals
Reactivity based on ease of decomposition of the metal nitrates carbonates oxides and
hydroxides
The more reactive a metal the more difficult it is to decompose its nitrate carbonate oxide or
hydroxide on heating
For example Decomposition of carbonates
Procedure
1 Put a large spatula measure of the carbonate to be tested in a test tube
2 Fit a delivery tube and then clamp the test tube so that the delivery tube dips into a second test
tube containing 2ndash3 cm3 limewater
3 Heat the solid gently at first then more strongly
4 Lift the delivery tube from the limewater before or as soon as the heating is stopped This is to
avoid suck-back
5 Write down all observations Notice what happens to the limewater and how long it takes to turn
milky (if at all) Notice whether any melting occurs in the heated test tube and any colour
changes taking place Write your results in tabular form
6 Repeat the experiment with the other metal carbonates supplied and in each case write down
your observations
7 Wash your hands thoroughly at the end of these experiments since some of the metal carbonates
are toxic
9
Results
Metal Formula Gas evolved Ease of decomposition
Zinc ZnCO3 Carbon dioxide Fairly easy
Copper CuCO3 Carbon dioxide Easy
Sodium Na2CO3 None Very difficult
Using the results of the above activity the reactivity of the metals can be determined
Ease of decomposition Copper gt Zinc gt Sodium
The order of reactivity is the opposite for the ease of decomposition
Order of reactivity Sodium (most reactive) gt Zinc gt Copper (least reactive)
10
WEEK 5 LESSON 3 WORKSHEET
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
11
WEEK 6 LESSON 1
TOPIC Extraction of metals
Elements exist all over the earth Some are found as free elements eg copper silver and gold
Others are found combined with other elements in compounds To get the elements the
compounds have to be broken up These compounds are generally called ores the most
convenient sources of which are rocks sea and air
The extraction of a metal from its ore is a reduction process where the metals ions gain electrons
to form atoms
The general equation is Mn+ + n e- M
The choice of the extraction method depends on the position of the metal in the reactivity series
As we go down the series the metals become more stable and the metal ions (in the ores)
become less stable
The very reactive metals that are high in the series K Na Ca Mg Al have very stable ores
Therefore they require a powerful method of reduction namely electrolysis During the process
the cathode provides the electrons and acts as the reducing agent
The metals in the middle of the series (Zn Fe Pb) do not have stable ores and can be extracted
by reduction with carbon in the case of zinc and with carbon monoxide in the case of iron and
lead
Metals low in the reactivity series if present as ores can be extracted simply by heating the ores
in air at high temperatures
12
Extraction of Aluminium from purified bauxite
Pure bauxite is pure alumina (Al2O3) Aluminium is obtained from bauxite by electrolysis
Aluminium oxide has a very high melting point approximately 2050 0C so it is first dissolved in
molten cryolite (Na2AlF6) The addition of cryolite lowers the melting point to approximately
900 0C
The electrolyte is a molten mixture of alumina and molten cryolite The cathode is the graphite
lining of the cell The anodes are blocks of graphite or titanium alloys
Reaction at the cathode
Al3+ (l) + 3 e- Al (l)
Reaction at the anode
2 O2- (l) ndash 4 e- O2 (g)
Aluminium (melting point 660 0C) is a liquid at the temperature at which electrolysis is carried
out and is collected at the bottom of the cell and tapped off Oxygen gas which is given off in the
main cathode reaction together with the heat causes the anodes to burn away The anodes have
to be replaced from time to time The use of anodes from titanium alloys reduce the number of
times that the anodes have to be replaced
13
WEEK 6 LESSON 1 Worksheet
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 6 LESSON 2
TOPIC Extraction of metals
Extraction of Iron
The traditional method of production of iron is by reduction of haematite by carbon monoxide in
a blast furnace
Ores Haematite ndash Fe2O3 Magnetite ndash Fe3O4 Siderite ndash FeCO3 Magnetite and Siderite are
converted to Haematite
A mixture of haematite limestone (CaCO3) and coke (C) called the charge is placed into the top
of the furnace
Hot air is blown into the bottom of the furnace
Coke burns in air forming carbon dioxide
C (s) + O2(g) CO2 (g) ΔH -ve
The heat produced keeps the temperature at about 1900 0C
The carbon dioxide is reduced to carbon monoxide by the hot coke
CO2 (g) + C (s) 2 CO(g) Δ +ve
Heat absorbed reduces the temperature to about 1100 0C
The carbon monoxide reduces the hot iron ore to molten iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + 3 CO2(g)
The temperature at this part of the furnace is about 700 0C The iron runs to the bottom of the
furnace
The impurities are removed by the addition of limestone (CaCO3) The limestone at the
temperature of the furnace breaks down
CaCO3 (s) CaO (s) + CO2 (g)
15
The calcium oxide formed combines with silicon dioxide (sand) the main impurity in the iron
ore to form molten slag
CaO (s) + SiO2 (s) CaSiO3 (l)
The slag does not mix with the molten iron but floats on it The molten iron and slag are run off
separately
The iron formed in a blast furnace is an impure form of the metal Because the molten metal is
allowed to solidify in shallow trays known as casts the iron is called lsquocast ironrsquo or lsquopigrsquo iron
Cast iron is quite brittle and contains 2 - 4 carbon and other impurities Most of the cast iron is
converted to steel
A blast furnace used for extracting iron
16
WEEK 6 LESSON 2 Worksheet
(a) What are the three raw materials that are added through the top of the blast furnace
during the extraction process for iron
______________________________________________________________________________
______________________________________________________________________________
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
17
WEEK 6 LESSON 3
TOPIC Alloys
An alloy is a mixture of two or more metals Alloys are made by melting the individual metals
mixing them and allowing the molten mixture to solidify
In general alloys are harder stronger and more resistant to corrosion than the actual metals they
are made up from
Alloy Use Properties
ALUMINIUM
-Duralumin
(AlMgCu)
-Magnalium (AlMg)
Alloys used in the
construction of
aircraft and ships
buses
Aluminium is used in
making cooking
utensils electrical
cables paint for fuel
storage tanks bottle
caps foil and utensils
for handling nitric
acid
The alloys have a low
density They are as
light as aluminium
and more resistant to
corrosion than
aluminium
LEAD
-Solder (PbSn)
Alloy is used in
joining metals
(soldering)
Lead is used in
underground cables
plates in
The alloy has a lower
melting point than
lead and is harder
than lead
18
Alloy Use Properties
accumulators shield
against x ndash rays
IRON
- Stainless Steel
(FeCONiC)
-Tungsten steel
(FeWC)
-Invar steel (FeNi)
Manganese steel
(FeMnC)
Iron is the main metal
of a variety of
constructions
Steel is used in
cutlery rock drills
electromagnets
vehicle body and
engine parts fences
pipes etc
Steel resists
corrosion is usually
harder than iron and
may be tough though
malleable and ductile
19
WEEK 6 LESSON 3 Worksheet
(a) Define the term alloy
______________________________________________________________________________
(b) State 3 general advantages that alloys have over the individual metals they are made
from
______________________________________________________________________________
______________________________________________________________________________
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
______________________________________________________________________________
______________________________________________________________________________
Uses
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 7 LESSON 1
TOPIC Corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
Familiar examples of corrosion are
- the formation of a green powder on copper sheeting
- the eating away of iron (rusting)
- the development by aluminum of a thin compact layer of oxide which protects the
underlying metal from further corrosion
When corrosion occurs in water ndash free environment it is called dry oxidation When it occurs in
aerated aqueous environments it is called wet corrosion Wet corrosion is the most common and
troublesome form of corrosion
The most familiar corrosion is the rusting of iron and steel On exposure to the atmosphere iron
and steel corrode to form rust which is hydrated iron (III) oxide Fe2O3xH2O Iron and steel
corrode easily and the rust formed flakes off easily thus exposing fresh surface for attack
When iron rust it loses electrons
Fe (s) ndash 2e- Fe 2+ (aq)
The iron (II) ions pass into solution and then combine with the hydroxyl (OH-) ions in the
aerated aqueous environment to form iron (II) hydroxide The oxygen present oxidises the iron
(II) hydroxide to hydrated iron (III) oxide or rust
Fe(OH)2 + O2 Fe2O3xH2O
21
Methods of preventing rusting
1 Coating the object with paint grease plastic or rubber which prevent contact with air or
water
2 Galvanising ndash coating the object with zinc The zinc forms an adherent oxide layer which
protects against further corrosion If damaged the zinc is oxidized in preference to the
iron since it is higher in the electrochemical series
3 Coating with tin lsquoTinrsquo cans are made of steel plated with tin However if scratched
rusting occurs since iron is more reactive than tin
4 Attaching a sacrificial anode to the object A piece of metal higher in the electrochemical
series such as magnesium is attached The magnesium will be oxidized in preference
since it is higher in the electrochemical series than iron
22
WEEK 7 LESSON 1 WORKSHEET
(a) Define the term corrosion
______________________________________________________________________________
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
23
WEEK 7 LESSON 2
TOPIC Importance of metals and their compounds on living systems and environment
Some metals are an integral part of different structures of living things
Metal Presence and Function
Potassium Main cation in fluid or animal cells essential for healthy plant growth
Calcium Necessary for strong bones teeth and shells needed by some enzymes Present
in dairy produce eggs nuts and cereals
Magnesium Central atom of chlorophyll needed for some enzyme action Involved in energy
and calcium metabolism
Zinc Present in many enzymes Needed for protein metabolism Essential for growth
of animals
Iron Present in haemoglobin Needed for protein metabolism Essential for growth of
animals
Chromium Needed for glucose uptake by cells and thus linked to the action of insulin
Manganese Needed for bone development and amino acid metabolism Present in several
enzymes Needed for plant growth
Cobalt Present in Vitamin B12 Needed for plant growth
Copper Involved in formation of haemoglobin and melanin Present in enzymes
controlling oxidation Needed for plant growth
24
Harmful effects of metals and their compounds to living systems and the environment
There are some metals and metal compounds which may cause harm to living systems and the
environment
Lead
Lead is a heavy metal poison that is widely encountered It may occur in food beverages paint
water formed from ndash sealed pipes in air polluted by combustion by fuels containing lead
compounds Lead is also used in some car batteries If these are paints or batteries are not
disposed of correctly lead may get into groundwater or air Lead and lead compounds harm the
nervous system including the brain especially young children
Arsenic
Arsenic compounds are poisonous They can get into the groundwater from mining waste and
from disposal of some electrical components
Cadmium
Cadmium compounds are poisonous They can get into the ground by improper disposal of
nickel ndash cadmium batteries Persons can get cadmium poisoning if they eat food grown in
contaminated soil
Mercury
Mercury can be spilled from broken thermometers in hospitals and laboratories Mercury and its
compounds are particularly poisonous to fish and it can accumulate in the food chain and
eventually poison humans
Problems of disposal of solid waste
Metals may react with water andor air and corrode to form soluble compounds that are
poisonous These toxic compounds diffuse into the soil and eventually enter rivers
Rust from iron may form unsightly pools of waste that reduce plant growth
Waste from aluminium extraction may react with water and form flammable gases
25
WEEK 7 LESSON 2 WORKSHEET
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Lead
______________________________________________________________________________
Mercury
______________________________________________________________________________
26
WEEK 7 LESSON 3
TOPIC Chemical properties of non ndash metals
Reaction with oxygen
Many non ndash metals burn in excess oxygen or air to form oxides For example
S (s) + O2 (g) SO2 (g)
C (s) + O2 (g) CO2 (g)
Reactions with metals
Some non ndash metals react with metals high in the electrochemical series when heated
For example
Sodium burns in chlorine to form sodium chloride
Na (s) + Cl2 (g) NaCl (s)
Magnesium burns in oxygen to form magnesium oxide
Mg (s) + O2 (g) MgO (s)
When heated iron combines with molten sulphur to form iron (II) sulphide
Fe (s) + S (l) FeS (s)
When heated reactive metals such as sodium and aluminium react with hydrogen to form metal
hydrides
2 Na (s) + H2 (g) 2 NaH (s)
Oxidising and Reducing properties
Hydrogen and Carbon are very good reducing agents
At high temperatures hydrogen reduces metal oxides below zinc in the electrochemical series to
form the metal For example PbO (s) + H2 (g) Pb (s) + H2O (g)
Under suitable conditions hydrogen reduces nitrogen to ammonia
N2(g) + 3 H2 (g) 2 NH3 (g)
27
At high temperatures carbon reduces metal oxides below aluminium in the reactivity series to
the metal For example
ZnO (s) + C (s) Zn (s) + CO (g)
Oxygen and Chlorine are very good oxidizing agents
Oxygen oxidized most metals to form metal oxides and some non ndash metals to non ndash metal oxides
For example
2 Mg (s) + O2(g) 2 MgO (s)
4 P (s) + 5 O2 (g) P4O10 (s)
Chlorine acts as an oxidizing agent either as a gas or as an aqueous solution For example
H2 (g) + Cl2 (g) 2 HCl (g)
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
28
WEEK 7 LESSON 3 WORKSHEET
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
______________________________________________________________________________
(b) Write the ionic equation for the above reaction
______________________________________________________________________________
(c) Identify the oxidising agent in the reaction
______________________________________________________________________________
(d) Justify your answer in part (c) in terms of oxidation number
______________________________________________________________________________
29
WEEK 8 LESSON 1
TOPIC Laboratory preparation of gases
Preparation of oxygen
Oxygen can be prepared by the decomposition of hydrogen peroxide potassium chlorate (V) or
potassium nitrate The safest method is the decomposition of hydrogen peroxide
Manganese (IV) oxide catalyses the decomposition of hydrogen peroxide
Silica gel anhydrous calcium chloride or concentrated sulphuric acid can be used as a drying
agent
The gas is collected by downward delivery since it is slightly denser than air
Equation
2 H2O2 (aq) 2 H2O (l) + O2 (g)
Apparatus used for laboratory preparation of oxygen
30
WEEK 8 LESSON 1 WORKSHEET
Describe the laboratory preparation of oxygen gas
In your answer include
The starting material
A suitable catalyst
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
31
WEEK 8 LESSON 2
TOPIC Laboratory preparation of gases
Preparation of carbon dioxide
Carbon dioxide can be prepared by the action of dilute acid on carbonates Marble chips (calcium
carbonate) and dilute hydrochloric acid are the common reagents The gas is collected by
downward delivery since it is denser than air
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
Apparatus used for laboratory preparation of carbon dioxide
32
WEEK 8 LESSON 2 WORKSHEET
Describe the laboratory preparation of carbon dioxide gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
33
WEEK 8 LESSON 3
TOPIC Laboratory preparation of gases
Preparation of ammonia
Ammonia may be prepared by heating a mixture of ammonium salt and a hydroxide The
ammonia gas is collected by upward delivery since it is less dense than air
For example
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
Calcium oxide is the only suitable drying agent since ammonia reacts with conc H2SO4 and
CaCl2
Apparatus used for laboratory preparation of dry ammonia
34
11
WEEK 8 LESSON 3 WORKSHEET
Describe the laboratory preparation of ammonia gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
35
WEEK 9 LESSON 1
TOPIC Uses of gases
Carbon dioxide
Used in fire extinguishers to put out fires Carbon dioxide is denser than air and lsquoblanketsrsquo the
fire preventing oxygen from reaching it Carbon dioxide extinguishers are especially useful for
dealing with fires involving flammable liquids and electrical equipment
Carbonation in soda is created when carbon dioxide is pumped into the soda can or bottle then
held under pressure As long as the can or bottle is sealed the carbon dioxide remains mostly
stable However if the drink gets shaken up or the top is opened the tiny carbon dioxide bubbles
react by bursting
Oxygen
Oxygen is needed for aerobic respiration We need a constant supply of oxygen for this process
Oxygen is used in hospitals to improve the respiration of patients with poor blood flow blood
poisoning and heart disease
Oxygen in used in welding (joining) metals In an oxyacetylene welding torch acetylene or
ethyne (C2H2) burns in oxygen and produces a very hot flame This flame is capable of melting
most metals
Oxygen is used in steel production A blast of oxygen is blown through the molten iron The
oxygen oxidises many of the impurities of the iron and the impurities are then removed
36
WEEK 9 LESSON 1 WORKSHEET
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Put out fires
Welding metals
Create lsquofizzrsquo in drinks
Used in steel production
Aerobic respiration
37
WEEK 9 LESSON 2
TOPIC Uses of non ndash metals and their compounds
Carbon (allotrophes carbon dioxide)
Carbon is used as a reducing agent in extraction of some metals
Carbon as graphite is used as electrodes lubricants and lsquoleadrsquo for pencils
Carbon in the form of diamond is used for jewellery (because of its lustre) and in drill tips for
high ndash speed drills (because of its hardness)
Carbon dioxide is used as refrigerant (as dry ice) for carbonated beverages
Sodium hydrogen carbonate and sodium carbonate are used for water softening and raising
agent
Sulphur
Sulphur is used in the manufacture of sulphuric acid Sulphur is also used in the manufacture of
tyres to make the rubber harder (vulcanisation)
Sulphur powder is used as fungicide on plant materials
Phosphorus
Phosphorus is used in the manufacture of fertilizers
Phosphorus is used to make phosphor bronze alloys
Phosphorus sulphide is used to make the heads of lsquostrike anywherersquo matches
38
Chlorine
Chlorine is used to make sodium hypochlorite which is present in bleach It is also used in
sterilizing swimming pools and in water treatment
Chlorine is used to make the monomer vinyl chloride which is used to make the plastic PVC
Nitrogen
Nitrogen is used to make fertilisers ammonia dyes and nitric acid
Nitrogen is used as an inert atmosphere to prevent substances being oxidised and as a coolant
Silicon
Silicon is used for making silicon chips for computers
Silicon (V) oxide is present in sand Glass is made by heating sand with lime (calcium oxide) and
sodium carbonate
Silicon in the form of silicates is used in jewellery
Silica gel is used as a drying agent
39
WEEK 9 LESSON 2 WORKSHEET
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Used to make sodium hypochlorite
Used as a fungicide on plant materials
Used for lsquoleadrsquo in pencils
Used in the manufacture of bronze alloys
Used in the manufacture of nitric acid
Used in the manufacture of computer chips
Used to make fertilisers
40
WEEK 9 LESSON 3
TOPIC Harmful effects of non ndash metals and their compounds on living systems and the
environment
Sulphur dioxide
Sulphur dioxide can cause a disease of the lungs Sulphur dioxide also poisons plants in two
main ways It may enter the stomata of leaves and react with the tissue fluids to form sulphites
with the on ndash going water loss the concentration of sulphites could build up killing the cells
The second adverse effect on plants occurs when sulphur dioxide dissolves in rain thereby
increasing soil acidity A prolonged acid soil situation may lead to plasmolysis and the death of
vegetation in an area
Carbon monoxide
Carbon monoxide combines much more readily than oxygen with haemoglobin When carbon
monoxide is inhaled it prevents the haemoglobin from taking oxygen to the bodyrsquos cells
Continued breathing of air containing carbon monoxide eventually causes death
Hydrogen sulphide
Hydrogen sulphide reacts readily with many cations forming insoluble sulphides Many cations
contribute to good health by contributing to enzyme activity and to the formation of bone
pigment and haemoglobin Although these cations are required in extremely small
concentrations they are removed by being precipitated as sulphides and thus not available for
regular function Careless dumping of refuse contributes to atmospheric pollution by hydrogen
sulphide
Oxides of nitrogen
In the presence of hydrocarbons from car exhausts ozone and sunlight nitrogen oxides react to
form photochemical smog which contains many harmful chemicals
Nitrogen dioxide can harm the lungs and irritate the nose throat and eyes The other compounds
present in photochemical smog are even more harmful irritants and can cause asthma
41
Carbon dioxide
Carbon dioxide water vapour and ozone referred to as ldquogreenhouse gasesrdquo acting as a blanket
readily absorb some of the radiated heat energy and in turn warms the earthrsquos atmosphere This is
called the ldquogreenhouse effectrdquo Scientists have found direct correlation between carbon dioxide
concentration and global warming An increase in carbon dioxide concentration resulted in an
increase global temperatures Global warming is a major potential problem that the world faces
Chloroflourocarbons (CFCs)
It is believed that CFCs might be responsible for destroying the ozone layer which prevents
harmful ultraviolet (UV) radiation from reaching the earth The carbon ndash chlorine bond in CFC
molecule is easily broken by a UV photon producing an active chlorine atom This atom
combines with an ozone molecule forming a chlorine oxide radical and oxygen The radicle
reacts with more ozone producing the chlorine atom again This kind of reaction is repeated
thousands of times This type of reaction is thought to account for about eighty percent of the
loss of ozone observed
Nitrates and phospates
Nitrates and phosphates cause eutrophication The process leading to eutrophication are
Nitrates and phosphates from fertilisers spread on fields may dissolve in groundwater and
get into lakes and rivers
Nitrates and phosphates cause excessive growth of algae so that they cover the surface of
the water
Water plants including algae die because of lack of sunlight Aerobic bacteria feed on
the plant remains The bacteria multiply
The aerobic bacteria use up the oxygen in the water so aquatic animals die
42
Solid waste
The main sources of pollution from non ndash metals is from glass paper and plastics
Broken glass can cause injury to animals It can also cause fires by acting as lens focusing the
sunrsquos rays on flammable materials
Printing inks from paper dumped in the ground may contain toxic elements such as arsenic and
cadmium Bleaches and chlorine compounds from paper are also harmful
43
WEEK 9 LESSON 3 WORKSHEET
Describe ONE harmful effect of the following non ndash metals andor their compounds on
living systems and the environment
Sulphur dioxide
______________________________________________________________________________
______________________________________________________________________________
Carbon monoxide
______________________________________________________________________________
______________________________________________________________________________
Carbon dioxide
______________________________________________________________________________
______________________________________________________________________________
Oxides of nitrogen
______________________________________________________________________________
______________________________________________________________________________
Hydrogen sulphide
______________________________________________________________________________
______________________________________________________________________________
44
Chloroflourocarbons (CFCs)
______________________________________________________________________________
______________________________________________________________________________
Nitrates and phospates
______________________________________________________________________________
______________________________________________________________________________
45
WEEK 10 LESSON 1
TOPIC Green Chemistry
Green Chemistry is defined as the utilisation of a set of principles that reduces or eliminates the
use and generation of hazardous substances
There are twelve principles of green chemistry as proposed by Paul T Anastas and John C
Warner These twelve principles are
1 Prevention ndash It is better to prevent waste than to treat or clean up waste after it has been
created
2 Atom economy - Synthetic methods should be designed to maximize the incorporation of
all materials used in the process into the final product
3 Less hazardous chemical synthesis - Wherever practicable synthetic methods should be
designed to use and generate substances that possess little or no toxicity to human health
and the environment
4 Safer chemical products - Chemical products should be designed to affect their desired
function while minimizing their toxicity
5 Safer solvents and other agents - The use of auxiliary substances (eg solvents
separation agents etc) should be made unnecessary wherever possible and harmless
when used
6 Minimum energy requirements - Energy requirements of chemical processes should be
recognized for their environmental and economic impacts and should be minimized If
possible synthetic methods should be conducted at ambient temperature and pressure
7 Use of renewable raw materials - A raw material or feedstock should be renewable rather
than depleting whenever technically and economically practicable
8 Reduce use of additional chemicals or additional steps - Unnecessary derivatization (use
of blocking groups protection deprotection temporary modification of
physicalchemical processes) should be minimized or avoided if possible because such
steps require additional reagents and can generate waste
46
9 Use of catalysts ndash The use of catalysts reduce energy costs because the reactions take
place at lower temperatures The more specific the catalyst for a particular reaction is the
less it the likelihood of getting additional unwanted products
10 Nature of breakdown of products - Chemical products should be designed so that at the
end of their function they break down into innocuous degradation products and do not
persist in the environment
11 Monitoring to prevent pollution - Analytical methodologies need to be further developed
to allow for real-time in-process monitoring and control prior to the formation of
hazardous substances
12 Minimise chemical accidents - Substances and the form of a substance used in a chemical
process should be chosen to minimize the potential for chemical accidents including
releases explosions and fires
47
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
48
WEEK 10 LESSON 2
TOPIC Qualitative Analysis ndash Identification of cations
Qualitative Analysis involves identifying the constituents of single substances or mixture of
substances
Appearance
An examination of the appearance of a substance can indicate which ion it contains
Appearances of substances
Observation Indication
Blue or blue ndash green Cu2+ salt
Pale green Fe2+ salt
Yellow ndash brown Fe3+ salt
Ammonia smell NH4+ salt
49
Test for cation using sodium hydroxide
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
(d) If no precipitate forms in step b warm gently and test for ammonia
Effect of dilute sodium hydroxide solution
Effect of dilute sodium hydroxide solution Cation
Dropwise Excess
White precipitate Precipitate soluble Ca2+
White precipitate Precipitate insoluble Al3+ Pb2+ Zn2+
Blue precipitate Precipitate insoluble Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
No precipitate ndash ammonia gas
evolved on heating
ndash NH4+
The metal cations all form insoluble hydroxides with sodium hydroxide solution
For example Ca2+ (aq) + 2 OH- (aq) Ca(OH)2 (s)
Ca(OH)2 Cu(OH)2 Fe(OH)2 and Fe(OH)3 are basic and therefore do not react with excess
sodium hydroxide solution Therefore the precipitate does not dissolve in excess sodium
hydroxide solution
Al(OH)3 Pb(OH)2 and Zn(OH)2 are amphoteric Therefore the precipitates react with the excess
sodium hydroxide solution forming soluble salts and the precipitate disappears in excess sodium
hydroxide solution
The NH4+ ion forms a soluble hydroxide However on heating it reacts with the hydroxide ion to
form ammonia and water
NH4+ (aq) + OH- (aq) NH3 (g) + H2O (l)
50
WEEK 10 LESSON 2 WORKSHEET
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P _____________ Q ___________________
R _____________ S ___________________
R + NaOH
______________________________________________________________________________
51
WEEK 10 LESSON 3
TOPIC Qualitative Analysis ndash Identification of cations
Test for cation using ammonia solution (ammonium hydroxide solution)
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
Effect of dilute ammonia (ammonium hydroxide) solution
Effect of dilute ammonia solution Cation
Dropwise Excess
No precipitate ndash Ca2+
White precipitate Precipitate soluble
(forming colourless solution)
Zn2+
White precipitate Precipitate insoluble Al3+ Pb2+
Blue precipitate Precipitate soluble
(forming deep blue solution)
Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
52
Ammonia solution is a weak alkali Metal cations except Ca2+ form insoluble hydroxides with
ammonia solution as with the sodium hydroxide solution
The amphoteric hydroxides Al(OH)3 and Pb(OH)2 and the basic hydroxides Fe(OH)2 and
Fe(OH)3 do not react with excess ammonia solution Therefore the precipitates remain
However Zn(OH)2 and Cu(OH)2 do react with excess ammonia solution to form complex
soluble hydroxides each Hence their precipitates disappear on the addition of excess ammonia
solution
Confirmatory test
After carrying out test for cations using sodium hydroxide solution and ammonia solution the
only cations which cannot be distinguished are Al3+ and Pb2+ A confirmatory test is carried out
to distinguish between the two cations
Confirmatory test
Test Observation Cation Ionic equation
Add potassium
or sodium
iodide solution
Bright yellow precipitate
No precipitate
Pb2+
Al3+
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
53
WEEK 10 LESSON 3 WORKSHEET
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A __________ B ________________ C ________________________
(b) State the inference after Test 2
C _______________________
(c) Write an ionic equation to support your answer in (b) above
___________________________________________________________________________
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
54
ANSWERS TO WORKSHEETS
55
WEEK 5 LESSON 1 WORKSHEET ANSWERS
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
Answer
Zinc + Iron (II) sulphate Zinc is higher in the electrochemical series and therefore displace
iron ions in iron (II) sulphate
Equation Zn (s) + FeSO4 (aq) ZnSO4 (aq) + Fe (s)
Ionic equation Zn (s) + Fe2+ (aq) Zn2+ (aq) + Fe (s)
Iron + Zinc sulphate No reaction iron is lower in the electrochemical series and cannot
displace the zinc ions in zinc sulphate
56
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
Answer
X displaces lead from an aqueous solution of its salts
X (s) + Pb2+ (aq) Xn+ (aq) + Pb (s)
rarr X is more reactive than Pb
X did not react with iron salts
rarr X is less reactive than Fe
Y burns very easily
Y is more reactive than Fe and Pb (both forming their corresponding oxide at a slower rate)
From electrochemical series Fe is higher and therefore more reactive than Pb
Order of reactivity
Y (most reactive) gt Fe gt X gt Pb (least reactive)
57
WEEK 5 LESSON 2 WORKSHEET ANSWERS
1
Metal Reactivity with acid
Copper X
Magnesium
Aluminium
Silver X
Zinc
58
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
Answer
Y and Z are the most reactive since they can react with dilute acid
Z is more reactive than Y since a reaction occurs with Z is added to an aqueous solution of Y
X is less reactive than W since it does not occur in nature as compounds
Order of reactivity Z (most reactive) gt Y gt W gt X
59
WEEK 5 LESSON 3 WORKSHEET ANSWERS
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
Answer
Ease of decomposition (from easiest to decompose to most difficult to decompose)
B rarrD rarrArarr C
Reactivity (most reactive to least reactive)
C (most reactive) gt A gt D gt B (least reactive)
60
WEEK 6 LESSON 1 Worksheet Answers
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
Potassium Zinc Copper
Calcium Lead Gold
Magnesium Iron
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
Aluminium is extracted from its ore bauxite through the process of electrolysis
Cryolite is added to bauxite to lower the melting point to about 900 0C The melting point of
bauxite is very high (about 2040 0C) It is difficult and expensive to keep the molten aluminium
oxide at this temperature
Reaction at the cathode Al3+ (l) + 3 e- Al (l)
61
WEEK 6 LESSON 2 Worksheet Answers
(a) What are the three raw materials that are added through the top of the blast
furnace during the extraction process for iron
Coke (carbon)
iron ore (haematitie mainly iron (II) oxide)
limestone (calcium carbonate)
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
Coke ndash coke burns to produce carbon dioxide The carbon dioxide further reacts with coke to
form carbon monoxide (reducing agent in the process)
C (s) + O2 (g) CO2 (g)
C (s) + CO2 (g) 2 CO
Haematite ndash iron ore provides the iron which is reduced by the carbon monoxide to produce
iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + CO2 (g)
Limestone ndash decomposes to form calcium oxide The calcium oxide reacts with the impurity
silicon dioxide to form slag (calcium silicate)
CaCO3 (s) CaO (s) + CO2 (g)
CaO (s) + SiO2 (l) CaSiO3(l)
62
WEEK 6 LESSON 3 Worksheet Answers
(a) Define the term alloy
An alloy is a material made from a mixture of two or more metals
(b) State 3 general advantages that alloys have over the individual metals they are made
from
They are harder stronger and more resistant to corrosion
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
1 High strength
2 Low density
Uses
1 Used to make aircraft bodies
2 Used to make space satellites
63
WEEK 7 LESSON 1 WORKSHEET ANSWERS
(a) Define the term corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
The paint forms a barrier which stops contact with air or water and the iron Hence rusting
will not take place
However when the paint is scratched that part of the iron nail is exposed to air or water and
rusting will take place
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
Magnesium is higher in the electrochemical series and will be oxidised in preference to iron
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
Aluminium is partly protected from corrosion by its coat of aluminium oxide However as the
iron rust it flakes and fall off and the rusting process continues
64
WEEK 7 LESSON 2 WORKSHEET ANSWERS
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
Magnesium is the ion found in chlorophyll Chlorophyll plays a vital part in the process of
photosynthesis A deficiency in magnesium will lead to low chlorophyll level in the tomato
plants and hence reduce the process of photosynthesis There will be less food storage and
hence will lead to smaller yield of tomatoes
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Any correct harmful effect of lead on health or environment
Any correct harmful effect of mercury on health or environment
65
WEEK 7 LESSON 3 WORKSHEET ANSWERS
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
(b) Write the ionic equation for the above reaction
2 Br- (aq) + Cl2 (aq) 2 Cl- (aq) + Br2 (aq)
(c) Identify the oxidising agent in the reaction
Cl2 (aq)
(d) Justify your answer in part (c) in terms of oxidation number
There is a reduction of the oxidation number for chlorine from 0 to ndash1
hence it has been reduced Therefore chlorine is the oxidising agent
66
WEEK 8 LESSON 1 WORKSHEET ANSWERS
Describe the laboratory preparation of oxygen gas
Oxygen is prepared in the laboratory by the decomposition of hydrogen peroxide
A suitable catalyst is manganese (IV) oxide
Drying agent silica gel OR anhydrous calcium chloride OR conc sulphuric acid
The gas is collected by downward delivery since oxygen is slightly denser than air
Balanced chemical equation 2 H2O2 (aq) 2 H2O (l) + O2 (g)
67
WEEK 8 LESSON 2 WORKSHEET ANSWERS
Describe the laboratory preparation of carbon dioxide gas
Carbon dioxide is commonly prepared in the laboratory by the reacting hydrochloric acid and
marble chips (calcium carbonate)
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
The carbon dioxide gas is collected by downward delivery since it is denser than air
Balanced chemical equation
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
68
WEEK 8 LESSON 3 WORKSHEET ANSWERS
Describe the laboratory preparation of ammonia gas
An ammonium salt (ammonium chloride) and a base (sodium hydroxide) are mixed together and
heated
Calcium oxide is used as the drying agent Calcium chloride and concentrated sulphuric acid
cannot be used since ammonia can react with them
The gas is collected by upward delivery since ammonia is less dense than air
Balanced chemical equation
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
69
WEEK 9 LESSON 1 WORKSHEET ANSWERS
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Carbon dioxide Put out fires
Oxygen Welding metals
Carbon dioxide Create lsquofizzrsquo in drinks
Oxygen Used in steel production
Oxygen Aerobic respiration
70
WEEK 9 LESSON 2 WORKSHEET ANSWERS
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Chlorine Used to make sodium hypochlorite
Sulphur Used as a fungicide on plant materials
Carbon (graphite) Used for lsquoleadrsquo in pencils
Phosphorus Used in the manufacture of bronze alloys
Nitrogen Used in the manufacture of nitric acid
Silicon Used in the manufacture of computer chips
Nitrogen Phosphorus Used to make fertilisers
71
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
Green Chemistry is using principles that reduceeliminate the use of hazardous materials in
the design manufacture and application of chemical products
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
Makes the environment safer
Reduces waste
Creates new jobs
Reduces respiratory illnesses
Atom economy
72
WEEK 10 LESSON 2 WORKSHEET ANSWERS
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P Cu2+ Q Fe2+
R Fe3+ S Ca2+
Ionic equation for R + NaOH
Fe3+ (aq) + 3 OH- (aq) Fe(OH)3 (s)
73
WEEK 10 LESSON 3 WORKSHEET ANSWERS
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A Fe3+ B Ca2+ C Al3+ Pb2+
(b) State the inference after Test 2
C Pb2+
(c) Write an ionic equation to support your answer in (b) above
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
11 Qualitative Analysis
ndash Test for gases
Qualitative Analysis
ndash Identification of
anions
Qualitative Analysis
ndash Identification of
anions
12 Problem solving of
Past CSEC Chemistry Paper 2
on topics completed in the term
13
14
15
2
WEEK 11 LESSON 1
TOPIC Qualitative Analysis ndash Test for gases
Identification of gases
Gas Colour Odour Effect on moist
litmus
Method of identification
Oxygen
O2
Colourless Odourless Neutral ndash no
effect
Relights a glowing splint
Hydrogen
H2
Colourless Odourless Neutral ndash no
effect
Lighted splint lsquopopsrsquo if air is also
present
Carbon
dioxide
CO2
Colourless Odourless Weakly acidic ndash
blue to slightly
red
A white precipitate forms in
limewater
Ca(OH)2 (aq) + CO2
CaCO3 (s) + H2O (l)
Precipitate redissolves on
continued bubbling
CaCO3 (s) + H2O (l) + CO2 (g)
Ca(HCO3)2 (aq)
Ammonia
NH3
Colourless Pungent Alkaline ndash red
to blue (only
common
alkaline gas)
Turns moist red litmus blue forms
dense white fumes with hydrogen
chloride gas
NH3 (g) + HCl (g) NH4Cl (s)
Gas Colour Odour Effect on moist
litmus
Method of identification
3
Sulphur
dioxide
SO2
Colourless Choking
smell
Acidic ndash blue to
red
Turns acidified potassium
manganate (VII) solution from
purple to colourless
Turns acidified potassium
dichromate (VI) solution from
orange to green
Chlorine
Cl2
Yellow ndash
green
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Bromine
Br2
Red ndash
brown
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Nitrogen
dioxide
NO2
Red ndash
brown
Irritating
smell
Acidic blue to
red
Turns moist blue litmus red but
does not bleach it
Water
vapour
H2O
Colourless Odourless Neutral ndash no
effect
Turns anhydrous cobalt (II)
chloride from blue to pink
Turns anhydrous copper (II)
sulphate from white to blue
4
WEEK 11 LESSON 1 WORKSHEET
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless
Yellow ndash green
Red ndash brown
Gases according to their odour
Odour of gas Identity of gas
Odourless
Pungent smell
Choking smell
Irritating smell
5
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect
Red to blue
Blue to red
Blue to red then bleaches it
6
WEEK 11 LESSON 2
TOPIC Qualitative Analysis ndash Identification of anions
Effect of heating
Method Heat a sample of the solid in a dry test tube
Effect of heating
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) not
of K or Na
CO32- (s) O2- (s) + CO2 (g)
Oxygen evolved NO3- of K or Na 2 NO3
- (s) 2 NO2- (s) + O2
(g)
Oxygen and nitrogen
dioxide evolved
NO3- of Ca and below
in reactivity series
4 NO3- (s) 2 O2- (s) + 4 NO2
(g) + O2
(g)
Sulphur dioxide evolved SO32- SO3
2- O2- (s) + SO2 (g)
Effect of dilute acid
Add dilute hydrochloric acid or nitric acid to a sample of the solid Warm if no reaction occurs
when cold
Effect of dilute acid
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) CO32- (s) + 2 H+ (aq) H2O (l) + CO2 (g)
Sulphur dioxide evolved SO32- SO3
2- (s) + 2 H+ (aq) H2O (l) + SO2 (g)
7
Effect of concentrated acid
Add concentrated sulphuric acid to a sample of the solid Warm if not reaction occurs when cold
Effect of concentrated sulphuric acid
Observation Anion
Carbon dioxide evolved CO32- or HCO3
-
Sulphur dioxide evolved SO3-
Hydrogen chloride evolved Cl-
Hydrogen bromide (colourless) and bromine
vapour (brown) evolved
Br-
Black iodine present and purple iodine vapour
evolved
I-
8
WEEK 11 LESSON 2 WORKSHEET
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater
Produces a gas which relights a glowing splint as the only gas
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green
Produces a gas forms a precipitate in limewater
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia
Black iodine present and purple iodine vapour evolved
9
WEEK 11 LESSON 3
TOPIC Qualitative Analysis ndash Identification of anions
Test for the halides ndash using silver nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous silver nitrate and
observe the precipitate Add ammonia solution and observe the solubility of the precipitate
Test for halides using silver nitrate solution
Effect of silver
nitrate solution
Anion Explanation Effect of aqueous
ammonia
White precipitate ndash
turns white in
sunlight
Cl- Ag+ (aq) + Cl- AgCl (s) Precipitate soluble
Cream precipitate ndash
turns yellow ndash green
in sunlight
Br- Ag+ (aq) + Br- AgBr (s) Precipitate slightly
soluble
Pale yellow
precipitate
I- Ag+ (aq) + I- AgI (s) Precipitate insoluble
Test for the halides ndash using lead nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous lead nitrate and
observe the precipitate
Test for halides using lead nitrate solution
Effect of lead nitrate solution Anion Explanation
White precipitate Cl- Pb2+ (aq) + 2 Cl- PbCl2 (s)
Pale yellow Br- Pb2+ (aq) + 2 Br- PbBr2 (s)
Deep yellow I- Pb2+ (aq) + 2 I- PbI2 (s)
10
Effect of barium nitrate or chloride solution followed by dilute acid
Make a solution of the solid Add barium nitrate or chloride solution and observe the precipitate
Add dilute hydrochloric or nitric acid warn if necessary and observe the solubility of the
precipitate
Effect of barium nitrate or chloride solution followed by dilute acid
Effect of
Ba(NO3)2 (aq)
or BaCl2 (aq)
Effect of HCl (aq)
or HNO3 (aq)
Anion Explanation
White precipitate Precipitate insoluble SO42- Ba2+ (aq) + SO4
2- (aq) BaSO4 (s)
BaSO4 does not react with dilute acids
White precipitate Precipitate soluble ndash
CO2 evolved
CO32- Ba2+ (aq) + CO3
2- (aq) BaCO3 (s)
BaCO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + CO2 (g)
White precipitate Precipitate soluble ndash
SO2 evolved on
warming
SO32- Ba2+ (aq) + SO3
2- (aq) BaSO3 (s)
BaSO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + SO2 (g)
11
WEEK 11 LESSON 3 WORKSHEET
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
(Ionic equation required)
12
WEEK 12 LESSON 1 WORKSHEET
(a) The Caribbean islands are known for their many resources For example the ore of
aluminium is found in Jamaica and Guyana
(i) Briefly describe the extraction of aluminium from its named ore Include in your
description one ionic equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Although aluminium ore is mined in the Caribbean the extraction of aluminium usually
takes place in other countries Suggest ONE reason why it may be difficult to extract
aluminium in the Caribbean
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) An alloy can be described as a lsquomixed metal solutionrsquo Aluminium forms an alloy with
magnesium that is used to make an aircraft
13
Identify this alloy and suggest why it is better to use it rather than the pure metal in the
manufacture of aircraft
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) ldquoSome metals can be useful to man yet harmful to the environmentrdquo Comment on this
statement with reference to mercury
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 12 LESSON 2 Worksheet
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate formed
Soluble in excess
15
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate formed
Insoluble in excess
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate formed
(Ionic equation required)
16
WEEK 12 LESSON 3 Worksheet
Dry ammonia gas can be produced in a school laboratory
(a) Identify TWO reagents that are necessary for the laboratory production of ammonia
______________________________________________________________________________
______________________________________________________________________________
(b) Two common drying agents used in the laboratory are calcium oxide and concentrated
sulphuric acid However calcium oxide is the preferred choice for drying ammonia gas
Explain why concentrated sulphuric acid is now used Include in your answer a balanced
chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) When gases are prepared in the laboratory there are three main ways in which they can
be collected
- Upward delivery
- Downward delivery
- Displacement of water
(i) What TWO other factors should be considered when choosing an appropriate method for
the collection of gases in the laboratory
______________________________________________________________________________
______________________________________________________________________________
(ii) Identify ONE of the three methods that is best suited for the collection of ammonia gas in
the laboratory Explain why EACH of the other two methods would NOT have been
appropriate
______________________________________________________________________________
17
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(d) Hence draw a labelled diagram of the apparatus which could be used for the preparation
of dry ammonia in the laboratory
Be sure to identify in your diagram
- where the reagents are placed
- where the ammonia is dried and
- where the ammonia is collected
18
WEEK 13 LESSON 1 Worksheet
(a) In solution two metals A and B form A+ and B2+ ions respectively Metal A displaces Fe
from a solution containing Fe2+ ions but metal B does NOT
(i) Arrange the metals A B and Fe in order of reactivity from LEAST reactive to MOST
reactive Write a balanced chemical equation to show the reaction between metal A and
Fe2+ ions
______________________________________________________________________________
______________________________________________________________________________
(ii) Metal A is placed in a solution of copper (II) sulphate CuSO4 (aq) Write an equation for
the reaction State ONE observable change that will occur and explain why this reaction
takes place
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) For EACH metal A and B state ONE method that can be used to extract it from its
respective oxide Give a reason for EACH answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
19
______________________________________________________________________________
(b) Metal alloys are often used for making objects found in our daily lives Name an alloy of
iron and state ONE of its uses
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 13 LESSON 2 Worksheet
(a) Many important biological processes in plants and animals depend on the specific roles
of certain metal ions
(i) Farmer Jones reaped a crop of tomatoes and reported that the yield was far below what
was expected Analysis of the soil revealed that there was a deficiency of magnesium
Discuss the importance of magnesium in plant health and explain how a magnesium
deficiency can result in the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE other metal ion which is important to plant health and state the result of its
deficiency
______________________________________________________________________________
______________________________________________________________________________
21
(b) Many years ago car exhaust fumes were known to contain compounds of metals and
non ndash metals which could negatively impact both humans and the environment Identify
ONE metal and ONE non ndash metal whose compounds were present in car exhaust fumes
Discuss the effect of these compounds on human health and the environment
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) Define lsquogreen chemistryrsquo and discuss the measures that have been taken to produce a
lsquogreenerrsquo automotive fuel
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
22
WEEK 13 LESSON 3 Worksheet
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
Zn2+ ions are present
23
WEEK 14 LESSON 1 Worksheet
(a) Metal alloys are often used in place of metals because of their enhanced properties
(i) Define the term lsquoalloyrsquo
______________________________________________________________________________
______________________________________________________________________________
(ii) Name ONE alloy of aluminium and state its use based on one of its enhanced properties
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) A student conducted an experiment to investigate the reactivity of each of the following
metals (copper iron zinc and lead) by using solutionPs of their sulphate salts
The data presented in the table below shows whether a visible chemical reaction took
place when each metal was added to the four sulphate solutions
Key Visible chemical reaction took place
X No visible chemical reaction
CHEMICAL REACTION OF METALS IN SULPHATE SOLUTIONS
Sulphate solution Cu Fe Zn Pb
CuSO4 X
FeSO4 X X X
ZnSO4 X X X X
PbSO4 X X
24
(i) State which of the TWO metals is more reaction Fe or Zn Give a reason for our answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Using the data in the previous Table deduce the order of reactivity of the four metals Cu
Fe Zn and Pb from the most reactive to the least reactive metal
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The student recorded the following observations from the reaction between the iron and
copper (II) sulphate solution
Observations Reddish ndash brown solid coating formed on the iron strip
Blue colour of the solution changed to dirty green
Account for the observations made from the reaction between the iron and copper (II)
sulphate solution
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iv) Write an ionic equation including state symbols for the reaction between the iron and
copper (II) sulphate solution
______________________________________________________________________________
25
(c) Some metal compounds are health and environmental hazards
(i) Identify which of the metals used in the experiment in (b) is MOST hazardous to the
environment
______________________________________________________________________________
______________________________________________________________________________
(ii) State TWO harmful effects of continuous exposure to the metal identified in (c) (i) on
human beings
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
26
WEEK 14 LESSON 2 Worksheet
(a) Carbon is found in the form of diamond and graphite and is a main component in many
naturally occurring compounds such as organic matter and carbon dioxide gas
(i) State ONE way in which diamond differs physically from graphite
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE similarity between diamond and graphite other than they both contain carbon
______________________________________________________________________________
______________________________________________________________________________
(b) Carbon can react with a limited supply of oxygen to form carbon monoxide which can
negatively affect human health
(i) Write a balanced chemical equation including state symbols to show the formation of
carbon monoxide
______________________________________________________________________________
(ii) State TWO effects of carbon monoxide inhalation on the human body
______________________________________________________________________________
______________________________________________________________________________
(c) Jamal wants to prepare and collect a sample of carbon dioxide gas in the laboratory using
calcium carbonate
(i) Write a balanced chemical equation including state symbols for the laboratory
preparation of carbon dioxide gas from calcium carbonate
______________________________________________________________________________
______________________________________________________________________________
(ii) Draw a clearly labelled diagram to show the arrangement of the apparatus and materials
that could be used in the laboratory to prepare and collect the carbon dioxide gas
(iii) State ONE use of carbon dioxide as it relates to the beverage industry
______________________________________________________________________________
27
WEEK 14 LESSON 3 Worksheet
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
(Ionic equation required)
Suggest a possible identity of the solid R __________________________
28
WEEK 15 LESSON 1 Worksheet
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a small
portion of solid Y gently at
first and then strongly
Colourless gas evolved
with a choking odour
Turns acidified potassium
dichromate solution from
orange to green
(ii) To the remaining portion
of solid Y add 20 cm3 of
distilled water stir to dissolve
and filter Collect the filtrate
and divide into 3 equal
portions
Filtrate is pale green in
colour
(iii) To the first portion of the
filtrate from (ii) add aqueous
sodium hydroxide slowly
until in excess
A green precipitate
Insoluble in excess sodium
hydroxide
Ionic equation required
29
TEST OBSERVATIONS INFERENCES
(iv) To the second portion of
the filtrate from (ii) add
aqueous silver nitrate
followed by aqueous
ammonia
White precipitate
Soluble in aqueous
ammonia
(v) To the third portion of the
filtrate from (ii) add aqueous
barium nitrate followed by
aqueous hydrochloric acid
White precipitate formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with the
evolution of a colourless
gas with a choking smell
30
WEEK 15 LESSON 2 Worksheet
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
31
WEEK 15 LESSON 3 Worksheet
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in excess
aqueous NH3
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change
32
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
warm filter and then divide
the filtrate into two portions
Vigorous effervescence
observed upon addition of
dilute HNO3
Gas evolved turns lime water
cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Cu2+ ions present
33
ANSWERS TO WORKSHEETS
34
WEEK 11 LESSON 1 WORKSHEET ANSWERS
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless O2 H2 CO2 NH3 SO2 H2O
Yellow ndash green Cl2
Red ndash brown Br2 NO2
Gases according to their odour
Odour of gas Identity of gas
Odourless O2 H2 CO2 H2O
Pungent smell NH3
Choking smell SO2 Cl2 Br2
Irritating smell NO2
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect Neutral O2 H2 H2O
Red to blue Alkaline NH3
Blue to red Acidic CO2 SO2 NO2
Blue to red then bleaches it Acidic Cl2 Br2
35
WEEK 11 LESSON 2 WORKSHEET ANSWERS
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-) not
of K or Na
Produces a gas which relights a glowing splint as the only gas NO3- of K or Na
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green SO32-
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-)
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia Cl-
Black iodine present and purple iodine vapour evolved I-
36
WEEK 11 LESSON 3 WORKSHEET ANSWERS
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Br-
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
Cl-
Ag+ (aq) + Cl- AgCl (s)
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow Br-
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
SO42-
Ba2+ (aq) + SO42- (aq)
BaSO4 (s)
(Ionic equation required)
37
WEEK 12 LESSON 1 Worksheet Answers
(a) (i)
The ore bauxite is purified
The purified bauxite is dissolved in molten cryolite
The aluminium oxidecryolite solution is then eletrolysed
Equation at the cathode Al3+ (l) + 3 e- Al (l)
Equation at the anode 2 O2- (l) ndash 4 e- O2 (g)
(ii) The process is too expensive mainly because too much electricity or energy is needed
(b) The alloy of Al and Mg is magnalium It is less dense than the pure metals and hence allow
aircraft to be lighter It is also stronger than the pure metals and hence allows aircraft to last
longer since it is not easily destroyed
(c) Your answer should cater for the following aspects
Benefits of mercury to humans for example in thermometers barometers in dentistry
and gold mining
Entry of mercury to the environment For example this could have been through broken
thermometers barometers or lightbulbs or improper disposal of them or batteries and
indiscriminate use in gold mining in Guyana
The identification of a negative impact on the environment such as poisoned fish and the
persons who eat the fish death mood swings and psychosis
38
WEEK 12 LESSON 2 Worksheet Answers
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas
evolved
NO2 evolved OR nitrates
present OR
Br2 gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate
formed
Soluble in excess
Pb2+ Zn2+ Al3+ or Ca2+
present
Pb2+ Zn2+ Al3+ or present
39
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate
formed
Insoluble in excess
Pb2+ Zn2+ Al3+ or present
Pb2+ or Al3+ present
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate
formed
Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
40
WEEK 12 LESSON 3 Worksheet Answers
(a) an ammonium salt and a strong alkali
(b) Ammonia is basic and it will react with H2SO4
Equation 2 NH3 (aq) + H2SO4 (aq) (NH4)2SO4 (aq)
(c) (i) ndash Density of the gas relative to air ndash The solubility of the gas in water
(ii) Ammonia is collected by upward delivery
It cannot be collected by downward delivery since ammonia is less dense than air
It cannot be collected by displacement of water since it is soluble in water
(d)
41
WEEK 13 LESSON 1 Worksheet Answer
a) i) B ˂ Fe ˂ A
2A (s) + Fe 2+ (aq) rarr 2A+ (aq) + Fe (s)
ii) 2A (s) + CuSO4 (aq) rarr A2SO4 (aq) + Cu (s)
Observation blue colour fades gets lighter OR brown solid forms is deposited OR metal A
decreases in size dissolves
Explanation Metal A is higher (than Fe which is higher) than Cu in the reactivity series OR
Metal A is more reactive (than Fe which is more reactive) than Cu so Metal A can displace Cu
iii) Metal A can be extracted by electrolysis (of its molten oxide) because Metal A is a very
reactive metal is high in the reactivity series forms stable oxides needs a lot of energy to be
extracted and very reactive metals are extracted by electrolysis
Metal B can be extracted by heating with carbon carbon monoxide OR by chemical reduction
of the oxide because Metal B is less reactive than Fe is low in the reactivity series forms less
stable oxides does not need a lot of energy to be extracted and oxides of less reactive metals are
easily reduced
b) Alloy of iron steel
Use of alloy making buildings bridges ships motor vehicles furniture utensils
42
WEEK 13 LESSON 2 Worksheet Answer
(a) (i)
Magensium is the metal ion found in chlorophyll
Chlorophyll is essential for photosynthesis
A deficiency in magnesium will result in low chlorophyll yellow leaves and a reduction in
photosynthesis
Hence there will be low carbohydrates or energy production
Hence small fruits stunted growth and lower yield will result
(ii)
Metal ion Results of deficiency
Potassium Stunted growth premature loss of leaves yellowing of leaves curling of leaf tips
Calcium Growth abnormalities in tips of roots and shoots curling of leaves
Iron Yellowing of leaves
Zinc Low chlorophyll content yellowing of leaves
Manganese Yellowing of leaves poor flavors in some crops for example potato
(b)
Metal Lead is present in some types of gasoline Upon combustion lead compounds escape into
the atmosphere It accumulates in body tissues and slowly poisons the person It causes mental
illness
Non ndash metal SulphurSulphur dioxide or NitrogenNitrogen dioxide
Dissolves in rain water to form acid rain or cause respiratory illnessproblems Acid rain can
cause corrosion damage in buildings
(c)
Green chemistry is the utilisation of a set of principles that reduces or eliminates the use or
generation of hazardous substances
43
Automotive fuels are now produced without lead so as to eliminate the release of lead
compounds into the atmosphere
Low sulphur fuel is being produced with much reduced sulphur content which causes a reduction
of sulphur dioxide release into the atmosphere
44
WEEK 13 LESSON 3 Worksheet Answer
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
gas turns litmus blue
red
brown gas
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
white precipitate
precipitate soluble in
excess
Zn2+ ions are present
45
WEEK 14 LESSON 1 Worksheet Answers
(a)(i) An alloy is a material made from a mixture of two or more metals
(ii) Any suitable answer chosen from below
Alloy Enhance Property Use
Duralumin High strength
Low density
Light
Hard
Used to make aircraft bodies
space satellites
Magnalium Light
Hard
Easier to weld
Corrosion resistant
Strong
High ductability
Used in pyrotechnics
(fireworks)
Mirrors
Aircraft parts
To make scientific
instruments
Used to make marine castings
Alchlad Strong
Corrosion resistant
Cladding for buildings
(b) (i) Zinc is more reactive than iron
Zinc displaces iron from iron (II) sulphate
Zinc is higher in the reactivity series than iron
Iron does not displace zinc from zinc sulphate
(ii) Order of reactivity Zn gt Fe gt Pb gt Cu
(iii) Reddish brown solid ndash copper metal formed
46
Dirty green solution ndash presence of Fe2+ ion
(iv) Fe (s) + Cu2+ (aq) Fe2+ (aq) + Cu (s)
(c) (i) Lead
(ii) Any two correct harmful effects of lead on the body
Impedes brain development (in young children)
Affectimpede development of the immune system in humans
Affecthamper development of nervous system in humans
Long term exposure can result in kidney and liver damage
Mental retardation
Anaemia
Death
47
WEEK 14 LESSON 2 Worksheet Answers
a) i) Diamond is transparent clear Graphite is opaque black
OR hard OR brittle
OR does not conduct electricity OR conducts electricity
a) ii) Both have a macromolecular giant molecular giant covalent structure (lattice)
OR Both have high melting point boiling point
OR Both are insoluble in water organic solvent
b) i) 2C (s) + O2 (g) rarr 2CO (g)
ii) CO reduction in amount of oxygen carried by (the haemoglobin in the red blood
cells of) the blood
Headache OR dizziness OR nausea OR fatigue OR loss of consciousness OR
death
c) i) CaCO3 (s) + 2HCl (aq) rarr CaCl2 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) + H2SO4 (aq) rarr CaSO4 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) rarr CaO (s) + CO2 (g)
48
ii)
OR
OR
Entirely closed system thistle funnel below the level of the liquid OR tap that could be
closed
Two reagents labelled CaCO3marble chips and HCl H2SO4 or heat source
collection of CO2 upward displacement of air OR over watersulphuric acid OR in gas
syringe
iii) CO2 use put in aerated drinks carbonated beverages
OR put in carbon dioxide fire extinguishers
49
WEEK 14 LESSON 3 Worksheet Answers
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
NH4+
NH4+ confirmed OR
NH3 (g) produced
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
Cl- ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation required)
Suggest a possible identity of the solid R NH4Cl (ammonium chloride)
50
WEEK 15 LESSON 1 Worksheet Answers
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a
small portion of solid Y
gently at first and then
strongly
Colourless gas
evolved with a
choking odour
Turns acidified
potassium dichromate
solution from orange
to green
SO2 evolved
Presence of a sulphite
(ii) To the remaining
portion of solid Y add 20
cm3 of distilled water stir
to dissolve and filter
Collect the filtrate and
divide into 3 equal portions
Filtrate is pale green
in colour
Fe2+ ions present
(iii) To the first portion of
the filtrate from (ii) add
aqueous sodium hydroxide
slowly until in excess
A green precipitate
Insoluble in excess
sodium hydroxide
Fe2+ ions present
Fe2+ (aq) + 2 OH- (aq) Fe(OH)2 (s)
Ionic equation required
TEST OBSERVATIONS INFERENCES
(iv) To the second portion
of the filtrate from (ii) add
aqueous silver nitrate
White precipitate
Soluble in aqueous
ammonia
Cl- ions present
51
followed by aqueous
ammonia
(v) To the third portion of
the filtrate from (ii) add
aqueous barium nitrate
followed by aqueous
hydrochloric acid
White precipitate
formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with
the evolution of a
colourless gas with a
choking smell
SO32- CO3
2- SO42- ions present
SO32- ions present
52
WEEK 15 LESSON 2 Worksheet Answers
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
Chloride ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
Cu2+ ions present
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
X contains a reducing agent
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
SO32- SO4
2- or CO32- ions are
present
SO32- ions are present
53
WEEK 15 LESSON 3 Worksheet Answers
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
White ppt
Ppt soluble in excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in
excess aqueous NH3
Al3+ Pb2+ Zn2+ present
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change Cl- Br- I- absent
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
Vigorous effervescence
observed upon addition of
dilute HNO3
CO2 evolved OR
Carbonate present
54
warm filter and then divide
the filtrate into two portions
Gas evolved turns lime
water cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
Cu2+ (aq) + OH- (aq)
Cu(OH)2 (s)
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Blue ppt
ppt dissolves in excess
NH3 to give a deep blue
solution
Cu2+ ions present
55
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
REFERENCES
Hunte-King J Maragh P Nagir F amp Norris R (2013) Chemistry for CSEC United
Kingdom Nelson Thornes Ltd
Remy C Mason L Lambert N amp Mohammed M (2007) Chemistry for CSEC England and
Wales Pearson Education Limited
Taylor M amp Chung-Harris T (2010) CXC Chemistry England Macmillan Publishers
Limited
Tindale A (2016) Chemistry A Concise Revision for CXC London HarperCollins Publishers
Limited
14
Iron + WaterSteam
______________________________________________________________________________
Copper + WaterSteam
______________________________________________________________________________
Silver + WaterSteam
______________________________________________________________________________
15
WEEK 2 LESSON 2
TOPIC Chemical properties of metals
Action of dilute acids
Metals above hydrogen in the electrochemical series react with dilute acids to form a salt and
hydrogen gas They react with hydrochloric acid to form the metal chloride (a salt) and hydrogen
gas They also react with dilute suphuric acid to form the metal sulphate (a salt) and hydrogen
gas
Metal Reaction dilute hydrochloric or sulphuric acid
Potassium K Violent reaction forming a salt and hydrogen gas
eg 2 Na (s) + 2 HCl (aq) 2 NaCl (aq) + H2 (g) Sodium Na
Calcium Ca Vigorous reaction forming a salt and hydrogen gas
eg Mg (s) + 2 HCl (aq) MgCl2 (aq) + H2 (g) Magnesium Mg
Aluminium Al React forming a salt and hydrogen gas
eg Fe (s) + 2 HCl (aq) FeCl2 (aq) + H2 (g) Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
16
WEEK 2 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with
hydrochloric acid
Metal Balanced equation for reaction with hydrochloric acid
Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Copper
Silver
17
WEEK 2 LESSON 3
TOPIC Reactions of metal compounds
Reactions of metallic oxides with dilute acid
Metal oxides react with dilute hydrochloric acid or sulphuric acid to produce a salt and water
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
Some of these reactions may be slow and can be speeded up by adding heat
For example
zinc oxide + hydrochloric acid zinc chloride + water
ZnO (s) + 2 HCl (aq) ZnCl2 (aq) + H2O (l)
magnesium oxide + hydrochloric acid magnesium chloride + water
MgO (s) + 2 HCl (aq) MgCl2 (aq) + H2O (l)
aluminium oxide + sulphuric acid aluminium sulphate + water
Al2O3 3 H2SO4 (aq) Al2(SO4)3 (aq) + 3 H2O (l)
calcium oxide + sulphuric acid calcium sulphate + water
CaO H2SO4 (aq) CaSO4 (aq) + H2O (l)
18
WEEK 2 LESSON 3 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal oxides with the
corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium oxide Hydrochloric acid
Sodium oxide Sulphuric acid
Calcium oxide Hydrochloric acid
Magnesium oxide Sulphuric acid
Aluminium oxide Hydrochloric acid
Zinc oxide Sulphuric acid
19
WEEK 3 LESSON 1
TOPIC Reactions of metal compounds
Reactions of metallic hydroxides with dilute acid
Metal hydroxides react with dilute acids to form a salt and water in a neutralisation reaction
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
For example
magnesium hydroxide + hydrochloric acid magnesium chloride + water
Mg(OH)2 (aq) + 2 HCl (aq) MgCl2 (aq) + 2 H2O (l)
sodium hydroxide + hydrochloric acid sodium chloride + water
NaOH (aq) + HCl (aq) NaCl (aq) + H2O (l)
potassium hydroxide + sulphuric acid potassium sulphate + water
2 KOH + H2SO4 (aq) K2SO4 (aq) + 2 H2O (l)
calcium hydroxide + sulphuric acid calcium sulphate + water
Ca(OH)2 (aq) + H2SO4 (aq) CaSO4 (aq) + 2 H2O (l)
20
WEEK 3 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal hydroxides with
the corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium hydroxide Hydrochloric acid
Sodium hydroxide Sulphuric acid
Calcium hydroxide Hydrochloric acid
Magnesium hydroxide Sulphuric acid
Aluminium hydroxide Hydrochloric acid
Zinc hydroxide Sulphuric acid
21
WEEK 3 LESSON 2
TOPIC Reactions of metal compounds
Reactions of metallic carbonates with dilute acid
Metal carbonates react with dilute acid to form a salt carbon dioxide and water When
hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric acid is
used the corresponding sulphate salt is formed
For example
sodium carbonate + hydrochloric acid sodium chloride + carbon dioxide + water
Na2CO3 (s) + 2 HCl (aq) 2 NaCl (aq) + CO2 (g) + H2O (aq)
calcium carbonate + hydrochloric acid calcium chloride + carbon dioxide + water
CaCO3 (s) + 2 HCl (aq) CaCl2 (aq) + CO2 (g) + H2O (aq)
zinc carbonate + sulphuric acid zinc sulphate + carbon dioxide + water
ZnCO3 (s) + H2SO4 (aq) ZnSO4 (aq) CO2 (g) + H2O (aq)
potassium carbonate + sulphuric acid potassium sulphate + carbon dioxide + water
K2CO3 (s) H2SO4 (aq) K2SO4 (aq) CO2 (g) + 2 H2O (aq)
22
WEEK 3 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal carbonates with
the corresponding acid
Metallic
carbonate
Acid Balanced chemical equation
Potassium
carbonate
Hydrochloric
acid
Sodium
carbonate
Sulphuric acid
Zinc
carbonate
Hydrochloric
acid
Magnesium
carbonate
Sulphuric acid
Aluminium
carbonate
Hydrochloric
acid
Calcium
carbonate
Sulphuric acid
23
WEEK 3 LESSON 3
TOPIC Action of heat on metal compounds
Action of heat on nitrates
All nitrates decompose when heated The reactivity of the metal in the metal nitrate influences
the products of the decomposition
The nitrates of the alkali metals (Group I) with the exception of lithium nitrate decompose to
form the metal nitrite and oxygen
The nitrates of most other metals decompose to form the metal oxide nitrogen dioxide and
oxygen
The nitrates of the very unreactive metals decompose to form the meal nitrogen dioxide and
oxygen
Metal Nitrate Decomposition
Potassium K Products metal nitrite + oxygen
eg 2 NaNO3 (s) Heatrarr 2 NaNO2 (s) + O2 (g)
Sodium Na
Calcium Ca
Products metal oxide + nitrogen dioxide + oxygen
eg 2 Pb(NO3)2 (s)
Heatrarr 2 PbO (s) + 4 NO2 (g) + O2 (g)
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Products metal + nitrogen dioxide + oxygen
eg 2 AgNO3 (s) Heatrarr 2 Ag (s) + 2 NO2 (g) + O2 (g)
24
WEEK 3 LESSON 3 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
nitrates
Metal Balanced chemical equation
Potassium nitrate
Sodium nitrate
Calcium nitrate
Magnesium nitrate
Aluminium nitrate
Zinc nitrate
Lead nitrate
Copper nitrate
Silver nitrate
25
WEEK 4 LESSON 1
TOPIC Action of heat on metal compounds
Action of heat on carbonates
Upon application of heat many carbonates decompose to form the metal oxide and carbon
dioxide
Group I carbonates do not decompose on heating with the exception of lithium carbonate
Metal Carbonate decomposition
Potassium K
Stable not decomposed by heat Sodium Na
Calcium Ca
Decompose forming metal oxide and carbon dioxide
eg CaCO3 (s) Heatrarr CaO (s) + CO2 (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Unstable
26
WEEK 4 LESSON 1 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
carbonates
Metal Balanced chemical equation
Potassium carbonate
Sodium carbonate
Calcium carbonate
Magnesium carbonate
Aluminium carbonate
Zinc carbonate
Iron carbonate
Lead carbonate
Copper carbonate
27
WEEK 4 LESSON 2
TOPIC Action of heat on metal compounds
Action of heat on the metal hydroxides
Most metal hydroxides decompose on heating A metal oxide and water are formed
Group I hydroxides do not decompose on heating with the exception of lithium hydroxide
Metal Hydroxide decomposition
Potassium K Stable not decomposed by heat
Sodium Na
Calcium Ca Decompose forming metal oxide and water (as steam)
eg Zn(OH)2 (s) Heatrarr ZnO (s) + H2O (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag No hydroxide exist
28
WEEK 4 LESSON 2 WORKSHEET
Write the balanced chemical equations for the thermal decomposition of the following
metal hydroxides
Metal hydroxide Balanced chemical equation
Potassium hydroxide
Sodium hydroxide
Calcium hydroxide
Magnesium hydroxide
Aluminium hydroxide
Zinc hydroxide
Lead hydroxide
Copper hydroxide
29
WEEK 4 LESSON 3
TOPIC Reactivity of metals ndash The Reactivity Series
The reactivity series of metals is a list of metals arranged in order of their reactivity based on
Displacement reactions
Reactions with oxygen dilute acids and water
Relative ease of decomposition of their compounds
Metals at the top of the series are the most electropositive They lose electrons very easily and
readily form cations These ions are very stable and are not easily discharged to form atoms Due
to this fact they are the most reactive metals
Metals at the bottom of the series are the least electropositive They do not lose electrons easily
and do not readily form ions Their ions are very unstable and are easily discharged to form
atoms They are the least reactive metals
The reactivity series of metals
Mnemonic Metal Symbol Reactivity
People Potassium K Most reactive
Least reactive
Sometimes Sodium Na
Collect Calcium Ca
Magazines Magnesium Mg
About Aluminium Al
Zoos Zinc Zn
In Iron Fe
London Lead Pb
Having (Hydrogen) H
Cute Copper Cu
Monkeys and Mercury Hg
Small Silver Ag
Gorillas Gold Au
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
5 Reactivity of metals Reactivity of metals Reactivity of metals
6 Extraction of metals Extraction of metals Alloys
7 Corrosion Importance of metals
and their compounds
on living systems and
environment
Chemical properties
of non ndash metals
8 Laboratory
preparation of gases
Laboratory
preparation of gases
Laboratory
preparation of gases
9 Uses of gases Uses of non ndash metals
and their compounds
Harmful effects of
non ndash metals and
their compounds on
living systems and
the environment
10 Green Chemistry Qualitative Analysis
ndash Identification of
cations
Qualitative Analysis
ndash Identification of
cations
2
WEEK 5 LESSON 1
TOPIC Reactivity of metals
Reactivity based on displacement reactions between metals and metal ions
A metal will displace a metal which is lower than itself in the reactivity series from a solution of
the metal salt
Reaction of zinc and copper (II) sulphate
Expected observations
Explanation
The size of the zinc metal decreases
The zinc metal is reacting and forming the
salt zinc sulphate
The solution becomes lighter eventually
colourless
The Cu2+ (aq) ions (responsible for the blue
colour) is reduced to Cu (s)
A brown solid is deposited at the bottom of
the container
Copper metal is formed
Equation Zn (s) + CuSO4 (aq) ZnSO4 (aq) + Cu (s)
Ionic equation
Zn (s) + Cu2+ (aq) Zn2+ (aq) + Cu (s)
Zinc is higher in the reactivity series than copper Therefore it will displace the copper ions in
the reaction above
3
Examples of other displacement reactions
Magnesium will displace Zn2+ ions in zinc sulphate since it is higher in the series than zinc
Mg (s) + Zn2+(aq) Mg2+ (aq) + Zn (s)
Silver will not displace Cu2+ ions in copper (II) sulphate [Cu is higher in the series than Ag]
Using the information above we can arrange the metals in order of their reactivity with
magnesium being the most reactive and silver the least reactive metal among the four metals
Mg gt Zn gt Cu gt Ag
Reactivity based on reaction with oxygen
The reactivity of metals can also be deduced from their reaction with oxygen
The table below gives the observations for the reaction with oxygen with the selected metals
Reaction of metal with oxygen
Metal Observation
Copper The surface turns black upon heating
Magnesium Ribbon burns very rapidly
Sodium Burns vigorously
Gold No reaction
Based on the observations for the 4 metals the metal with highest reactivity is sodium and the
metal with the least reactivity is gold
The 4 metals can be arranged in terms of reactivity as follows
Na gt Mg gt Cu gt Au
4
WEEK 5 LESSON 1 WORKSHEET
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
5
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
6
WEEK 5 LESSON 2
TOPIC Reactivity of metals
Reactivity based on reactivity with acids
The metals that are higher than hydrogen in the electrochemical series react with non ndash oxidizing
acids to produce a salt and hydrogen gas
By using the same concentration of acid and same mass and size of the metals the order of
reactivity of the metals can be deduced
The table below shows the results for an experiment with the reaction of the named metals and
1 mol dm-3 hydrochloric acid
Reaction of metals with acid
Metal Observations
Silver No reaction
Magnesium Bubbles produced steadily
Calcium Bubbles produced very rapidly
Iron Bubbles produced slowly
Based on the above data the most reactive metal will be calcium with the least reactive being
silver The order of reactivity will be Ca gt Mg gt Fe gt Ag
By comparing this to the electrochemical series it can be seen that the reactivity of the metals
decrease as we go down the series
7
WEEK 5 LESSON 2 WORKSHEET
1 Place a next to the metals that will react with dilute acid and an X next to the metals
that will not react with dilute acid
Metal Reactivity with acid
Copper
Magnesium
Aluminium
Silver
Zinc
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
8
WEEK 5 LESSON 3
TOPIC Reactivity of metals
Reactivity based on ease of decomposition of the metal nitrates carbonates oxides and
hydroxides
The more reactive a metal the more difficult it is to decompose its nitrate carbonate oxide or
hydroxide on heating
For example Decomposition of carbonates
Procedure
1 Put a large spatula measure of the carbonate to be tested in a test tube
2 Fit a delivery tube and then clamp the test tube so that the delivery tube dips into a second test
tube containing 2ndash3 cm3 limewater
3 Heat the solid gently at first then more strongly
4 Lift the delivery tube from the limewater before or as soon as the heating is stopped This is to
avoid suck-back
5 Write down all observations Notice what happens to the limewater and how long it takes to turn
milky (if at all) Notice whether any melting occurs in the heated test tube and any colour
changes taking place Write your results in tabular form
6 Repeat the experiment with the other metal carbonates supplied and in each case write down
your observations
7 Wash your hands thoroughly at the end of these experiments since some of the metal carbonates
are toxic
9
Results
Metal Formula Gas evolved Ease of decomposition
Zinc ZnCO3 Carbon dioxide Fairly easy
Copper CuCO3 Carbon dioxide Easy
Sodium Na2CO3 None Very difficult
Using the results of the above activity the reactivity of the metals can be determined
Ease of decomposition Copper gt Zinc gt Sodium
The order of reactivity is the opposite for the ease of decomposition
Order of reactivity Sodium (most reactive) gt Zinc gt Copper (least reactive)
10
WEEK 5 LESSON 3 WORKSHEET
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
11
WEEK 6 LESSON 1
TOPIC Extraction of metals
Elements exist all over the earth Some are found as free elements eg copper silver and gold
Others are found combined with other elements in compounds To get the elements the
compounds have to be broken up These compounds are generally called ores the most
convenient sources of which are rocks sea and air
The extraction of a metal from its ore is a reduction process where the metals ions gain electrons
to form atoms
The general equation is Mn+ + n e- M
The choice of the extraction method depends on the position of the metal in the reactivity series
As we go down the series the metals become more stable and the metal ions (in the ores)
become less stable
The very reactive metals that are high in the series K Na Ca Mg Al have very stable ores
Therefore they require a powerful method of reduction namely electrolysis During the process
the cathode provides the electrons and acts as the reducing agent
The metals in the middle of the series (Zn Fe Pb) do not have stable ores and can be extracted
by reduction with carbon in the case of zinc and with carbon monoxide in the case of iron and
lead
Metals low in the reactivity series if present as ores can be extracted simply by heating the ores
in air at high temperatures
12
Extraction of Aluminium from purified bauxite
Pure bauxite is pure alumina (Al2O3) Aluminium is obtained from bauxite by electrolysis
Aluminium oxide has a very high melting point approximately 2050 0C so it is first dissolved in
molten cryolite (Na2AlF6) The addition of cryolite lowers the melting point to approximately
900 0C
The electrolyte is a molten mixture of alumina and molten cryolite The cathode is the graphite
lining of the cell The anodes are blocks of graphite or titanium alloys
Reaction at the cathode
Al3+ (l) + 3 e- Al (l)
Reaction at the anode
2 O2- (l) ndash 4 e- O2 (g)
Aluminium (melting point 660 0C) is a liquid at the temperature at which electrolysis is carried
out and is collected at the bottom of the cell and tapped off Oxygen gas which is given off in the
main cathode reaction together with the heat causes the anodes to burn away The anodes have
to be replaced from time to time The use of anodes from titanium alloys reduce the number of
times that the anodes have to be replaced
13
WEEK 6 LESSON 1 Worksheet
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 6 LESSON 2
TOPIC Extraction of metals
Extraction of Iron
The traditional method of production of iron is by reduction of haematite by carbon monoxide in
a blast furnace
Ores Haematite ndash Fe2O3 Magnetite ndash Fe3O4 Siderite ndash FeCO3 Magnetite and Siderite are
converted to Haematite
A mixture of haematite limestone (CaCO3) and coke (C) called the charge is placed into the top
of the furnace
Hot air is blown into the bottom of the furnace
Coke burns in air forming carbon dioxide
C (s) + O2(g) CO2 (g) ΔH -ve
The heat produced keeps the temperature at about 1900 0C
The carbon dioxide is reduced to carbon monoxide by the hot coke
CO2 (g) + C (s) 2 CO(g) Δ +ve
Heat absorbed reduces the temperature to about 1100 0C
The carbon monoxide reduces the hot iron ore to molten iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + 3 CO2(g)
The temperature at this part of the furnace is about 700 0C The iron runs to the bottom of the
furnace
The impurities are removed by the addition of limestone (CaCO3) The limestone at the
temperature of the furnace breaks down
CaCO3 (s) CaO (s) + CO2 (g)
15
The calcium oxide formed combines with silicon dioxide (sand) the main impurity in the iron
ore to form molten slag
CaO (s) + SiO2 (s) CaSiO3 (l)
The slag does not mix with the molten iron but floats on it The molten iron and slag are run off
separately
The iron formed in a blast furnace is an impure form of the metal Because the molten metal is
allowed to solidify in shallow trays known as casts the iron is called lsquocast ironrsquo or lsquopigrsquo iron
Cast iron is quite brittle and contains 2 - 4 carbon and other impurities Most of the cast iron is
converted to steel
A blast furnace used for extracting iron
16
WEEK 6 LESSON 2 Worksheet
(a) What are the three raw materials that are added through the top of the blast furnace
during the extraction process for iron
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______________________________________________________________________________
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
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17
WEEK 6 LESSON 3
TOPIC Alloys
An alloy is a mixture of two or more metals Alloys are made by melting the individual metals
mixing them and allowing the molten mixture to solidify
In general alloys are harder stronger and more resistant to corrosion than the actual metals they
are made up from
Alloy Use Properties
ALUMINIUM
-Duralumin
(AlMgCu)
-Magnalium (AlMg)
Alloys used in the
construction of
aircraft and ships
buses
Aluminium is used in
making cooking
utensils electrical
cables paint for fuel
storage tanks bottle
caps foil and utensils
for handling nitric
acid
The alloys have a low
density They are as
light as aluminium
and more resistant to
corrosion than
aluminium
LEAD
-Solder (PbSn)
Alloy is used in
joining metals
(soldering)
Lead is used in
underground cables
plates in
The alloy has a lower
melting point than
lead and is harder
than lead
18
Alloy Use Properties
accumulators shield
against x ndash rays
IRON
- Stainless Steel
(FeCONiC)
-Tungsten steel
(FeWC)
-Invar steel (FeNi)
Manganese steel
(FeMnC)
Iron is the main metal
of a variety of
constructions
Steel is used in
cutlery rock drills
electromagnets
vehicle body and
engine parts fences
pipes etc
Steel resists
corrosion is usually
harder than iron and
may be tough though
malleable and ductile
19
WEEK 6 LESSON 3 Worksheet
(a) Define the term alloy
______________________________________________________________________________
(b) State 3 general advantages that alloys have over the individual metals they are made
from
______________________________________________________________________________
______________________________________________________________________________
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
______________________________________________________________________________
______________________________________________________________________________
Uses
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 7 LESSON 1
TOPIC Corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
Familiar examples of corrosion are
- the formation of a green powder on copper sheeting
- the eating away of iron (rusting)
- the development by aluminum of a thin compact layer of oxide which protects the
underlying metal from further corrosion
When corrosion occurs in water ndash free environment it is called dry oxidation When it occurs in
aerated aqueous environments it is called wet corrosion Wet corrosion is the most common and
troublesome form of corrosion
The most familiar corrosion is the rusting of iron and steel On exposure to the atmosphere iron
and steel corrode to form rust which is hydrated iron (III) oxide Fe2O3xH2O Iron and steel
corrode easily and the rust formed flakes off easily thus exposing fresh surface for attack
When iron rust it loses electrons
Fe (s) ndash 2e- Fe 2+ (aq)
The iron (II) ions pass into solution and then combine with the hydroxyl (OH-) ions in the
aerated aqueous environment to form iron (II) hydroxide The oxygen present oxidises the iron
(II) hydroxide to hydrated iron (III) oxide or rust
Fe(OH)2 + O2 Fe2O3xH2O
21
Methods of preventing rusting
1 Coating the object with paint grease plastic or rubber which prevent contact with air or
water
2 Galvanising ndash coating the object with zinc The zinc forms an adherent oxide layer which
protects against further corrosion If damaged the zinc is oxidized in preference to the
iron since it is higher in the electrochemical series
3 Coating with tin lsquoTinrsquo cans are made of steel plated with tin However if scratched
rusting occurs since iron is more reactive than tin
4 Attaching a sacrificial anode to the object A piece of metal higher in the electrochemical
series such as magnesium is attached The magnesium will be oxidized in preference
since it is higher in the electrochemical series than iron
22
WEEK 7 LESSON 1 WORKSHEET
(a) Define the term corrosion
______________________________________________________________________________
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
23
WEEK 7 LESSON 2
TOPIC Importance of metals and their compounds on living systems and environment
Some metals are an integral part of different structures of living things
Metal Presence and Function
Potassium Main cation in fluid or animal cells essential for healthy plant growth
Calcium Necessary for strong bones teeth and shells needed by some enzymes Present
in dairy produce eggs nuts and cereals
Magnesium Central atom of chlorophyll needed for some enzyme action Involved in energy
and calcium metabolism
Zinc Present in many enzymes Needed for protein metabolism Essential for growth
of animals
Iron Present in haemoglobin Needed for protein metabolism Essential for growth of
animals
Chromium Needed for glucose uptake by cells and thus linked to the action of insulin
Manganese Needed for bone development and amino acid metabolism Present in several
enzymes Needed for plant growth
Cobalt Present in Vitamin B12 Needed for plant growth
Copper Involved in formation of haemoglobin and melanin Present in enzymes
controlling oxidation Needed for plant growth
24
Harmful effects of metals and their compounds to living systems and the environment
There are some metals and metal compounds which may cause harm to living systems and the
environment
Lead
Lead is a heavy metal poison that is widely encountered It may occur in food beverages paint
water formed from ndash sealed pipes in air polluted by combustion by fuels containing lead
compounds Lead is also used in some car batteries If these are paints or batteries are not
disposed of correctly lead may get into groundwater or air Lead and lead compounds harm the
nervous system including the brain especially young children
Arsenic
Arsenic compounds are poisonous They can get into the groundwater from mining waste and
from disposal of some electrical components
Cadmium
Cadmium compounds are poisonous They can get into the ground by improper disposal of
nickel ndash cadmium batteries Persons can get cadmium poisoning if they eat food grown in
contaminated soil
Mercury
Mercury can be spilled from broken thermometers in hospitals and laboratories Mercury and its
compounds are particularly poisonous to fish and it can accumulate in the food chain and
eventually poison humans
Problems of disposal of solid waste
Metals may react with water andor air and corrode to form soluble compounds that are
poisonous These toxic compounds diffuse into the soil and eventually enter rivers
Rust from iron may form unsightly pools of waste that reduce plant growth
Waste from aluminium extraction may react with water and form flammable gases
25
WEEK 7 LESSON 2 WORKSHEET
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Lead
______________________________________________________________________________
Mercury
______________________________________________________________________________
26
WEEK 7 LESSON 3
TOPIC Chemical properties of non ndash metals
Reaction with oxygen
Many non ndash metals burn in excess oxygen or air to form oxides For example
S (s) + O2 (g) SO2 (g)
C (s) + O2 (g) CO2 (g)
Reactions with metals
Some non ndash metals react with metals high in the electrochemical series when heated
For example
Sodium burns in chlorine to form sodium chloride
Na (s) + Cl2 (g) NaCl (s)
Magnesium burns in oxygen to form magnesium oxide
Mg (s) + O2 (g) MgO (s)
When heated iron combines with molten sulphur to form iron (II) sulphide
Fe (s) + S (l) FeS (s)
When heated reactive metals such as sodium and aluminium react with hydrogen to form metal
hydrides
2 Na (s) + H2 (g) 2 NaH (s)
Oxidising and Reducing properties
Hydrogen and Carbon are very good reducing agents
At high temperatures hydrogen reduces metal oxides below zinc in the electrochemical series to
form the metal For example PbO (s) + H2 (g) Pb (s) + H2O (g)
Under suitable conditions hydrogen reduces nitrogen to ammonia
N2(g) + 3 H2 (g) 2 NH3 (g)
27
At high temperatures carbon reduces metal oxides below aluminium in the reactivity series to
the metal For example
ZnO (s) + C (s) Zn (s) + CO (g)
Oxygen and Chlorine are very good oxidizing agents
Oxygen oxidized most metals to form metal oxides and some non ndash metals to non ndash metal oxides
For example
2 Mg (s) + O2(g) 2 MgO (s)
4 P (s) + 5 O2 (g) P4O10 (s)
Chlorine acts as an oxidizing agent either as a gas or as an aqueous solution For example
H2 (g) + Cl2 (g) 2 HCl (g)
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
28
WEEK 7 LESSON 3 WORKSHEET
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
______________________________________________________________________________
(b) Write the ionic equation for the above reaction
______________________________________________________________________________
(c) Identify the oxidising agent in the reaction
______________________________________________________________________________
(d) Justify your answer in part (c) in terms of oxidation number
______________________________________________________________________________
29
WEEK 8 LESSON 1
TOPIC Laboratory preparation of gases
Preparation of oxygen
Oxygen can be prepared by the decomposition of hydrogen peroxide potassium chlorate (V) or
potassium nitrate The safest method is the decomposition of hydrogen peroxide
Manganese (IV) oxide catalyses the decomposition of hydrogen peroxide
Silica gel anhydrous calcium chloride or concentrated sulphuric acid can be used as a drying
agent
The gas is collected by downward delivery since it is slightly denser than air
Equation
2 H2O2 (aq) 2 H2O (l) + O2 (g)
Apparatus used for laboratory preparation of oxygen
30
WEEK 8 LESSON 1 WORKSHEET
Describe the laboratory preparation of oxygen gas
In your answer include
The starting material
A suitable catalyst
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
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______________________________________________________________________________
31
WEEK 8 LESSON 2
TOPIC Laboratory preparation of gases
Preparation of carbon dioxide
Carbon dioxide can be prepared by the action of dilute acid on carbonates Marble chips (calcium
carbonate) and dilute hydrochloric acid are the common reagents The gas is collected by
downward delivery since it is denser than air
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
Apparatus used for laboratory preparation of carbon dioxide
32
WEEK 8 LESSON 2 WORKSHEET
Describe the laboratory preparation of carbon dioxide gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
33
WEEK 8 LESSON 3
TOPIC Laboratory preparation of gases
Preparation of ammonia
Ammonia may be prepared by heating a mixture of ammonium salt and a hydroxide The
ammonia gas is collected by upward delivery since it is less dense than air
For example
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
Calcium oxide is the only suitable drying agent since ammonia reacts with conc H2SO4 and
CaCl2
Apparatus used for laboratory preparation of dry ammonia
34
11
WEEK 8 LESSON 3 WORKSHEET
Describe the laboratory preparation of ammonia gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
35
WEEK 9 LESSON 1
TOPIC Uses of gases
Carbon dioxide
Used in fire extinguishers to put out fires Carbon dioxide is denser than air and lsquoblanketsrsquo the
fire preventing oxygen from reaching it Carbon dioxide extinguishers are especially useful for
dealing with fires involving flammable liquids and electrical equipment
Carbonation in soda is created when carbon dioxide is pumped into the soda can or bottle then
held under pressure As long as the can or bottle is sealed the carbon dioxide remains mostly
stable However if the drink gets shaken up or the top is opened the tiny carbon dioxide bubbles
react by bursting
Oxygen
Oxygen is needed for aerobic respiration We need a constant supply of oxygen for this process
Oxygen is used in hospitals to improve the respiration of patients with poor blood flow blood
poisoning and heart disease
Oxygen in used in welding (joining) metals In an oxyacetylene welding torch acetylene or
ethyne (C2H2) burns in oxygen and produces a very hot flame This flame is capable of melting
most metals
Oxygen is used in steel production A blast of oxygen is blown through the molten iron The
oxygen oxidises many of the impurities of the iron and the impurities are then removed
36
WEEK 9 LESSON 1 WORKSHEET
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Put out fires
Welding metals
Create lsquofizzrsquo in drinks
Used in steel production
Aerobic respiration
37
WEEK 9 LESSON 2
TOPIC Uses of non ndash metals and their compounds
Carbon (allotrophes carbon dioxide)
Carbon is used as a reducing agent in extraction of some metals
Carbon as graphite is used as electrodes lubricants and lsquoleadrsquo for pencils
Carbon in the form of diamond is used for jewellery (because of its lustre) and in drill tips for
high ndash speed drills (because of its hardness)
Carbon dioxide is used as refrigerant (as dry ice) for carbonated beverages
Sodium hydrogen carbonate and sodium carbonate are used for water softening and raising
agent
Sulphur
Sulphur is used in the manufacture of sulphuric acid Sulphur is also used in the manufacture of
tyres to make the rubber harder (vulcanisation)
Sulphur powder is used as fungicide on plant materials
Phosphorus
Phosphorus is used in the manufacture of fertilizers
Phosphorus is used to make phosphor bronze alloys
Phosphorus sulphide is used to make the heads of lsquostrike anywherersquo matches
38
Chlorine
Chlorine is used to make sodium hypochlorite which is present in bleach It is also used in
sterilizing swimming pools and in water treatment
Chlorine is used to make the monomer vinyl chloride which is used to make the plastic PVC
Nitrogen
Nitrogen is used to make fertilisers ammonia dyes and nitric acid
Nitrogen is used as an inert atmosphere to prevent substances being oxidised and as a coolant
Silicon
Silicon is used for making silicon chips for computers
Silicon (V) oxide is present in sand Glass is made by heating sand with lime (calcium oxide) and
sodium carbonate
Silicon in the form of silicates is used in jewellery
Silica gel is used as a drying agent
39
WEEK 9 LESSON 2 WORKSHEET
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Used to make sodium hypochlorite
Used as a fungicide on plant materials
Used for lsquoleadrsquo in pencils
Used in the manufacture of bronze alloys
Used in the manufacture of nitric acid
Used in the manufacture of computer chips
Used to make fertilisers
40
WEEK 9 LESSON 3
TOPIC Harmful effects of non ndash metals and their compounds on living systems and the
environment
Sulphur dioxide
Sulphur dioxide can cause a disease of the lungs Sulphur dioxide also poisons plants in two
main ways It may enter the stomata of leaves and react with the tissue fluids to form sulphites
with the on ndash going water loss the concentration of sulphites could build up killing the cells
The second adverse effect on plants occurs when sulphur dioxide dissolves in rain thereby
increasing soil acidity A prolonged acid soil situation may lead to plasmolysis and the death of
vegetation in an area
Carbon monoxide
Carbon monoxide combines much more readily than oxygen with haemoglobin When carbon
monoxide is inhaled it prevents the haemoglobin from taking oxygen to the bodyrsquos cells
Continued breathing of air containing carbon monoxide eventually causes death
Hydrogen sulphide
Hydrogen sulphide reacts readily with many cations forming insoluble sulphides Many cations
contribute to good health by contributing to enzyme activity and to the formation of bone
pigment and haemoglobin Although these cations are required in extremely small
concentrations they are removed by being precipitated as sulphides and thus not available for
regular function Careless dumping of refuse contributes to atmospheric pollution by hydrogen
sulphide
Oxides of nitrogen
In the presence of hydrocarbons from car exhausts ozone and sunlight nitrogen oxides react to
form photochemical smog which contains many harmful chemicals
Nitrogen dioxide can harm the lungs and irritate the nose throat and eyes The other compounds
present in photochemical smog are even more harmful irritants and can cause asthma
41
Carbon dioxide
Carbon dioxide water vapour and ozone referred to as ldquogreenhouse gasesrdquo acting as a blanket
readily absorb some of the radiated heat energy and in turn warms the earthrsquos atmosphere This is
called the ldquogreenhouse effectrdquo Scientists have found direct correlation between carbon dioxide
concentration and global warming An increase in carbon dioxide concentration resulted in an
increase global temperatures Global warming is a major potential problem that the world faces
Chloroflourocarbons (CFCs)
It is believed that CFCs might be responsible for destroying the ozone layer which prevents
harmful ultraviolet (UV) radiation from reaching the earth The carbon ndash chlorine bond in CFC
molecule is easily broken by a UV photon producing an active chlorine atom This atom
combines with an ozone molecule forming a chlorine oxide radical and oxygen The radicle
reacts with more ozone producing the chlorine atom again This kind of reaction is repeated
thousands of times This type of reaction is thought to account for about eighty percent of the
loss of ozone observed
Nitrates and phospates
Nitrates and phosphates cause eutrophication The process leading to eutrophication are
Nitrates and phosphates from fertilisers spread on fields may dissolve in groundwater and
get into lakes and rivers
Nitrates and phosphates cause excessive growth of algae so that they cover the surface of
the water
Water plants including algae die because of lack of sunlight Aerobic bacteria feed on
the plant remains The bacteria multiply
The aerobic bacteria use up the oxygen in the water so aquatic animals die
42
Solid waste
The main sources of pollution from non ndash metals is from glass paper and plastics
Broken glass can cause injury to animals It can also cause fires by acting as lens focusing the
sunrsquos rays on flammable materials
Printing inks from paper dumped in the ground may contain toxic elements such as arsenic and
cadmium Bleaches and chlorine compounds from paper are also harmful
43
WEEK 9 LESSON 3 WORKSHEET
Describe ONE harmful effect of the following non ndash metals andor their compounds on
living systems and the environment
Sulphur dioxide
______________________________________________________________________________
______________________________________________________________________________
Carbon monoxide
______________________________________________________________________________
______________________________________________________________________________
Carbon dioxide
______________________________________________________________________________
______________________________________________________________________________
Oxides of nitrogen
______________________________________________________________________________
______________________________________________________________________________
Hydrogen sulphide
______________________________________________________________________________
______________________________________________________________________________
44
Chloroflourocarbons (CFCs)
______________________________________________________________________________
______________________________________________________________________________
Nitrates and phospates
______________________________________________________________________________
______________________________________________________________________________
45
WEEK 10 LESSON 1
TOPIC Green Chemistry
Green Chemistry is defined as the utilisation of a set of principles that reduces or eliminates the
use and generation of hazardous substances
There are twelve principles of green chemistry as proposed by Paul T Anastas and John C
Warner These twelve principles are
1 Prevention ndash It is better to prevent waste than to treat or clean up waste after it has been
created
2 Atom economy - Synthetic methods should be designed to maximize the incorporation of
all materials used in the process into the final product
3 Less hazardous chemical synthesis - Wherever practicable synthetic methods should be
designed to use and generate substances that possess little or no toxicity to human health
and the environment
4 Safer chemical products - Chemical products should be designed to affect their desired
function while minimizing their toxicity
5 Safer solvents and other agents - The use of auxiliary substances (eg solvents
separation agents etc) should be made unnecessary wherever possible and harmless
when used
6 Minimum energy requirements - Energy requirements of chemical processes should be
recognized for their environmental and economic impacts and should be minimized If
possible synthetic methods should be conducted at ambient temperature and pressure
7 Use of renewable raw materials - A raw material or feedstock should be renewable rather
than depleting whenever technically and economically practicable
8 Reduce use of additional chemicals or additional steps - Unnecessary derivatization (use
of blocking groups protection deprotection temporary modification of
physicalchemical processes) should be minimized or avoided if possible because such
steps require additional reagents and can generate waste
46
9 Use of catalysts ndash The use of catalysts reduce energy costs because the reactions take
place at lower temperatures The more specific the catalyst for a particular reaction is the
less it the likelihood of getting additional unwanted products
10 Nature of breakdown of products - Chemical products should be designed so that at the
end of their function they break down into innocuous degradation products and do not
persist in the environment
11 Monitoring to prevent pollution - Analytical methodologies need to be further developed
to allow for real-time in-process monitoring and control prior to the formation of
hazardous substances
12 Minimise chemical accidents - Substances and the form of a substance used in a chemical
process should be chosen to minimize the potential for chemical accidents including
releases explosions and fires
47
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
48
WEEK 10 LESSON 2
TOPIC Qualitative Analysis ndash Identification of cations
Qualitative Analysis involves identifying the constituents of single substances or mixture of
substances
Appearance
An examination of the appearance of a substance can indicate which ion it contains
Appearances of substances
Observation Indication
Blue or blue ndash green Cu2+ salt
Pale green Fe2+ salt
Yellow ndash brown Fe3+ salt
Ammonia smell NH4+ salt
49
Test for cation using sodium hydroxide
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
(d) If no precipitate forms in step b warm gently and test for ammonia
Effect of dilute sodium hydroxide solution
Effect of dilute sodium hydroxide solution Cation
Dropwise Excess
White precipitate Precipitate soluble Ca2+
White precipitate Precipitate insoluble Al3+ Pb2+ Zn2+
Blue precipitate Precipitate insoluble Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
No precipitate ndash ammonia gas
evolved on heating
ndash NH4+
The metal cations all form insoluble hydroxides with sodium hydroxide solution
For example Ca2+ (aq) + 2 OH- (aq) Ca(OH)2 (s)
Ca(OH)2 Cu(OH)2 Fe(OH)2 and Fe(OH)3 are basic and therefore do not react with excess
sodium hydroxide solution Therefore the precipitate does not dissolve in excess sodium
hydroxide solution
Al(OH)3 Pb(OH)2 and Zn(OH)2 are amphoteric Therefore the precipitates react with the excess
sodium hydroxide solution forming soluble salts and the precipitate disappears in excess sodium
hydroxide solution
The NH4+ ion forms a soluble hydroxide However on heating it reacts with the hydroxide ion to
form ammonia and water
NH4+ (aq) + OH- (aq) NH3 (g) + H2O (l)
50
WEEK 10 LESSON 2 WORKSHEET
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P _____________ Q ___________________
R _____________ S ___________________
R + NaOH
______________________________________________________________________________
51
WEEK 10 LESSON 3
TOPIC Qualitative Analysis ndash Identification of cations
Test for cation using ammonia solution (ammonium hydroxide solution)
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
Effect of dilute ammonia (ammonium hydroxide) solution
Effect of dilute ammonia solution Cation
Dropwise Excess
No precipitate ndash Ca2+
White precipitate Precipitate soluble
(forming colourless solution)
Zn2+
White precipitate Precipitate insoluble Al3+ Pb2+
Blue precipitate Precipitate soluble
(forming deep blue solution)
Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
52
Ammonia solution is a weak alkali Metal cations except Ca2+ form insoluble hydroxides with
ammonia solution as with the sodium hydroxide solution
The amphoteric hydroxides Al(OH)3 and Pb(OH)2 and the basic hydroxides Fe(OH)2 and
Fe(OH)3 do not react with excess ammonia solution Therefore the precipitates remain
However Zn(OH)2 and Cu(OH)2 do react with excess ammonia solution to form complex
soluble hydroxides each Hence their precipitates disappear on the addition of excess ammonia
solution
Confirmatory test
After carrying out test for cations using sodium hydroxide solution and ammonia solution the
only cations which cannot be distinguished are Al3+ and Pb2+ A confirmatory test is carried out
to distinguish between the two cations
Confirmatory test
Test Observation Cation Ionic equation
Add potassium
or sodium
iodide solution
Bright yellow precipitate
No precipitate
Pb2+
Al3+
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
53
WEEK 10 LESSON 3 WORKSHEET
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A __________ B ________________ C ________________________
(b) State the inference after Test 2
C _______________________
(c) Write an ionic equation to support your answer in (b) above
___________________________________________________________________________
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
54
ANSWERS TO WORKSHEETS
55
WEEK 5 LESSON 1 WORKSHEET ANSWERS
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
Answer
Zinc + Iron (II) sulphate Zinc is higher in the electrochemical series and therefore displace
iron ions in iron (II) sulphate
Equation Zn (s) + FeSO4 (aq) ZnSO4 (aq) + Fe (s)
Ionic equation Zn (s) + Fe2+ (aq) Zn2+ (aq) + Fe (s)
Iron + Zinc sulphate No reaction iron is lower in the electrochemical series and cannot
displace the zinc ions in zinc sulphate
56
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
Answer
X displaces lead from an aqueous solution of its salts
X (s) + Pb2+ (aq) Xn+ (aq) + Pb (s)
rarr X is more reactive than Pb
X did not react with iron salts
rarr X is less reactive than Fe
Y burns very easily
Y is more reactive than Fe and Pb (both forming their corresponding oxide at a slower rate)
From electrochemical series Fe is higher and therefore more reactive than Pb
Order of reactivity
Y (most reactive) gt Fe gt X gt Pb (least reactive)
57
WEEK 5 LESSON 2 WORKSHEET ANSWERS
1
Metal Reactivity with acid
Copper X
Magnesium
Aluminium
Silver X
Zinc
58
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
Answer
Y and Z are the most reactive since they can react with dilute acid
Z is more reactive than Y since a reaction occurs with Z is added to an aqueous solution of Y
X is less reactive than W since it does not occur in nature as compounds
Order of reactivity Z (most reactive) gt Y gt W gt X
59
WEEK 5 LESSON 3 WORKSHEET ANSWERS
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
Answer
Ease of decomposition (from easiest to decompose to most difficult to decompose)
B rarrD rarrArarr C
Reactivity (most reactive to least reactive)
C (most reactive) gt A gt D gt B (least reactive)
60
WEEK 6 LESSON 1 Worksheet Answers
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
Potassium Zinc Copper
Calcium Lead Gold
Magnesium Iron
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
Aluminium is extracted from its ore bauxite through the process of electrolysis
Cryolite is added to bauxite to lower the melting point to about 900 0C The melting point of
bauxite is very high (about 2040 0C) It is difficult and expensive to keep the molten aluminium
oxide at this temperature
Reaction at the cathode Al3+ (l) + 3 e- Al (l)
61
WEEK 6 LESSON 2 Worksheet Answers
(a) What are the three raw materials that are added through the top of the blast
furnace during the extraction process for iron
Coke (carbon)
iron ore (haematitie mainly iron (II) oxide)
limestone (calcium carbonate)
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
Coke ndash coke burns to produce carbon dioxide The carbon dioxide further reacts with coke to
form carbon monoxide (reducing agent in the process)
C (s) + O2 (g) CO2 (g)
C (s) + CO2 (g) 2 CO
Haematite ndash iron ore provides the iron which is reduced by the carbon monoxide to produce
iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + CO2 (g)
Limestone ndash decomposes to form calcium oxide The calcium oxide reacts with the impurity
silicon dioxide to form slag (calcium silicate)
CaCO3 (s) CaO (s) + CO2 (g)
CaO (s) + SiO2 (l) CaSiO3(l)
62
WEEK 6 LESSON 3 Worksheet Answers
(a) Define the term alloy
An alloy is a material made from a mixture of two or more metals
(b) State 3 general advantages that alloys have over the individual metals they are made
from
They are harder stronger and more resistant to corrosion
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
1 High strength
2 Low density
Uses
1 Used to make aircraft bodies
2 Used to make space satellites
63
WEEK 7 LESSON 1 WORKSHEET ANSWERS
(a) Define the term corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
The paint forms a barrier which stops contact with air or water and the iron Hence rusting
will not take place
However when the paint is scratched that part of the iron nail is exposed to air or water and
rusting will take place
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
Magnesium is higher in the electrochemical series and will be oxidised in preference to iron
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
Aluminium is partly protected from corrosion by its coat of aluminium oxide However as the
iron rust it flakes and fall off and the rusting process continues
64
WEEK 7 LESSON 2 WORKSHEET ANSWERS
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
Magnesium is the ion found in chlorophyll Chlorophyll plays a vital part in the process of
photosynthesis A deficiency in magnesium will lead to low chlorophyll level in the tomato
plants and hence reduce the process of photosynthesis There will be less food storage and
hence will lead to smaller yield of tomatoes
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Any correct harmful effect of lead on health or environment
Any correct harmful effect of mercury on health or environment
65
WEEK 7 LESSON 3 WORKSHEET ANSWERS
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
(b) Write the ionic equation for the above reaction
2 Br- (aq) + Cl2 (aq) 2 Cl- (aq) + Br2 (aq)
(c) Identify the oxidising agent in the reaction
Cl2 (aq)
(d) Justify your answer in part (c) in terms of oxidation number
There is a reduction of the oxidation number for chlorine from 0 to ndash1
hence it has been reduced Therefore chlorine is the oxidising agent
66
WEEK 8 LESSON 1 WORKSHEET ANSWERS
Describe the laboratory preparation of oxygen gas
Oxygen is prepared in the laboratory by the decomposition of hydrogen peroxide
A suitable catalyst is manganese (IV) oxide
Drying agent silica gel OR anhydrous calcium chloride OR conc sulphuric acid
The gas is collected by downward delivery since oxygen is slightly denser than air
Balanced chemical equation 2 H2O2 (aq) 2 H2O (l) + O2 (g)
67
WEEK 8 LESSON 2 WORKSHEET ANSWERS
Describe the laboratory preparation of carbon dioxide gas
Carbon dioxide is commonly prepared in the laboratory by the reacting hydrochloric acid and
marble chips (calcium carbonate)
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
The carbon dioxide gas is collected by downward delivery since it is denser than air
Balanced chemical equation
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
68
WEEK 8 LESSON 3 WORKSHEET ANSWERS
Describe the laboratory preparation of ammonia gas
An ammonium salt (ammonium chloride) and a base (sodium hydroxide) are mixed together and
heated
Calcium oxide is used as the drying agent Calcium chloride and concentrated sulphuric acid
cannot be used since ammonia can react with them
The gas is collected by upward delivery since ammonia is less dense than air
Balanced chemical equation
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
69
WEEK 9 LESSON 1 WORKSHEET ANSWERS
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Carbon dioxide Put out fires
Oxygen Welding metals
Carbon dioxide Create lsquofizzrsquo in drinks
Oxygen Used in steel production
Oxygen Aerobic respiration
70
WEEK 9 LESSON 2 WORKSHEET ANSWERS
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Chlorine Used to make sodium hypochlorite
Sulphur Used as a fungicide on plant materials
Carbon (graphite) Used for lsquoleadrsquo in pencils
Phosphorus Used in the manufacture of bronze alloys
Nitrogen Used in the manufacture of nitric acid
Silicon Used in the manufacture of computer chips
Nitrogen Phosphorus Used to make fertilisers
71
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
Green Chemistry is using principles that reduceeliminate the use of hazardous materials in
the design manufacture and application of chemical products
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
Makes the environment safer
Reduces waste
Creates new jobs
Reduces respiratory illnesses
Atom economy
72
WEEK 10 LESSON 2 WORKSHEET ANSWERS
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P Cu2+ Q Fe2+
R Fe3+ S Ca2+
Ionic equation for R + NaOH
Fe3+ (aq) + 3 OH- (aq) Fe(OH)3 (s)
73
WEEK 10 LESSON 3 WORKSHEET ANSWERS
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A Fe3+ B Ca2+ C Al3+ Pb2+
(b) State the inference after Test 2
C Pb2+
(c) Write an ionic equation to support your answer in (b) above
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
11 Qualitative Analysis
ndash Test for gases
Qualitative Analysis
ndash Identification of
anions
Qualitative Analysis
ndash Identification of
anions
12 Problem solving of
Past CSEC Chemistry Paper 2
on topics completed in the term
13
14
15
2
WEEK 11 LESSON 1
TOPIC Qualitative Analysis ndash Test for gases
Identification of gases
Gas Colour Odour Effect on moist
litmus
Method of identification
Oxygen
O2
Colourless Odourless Neutral ndash no
effect
Relights a glowing splint
Hydrogen
H2
Colourless Odourless Neutral ndash no
effect
Lighted splint lsquopopsrsquo if air is also
present
Carbon
dioxide
CO2
Colourless Odourless Weakly acidic ndash
blue to slightly
red
A white precipitate forms in
limewater
Ca(OH)2 (aq) + CO2
CaCO3 (s) + H2O (l)
Precipitate redissolves on
continued bubbling
CaCO3 (s) + H2O (l) + CO2 (g)
Ca(HCO3)2 (aq)
Ammonia
NH3
Colourless Pungent Alkaline ndash red
to blue (only
common
alkaline gas)
Turns moist red litmus blue forms
dense white fumes with hydrogen
chloride gas
NH3 (g) + HCl (g) NH4Cl (s)
Gas Colour Odour Effect on moist
litmus
Method of identification
3
Sulphur
dioxide
SO2
Colourless Choking
smell
Acidic ndash blue to
red
Turns acidified potassium
manganate (VII) solution from
purple to colourless
Turns acidified potassium
dichromate (VI) solution from
orange to green
Chlorine
Cl2
Yellow ndash
green
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Bromine
Br2
Red ndash
brown
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Nitrogen
dioxide
NO2
Red ndash
brown
Irritating
smell
Acidic blue to
red
Turns moist blue litmus red but
does not bleach it
Water
vapour
H2O
Colourless Odourless Neutral ndash no
effect
Turns anhydrous cobalt (II)
chloride from blue to pink
Turns anhydrous copper (II)
sulphate from white to blue
4
WEEK 11 LESSON 1 WORKSHEET
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless
Yellow ndash green
Red ndash brown
Gases according to their odour
Odour of gas Identity of gas
Odourless
Pungent smell
Choking smell
Irritating smell
5
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect
Red to blue
Blue to red
Blue to red then bleaches it
6
WEEK 11 LESSON 2
TOPIC Qualitative Analysis ndash Identification of anions
Effect of heating
Method Heat a sample of the solid in a dry test tube
Effect of heating
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) not
of K or Na
CO32- (s) O2- (s) + CO2 (g)
Oxygen evolved NO3- of K or Na 2 NO3
- (s) 2 NO2- (s) + O2
(g)
Oxygen and nitrogen
dioxide evolved
NO3- of Ca and below
in reactivity series
4 NO3- (s) 2 O2- (s) + 4 NO2
(g) + O2
(g)
Sulphur dioxide evolved SO32- SO3
2- O2- (s) + SO2 (g)
Effect of dilute acid
Add dilute hydrochloric acid or nitric acid to a sample of the solid Warm if no reaction occurs
when cold
Effect of dilute acid
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) CO32- (s) + 2 H+ (aq) H2O (l) + CO2 (g)
Sulphur dioxide evolved SO32- SO3
2- (s) + 2 H+ (aq) H2O (l) + SO2 (g)
7
Effect of concentrated acid
Add concentrated sulphuric acid to a sample of the solid Warm if not reaction occurs when cold
Effect of concentrated sulphuric acid
Observation Anion
Carbon dioxide evolved CO32- or HCO3
-
Sulphur dioxide evolved SO3-
Hydrogen chloride evolved Cl-
Hydrogen bromide (colourless) and bromine
vapour (brown) evolved
Br-
Black iodine present and purple iodine vapour
evolved
I-
8
WEEK 11 LESSON 2 WORKSHEET
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater
Produces a gas which relights a glowing splint as the only gas
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green
Produces a gas forms a precipitate in limewater
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia
Black iodine present and purple iodine vapour evolved
9
WEEK 11 LESSON 3
TOPIC Qualitative Analysis ndash Identification of anions
Test for the halides ndash using silver nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous silver nitrate and
observe the precipitate Add ammonia solution and observe the solubility of the precipitate
Test for halides using silver nitrate solution
Effect of silver
nitrate solution
Anion Explanation Effect of aqueous
ammonia
White precipitate ndash
turns white in
sunlight
Cl- Ag+ (aq) + Cl- AgCl (s) Precipitate soluble
Cream precipitate ndash
turns yellow ndash green
in sunlight
Br- Ag+ (aq) + Br- AgBr (s) Precipitate slightly
soluble
Pale yellow
precipitate
I- Ag+ (aq) + I- AgI (s) Precipitate insoluble
Test for the halides ndash using lead nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous lead nitrate and
observe the precipitate
Test for halides using lead nitrate solution
Effect of lead nitrate solution Anion Explanation
White precipitate Cl- Pb2+ (aq) + 2 Cl- PbCl2 (s)
Pale yellow Br- Pb2+ (aq) + 2 Br- PbBr2 (s)
Deep yellow I- Pb2+ (aq) + 2 I- PbI2 (s)
10
Effect of barium nitrate or chloride solution followed by dilute acid
Make a solution of the solid Add barium nitrate or chloride solution and observe the precipitate
Add dilute hydrochloric or nitric acid warn if necessary and observe the solubility of the
precipitate
Effect of barium nitrate or chloride solution followed by dilute acid
Effect of
Ba(NO3)2 (aq)
or BaCl2 (aq)
Effect of HCl (aq)
or HNO3 (aq)
Anion Explanation
White precipitate Precipitate insoluble SO42- Ba2+ (aq) + SO4
2- (aq) BaSO4 (s)
BaSO4 does not react with dilute acids
White precipitate Precipitate soluble ndash
CO2 evolved
CO32- Ba2+ (aq) + CO3
2- (aq) BaCO3 (s)
BaCO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + CO2 (g)
White precipitate Precipitate soluble ndash
SO2 evolved on
warming
SO32- Ba2+ (aq) + SO3
2- (aq) BaSO3 (s)
BaSO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + SO2 (g)
11
WEEK 11 LESSON 3 WORKSHEET
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
(Ionic equation required)
12
WEEK 12 LESSON 1 WORKSHEET
(a) The Caribbean islands are known for their many resources For example the ore of
aluminium is found in Jamaica and Guyana
(i) Briefly describe the extraction of aluminium from its named ore Include in your
description one ionic equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Although aluminium ore is mined in the Caribbean the extraction of aluminium usually
takes place in other countries Suggest ONE reason why it may be difficult to extract
aluminium in the Caribbean
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) An alloy can be described as a lsquomixed metal solutionrsquo Aluminium forms an alloy with
magnesium that is used to make an aircraft
13
Identify this alloy and suggest why it is better to use it rather than the pure metal in the
manufacture of aircraft
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) ldquoSome metals can be useful to man yet harmful to the environmentrdquo Comment on this
statement with reference to mercury
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 12 LESSON 2 Worksheet
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate formed
Soluble in excess
15
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate formed
Insoluble in excess
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate formed
(Ionic equation required)
16
WEEK 12 LESSON 3 Worksheet
Dry ammonia gas can be produced in a school laboratory
(a) Identify TWO reagents that are necessary for the laboratory production of ammonia
______________________________________________________________________________
______________________________________________________________________________
(b) Two common drying agents used in the laboratory are calcium oxide and concentrated
sulphuric acid However calcium oxide is the preferred choice for drying ammonia gas
Explain why concentrated sulphuric acid is now used Include in your answer a balanced
chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) When gases are prepared in the laboratory there are three main ways in which they can
be collected
- Upward delivery
- Downward delivery
- Displacement of water
(i) What TWO other factors should be considered when choosing an appropriate method for
the collection of gases in the laboratory
______________________________________________________________________________
______________________________________________________________________________
(ii) Identify ONE of the three methods that is best suited for the collection of ammonia gas in
the laboratory Explain why EACH of the other two methods would NOT have been
appropriate
______________________________________________________________________________
17
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(d) Hence draw a labelled diagram of the apparatus which could be used for the preparation
of dry ammonia in the laboratory
Be sure to identify in your diagram
- where the reagents are placed
- where the ammonia is dried and
- where the ammonia is collected
18
WEEK 13 LESSON 1 Worksheet
(a) In solution two metals A and B form A+ and B2+ ions respectively Metal A displaces Fe
from a solution containing Fe2+ ions but metal B does NOT
(i) Arrange the metals A B and Fe in order of reactivity from LEAST reactive to MOST
reactive Write a balanced chemical equation to show the reaction between metal A and
Fe2+ ions
______________________________________________________________________________
______________________________________________________________________________
(ii) Metal A is placed in a solution of copper (II) sulphate CuSO4 (aq) Write an equation for
the reaction State ONE observable change that will occur and explain why this reaction
takes place
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) For EACH metal A and B state ONE method that can be used to extract it from its
respective oxide Give a reason for EACH answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
19
______________________________________________________________________________
(b) Metal alloys are often used for making objects found in our daily lives Name an alloy of
iron and state ONE of its uses
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 13 LESSON 2 Worksheet
(a) Many important biological processes in plants and animals depend on the specific roles
of certain metal ions
(i) Farmer Jones reaped a crop of tomatoes and reported that the yield was far below what
was expected Analysis of the soil revealed that there was a deficiency of magnesium
Discuss the importance of magnesium in plant health and explain how a magnesium
deficiency can result in the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE other metal ion which is important to plant health and state the result of its
deficiency
______________________________________________________________________________
______________________________________________________________________________
21
(b) Many years ago car exhaust fumes were known to contain compounds of metals and
non ndash metals which could negatively impact both humans and the environment Identify
ONE metal and ONE non ndash metal whose compounds were present in car exhaust fumes
Discuss the effect of these compounds on human health and the environment
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) Define lsquogreen chemistryrsquo and discuss the measures that have been taken to produce a
lsquogreenerrsquo automotive fuel
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
22
WEEK 13 LESSON 3 Worksheet
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
Zn2+ ions are present
23
WEEK 14 LESSON 1 Worksheet
(a) Metal alloys are often used in place of metals because of their enhanced properties
(i) Define the term lsquoalloyrsquo
______________________________________________________________________________
______________________________________________________________________________
(ii) Name ONE alloy of aluminium and state its use based on one of its enhanced properties
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) A student conducted an experiment to investigate the reactivity of each of the following
metals (copper iron zinc and lead) by using solutionPs of their sulphate salts
The data presented in the table below shows whether a visible chemical reaction took
place when each metal was added to the four sulphate solutions
Key Visible chemical reaction took place
X No visible chemical reaction
CHEMICAL REACTION OF METALS IN SULPHATE SOLUTIONS
Sulphate solution Cu Fe Zn Pb
CuSO4 X
FeSO4 X X X
ZnSO4 X X X X
PbSO4 X X
24
(i) State which of the TWO metals is more reaction Fe or Zn Give a reason for our answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Using the data in the previous Table deduce the order of reactivity of the four metals Cu
Fe Zn and Pb from the most reactive to the least reactive metal
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The student recorded the following observations from the reaction between the iron and
copper (II) sulphate solution
Observations Reddish ndash brown solid coating formed on the iron strip
Blue colour of the solution changed to dirty green
Account for the observations made from the reaction between the iron and copper (II)
sulphate solution
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iv) Write an ionic equation including state symbols for the reaction between the iron and
copper (II) sulphate solution
______________________________________________________________________________
25
(c) Some metal compounds are health and environmental hazards
(i) Identify which of the metals used in the experiment in (b) is MOST hazardous to the
environment
______________________________________________________________________________
______________________________________________________________________________
(ii) State TWO harmful effects of continuous exposure to the metal identified in (c) (i) on
human beings
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
26
WEEK 14 LESSON 2 Worksheet
(a) Carbon is found in the form of diamond and graphite and is a main component in many
naturally occurring compounds such as organic matter and carbon dioxide gas
(i) State ONE way in which diamond differs physically from graphite
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE similarity between diamond and graphite other than they both contain carbon
______________________________________________________________________________
______________________________________________________________________________
(b) Carbon can react with a limited supply of oxygen to form carbon monoxide which can
negatively affect human health
(i) Write a balanced chemical equation including state symbols to show the formation of
carbon monoxide
______________________________________________________________________________
(ii) State TWO effects of carbon monoxide inhalation on the human body
______________________________________________________________________________
______________________________________________________________________________
(c) Jamal wants to prepare and collect a sample of carbon dioxide gas in the laboratory using
calcium carbonate
(i) Write a balanced chemical equation including state symbols for the laboratory
preparation of carbon dioxide gas from calcium carbonate
______________________________________________________________________________
______________________________________________________________________________
(ii) Draw a clearly labelled diagram to show the arrangement of the apparatus and materials
that could be used in the laboratory to prepare and collect the carbon dioxide gas
(iii) State ONE use of carbon dioxide as it relates to the beverage industry
______________________________________________________________________________
27
WEEK 14 LESSON 3 Worksheet
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
(Ionic equation required)
Suggest a possible identity of the solid R __________________________
28
WEEK 15 LESSON 1 Worksheet
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a small
portion of solid Y gently at
first and then strongly
Colourless gas evolved
with a choking odour
Turns acidified potassium
dichromate solution from
orange to green
(ii) To the remaining portion
of solid Y add 20 cm3 of
distilled water stir to dissolve
and filter Collect the filtrate
and divide into 3 equal
portions
Filtrate is pale green in
colour
(iii) To the first portion of the
filtrate from (ii) add aqueous
sodium hydroxide slowly
until in excess
A green precipitate
Insoluble in excess sodium
hydroxide
Ionic equation required
29
TEST OBSERVATIONS INFERENCES
(iv) To the second portion of
the filtrate from (ii) add
aqueous silver nitrate
followed by aqueous
ammonia
White precipitate
Soluble in aqueous
ammonia
(v) To the third portion of the
filtrate from (ii) add aqueous
barium nitrate followed by
aqueous hydrochloric acid
White precipitate formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with the
evolution of a colourless
gas with a choking smell
30
WEEK 15 LESSON 2 Worksheet
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
31
WEEK 15 LESSON 3 Worksheet
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in excess
aqueous NH3
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change
32
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
warm filter and then divide
the filtrate into two portions
Vigorous effervescence
observed upon addition of
dilute HNO3
Gas evolved turns lime water
cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Cu2+ ions present
33
ANSWERS TO WORKSHEETS
34
WEEK 11 LESSON 1 WORKSHEET ANSWERS
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless O2 H2 CO2 NH3 SO2 H2O
Yellow ndash green Cl2
Red ndash brown Br2 NO2
Gases according to their odour
Odour of gas Identity of gas
Odourless O2 H2 CO2 H2O
Pungent smell NH3
Choking smell SO2 Cl2 Br2
Irritating smell NO2
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect Neutral O2 H2 H2O
Red to blue Alkaline NH3
Blue to red Acidic CO2 SO2 NO2
Blue to red then bleaches it Acidic Cl2 Br2
35
WEEK 11 LESSON 2 WORKSHEET ANSWERS
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-) not
of K or Na
Produces a gas which relights a glowing splint as the only gas NO3- of K or Na
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green SO32-
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-)
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia Cl-
Black iodine present and purple iodine vapour evolved I-
36
WEEK 11 LESSON 3 WORKSHEET ANSWERS
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Br-
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
Cl-
Ag+ (aq) + Cl- AgCl (s)
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow Br-
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
SO42-
Ba2+ (aq) + SO42- (aq)
BaSO4 (s)
(Ionic equation required)
37
WEEK 12 LESSON 1 Worksheet Answers
(a) (i)
The ore bauxite is purified
The purified bauxite is dissolved in molten cryolite
The aluminium oxidecryolite solution is then eletrolysed
Equation at the cathode Al3+ (l) + 3 e- Al (l)
Equation at the anode 2 O2- (l) ndash 4 e- O2 (g)
(ii) The process is too expensive mainly because too much electricity or energy is needed
(b) The alloy of Al and Mg is magnalium It is less dense than the pure metals and hence allow
aircraft to be lighter It is also stronger than the pure metals and hence allows aircraft to last
longer since it is not easily destroyed
(c) Your answer should cater for the following aspects
Benefits of mercury to humans for example in thermometers barometers in dentistry
and gold mining
Entry of mercury to the environment For example this could have been through broken
thermometers barometers or lightbulbs or improper disposal of them or batteries and
indiscriminate use in gold mining in Guyana
The identification of a negative impact on the environment such as poisoned fish and the
persons who eat the fish death mood swings and psychosis
38
WEEK 12 LESSON 2 Worksheet Answers
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas
evolved
NO2 evolved OR nitrates
present OR
Br2 gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate
formed
Soluble in excess
Pb2+ Zn2+ Al3+ or Ca2+
present
Pb2+ Zn2+ Al3+ or present
39
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate
formed
Insoluble in excess
Pb2+ Zn2+ Al3+ or present
Pb2+ or Al3+ present
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate
formed
Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
40
WEEK 12 LESSON 3 Worksheet Answers
(a) an ammonium salt and a strong alkali
(b) Ammonia is basic and it will react with H2SO4
Equation 2 NH3 (aq) + H2SO4 (aq) (NH4)2SO4 (aq)
(c) (i) ndash Density of the gas relative to air ndash The solubility of the gas in water
(ii) Ammonia is collected by upward delivery
It cannot be collected by downward delivery since ammonia is less dense than air
It cannot be collected by displacement of water since it is soluble in water
(d)
41
WEEK 13 LESSON 1 Worksheet Answer
a) i) B ˂ Fe ˂ A
2A (s) + Fe 2+ (aq) rarr 2A+ (aq) + Fe (s)
ii) 2A (s) + CuSO4 (aq) rarr A2SO4 (aq) + Cu (s)
Observation blue colour fades gets lighter OR brown solid forms is deposited OR metal A
decreases in size dissolves
Explanation Metal A is higher (than Fe which is higher) than Cu in the reactivity series OR
Metal A is more reactive (than Fe which is more reactive) than Cu so Metal A can displace Cu
iii) Metal A can be extracted by electrolysis (of its molten oxide) because Metal A is a very
reactive metal is high in the reactivity series forms stable oxides needs a lot of energy to be
extracted and very reactive metals are extracted by electrolysis
Metal B can be extracted by heating with carbon carbon monoxide OR by chemical reduction
of the oxide because Metal B is less reactive than Fe is low in the reactivity series forms less
stable oxides does not need a lot of energy to be extracted and oxides of less reactive metals are
easily reduced
b) Alloy of iron steel
Use of alloy making buildings bridges ships motor vehicles furniture utensils
42
WEEK 13 LESSON 2 Worksheet Answer
(a) (i)
Magensium is the metal ion found in chlorophyll
Chlorophyll is essential for photosynthesis
A deficiency in magnesium will result in low chlorophyll yellow leaves and a reduction in
photosynthesis
Hence there will be low carbohydrates or energy production
Hence small fruits stunted growth and lower yield will result
(ii)
Metal ion Results of deficiency
Potassium Stunted growth premature loss of leaves yellowing of leaves curling of leaf tips
Calcium Growth abnormalities in tips of roots and shoots curling of leaves
Iron Yellowing of leaves
Zinc Low chlorophyll content yellowing of leaves
Manganese Yellowing of leaves poor flavors in some crops for example potato
(b)
Metal Lead is present in some types of gasoline Upon combustion lead compounds escape into
the atmosphere It accumulates in body tissues and slowly poisons the person It causes mental
illness
Non ndash metal SulphurSulphur dioxide or NitrogenNitrogen dioxide
Dissolves in rain water to form acid rain or cause respiratory illnessproblems Acid rain can
cause corrosion damage in buildings
(c)
Green chemistry is the utilisation of a set of principles that reduces or eliminates the use or
generation of hazardous substances
43
Automotive fuels are now produced without lead so as to eliminate the release of lead
compounds into the atmosphere
Low sulphur fuel is being produced with much reduced sulphur content which causes a reduction
of sulphur dioxide release into the atmosphere
44
WEEK 13 LESSON 3 Worksheet Answer
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
gas turns litmus blue
red
brown gas
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
white precipitate
precipitate soluble in
excess
Zn2+ ions are present
45
WEEK 14 LESSON 1 Worksheet Answers
(a)(i) An alloy is a material made from a mixture of two or more metals
(ii) Any suitable answer chosen from below
Alloy Enhance Property Use
Duralumin High strength
Low density
Light
Hard
Used to make aircraft bodies
space satellites
Magnalium Light
Hard
Easier to weld
Corrosion resistant
Strong
High ductability
Used in pyrotechnics
(fireworks)
Mirrors
Aircraft parts
To make scientific
instruments
Used to make marine castings
Alchlad Strong
Corrosion resistant
Cladding for buildings
(b) (i) Zinc is more reactive than iron
Zinc displaces iron from iron (II) sulphate
Zinc is higher in the reactivity series than iron
Iron does not displace zinc from zinc sulphate
(ii) Order of reactivity Zn gt Fe gt Pb gt Cu
(iii) Reddish brown solid ndash copper metal formed
46
Dirty green solution ndash presence of Fe2+ ion
(iv) Fe (s) + Cu2+ (aq) Fe2+ (aq) + Cu (s)
(c) (i) Lead
(ii) Any two correct harmful effects of lead on the body
Impedes brain development (in young children)
Affectimpede development of the immune system in humans
Affecthamper development of nervous system in humans
Long term exposure can result in kidney and liver damage
Mental retardation
Anaemia
Death
47
WEEK 14 LESSON 2 Worksheet Answers
a) i) Diamond is transparent clear Graphite is opaque black
OR hard OR brittle
OR does not conduct electricity OR conducts electricity
a) ii) Both have a macromolecular giant molecular giant covalent structure (lattice)
OR Both have high melting point boiling point
OR Both are insoluble in water organic solvent
b) i) 2C (s) + O2 (g) rarr 2CO (g)
ii) CO reduction in amount of oxygen carried by (the haemoglobin in the red blood
cells of) the blood
Headache OR dizziness OR nausea OR fatigue OR loss of consciousness OR
death
c) i) CaCO3 (s) + 2HCl (aq) rarr CaCl2 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) + H2SO4 (aq) rarr CaSO4 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) rarr CaO (s) + CO2 (g)
48
ii)
OR
OR
Entirely closed system thistle funnel below the level of the liquid OR tap that could be
closed
Two reagents labelled CaCO3marble chips and HCl H2SO4 or heat source
collection of CO2 upward displacement of air OR over watersulphuric acid OR in gas
syringe
iii) CO2 use put in aerated drinks carbonated beverages
OR put in carbon dioxide fire extinguishers
49
WEEK 14 LESSON 3 Worksheet Answers
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
NH4+
NH4+ confirmed OR
NH3 (g) produced
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
Cl- ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation required)
Suggest a possible identity of the solid R NH4Cl (ammonium chloride)
50
WEEK 15 LESSON 1 Worksheet Answers
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a
small portion of solid Y
gently at first and then
strongly
Colourless gas
evolved with a
choking odour
Turns acidified
potassium dichromate
solution from orange
to green
SO2 evolved
Presence of a sulphite
(ii) To the remaining
portion of solid Y add 20
cm3 of distilled water stir
to dissolve and filter
Collect the filtrate and
divide into 3 equal portions
Filtrate is pale green
in colour
Fe2+ ions present
(iii) To the first portion of
the filtrate from (ii) add
aqueous sodium hydroxide
slowly until in excess
A green precipitate
Insoluble in excess
sodium hydroxide
Fe2+ ions present
Fe2+ (aq) + 2 OH- (aq) Fe(OH)2 (s)
Ionic equation required
TEST OBSERVATIONS INFERENCES
(iv) To the second portion
of the filtrate from (ii) add
aqueous silver nitrate
White precipitate
Soluble in aqueous
ammonia
Cl- ions present
51
followed by aqueous
ammonia
(v) To the third portion of
the filtrate from (ii) add
aqueous barium nitrate
followed by aqueous
hydrochloric acid
White precipitate
formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with
the evolution of a
colourless gas with a
choking smell
SO32- CO3
2- SO42- ions present
SO32- ions present
52
WEEK 15 LESSON 2 Worksheet Answers
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
Chloride ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
Cu2+ ions present
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
X contains a reducing agent
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
SO32- SO4
2- or CO32- ions are
present
SO32- ions are present
53
WEEK 15 LESSON 3 Worksheet Answers
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
White ppt
Ppt soluble in excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in
excess aqueous NH3
Al3+ Pb2+ Zn2+ present
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change Cl- Br- I- absent
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
Vigorous effervescence
observed upon addition of
dilute HNO3
CO2 evolved OR
Carbonate present
54
warm filter and then divide
the filtrate into two portions
Gas evolved turns lime
water cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
Cu2+ (aq) + OH- (aq)
Cu(OH)2 (s)
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Blue ppt
ppt dissolves in excess
NH3 to give a deep blue
solution
Cu2+ ions present
55
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
REFERENCES
Hunte-King J Maragh P Nagir F amp Norris R (2013) Chemistry for CSEC United
Kingdom Nelson Thornes Ltd
Remy C Mason L Lambert N amp Mohammed M (2007) Chemistry for CSEC England and
Wales Pearson Education Limited
Taylor M amp Chung-Harris T (2010) CXC Chemistry England Macmillan Publishers
Limited
Tindale A (2016) Chemistry A Concise Revision for CXC London HarperCollins Publishers
Limited
15
WEEK 2 LESSON 2
TOPIC Chemical properties of metals
Action of dilute acids
Metals above hydrogen in the electrochemical series react with dilute acids to form a salt and
hydrogen gas They react with hydrochloric acid to form the metal chloride (a salt) and hydrogen
gas They also react with dilute suphuric acid to form the metal sulphate (a salt) and hydrogen
gas
Metal Reaction dilute hydrochloric or sulphuric acid
Potassium K Violent reaction forming a salt and hydrogen gas
eg 2 Na (s) + 2 HCl (aq) 2 NaCl (aq) + H2 (g) Sodium Na
Calcium Ca Vigorous reaction forming a salt and hydrogen gas
eg Mg (s) + 2 HCl (aq) MgCl2 (aq) + H2 (g) Magnesium Mg
Aluminium Al React forming a salt and hydrogen gas
eg Fe (s) + 2 HCl (aq) FeCl2 (aq) + H2 (g) Zinc Zn
Iron Fe
Lead Pb
No reaction Copper Cu
Silver Ag
16
WEEK 2 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metals with
hydrochloric acid
Metal Balanced equation for reaction with hydrochloric acid
Potassium
Sodium
Calcium
Magnesium
Aluminium
Zinc
Iron
Copper
Silver
17
WEEK 2 LESSON 3
TOPIC Reactions of metal compounds
Reactions of metallic oxides with dilute acid
Metal oxides react with dilute hydrochloric acid or sulphuric acid to produce a salt and water
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
Some of these reactions may be slow and can be speeded up by adding heat
For example
zinc oxide + hydrochloric acid zinc chloride + water
ZnO (s) + 2 HCl (aq) ZnCl2 (aq) + H2O (l)
magnesium oxide + hydrochloric acid magnesium chloride + water
MgO (s) + 2 HCl (aq) MgCl2 (aq) + H2O (l)
aluminium oxide + sulphuric acid aluminium sulphate + water
Al2O3 3 H2SO4 (aq) Al2(SO4)3 (aq) + 3 H2O (l)
calcium oxide + sulphuric acid calcium sulphate + water
CaO H2SO4 (aq) CaSO4 (aq) + H2O (l)
18
WEEK 2 LESSON 3 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal oxides with the
corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium oxide Hydrochloric acid
Sodium oxide Sulphuric acid
Calcium oxide Hydrochloric acid
Magnesium oxide Sulphuric acid
Aluminium oxide Hydrochloric acid
Zinc oxide Sulphuric acid
19
WEEK 3 LESSON 1
TOPIC Reactions of metal compounds
Reactions of metallic hydroxides with dilute acid
Metal hydroxides react with dilute acids to form a salt and water in a neutralisation reaction
When hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric
acid is used the corresponding sulphate salt is formed
For example
magnesium hydroxide + hydrochloric acid magnesium chloride + water
Mg(OH)2 (aq) + 2 HCl (aq) MgCl2 (aq) + 2 H2O (l)
sodium hydroxide + hydrochloric acid sodium chloride + water
NaOH (aq) + HCl (aq) NaCl (aq) + H2O (l)
potassium hydroxide + sulphuric acid potassium sulphate + water
2 KOH + H2SO4 (aq) K2SO4 (aq) + 2 H2O (l)
calcium hydroxide + sulphuric acid calcium sulphate + water
Ca(OH)2 (aq) + H2SO4 (aq) CaSO4 (aq) + 2 H2O (l)
20
WEEK 3 LESSON 1 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal hydroxides with
the corresponding acid
Metallic oxide Acid Balanced chemical equation
Potassium hydroxide Hydrochloric acid
Sodium hydroxide Sulphuric acid
Calcium hydroxide Hydrochloric acid
Magnesium hydroxide Sulphuric acid
Aluminium hydroxide Hydrochloric acid
Zinc hydroxide Sulphuric acid
21
WEEK 3 LESSON 2
TOPIC Reactions of metal compounds
Reactions of metallic carbonates with dilute acid
Metal carbonates react with dilute acid to form a salt carbon dioxide and water When
hydrochloric acid is used the corresponding chloride salt is formed and when sulphuric acid is
used the corresponding sulphate salt is formed
For example
sodium carbonate + hydrochloric acid sodium chloride + carbon dioxide + water
Na2CO3 (s) + 2 HCl (aq) 2 NaCl (aq) + CO2 (g) + H2O (aq)
calcium carbonate + hydrochloric acid calcium chloride + carbon dioxide + water
CaCO3 (s) + 2 HCl (aq) CaCl2 (aq) + CO2 (g) + H2O (aq)
zinc carbonate + sulphuric acid zinc sulphate + carbon dioxide + water
ZnCO3 (s) + H2SO4 (aq) ZnSO4 (aq) CO2 (g) + H2O (aq)
potassium carbonate + sulphuric acid potassium sulphate + carbon dioxide + water
K2CO3 (s) H2SO4 (aq) K2SO4 (aq) CO2 (g) + 2 H2O (aq)
22
WEEK 3 LESSON 2 WORKSHEET
Write the balanced chemical equation for the reaction of the named metal carbonates with
the corresponding acid
Metallic
carbonate
Acid Balanced chemical equation
Potassium
carbonate
Hydrochloric
acid
Sodium
carbonate
Sulphuric acid
Zinc
carbonate
Hydrochloric
acid
Magnesium
carbonate
Sulphuric acid
Aluminium
carbonate
Hydrochloric
acid
Calcium
carbonate
Sulphuric acid
23
WEEK 3 LESSON 3
TOPIC Action of heat on metal compounds
Action of heat on nitrates
All nitrates decompose when heated The reactivity of the metal in the metal nitrate influences
the products of the decomposition
The nitrates of the alkali metals (Group I) with the exception of lithium nitrate decompose to
form the metal nitrite and oxygen
The nitrates of most other metals decompose to form the metal oxide nitrogen dioxide and
oxygen
The nitrates of the very unreactive metals decompose to form the meal nitrogen dioxide and
oxygen
Metal Nitrate Decomposition
Potassium K Products metal nitrite + oxygen
eg 2 NaNO3 (s) Heatrarr 2 NaNO2 (s) + O2 (g)
Sodium Na
Calcium Ca
Products metal oxide + nitrogen dioxide + oxygen
eg 2 Pb(NO3)2 (s)
Heatrarr 2 PbO (s) + 4 NO2 (g) + O2 (g)
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Products metal + nitrogen dioxide + oxygen
eg 2 AgNO3 (s) Heatrarr 2 Ag (s) + 2 NO2 (g) + O2 (g)
24
WEEK 3 LESSON 3 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
nitrates
Metal Balanced chemical equation
Potassium nitrate
Sodium nitrate
Calcium nitrate
Magnesium nitrate
Aluminium nitrate
Zinc nitrate
Lead nitrate
Copper nitrate
Silver nitrate
25
WEEK 4 LESSON 1
TOPIC Action of heat on metal compounds
Action of heat on carbonates
Upon application of heat many carbonates decompose to form the metal oxide and carbon
dioxide
Group I carbonates do not decompose on heating with the exception of lithium carbonate
Metal Carbonate decomposition
Potassium K
Stable not decomposed by heat Sodium Na
Calcium Ca
Decompose forming metal oxide and carbon dioxide
eg CaCO3 (s) Heatrarr CaO (s) + CO2 (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag Unstable
26
WEEK 4 LESSON 1 WORKSHEET
Write the balanced chemical equation for the thermal decomposition of the following metal
carbonates
Metal Balanced chemical equation
Potassium carbonate
Sodium carbonate
Calcium carbonate
Magnesium carbonate
Aluminium carbonate
Zinc carbonate
Iron carbonate
Lead carbonate
Copper carbonate
27
WEEK 4 LESSON 2
TOPIC Action of heat on metal compounds
Action of heat on the metal hydroxides
Most metal hydroxides decompose on heating A metal oxide and water are formed
Group I hydroxides do not decompose on heating with the exception of lithium hydroxide
Metal Hydroxide decomposition
Potassium K Stable not decomposed by heat
Sodium Na
Calcium Ca Decompose forming metal oxide and water (as steam)
eg Zn(OH)2 (s) Heatrarr ZnO (s) + H2O (g)
NB the ease increases down the series
Magnesium Mg
Aluminium Al
Zinc Zn
Iron Fe
Lead Pb
Copper Cu
Silver Ag No hydroxide exist
28
WEEK 4 LESSON 2 WORKSHEET
Write the balanced chemical equations for the thermal decomposition of the following
metal hydroxides
Metal hydroxide Balanced chemical equation
Potassium hydroxide
Sodium hydroxide
Calcium hydroxide
Magnesium hydroxide
Aluminium hydroxide
Zinc hydroxide
Lead hydroxide
Copper hydroxide
29
WEEK 4 LESSON 3
TOPIC Reactivity of metals ndash The Reactivity Series
The reactivity series of metals is a list of metals arranged in order of their reactivity based on
Displacement reactions
Reactions with oxygen dilute acids and water
Relative ease of decomposition of their compounds
Metals at the top of the series are the most electropositive They lose electrons very easily and
readily form cations These ions are very stable and are not easily discharged to form atoms Due
to this fact they are the most reactive metals
Metals at the bottom of the series are the least electropositive They do not lose electrons easily
and do not readily form ions Their ions are very unstable and are easily discharged to form
atoms They are the least reactive metals
The reactivity series of metals
Mnemonic Metal Symbol Reactivity
People Potassium K Most reactive
Least reactive
Sometimes Sodium Na
Collect Calcium Ca
Magazines Magnesium Mg
About Aluminium Al
Zoos Zinc Zn
In Iron Fe
London Lead Pb
Having (Hydrogen) H
Cute Copper Cu
Monkeys and Mercury Hg
Small Silver Ag
Gorillas Gold Au
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
5 Reactivity of metals Reactivity of metals Reactivity of metals
6 Extraction of metals Extraction of metals Alloys
7 Corrosion Importance of metals
and their compounds
on living systems and
environment
Chemical properties
of non ndash metals
8 Laboratory
preparation of gases
Laboratory
preparation of gases
Laboratory
preparation of gases
9 Uses of gases Uses of non ndash metals
and their compounds
Harmful effects of
non ndash metals and
their compounds on
living systems and
the environment
10 Green Chemistry Qualitative Analysis
ndash Identification of
cations
Qualitative Analysis
ndash Identification of
cations
2
WEEK 5 LESSON 1
TOPIC Reactivity of metals
Reactivity based on displacement reactions between metals and metal ions
A metal will displace a metal which is lower than itself in the reactivity series from a solution of
the metal salt
Reaction of zinc and copper (II) sulphate
Expected observations
Explanation
The size of the zinc metal decreases
The zinc metal is reacting and forming the
salt zinc sulphate
The solution becomes lighter eventually
colourless
The Cu2+ (aq) ions (responsible for the blue
colour) is reduced to Cu (s)
A brown solid is deposited at the bottom of
the container
Copper metal is formed
Equation Zn (s) + CuSO4 (aq) ZnSO4 (aq) + Cu (s)
Ionic equation
Zn (s) + Cu2+ (aq) Zn2+ (aq) + Cu (s)
Zinc is higher in the reactivity series than copper Therefore it will displace the copper ions in
the reaction above
3
Examples of other displacement reactions
Magnesium will displace Zn2+ ions in zinc sulphate since it is higher in the series than zinc
Mg (s) + Zn2+(aq) Mg2+ (aq) + Zn (s)
Silver will not displace Cu2+ ions in copper (II) sulphate [Cu is higher in the series than Ag]
Using the information above we can arrange the metals in order of their reactivity with
magnesium being the most reactive and silver the least reactive metal among the four metals
Mg gt Zn gt Cu gt Ag
Reactivity based on reaction with oxygen
The reactivity of metals can also be deduced from their reaction with oxygen
The table below gives the observations for the reaction with oxygen with the selected metals
Reaction of metal with oxygen
Metal Observation
Copper The surface turns black upon heating
Magnesium Ribbon burns very rapidly
Sodium Burns vigorously
Gold No reaction
Based on the observations for the 4 metals the metal with highest reactivity is sodium and the
metal with the least reactivity is gold
The 4 metals can be arranged in terms of reactivity as follows
Na gt Mg gt Cu gt Au
4
WEEK 5 LESSON 1 WORKSHEET
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
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5
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
6
WEEK 5 LESSON 2
TOPIC Reactivity of metals
Reactivity based on reactivity with acids
The metals that are higher than hydrogen in the electrochemical series react with non ndash oxidizing
acids to produce a salt and hydrogen gas
By using the same concentration of acid and same mass and size of the metals the order of
reactivity of the metals can be deduced
The table below shows the results for an experiment with the reaction of the named metals and
1 mol dm-3 hydrochloric acid
Reaction of metals with acid
Metal Observations
Silver No reaction
Magnesium Bubbles produced steadily
Calcium Bubbles produced very rapidly
Iron Bubbles produced slowly
Based on the above data the most reactive metal will be calcium with the least reactive being
silver The order of reactivity will be Ca gt Mg gt Fe gt Ag
By comparing this to the electrochemical series it can be seen that the reactivity of the metals
decrease as we go down the series
7
WEEK 5 LESSON 2 WORKSHEET
1 Place a next to the metals that will react with dilute acid and an X next to the metals
that will not react with dilute acid
Metal Reactivity with acid
Copper
Magnesium
Aluminium
Silver
Zinc
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
8
WEEK 5 LESSON 3
TOPIC Reactivity of metals
Reactivity based on ease of decomposition of the metal nitrates carbonates oxides and
hydroxides
The more reactive a metal the more difficult it is to decompose its nitrate carbonate oxide or
hydroxide on heating
For example Decomposition of carbonates
Procedure
1 Put a large spatula measure of the carbonate to be tested in a test tube
2 Fit a delivery tube and then clamp the test tube so that the delivery tube dips into a second test
tube containing 2ndash3 cm3 limewater
3 Heat the solid gently at first then more strongly
4 Lift the delivery tube from the limewater before or as soon as the heating is stopped This is to
avoid suck-back
5 Write down all observations Notice what happens to the limewater and how long it takes to turn
milky (if at all) Notice whether any melting occurs in the heated test tube and any colour
changes taking place Write your results in tabular form
6 Repeat the experiment with the other metal carbonates supplied and in each case write down
your observations
7 Wash your hands thoroughly at the end of these experiments since some of the metal carbonates
are toxic
9
Results
Metal Formula Gas evolved Ease of decomposition
Zinc ZnCO3 Carbon dioxide Fairly easy
Copper CuCO3 Carbon dioxide Easy
Sodium Na2CO3 None Very difficult
Using the results of the above activity the reactivity of the metals can be determined
Ease of decomposition Copper gt Zinc gt Sodium
The order of reactivity is the opposite for the ease of decomposition
Order of reactivity Sodium (most reactive) gt Zinc gt Copper (least reactive)
10
WEEK 5 LESSON 3 WORKSHEET
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
11
WEEK 6 LESSON 1
TOPIC Extraction of metals
Elements exist all over the earth Some are found as free elements eg copper silver and gold
Others are found combined with other elements in compounds To get the elements the
compounds have to be broken up These compounds are generally called ores the most
convenient sources of which are rocks sea and air
The extraction of a metal from its ore is a reduction process where the metals ions gain electrons
to form atoms
The general equation is Mn+ + n e- M
The choice of the extraction method depends on the position of the metal in the reactivity series
As we go down the series the metals become more stable and the metal ions (in the ores)
become less stable
The very reactive metals that are high in the series K Na Ca Mg Al have very stable ores
Therefore they require a powerful method of reduction namely electrolysis During the process
the cathode provides the electrons and acts as the reducing agent
The metals in the middle of the series (Zn Fe Pb) do not have stable ores and can be extracted
by reduction with carbon in the case of zinc and with carbon monoxide in the case of iron and
lead
Metals low in the reactivity series if present as ores can be extracted simply by heating the ores
in air at high temperatures
12
Extraction of Aluminium from purified bauxite
Pure bauxite is pure alumina (Al2O3) Aluminium is obtained from bauxite by electrolysis
Aluminium oxide has a very high melting point approximately 2050 0C so it is first dissolved in
molten cryolite (Na2AlF6) The addition of cryolite lowers the melting point to approximately
900 0C
The electrolyte is a molten mixture of alumina and molten cryolite The cathode is the graphite
lining of the cell The anodes are blocks of graphite or titanium alloys
Reaction at the cathode
Al3+ (l) + 3 e- Al (l)
Reaction at the anode
2 O2- (l) ndash 4 e- O2 (g)
Aluminium (melting point 660 0C) is a liquid at the temperature at which electrolysis is carried
out and is collected at the bottom of the cell and tapped off Oxygen gas which is given off in the
main cathode reaction together with the heat causes the anodes to burn away The anodes have
to be replaced from time to time The use of anodes from titanium alloys reduce the number of
times that the anodes have to be replaced
13
WEEK 6 LESSON 1 Worksheet
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 6 LESSON 2
TOPIC Extraction of metals
Extraction of Iron
The traditional method of production of iron is by reduction of haematite by carbon monoxide in
a blast furnace
Ores Haematite ndash Fe2O3 Magnetite ndash Fe3O4 Siderite ndash FeCO3 Magnetite and Siderite are
converted to Haematite
A mixture of haematite limestone (CaCO3) and coke (C) called the charge is placed into the top
of the furnace
Hot air is blown into the bottom of the furnace
Coke burns in air forming carbon dioxide
C (s) + O2(g) CO2 (g) ΔH -ve
The heat produced keeps the temperature at about 1900 0C
The carbon dioxide is reduced to carbon monoxide by the hot coke
CO2 (g) + C (s) 2 CO(g) Δ +ve
Heat absorbed reduces the temperature to about 1100 0C
The carbon monoxide reduces the hot iron ore to molten iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + 3 CO2(g)
The temperature at this part of the furnace is about 700 0C The iron runs to the bottom of the
furnace
The impurities are removed by the addition of limestone (CaCO3) The limestone at the
temperature of the furnace breaks down
CaCO3 (s) CaO (s) + CO2 (g)
15
The calcium oxide formed combines with silicon dioxide (sand) the main impurity in the iron
ore to form molten slag
CaO (s) + SiO2 (s) CaSiO3 (l)
The slag does not mix with the molten iron but floats on it The molten iron and slag are run off
separately
The iron formed in a blast furnace is an impure form of the metal Because the molten metal is
allowed to solidify in shallow trays known as casts the iron is called lsquocast ironrsquo or lsquopigrsquo iron
Cast iron is quite brittle and contains 2 - 4 carbon and other impurities Most of the cast iron is
converted to steel
A blast furnace used for extracting iron
16
WEEK 6 LESSON 2 Worksheet
(a) What are the three raw materials that are added through the top of the blast furnace
during the extraction process for iron
______________________________________________________________________________
______________________________________________________________________________
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
17
WEEK 6 LESSON 3
TOPIC Alloys
An alloy is a mixture of two or more metals Alloys are made by melting the individual metals
mixing them and allowing the molten mixture to solidify
In general alloys are harder stronger and more resistant to corrosion than the actual metals they
are made up from
Alloy Use Properties
ALUMINIUM
-Duralumin
(AlMgCu)
-Magnalium (AlMg)
Alloys used in the
construction of
aircraft and ships
buses
Aluminium is used in
making cooking
utensils electrical
cables paint for fuel
storage tanks bottle
caps foil and utensils
for handling nitric
acid
The alloys have a low
density They are as
light as aluminium
and more resistant to
corrosion than
aluminium
LEAD
-Solder (PbSn)
Alloy is used in
joining metals
(soldering)
Lead is used in
underground cables
plates in
The alloy has a lower
melting point than
lead and is harder
than lead
18
Alloy Use Properties
accumulators shield
against x ndash rays
IRON
- Stainless Steel
(FeCONiC)
-Tungsten steel
(FeWC)
-Invar steel (FeNi)
Manganese steel
(FeMnC)
Iron is the main metal
of a variety of
constructions
Steel is used in
cutlery rock drills
electromagnets
vehicle body and
engine parts fences
pipes etc
Steel resists
corrosion is usually
harder than iron and
may be tough though
malleable and ductile
19
WEEK 6 LESSON 3 Worksheet
(a) Define the term alloy
______________________________________________________________________________
(b) State 3 general advantages that alloys have over the individual metals they are made
from
______________________________________________________________________________
______________________________________________________________________________
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
______________________________________________________________________________
______________________________________________________________________________
Uses
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 7 LESSON 1
TOPIC Corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
Familiar examples of corrosion are
- the formation of a green powder on copper sheeting
- the eating away of iron (rusting)
- the development by aluminum of a thin compact layer of oxide which protects the
underlying metal from further corrosion
When corrosion occurs in water ndash free environment it is called dry oxidation When it occurs in
aerated aqueous environments it is called wet corrosion Wet corrosion is the most common and
troublesome form of corrosion
The most familiar corrosion is the rusting of iron and steel On exposure to the atmosphere iron
and steel corrode to form rust which is hydrated iron (III) oxide Fe2O3xH2O Iron and steel
corrode easily and the rust formed flakes off easily thus exposing fresh surface for attack
When iron rust it loses electrons
Fe (s) ndash 2e- Fe 2+ (aq)
The iron (II) ions pass into solution and then combine with the hydroxyl (OH-) ions in the
aerated aqueous environment to form iron (II) hydroxide The oxygen present oxidises the iron
(II) hydroxide to hydrated iron (III) oxide or rust
Fe(OH)2 + O2 Fe2O3xH2O
21
Methods of preventing rusting
1 Coating the object with paint grease plastic or rubber which prevent contact with air or
water
2 Galvanising ndash coating the object with zinc The zinc forms an adherent oxide layer which
protects against further corrosion If damaged the zinc is oxidized in preference to the
iron since it is higher in the electrochemical series
3 Coating with tin lsquoTinrsquo cans are made of steel plated with tin However if scratched
rusting occurs since iron is more reactive than tin
4 Attaching a sacrificial anode to the object A piece of metal higher in the electrochemical
series such as magnesium is attached The magnesium will be oxidized in preference
since it is higher in the electrochemical series than iron
22
WEEK 7 LESSON 1 WORKSHEET
(a) Define the term corrosion
______________________________________________________________________________
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
23
WEEK 7 LESSON 2
TOPIC Importance of metals and their compounds on living systems and environment
Some metals are an integral part of different structures of living things
Metal Presence and Function
Potassium Main cation in fluid or animal cells essential for healthy plant growth
Calcium Necessary for strong bones teeth and shells needed by some enzymes Present
in dairy produce eggs nuts and cereals
Magnesium Central atom of chlorophyll needed for some enzyme action Involved in energy
and calcium metabolism
Zinc Present in many enzymes Needed for protein metabolism Essential for growth
of animals
Iron Present in haemoglobin Needed for protein metabolism Essential for growth of
animals
Chromium Needed for glucose uptake by cells and thus linked to the action of insulin
Manganese Needed for bone development and amino acid metabolism Present in several
enzymes Needed for plant growth
Cobalt Present in Vitamin B12 Needed for plant growth
Copper Involved in formation of haemoglobin and melanin Present in enzymes
controlling oxidation Needed for plant growth
24
Harmful effects of metals and their compounds to living systems and the environment
There are some metals and metal compounds which may cause harm to living systems and the
environment
Lead
Lead is a heavy metal poison that is widely encountered It may occur in food beverages paint
water formed from ndash sealed pipes in air polluted by combustion by fuels containing lead
compounds Lead is also used in some car batteries If these are paints or batteries are not
disposed of correctly lead may get into groundwater or air Lead and lead compounds harm the
nervous system including the brain especially young children
Arsenic
Arsenic compounds are poisonous They can get into the groundwater from mining waste and
from disposal of some electrical components
Cadmium
Cadmium compounds are poisonous They can get into the ground by improper disposal of
nickel ndash cadmium batteries Persons can get cadmium poisoning if they eat food grown in
contaminated soil
Mercury
Mercury can be spilled from broken thermometers in hospitals and laboratories Mercury and its
compounds are particularly poisonous to fish and it can accumulate in the food chain and
eventually poison humans
Problems of disposal of solid waste
Metals may react with water andor air and corrode to form soluble compounds that are
poisonous These toxic compounds diffuse into the soil and eventually enter rivers
Rust from iron may form unsightly pools of waste that reduce plant growth
Waste from aluminium extraction may react with water and form flammable gases
25
WEEK 7 LESSON 2 WORKSHEET
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Lead
______________________________________________________________________________
Mercury
______________________________________________________________________________
26
WEEK 7 LESSON 3
TOPIC Chemical properties of non ndash metals
Reaction with oxygen
Many non ndash metals burn in excess oxygen or air to form oxides For example
S (s) + O2 (g) SO2 (g)
C (s) + O2 (g) CO2 (g)
Reactions with metals
Some non ndash metals react with metals high in the electrochemical series when heated
For example
Sodium burns in chlorine to form sodium chloride
Na (s) + Cl2 (g) NaCl (s)
Magnesium burns in oxygen to form magnesium oxide
Mg (s) + O2 (g) MgO (s)
When heated iron combines with molten sulphur to form iron (II) sulphide
Fe (s) + S (l) FeS (s)
When heated reactive metals such as sodium and aluminium react with hydrogen to form metal
hydrides
2 Na (s) + H2 (g) 2 NaH (s)
Oxidising and Reducing properties
Hydrogen and Carbon are very good reducing agents
At high temperatures hydrogen reduces metal oxides below zinc in the electrochemical series to
form the metal For example PbO (s) + H2 (g) Pb (s) + H2O (g)
Under suitable conditions hydrogen reduces nitrogen to ammonia
N2(g) + 3 H2 (g) 2 NH3 (g)
27
At high temperatures carbon reduces metal oxides below aluminium in the reactivity series to
the metal For example
ZnO (s) + C (s) Zn (s) + CO (g)
Oxygen and Chlorine are very good oxidizing agents
Oxygen oxidized most metals to form metal oxides and some non ndash metals to non ndash metal oxides
For example
2 Mg (s) + O2(g) 2 MgO (s)
4 P (s) + 5 O2 (g) P4O10 (s)
Chlorine acts as an oxidizing agent either as a gas or as an aqueous solution For example
H2 (g) + Cl2 (g) 2 HCl (g)
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
28
WEEK 7 LESSON 3 WORKSHEET
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
______________________________________________________________________________
(b) Write the ionic equation for the above reaction
______________________________________________________________________________
(c) Identify the oxidising agent in the reaction
______________________________________________________________________________
(d) Justify your answer in part (c) in terms of oxidation number
______________________________________________________________________________
29
WEEK 8 LESSON 1
TOPIC Laboratory preparation of gases
Preparation of oxygen
Oxygen can be prepared by the decomposition of hydrogen peroxide potassium chlorate (V) or
potassium nitrate The safest method is the decomposition of hydrogen peroxide
Manganese (IV) oxide catalyses the decomposition of hydrogen peroxide
Silica gel anhydrous calcium chloride or concentrated sulphuric acid can be used as a drying
agent
The gas is collected by downward delivery since it is slightly denser than air
Equation
2 H2O2 (aq) 2 H2O (l) + O2 (g)
Apparatus used for laboratory preparation of oxygen
30
WEEK 8 LESSON 1 WORKSHEET
Describe the laboratory preparation of oxygen gas
In your answer include
The starting material
A suitable catalyst
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
31
WEEK 8 LESSON 2
TOPIC Laboratory preparation of gases
Preparation of carbon dioxide
Carbon dioxide can be prepared by the action of dilute acid on carbonates Marble chips (calcium
carbonate) and dilute hydrochloric acid are the common reagents The gas is collected by
downward delivery since it is denser than air
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
Apparatus used for laboratory preparation of carbon dioxide
32
WEEK 8 LESSON 2 WORKSHEET
Describe the laboratory preparation of carbon dioxide gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
33
WEEK 8 LESSON 3
TOPIC Laboratory preparation of gases
Preparation of ammonia
Ammonia may be prepared by heating a mixture of ammonium salt and a hydroxide The
ammonia gas is collected by upward delivery since it is less dense than air
For example
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
Calcium oxide is the only suitable drying agent since ammonia reacts with conc H2SO4 and
CaCl2
Apparatus used for laboratory preparation of dry ammonia
34
11
WEEK 8 LESSON 3 WORKSHEET
Describe the laboratory preparation of ammonia gas
In your answer include
The reagents
Drying agent
Type of collection (delivery) and reason for such type
Balanced chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
35
WEEK 9 LESSON 1
TOPIC Uses of gases
Carbon dioxide
Used in fire extinguishers to put out fires Carbon dioxide is denser than air and lsquoblanketsrsquo the
fire preventing oxygen from reaching it Carbon dioxide extinguishers are especially useful for
dealing with fires involving flammable liquids and electrical equipment
Carbonation in soda is created when carbon dioxide is pumped into the soda can or bottle then
held under pressure As long as the can or bottle is sealed the carbon dioxide remains mostly
stable However if the drink gets shaken up or the top is opened the tiny carbon dioxide bubbles
react by bursting
Oxygen
Oxygen is needed for aerobic respiration We need a constant supply of oxygen for this process
Oxygen is used in hospitals to improve the respiration of patients with poor blood flow blood
poisoning and heart disease
Oxygen in used in welding (joining) metals In an oxyacetylene welding torch acetylene or
ethyne (C2H2) burns in oxygen and produces a very hot flame This flame is capable of melting
most metals
Oxygen is used in steel production A blast of oxygen is blown through the molten iron The
oxygen oxidises many of the impurities of the iron and the impurities are then removed
36
WEEK 9 LESSON 1 WORKSHEET
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Put out fires
Welding metals
Create lsquofizzrsquo in drinks
Used in steel production
Aerobic respiration
37
WEEK 9 LESSON 2
TOPIC Uses of non ndash metals and their compounds
Carbon (allotrophes carbon dioxide)
Carbon is used as a reducing agent in extraction of some metals
Carbon as graphite is used as electrodes lubricants and lsquoleadrsquo for pencils
Carbon in the form of diamond is used for jewellery (because of its lustre) and in drill tips for
high ndash speed drills (because of its hardness)
Carbon dioxide is used as refrigerant (as dry ice) for carbonated beverages
Sodium hydrogen carbonate and sodium carbonate are used for water softening and raising
agent
Sulphur
Sulphur is used in the manufacture of sulphuric acid Sulphur is also used in the manufacture of
tyres to make the rubber harder (vulcanisation)
Sulphur powder is used as fungicide on plant materials
Phosphorus
Phosphorus is used in the manufacture of fertilizers
Phosphorus is used to make phosphor bronze alloys
Phosphorus sulphide is used to make the heads of lsquostrike anywherersquo matches
38
Chlorine
Chlorine is used to make sodium hypochlorite which is present in bleach It is also used in
sterilizing swimming pools and in water treatment
Chlorine is used to make the monomer vinyl chloride which is used to make the plastic PVC
Nitrogen
Nitrogen is used to make fertilisers ammonia dyes and nitric acid
Nitrogen is used as an inert atmosphere to prevent substances being oxidised and as a coolant
Silicon
Silicon is used for making silicon chips for computers
Silicon (V) oxide is present in sand Glass is made by heating sand with lime (calcium oxide) and
sodium carbonate
Silicon in the form of silicates is used in jewellery
Silica gel is used as a drying agent
39
WEEK 9 LESSON 2 WORKSHEET
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Used to make sodium hypochlorite
Used as a fungicide on plant materials
Used for lsquoleadrsquo in pencils
Used in the manufacture of bronze alloys
Used in the manufacture of nitric acid
Used in the manufacture of computer chips
Used to make fertilisers
40
WEEK 9 LESSON 3
TOPIC Harmful effects of non ndash metals and their compounds on living systems and the
environment
Sulphur dioxide
Sulphur dioxide can cause a disease of the lungs Sulphur dioxide also poisons plants in two
main ways It may enter the stomata of leaves and react with the tissue fluids to form sulphites
with the on ndash going water loss the concentration of sulphites could build up killing the cells
The second adverse effect on plants occurs when sulphur dioxide dissolves in rain thereby
increasing soil acidity A prolonged acid soil situation may lead to plasmolysis and the death of
vegetation in an area
Carbon monoxide
Carbon monoxide combines much more readily than oxygen with haemoglobin When carbon
monoxide is inhaled it prevents the haemoglobin from taking oxygen to the bodyrsquos cells
Continued breathing of air containing carbon monoxide eventually causes death
Hydrogen sulphide
Hydrogen sulphide reacts readily with many cations forming insoluble sulphides Many cations
contribute to good health by contributing to enzyme activity and to the formation of bone
pigment and haemoglobin Although these cations are required in extremely small
concentrations they are removed by being precipitated as sulphides and thus not available for
regular function Careless dumping of refuse contributes to atmospheric pollution by hydrogen
sulphide
Oxides of nitrogen
In the presence of hydrocarbons from car exhausts ozone and sunlight nitrogen oxides react to
form photochemical smog which contains many harmful chemicals
Nitrogen dioxide can harm the lungs and irritate the nose throat and eyes The other compounds
present in photochemical smog are even more harmful irritants and can cause asthma
41
Carbon dioxide
Carbon dioxide water vapour and ozone referred to as ldquogreenhouse gasesrdquo acting as a blanket
readily absorb some of the radiated heat energy and in turn warms the earthrsquos atmosphere This is
called the ldquogreenhouse effectrdquo Scientists have found direct correlation between carbon dioxide
concentration and global warming An increase in carbon dioxide concentration resulted in an
increase global temperatures Global warming is a major potential problem that the world faces
Chloroflourocarbons (CFCs)
It is believed that CFCs might be responsible for destroying the ozone layer which prevents
harmful ultraviolet (UV) radiation from reaching the earth The carbon ndash chlorine bond in CFC
molecule is easily broken by a UV photon producing an active chlorine atom This atom
combines with an ozone molecule forming a chlorine oxide radical and oxygen The radicle
reacts with more ozone producing the chlorine atom again This kind of reaction is repeated
thousands of times This type of reaction is thought to account for about eighty percent of the
loss of ozone observed
Nitrates and phospates
Nitrates and phosphates cause eutrophication The process leading to eutrophication are
Nitrates and phosphates from fertilisers spread on fields may dissolve in groundwater and
get into lakes and rivers
Nitrates and phosphates cause excessive growth of algae so that they cover the surface of
the water
Water plants including algae die because of lack of sunlight Aerobic bacteria feed on
the plant remains The bacteria multiply
The aerobic bacteria use up the oxygen in the water so aquatic animals die
42
Solid waste
The main sources of pollution from non ndash metals is from glass paper and plastics
Broken glass can cause injury to animals It can also cause fires by acting as lens focusing the
sunrsquos rays on flammable materials
Printing inks from paper dumped in the ground may contain toxic elements such as arsenic and
cadmium Bleaches and chlorine compounds from paper are also harmful
43
WEEK 9 LESSON 3 WORKSHEET
Describe ONE harmful effect of the following non ndash metals andor their compounds on
living systems and the environment
Sulphur dioxide
______________________________________________________________________________
______________________________________________________________________________
Carbon monoxide
______________________________________________________________________________
______________________________________________________________________________
Carbon dioxide
______________________________________________________________________________
______________________________________________________________________________
Oxides of nitrogen
______________________________________________________________________________
______________________________________________________________________________
Hydrogen sulphide
______________________________________________________________________________
______________________________________________________________________________
44
Chloroflourocarbons (CFCs)
______________________________________________________________________________
______________________________________________________________________________
Nitrates and phospates
______________________________________________________________________________
______________________________________________________________________________
45
WEEK 10 LESSON 1
TOPIC Green Chemistry
Green Chemistry is defined as the utilisation of a set of principles that reduces or eliminates the
use and generation of hazardous substances
There are twelve principles of green chemistry as proposed by Paul T Anastas and John C
Warner These twelve principles are
1 Prevention ndash It is better to prevent waste than to treat or clean up waste after it has been
created
2 Atom economy - Synthetic methods should be designed to maximize the incorporation of
all materials used in the process into the final product
3 Less hazardous chemical synthesis - Wherever practicable synthetic methods should be
designed to use and generate substances that possess little or no toxicity to human health
and the environment
4 Safer chemical products - Chemical products should be designed to affect their desired
function while minimizing their toxicity
5 Safer solvents and other agents - The use of auxiliary substances (eg solvents
separation agents etc) should be made unnecessary wherever possible and harmless
when used
6 Minimum energy requirements - Energy requirements of chemical processes should be
recognized for their environmental and economic impacts and should be minimized If
possible synthetic methods should be conducted at ambient temperature and pressure
7 Use of renewable raw materials - A raw material or feedstock should be renewable rather
than depleting whenever technically and economically practicable
8 Reduce use of additional chemicals or additional steps - Unnecessary derivatization (use
of blocking groups protection deprotection temporary modification of
physicalchemical processes) should be minimized or avoided if possible because such
steps require additional reagents and can generate waste
46
9 Use of catalysts ndash The use of catalysts reduce energy costs because the reactions take
place at lower temperatures The more specific the catalyst for a particular reaction is the
less it the likelihood of getting additional unwanted products
10 Nature of breakdown of products - Chemical products should be designed so that at the
end of their function they break down into innocuous degradation products and do not
persist in the environment
11 Monitoring to prevent pollution - Analytical methodologies need to be further developed
to allow for real-time in-process monitoring and control prior to the formation of
hazardous substances
12 Minimise chemical accidents - Substances and the form of a substance used in a chemical
process should be chosen to minimize the potential for chemical accidents including
releases explosions and fires
47
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
48
WEEK 10 LESSON 2
TOPIC Qualitative Analysis ndash Identification of cations
Qualitative Analysis involves identifying the constituents of single substances or mixture of
substances
Appearance
An examination of the appearance of a substance can indicate which ion it contains
Appearances of substances
Observation Indication
Blue or blue ndash green Cu2+ salt
Pale green Fe2+ salt
Yellow ndash brown Fe3+ salt
Ammonia smell NH4+ salt
49
Test for cation using sodium hydroxide
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
(d) If no precipitate forms in step b warm gently and test for ammonia
Effect of dilute sodium hydroxide solution
Effect of dilute sodium hydroxide solution Cation
Dropwise Excess
White precipitate Precipitate soluble Ca2+
White precipitate Precipitate insoluble Al3+ Pb2+ Zn2+
Blue precipitate Precipitate insoluble Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
No precipitate ndash ammonia gas
evolved on heating
ndash NH4+
The metal cations all form insoluble hydroxides with sodium hydroxide solution
For example Ca2+ (aq) + 2 OH- (aq) Ca(OH)2 (s)
Ca(OH)2 Cu(OH)2 Fe(OH)2 and Fe(OH)3 are basic and therefore do not react with excess
sodium hydroxide solution Therefore the precipitate does not dissolve in excess sodium
hydroxide solution
Al(OH)3 Pb(OH)2 and Zn(OH)2 are amphoteric Therefore the precipitates react with the excess
sodium hydroxide solution forming soluble salts and the precipitate disappears in excess sodium
hydroxide solution
The NH4+ ion forms a soluble hydroxide However on heating it reacts with the hydroxide ion to
form ammonia and water
NH4+ (aq) + OH- (aq) NH3 (g) + H2O (l)
50
WEEK 10 LESSON 2 WORKSHEET
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P _____________ Q ___________________
R _____________ S ___________________
R + NaOH
______________________________________________________________________________
51
WEEK 10 LESSON 3
TOPIC Qualitative Analysis ndash Identification of cations
Test for cation using ammonia solution (ammonium hydroxide solution)
Method
(a) Prepare a solution of the solid
(b) Add dilute sodium hydroxide solution dropwise Look for a precipitate
(c) Add excess sodium hydroxide solution Look for the precipitate redissolving
Effect of dilute ammonia (ammonium hydroxide) solution
Effect of dilute ammonia solution Cation
Dropwise Excess
No precipitate ndash Ca2+
White precipitate Precipitate soluble
(forming colourless solution)
Zn2+
White precipitate Precipitate insoluble Al3+ Pb2+
Blue precipitate Precipitate soluble
(forming deep blue solution)
Cu2+
Dirty green precipitate Precipitate insoluble Fe2+
Rusty brown precipitate Precipitate insoluble Fe3+
52
Ammonia solution is a weak alkali Metal cations except Ca2+ form insoluble hydroxides with
ammonia solution as with the sodium hydroxide solution
The amphoteric hydroxides Al(OH)3 and Pb(OH)2 and the basic hydroxides Fe(OH)2 and
Fe(OH)3 do not react with excess ammonia solution Therefore the precipitates remain
However Zn(OH)2 and Cu(OH)2 do react with excess ammonia solution to form complex
soluble hydroxides each Hence their precipitates disappear on the addition of excess ammonia
solution
Confirmatory test
After carrying out test for cations using sodium hydroxide solution and ammonia solution the
only cations which cannot be distinguished are Al3+ and Pb2+ A confirmatory test is carried out
to distinguish between the two cations
Confirmatory test
Test Observation Cation Ionic equation
Add potassium
or sodium
iodide solution
Bright yellow precipitate
No precipitate
Pb2+
Al3+
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
53
WEEK 10 LESSON 3 WORKSHEET
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A __________ B ________________ C ________________________
(b) State the inference after Test 2
C _______________________
(c) Write an ionic equation to support your answer in (b) above
___________________________________________________________________________
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
54
ANSWERS TO WORKSHEETS
55
WEEK 5 LESSON 1 WORKSHEET ANSWERS
1 A piece of zinc is placed in iron (II) suphate solution and a piece of iron is placed in zinc
sulphate solution
In which solution will there be a reaction With reference to the electrochemical series
explain your answer
Give the equation for the reaction
Answer
Zinc + Iron (II) sulphate Zinc is higher in the electrochemical series and therefore displace
iron ions in iron (II) sulphate
Equation Zn (s) + FeSO4 (aq) ZnSO4 (aq) + Fe (s)
Ionic equation Zn (s) + Fe2+ (aq) Zn2+ (aq) + Fe (s)
Iron + Zinc sulphate No reaction iron is lower in the electrochemical series and cannot
displace the zinc ions in zinc sulphate
56
2 A group of students carried out experiments with metals X and Y and obtained the
following results
X displaced lead from an aqueous solution of its salts but did not react with iron salts
Y burns very easily
Based on the above results and your knowledge of the reactivity series of metals place
Metals X Y Pb and Fe in order of reactivity
Support your answers with appropriate ionic equation (s)
Answer
X displaces lead from an aqueous solution of its salts
X (s) + Pb2+ (aq) Xn+ (aq) + Pb (s)
rarr X is more reactive than Pb
X did not react with iron salts
rarr X is less reactive than Fe
Y burns very easily
Y is more reactive than Fe and Pb (both forming their corresponding oxide at a slower rate)
From electrochemical series Fe is higher and therefore more reactive than Pb
Order of reactivity
Y (most reactive) gt Fe gt X gt Pb (least reactive)
57
WEEK 5 LESSON 2 WORKSHEET ANSWERS
1
Metal Reactivity with acid
Copper X
Magnesium
Aluminium
Silver X
Zinc
58
2 The following data refer to four metals W X Y and Z
Metal Reacts with dilute acid Occurs in nature as compounds
W ndash +
X ndash ndash
Y + +
Z + +
+ = Yes ndash = No
When Z is added to an aqueous solution of Y a precipitate is formed
From the above data deduce the correct order of these metals in the electrochemical series
Answer
Y and Z are the most reactive since they can react with dilute acid
Z is more reactive than Y since a reaction occurs with Z is added to an aqueous solution of Y
X is less reactive than W since it does not occur in nature as compounds
Order of reactivity Z (most reactive) gt Y gt W gt X
59
WEEK 5 LESSON 3 WORKSHEET ANSWERS
The following data refer to the decomposition of four metal nitrates A B C and D
Metal nitrate Effect of heating
A Hardly any brown gas is produced even on strong heating
B Large amounts of brown gas are produced on gentle heating
C No brown gas is produced
D Some brown gas is produced on strong heating
Use the data above to deduce the order of reactivity of the metal nitrates A B C and D
Answer
Ease of decomposition (from easiest to decompose to most difficult to decompose)
B rarrD rarrArarr C
Reactivity (most reactive to least reactive)
C (most reactive) gt A gt D gt B (least reactive)
60
WEEK 6 LESSON 1 Worksheet Answers
(a) Place the following metals in the appropriate table in terms of their method of extraction
from their ores
Potassium Zinc Lead Copper Gold Calcium Magnesium Iron
Electrolysis Reduction with a reducing
agent
Heating of the ore
Potassium Zinc Copper
Calcium Lead Gold
Magnesium Iron
(b) Describe the extraction of aluminium from its ore Include in your answer the name of the
ore the main purpose of cyrolite and the reaction at the cathode
Aluminium is extracted from its ore bauxite through the process of electrolysis
Cryolite is added to bauxite to lower the melting point to about 900 0C The melting point of
bauxite is very high (about 2040 0C) It is difficult and expensive to keep the molten aluminium
oxide at this temperature
Reaction at the cathode Al3+ (l) + 3 e- Al (l)
61
WEEK 6 LESSON 2 Worksheet Answers
(a) What are the three raw materials that are added through the top of the blast
furnace during the extraction process for iron
Coke (carbon)
iron ore (haematitie mainly iron (II) oxide)
limestone (calcium carbonate)
(b) Explain the importance of each one of the materials stated above Give equations to
support your answers
Coke ndash coke burns to produce carbon dioxide The carbon dioxide further reacts with coke to
form carbon monoxide (reducing agent in the process)
C (s) + O2 (g) CO2 (g)
C (s) + CO2 (g) 2 CO
Haematite ndash iron ore provides the iron which is reduced by the carbon monoxide to produce
iron
Fe2O3 (s) + 3 CO (g) 2 Fe (l) + CO2 (g)
Limestone ndash decomposes to form calcium oxide The calcium oxide reacts with the impurity
silicon dioxide to form slag (calcium silicate)
CaCO3 (s) CaO (s) + CO2 (g)
CaO (s) + SiO2 (l) CaSiO3(l)
62
WEEK 6 LESSON 3 Worksheet Answers
(a) Define the term alloy
An alloy is a material made from a mixture of two or more metals
(b) State 3 general advantages that alloys have over the individual metals they are made
from
They are harder stronger and more resistant to corrosion
(c) Duralumin is an alloy of aluminium State TWO enhanced properties of this alloy and
TWO uses of it
Enhanced properties
1 High strength
2 Low density
Uses
1 Used to make aircraft bodies
2 Used to make space satellites
63
WEEK 7 LESSON 1 WORKSHEET ANSWERS
(a) Define the term corrosion
Corrosion occurs when the surface of a metal reacts with water or water and oxygen to form a
layer of oxide
(b) Explain each of these statements
(i) An iron nail will not rust if it is painted but if the paint is scratched the object will
develop a large rust patch
The paint forms a barrier which stops contact with air or water and the iron Hence rusting
will not take place
However when the paint is scratched that part of the iron nail is exposed to air or water and
rusting will take place
(ii) The hull of a ship can be protected from rusting by attaching blocks of a magnesium alloy
to it
Magnesium is higher in the electrochemical series and will be oxidised in preference to iron
(iii) The corrosion of an aluminium object is a good thing where as the corrosion of an iron
object is detrimental to that iron object
Aluminium is partly protected from corrosion by its coat of aluminium oxide However as the
iron rust it flakes and fall off and the rusting process continues
64
WEEK 7 LESSON 2 WORKSHEET ANSWERS
(a) A farmer reaped a crop of tomatoes and reported that the yield was far below what was
expected He analysed the soil and found that there was a deficiency of magnesium
Discuss how the deficiency of magnesium would account for the low yield of tomatoes
Magnesium is the ion found in chlorophyll Chlorophyll plays a vital part in the process of
photosynthesis A deficiency in magnesium will lead to low chlorophyll level in the tomato
plants and hence reduce the process of photosynthesis There will be less food storage and
hence will lead to smaller yield of tomatoes
(b) Some metal compounds are health and environmental hazards
State ONE harmful effect each of continuous exposure to lead and mercury
Any correct harmful effect of lead on health or environment
Any correct harmful effect of mercury on health or environment
65
WEEK 7 LESSON 3 WORKSHEET ANSWERS
(a) Write the balanced chemical equation for the reaction
Potassium bromide + Chlorine Potassium chloride + Bromine
2 KBr (aq) + Cl2 (aq) 2 KCl (aq) + Br2 (aq)
(b) Write the ionic equation for the above reaction
2 Br- (aq) + Cl2 (aq) 2 Cl- (aq) + Br2 (aq)
(c) Identify the oxidising agent in the reaction
Cl2 (aq)
(d) Justify your answer in part (c) in terms of oxidation number
There is a reduction of the oxidation number for chlorine from 0 to ndash1
hence it has been reduced Therefore chlorine is the oxidising agent
66
WEEK 8 LESSON 1 WORKSHEET ANSWERS
Describe the laboratory preparation of oxygen gas
Oxygen is prepared in the laboratory by the decomposition of hydrogen peroxide
A suitable catalyst is manganese (IV) oxide
Drying agent silica gel OR anhydrous calcium chloride OR conc sulphuric acid
The gas is collected by downward delivery since oxygen is slightly denser than air
Balanced chemical equation 2 H2O2 (aq) 2 H2O (l) + O2 (g)
67
WEEK 8 LESSON 2 WORKSHEET ANSWERS
Describe the laboratory preparation of carbon dioxide gas
Carbon dioxide is commonly prepared in the laboratory by the reacting hydrochloric acid and
marble chips (calcium carbonate)
The drying agent could be silica gel anhydrous calcium chloride or cold concentrated sulphuric
acid
The carbon dioxide gas is collected by downward delivery since it is denser than air
Balanced chemical equation
2 HCl (aq) + CaCO3 (s) CaCl2 (aq) + H2O (l) + CO2 (g)
68
WEEK 8 LESSON 3 WORKSHEET ANSWERS
Describe the laboratory preparation of ammonia gas
An ammonium salt (ammonium chloride) and a base (sodium hydroxide) are mixed together and
heated
Calcium oxide is used as the drying agent Calcium chloride and concentrated sulphuric acid
cannot be used since ammonia can react with them
The gas is collected by upward delivery since ammonia is less dense than air
Balanced chemical equation
2 NH4Cl (s) + Ca(OH)2 (s) 2 NH3 (g) + CaCl2 (aq) + H2O (l)
69
WEEK 9 LESSON 1 WORKSHEET ANSWERS
Complete the table showing uses of gases by inserting either oxygen or carbon dioxide gases
in the column gas to match a correct use
Gas Uses
Carbon dioxide Put out fires
Oxygen Welding metals
Carbon dioxide Create lsquofizzrsquo in drinks
Oxygen Used in steel production
Oxygen Aerobic respiration
70
WEEK 9 LESSON 2 WORKSHEET ANSWERS
Insert the non ndash metals carbon sulphur phosphorus chlorine nitrogen and silicon to
match a correct use An option may be used once more than once or not at all
Non ndash metal Uses
Chlorine Used to make sodium hypochlorite
Sulphur Used as a fungicide on plant materials
Carbon (graphite) Used for lsquoleadrsquo in pencils
Phosphorus Used in the manufacture of bronze alloys
Nitrogen Used in the manufacture of nitric acid
Silicon Used in the manufacture of computer chips
Nitrogen Phosphorus Used to make fertilisers
71
WEEK 10 LESSON 1 WORKSHEET
In recent years emphasis has been placed on preserving the environment and as such a new area
of chemistry Green Chemistry has evolved
(i) What is meant by the term lsquoGreen Chemistryrsquo
Green Chemistry is using principles that reduceeliminate the use of hazardous materials in
the design manufacture and application of chemical products
(ii) Discuss TWO benefits of utilizing the principles involved in Green Chemistry
Makes the environment safer
Reduces waste
Creates new jobs
Reduces respiratory illnesses
Atom economy
72
WEEK 10 LESSON 2 WORKSHEET ANSWERS
The following chart shows reactions of cations with sodium hydroxide
(a) Identify the cations P Q R and S
(b) Write an ionic equation for R with NaOH
P Cu2+ Q Fe2+
R Fe3+ S Ca2+
Ionic equation for R + NaOH
Fe3+ (aq) + 3 OH- (aq) Fe(OH)3 (s)
73
WEEK 10 LESSON 3 WORKSHEET ANSWERS
The following chart shows reactions of cations with aqueous ammonia
(a) State the inferences after Test 1
A Fe3+ B Ca2+ C Al3+ Pb2+
(b) State the inference after Test 2
C Pb2+
(c) Write an ionic equation to support your answer in (b) above
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
Test 1 Reaction of cations with aqueous ammonia solution
Test 2 Reaction of cation C with sodium iodine solution
1
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
Topics per lesson
WEEK
LESSON
1 2 3
11 Qualitative Analysis
ndash Test for gases
Qualitative Analysis
ndash Identification of
anions
Qualitative Analysis
ndash Identification of
anions
12 Problem solving of
Past CSEC Chemistry Paper 2
on topics completed in the term
13
14
15
2
WEEK 11 LESSON 1
TOPIC Qualitative Analysis ndash Test for gases
Identification of gases
Gas Colour Odour Effect on moist
litmus
Method of identification
Oxygen
O2
Colourless Odourless Neutral ndash no
effect
Relights a glowing splint
Hydrogen
H2
Colourless Odourless Neutral ndash no
effect
Lighted splint lsquopopsrsquo if air is also
present
Carbon
dioxide
CO2
Colourless Odourless Weakly acidic ndash
blue to slightly
red
A white precipitate forms in
limewater
Ca(OH)2 (aq) + CO2
CaCO3 (s) + H2O (l)
Precipitate redissolves on
continued bubbling
CaCO3 (s) + H2O (l) + CO2 (g)
Ca(HCO3)2 (aq)
Ammonia
NH3
Colourless Pungent Alkaline ndash red
to blue (only
common
alkaline gas)
Turns moist red litmus blue forms
dense white fumes with hydrogen
chloride gas
NH3 (g) + HCl (g) NH4Cl (s)
Gas Colour Odour Effect on moist
litmus
Method of identification
3
Sulphur
dioxide
SO2
Colourless Choking
smell
Acidic ndash blue to
red
Turns acidified potassium
manganate (VII) solution from
purple to colourless
Turns acidified potassium
dichromate (VI) solution from
orange to green
Chlorine
Cl2
Yellow ndash
green
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Bromine
Br2
Red ndash
brown
Choking
smell
Acidic ndash blue to
red then
bleached
Turns moist blue litmus red and
then bleaches it
Nitrogen
dioxide
NO2
Red ndash
brown
Irritating
smell
Acidic blue to
red
Turns moist blue litmus red but
does not bleach it
Water
vapour
H2O
Colourless Odourless Neutral ndash no
effect
Turns anhydrous cobalt (II)
chloride from blue to pink
Turns anhydrous copper (II)
sulphate from white to blue
4
WEEK 11 LESSON 1 WORKSHEET
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless
Yellow ndash green
Red ndash brown
Gases according to their odour
Odour of gas Identity of gas
Odourless
Pungent smell
Choking smell
Irritating smell
5
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect
Red to blue
Blue to red
Blue to red then bleaches it
6
WEEK 11 LESSON 2
TOPIC Qualitative Analysis ndash Identification of anions
Effect of heating
Method Heat a sample of the solid in a dry test tube
Effect of heating
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) not
of K or Na
CO32- (s) O2- (s) + CO2 (g)
Oxygen evolved NO3- of K or Na 2 NO3
- (s) 2 NO2- (s) + O2
(g)
Oxygen and nitrogen
dioxide evolved
NO3- of Ca and below
in reactivity series
4 NO3- (s) 2 O2- (s) + 4 NO2
(g) + O2
(g)
Sulphur dioxide evolved SO32- SO3
2- O2- (s) + SO2 (g)
Effect of dilute acid
Add dilute hydrochloric acid or nitric acid to a sample of the solid Warm if no reaction occurs
when cold
Effect of dilute acid
Observation Anion Explanation
Carbon dioxide evolved CO32- (or HCO3
-) CO32- (s) + 2 H+ (aq) H2O (l) + CO2 (g)
Sulphur dioxide evolved SO32- SO3
2- (s) + 2 H+ (aq) H2O (l) + SO2 (g)
7
Effect of concentrated acid
Add concentrated sulphuric acid to a sample of the solid Warm if not reaction occurs when cold
Effect of concentrated sulphuric acid
Observation Anion
Carbon dioxide evolved CO32- or HCO3
-
Sulphur dioxide evolved SO3-
Hydrogen chloride evolved Cl-
Hydrogen bromide (colourless) and bromine
vapour (brown) evolved
Br-
Black iodine present and purple iodine vapour
evolved
I-
8
WEEK 11 LESSON 2 WORKSHEET
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater
Produces a gas which relights a glowing splint as the only gas
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green
Produces a gas forms a precipitate in limewater
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia
Black iodine present and purple iodine vapour evolved
9
WEEK 11 LESSON 3
TOPIC Qualitative Analysis ndash Identification of anions
Test for the halides ndash using silver nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous silver nitrate and
observe the precipitate Add ammonia solution and observe the solubility of the precipitate
Test for halides using silver nitrate solution
Effect of silver
nitrate solution
Anion Explanation Effect of aqueous
ammonia
White precipitate ndash
turns white in
sunlight
Cl- Ag+ (aq) + Cl- AgCl (s) Precipitate soluble
Cream precipitate ndash
turns yellow ndash green
in sunlight
Br- Ag+ (aq) + Br- AgBr (s) Precipitate slightly
soluble
Pale yellow
precipitate
I- Ag+ (aq) + I- AgI (s) Precipitate insoluble
Test for the halides ndash using lead nitrate solution
Make a solution of the solid in dilute nitric acid Add a few drops of aqueous lead nitrate and
observe the precipitate
Test for halides using lead nitrate solution
Effect of lead nitrate solution Anion Explanation
White precipitate Cl- Pb2+ (aq) + 2 Cl- PbCl2 (s)
Pale yellow Br- Pb2+ (aq) + 2 Br- PbBr2 (s)
Deep yellow I- Pb2+ (aq) + 2 I- PbI2 (s)
10
Effect of barium nitrate or chloride solution followed by dilute acid
Make a solution of the solid Add barium nitrate or chloride solution and observe the precipitate
Add dilute hydrochloric or nitric acid warn if necessary and observe the solubility of the
precipitate
Effect of barium nitrate or chloride solution followed by dilute acid
Effect of
Ba(NO3)2 (aq)
or BaCl2 (aq)
Effect of HCl (aq)
or HNO3 (aq)
Anion Explanation
White precipitate Precipitate insoluble SO42- Ba2+ (aq) + SO4
2- (aq) BaSO4 (s)
BaSO4 does not react with dilute acids
White precipitate Precipitate soluble ndash
CO2 evolved
CO32- Ba2+ (aq) + CO3
2- (aq) BaCO3 (s)
BaCO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + CO2 (g)
White precipitate Precipitate soluble ndash
SO2 evolved on
warming
SO32- Ba2+ (aq) + SO3
2- (aq) BaSO3 (s)
BaSO3 (s) + 2 HCl (aq)
BaCl2 (aq) + H2O (l) + SO2 (g)
11
WEEK 11 LESSON 3 WORKSHEET
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
(Ionic equation required)
12
WEEK 12 LESSON 1 WORKSHEET
(a) The Caribbean islands are known for their many resources For example the ore of
aluminium is found in Jamaica and Guyana
(i) Briefly describe the extraction of aluminium from its named ore Include in your
description one ionic equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Although aluminium ore is mined in the Caribbean the extraction of aluminium usually
takes place in other countries Suggest ONE reason why it may be difficult to extract
aluminium in the Caribbean
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) An alloy can be described as a lsquomixed metal solutionrsquo Aluminium forms an alloy with
magnesium that is used to make an aircraft
13
Identify this alloy and suggest why it is better to use it rather than the pure metal in the
manufacture of aircraft
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) ldquoSome metals can be useful to man yet harmful to the environmentrdquo Comment on this
statement with reference to mercury
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
14
WEEK 12 LESSON 2 Worksheet
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate formed
Soluble in excess
15
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate formed
Insoluble in excess
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate formed
(Ionic equation required)
16
WEEK 12 LESSON 3 Worksheet
Dry ammonia gas can be produced in a school laboratory
(a) Identify TWO reagents that are necessary for the laboratory production of ammonia
______________________________________________________________________________
______________________________________________________________________________
(b) Two common drying agents used in the laboratory are calcium oxide and concentrated
sulphuric acid However calcium oxide is the preferred choice for drying ammonia gas
Explain why concentrated sulphuric acid is now used Include in your answer a balanced
chemical equation
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) When gases are prepared in the laboratory there are three main ways in which they can
be collected
- Upward delivery
- Downward delivery
- Displacement of water
(i) What TWO other factors should be considered when choosing an appropriate method for
the collection of gases in the laboratory
______________________________________________________________________________
______________________________________________________________________________
(ii) Identify ONE of the three methods that is best suited for the collection of ammonia gas in
the laboratory Explain why EACH of the other two methods would NOT have been
appropriate
______________________________________________________________________________
17
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(d) Hence draw a labelled diagram of the apparatus which could be used for the preparation
of dry ammonia in the laboratory
Be sure to identify in your diagram
- where the reagents are placed
- where the ammonia is dried and
- where the ammonia is collected
18
WEEK 13 LESSON 1 Worksheet
(a) In solution two metals A and B form A+ and B2+ ions respectively Metal A displaces Fe
from a solution containing Fe2+ ions but metal B does NOT
(i) Arrange the metals A B and Fe in order of reactivity from LEAST reactive to MOST
reactive Write a balanced chemical equation to show the reaction between metal A and
Fe2+ ions
______________________________________________________________________________
______________________________________________________________________________
(ii) Metal A is placed in a solution of copper (II) sulphate CuSO4 (aq) Write an equation for
the reaction State ONE observable change that will occur and explain why this reaction
takes place
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) For EACH metal A and B state ONE method that can be used to extract it from its
respective oxide Give a reason for EACH answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
19
______________________________________________________________________________
(b) Metal alloys are often used for making objects found in our daily lives Name an alloy of
iron and state ONE of its uses
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
20
WEEK 13 LESSON 2 Worksheet
(a) Many important biological processes in plants and animals depend on the specific roles
of certain metal ions
(i) Farmer Jones reaped a crop of tomatoes and reported that the yield was far below what
was expected Analysis of the soil revealed that there was a deficiency of magnesium
Discuss the importance of magnesium in plant health and explain how a magnesium
deficiency can result in the low yield of tomatoes
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE other metal ion which is important to plant health and state the result of its
deficiency
______________________________________________________________________________
______________________________________________________________________________
21
(b) Many years ago car exhaust fumes were known to contain compounds of metals and
non ndash metals which could negatively impact both humans and the environment Identify
ONE metal and ONE non ndash metal whose compounds were present in car exhaust fumes
Discuss the effect of these compounds on human health and the environment
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(c) Define lsquogreen chemistryrsquo and discuss the measures that have been taken to produce a
lsquogreenerrsquo automotive fuel
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
22
WEEK 13 LESSON 3 Worksheet
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
Zn2+ ions are present
23
WEEK 14 LESSON 1 Worksheet
(a) Metal alloys are often used in place of metals because of their enhanced properties
(i) Define the term lsquoalloyrsquo
______________________________________________________________________________
______________________________________________________________________________
(ii) Name ONE alloy of aluminium and state its use based on one of its enhanced properties
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(b) A student conducted an experiment to investigate the reactivity of each of the following
metals (copper iron zinc and lead) by using solutionPs of their sulphate salts
The data presented in the table below shows whether a visible chemical reaction took
place when each metal was added to the four sulphate solutions
Key Visible chemical reaction took place
X No visible chemical reaction
CHEMICAL REACTION OF METALS IN SULPHATE SOLUTIONS
Sulphate solution Cu Fe Zn Pb
CuSO4 X
FeSO4 X X X
ZnSO4 X X X X
PbSO4 X X
24
(i) State which of the TWO metals is more reaction Fe or Zn Give a reason for our answer
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(ii) Using the data in the previous Table deduce the order of reactivity of the four metals Cu
Fe Zn and Pb from the most reactive to the least reactive metal
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iii) The student recorded the following observations from the reaction between the iron and
copper (II) sulphate solution
Observations Reddish ndash brown solid coating formed on the iron strip
Blue colour of the solution changed to dirty green
Account for the observations made from the reaction between the iron and copper (II)
sulphate solution
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
(iv) Write an ionic equation including state symbols for the reaction between the iron and
copper (II) sulphate solution
______________________________________________________________________________
25
(c) Some metal compounds are health and environmental hazards
(i) Identify which of the metals used in the experiment in (b) is MOST hazardous to the
environment
______________________________________________________________________________
______________________________________________________________________________
(ii) State TWO harmful effects of continuous exposure to the metal identified in (c) (i) on
human beings
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
26
WEEK 14 LESSON 2 Worksheet
(a) Carbon is found in the form of diamond and graphite and is a main component in many
naturally occurring compounds such as organic matter and carbon dioxide gas
(i) State ONE way in which diamond differs physically from graphite
______________________________________________________________________________
______________________________________________________________________________
(ii) State ONE similarity between diamond and graphite other than they both contain carbon
______________________________________________________________________________
______________________________________________________________________________
(b) Carbon can react with a limited supply of oxygen to form carbon monoxide which can
negatively affect human health
(i) Write a balanced chemical equation including state symbols to show the formation of
carbon monoxide
______________________________________________________________________________
(ii) State TWO effects of carbon monoxide inhalation on the human body
______________________________________________________________________________
______________________________________________________________________________
(c) Jamal wants to prepare and collect a sample of carbon dioxide gas in the laboratory using
calcium carbonate
(i) Write a balanced chemical equation including state symbols for the laboratory
preparation of carbon dioxide gas from calcium carbonate
______________________________________________________________________________
______________________________________________________________________________
(ii) Draw a clearly labelled diagram to show the arrangement of the apparatus and materials
that could be used in the laboratory to prepare and collect the carbon dioxide gas
(iii) State ONE use of carbon dioxide as it relates to the beverage industry
______________________________________________________________________________
27
WEEK 14 LESSON 3 Worksheet
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
(Ionic equation required)
Suggest a possible identity of the solid R __________________________
28
WEEK 15 LESSON 1 Worksheet
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a small
portion of solid Y gently at
first and then strongly
Colourless gas evolved
with a choking odour
Turns acidified potassium
dichromate solution from
orange to green
(ii) To the remaining portion
of solid Y add 20 cm3 of
distilled water stir to dissolve
and filter Collect the filtrate
and divide into 3 equal
portions
Filtrate is pale green in
colour
(iii) To the first portion of the
filtrate from (ii) add aqueous
sodium hydroxide slowly
until in excess
A green precipitate
Insoluble in excess sodium
hydroxide
Ionic equation required
29
TEST OBSERVATIONS INFERENCES
(iv) To the second portion of
the filtrate from (ii) add
aqueous silver nitrate
followed by aqueous
ammonia
White precipitate
Soluble in aqueous
ammonia
(v) To the third portion of the
filtrate from (ii) add aqueous
barium nitrate followed by
aqueous hydrochloric acid
White precipitate formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with the
evolution of a colourless
gas with a choking smell
30
WEEK 15 LESSON 2 Worksheet
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
31
WEEK 15 LESSON 3 Worksheet
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in excess
aqueous NH3
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change
32
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
warm filter and then divide
the filtrate into two portions
Vigorous effervescence
observed upon addition of
dilute HNO3
Gas evolved turns lime water
cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Cu2+ ions present
33
ANSWERS TO WORKSHEETS
34
WEEK 11 LESSON 1 WORKSHEET ANSWERS
Summarise the properties of the following gases using the tables below
O2 H2 CO2 NH3 SO2 Cl2 Br2 NO2 H2O
Gases according to their colours
Colour of gas Identity of gas
Colourless O2 H2 CO2 NH3 SO2 H2O
Yellow ndash green Cl2
Red ndash brown Br2 NO2
Gases according to their odour
Odour of gas Identity of gas
Odourless O2 H2 CO2 H2O
Pungent smell NH3
Choking smell SO2 Cl2 Br2
Irritating smell NO2
Gases according to their effect on moist litmus
Effect on moist litmus Type of gas
(acidic alkaline
neutral)
Identity of gas
No effect Neutral O2 H2 H2O
Red to blue Alkaline NH3
Blue to red Acidic CO2 SO2 NO2
Blue to red then bleaches it Acidic Cl2 Br2
35
WEEK 11 LESSON 2 WORKSHEET ANSWERS
Identify the anion in different solids in each of the scenarios
Effect of heat on a solid
Observation Anion
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-) not
of K or Na
Produces a gas which relights a glowing splint as the only gas NO3- of K or Na
Effect of dilute hydrochloric acid on the solid
Observation Anion
Produces a gas which turns potassium dichromate from orange to green SO32-
Produces a gas forms a precipitate in limewater CO32- (or HCO3
-)
Effect of concentrated sulphuric on the solid
Observation Anion
Produces a gas which forms dense white fumes with ammonia Cl-
Black iodine present and purple iodine vapour evolved I-
36
WEEK 11 LESSON 3 WORKSHEET ANSWERS
Complete the table below to show the inferences for the observations corresponding to the
respective tests
Test Observations Inference
Addition of AgNO3 (aq)
followed by aqueous NH3
Cream precipitate ndash turns
yellow ndash green in sunlight
Precipitate slightly soluble
Br-
Addition of AgNO3 (aq)
followed by aqueous NH3
White precipitate ndash turns
white in sunlight
Precipitate soluble
Cl-
Ag+ (aq) + Cl- AgCl (s)
(Ionic equation required)
Addition of Pb(NO3)2 (aq) Pale yellow Br-
Addition of Ba(NO3)2 (aq)
followed by HCl (aq)
White precipitate
Precipitate insoluble
SO42-
Ba2+ (aq) + SO42- (aq)
BaSO4 (s)
(Ionic equation required)
37
WEEK 12 LESSON 1 Worksheet Answers
(a) (i)
The ore bauxite is purified
The purified bauxite is dissolved in molten cryolite
The aluminium oxidecryolite solution is then eletrolysed
Equation at the cathode Al3+ (l) + 3 e- Al (l)
Equation at the anode 2 O2- (l) ndash 4 e- O2 (g)
(ii) The process is too expensive mainly because too much electricity or energy is needed
(b) The alloy of Al and Mg is magnalium It is less dense than the pure metals and hence allow
aircraft to be lighter It is also stronger than the pure metals and hence allows aircraft to last
longer since it is not easily destroyed
(c) Your answer should cater for the following aspects
Benefits of mercury to humans for example in thermometers barometers in dentistry
and gold mining
Entry of mercury to the environment For example this could have been through broken
thermometers barometers or lightbulbs or improper disposal of them or batteries and
indiscriminate use in gold mining in Guyana
The identification of a negative impact on the environment such as poisoned fish and the
persons who eat the fish death mood swings and psychosis
38
WEEK 12 LESSON 2 Worksheet Answers
A group of students were given an unknown solid B and asked to identify it They performed a
series of tests and made some observations which are recorded in the table below Complete the
table by inserting the appropriate inferences
TEST OBSERVATION INFERENCE
(i) Place a small portion
of solid B in a test
tube and heat
strongly using a
Bunsen flame
A reddish brown gas
evolved
NO2 evolved OR nitrates
present OR
Br2 gas evolved
(ii) Dissolve the
remainder of B in
about 10 cm3 of
distilled water stir
then filter Collect the
filtrate and divide it
into three equal
portions for use in the
following tests
(iii) To the first portion of
the filtrate from (ii)
add NaOH solution
slowly until in
excess
White precipitate
formed
Soluble in excess
Pb2+ Zn2+ Al3+ or Ca2+
present
Pb2+ Zn2+ Al3+ or present
39
TEST OBSERVATION INFERENCE
(iv) To the second portion
of the filtrate from
(ii) add aqueous NH3
slowly until in excess
White precipitate
formed
Insoluble in excess
Pb2+ Zn2+ Al3+ or present
Pb2+ or Al3+ present
(v) To the third portion
of the filtrate from
(ii) add aqueous KI
Yellow precipitate
formed
Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
40
WEEK 12 LESSON 3 Worksheet Answers
(a) an ammonium salt and a strong alkali
(b) Ammonia is basic and it will react with H2SO4
Equation 2 NH3 (aq) + H2SO4 (aq) (NH4)2SO4 (aq)
(c) (i) ndash Density of the gas relative to air ndash The solubility of the gas in water
(ii) Ammonia is collected by upward delivery
It cannot be collected by downward delivery since ammonia is less dense than air
It cannot be collected by displacement of water since it is soluble in water
(d)
41
WEEK 13 LESSON 1 Worksheet Answer
a) i) B ˂ Fe ˂ A
2A (s) + Fe 2+ (aq) rarr 2A+ (aq) + Fe (s)
ii) 2A (s) + CuSO4 (aq) rarr A2SO4 (aq) + Cu (s)
Observation blue colour fades gets lighter OR brown solid forms is deposited OR metal A
decreases in size dissolves
Explanation Metal A is higher (than Fe which is higher) than Cu in the reactivity series OR
Metal A is more reactive (than Fe which is more reactive) than Cu so Metal A can displace Cu
iii) Metal A can be extracted by electrolysis (of its molten oxide) because Metal A is a very
reactive metal is high in the reactivity series forms stable oxides needs a lot of energy to be
extracted and very reactive metals are extracted by electrolysis
Metal B can be extracted by heating with carbon carbon monoxide OR by chemical reduction
of the oxide because Metal B is less reactive than Fe is low in the reactivity series forms less
stable oxides does not need a lot of energy to be extracted and oxides of less reactive metals are
easily reduced
b) Alloy of iron steel
Use of alloy making buildings bridges ships motor vehicles furniture utensils
42
WEEK 13 LESSON 2 Worksheet Answer
(a) (i)
Magensium is the metal ion found in chlorophyll
Chlorophyll is essential for photosynthesis
A deficiency in magnesium will result in low chlorophyll yellow leaves and a reduction in
photosynthesis
Hence there will be low carbohydrates or energy production
Hence small fruits stunted growth and lower yield will result
(ii)
Metal ion Results of deficiency
Potassium Stunted growth premature loss of leaves yellowing of leaves curling of leaf tips
Calcium Growth abnormalities in tips of roots and shoots curling of leaves
Iron Yellowing of leaves
Zinc Low chlorophyll content yellowing of leaves
Manganese Yellowing of leaves poor flavors in some crops for example potato
(b)
Metal Lead is present in some types of gasoline Upon combustion lead compounds escape into
the atmosphere It accumulates in body tissues and slowly poisons the person It causes mental
illness
Non ndash metal SulphurSulphur dioxide or NitrogenNitrogen dioxide
Dissolves in rain water to form acid rain or cause respiratory illnessproblems Acid rain can
cause corrosion damage in buildings
(c)
Green chemistry is the utilisation of a set of principles that reduces or eliminates the use or
generation of hazardous substances
43
Automotive fuels are now produced without lead so as to eliminate the release of lead
compounds into the atmosphere
Low sulphur fuel is being produced with much reduced sulphur content which causes a reduction
of sulphur dioxide release into the atmosphere
44
WEEK 13 LESSON 3 Worksheet Answer
Complete the table below by writing the observations for the tests carried out on a Salt S
Test Observation Inference
A sample of salt S is heated
strongly in a dry test tube
Moist red and blue litmus is
held at the mouth of the test
tube
gas turns litmus blue
red
brown gas
An acidic gas is produced
Nitrate ions are present
To an aqueous solution of salt
S aqueous sodium hydroxide
is added gradually until in
excess
white precipitate
precipitate soluble in
excess
Zn2+ ions are present
45
WEEK 14 LESSON 1 Worksheet Answers
(a)(i) An alloy is a material made from a mixture of two or more metals
(ii) Any suitable answer chosen from below
Alloy Enhance Property Use
Duralumin High strength
Low density
Light
Hard
Used to make aircraft bodies
space satellites
Magnalium Light
Hard
Easier to weld
Corrosion resistant
Strong
High ductability
Used in pyrotechnics
(fireworks)
Mirrors
Aircraft parts
To make scientific
instruments
Used to make marine castings
Alchlad Strong
Corrosion resistant
Cladding for buildings
(b) (i) Zinc is more reactive than iron
Zinc displaces iron from iron (II) sulphate
Zinc is higher in the reactivity series than iron
Iron does not displace zinc from zinc sulphate
(ii) Order of reactivity Zn gt Fe gt Pb gt Cu
(iii) Reddish brown solid ndash copper metal formed
46
Dirty green solution ndash presence of Fe2+ ion
(iv) Fe (s) + Cu2+ (aq) Fe2+ (aq) + Cu (s)
(c) (i) Lead
(ii) Any two correct harmful effects of lead on the body
Impedes brain development (in young children)
Affectimpede development of the immune system in humans
Affecthamper development of nervous system in humans
Long term exposure can result in kidney and liver damage
Mental retardation
Anaemia
Death
47
WEEK 14 LESSON 2 Worksheet Answers
a) i) Diamond is transparent clear Graphite is opaque black
OR hard OR brittle
OR does not conduct electricity OR conducts electricity
a) ii) Both have a macromolecular giant molecular giant covalent structure (lattice)
OR Both have high melting point boiling point
OR Both are insoluble in water organic solvent
b) i) 2C (s) + O2 (g) rarr 2CO (g)
ii) CO reduction in amount of oxygen carried by (the haemoglobin in the red blood
cells of) the blood
Headache OR dizziness OR nausea OR fatigue OR loss of consciousness OR
death
c) i) CaCO3 (s) + 2HCl (aq) rarr CaCl2 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) + H2SO4 (aq) rarr CaSO4 (aq) + H2O (l) CO2 (g)
OR CaCO3 (s) rarr CaO (s) + CO2 (g)
48
ii)
OR
OR
Entirely closed system thistle funnel below the level of the liquid OR tap that could be
closed
Two reagents labelled CaCO3marble chips and HCl H2SO4 or heat source
collection of CO2 upward displacement of air OR over watersulphuric acid OR in gas
syringe
iii) CO2 use put in aerated drinks carbonated beverages
OR put in carbon dioxide fire extinguishers
49
WEEK 14 LESSON 3 Worksheet Answers
A student conducts the following tests on a solid R and makes the observations recorded in the
table
Complete the table to show all of the possible inferences and write ionic equations where
indicated
TESTS PERFORMED ON SOLID R
Test Observation Inference
A portion of R is dissolved in
approximately 6 cm3 of
water The resulting solution
is divided into equal portions
for Tests (1) and (2)
A colourless solution is
formed
(1) To one portion of Solution
R from above aqueous
sodium hydroxide is added
dropwise until in excess
heated
No precipitate
Upon heating a pungent
gas evolves which turns
moist red litmus blue
NH4+
NH4+ confirmed OR
NH3 (g) produced
(2) To another portion of R
from above dilute nitric acid
followed by silver nitrate is
added dropwise This is
followed by the addition of
aqueous ammonia
A white precipitate is
formed
Precipitate dissolves in
aqueous ammonia
Cl- ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation required)
Suggest a possible identity of the solid R NH4Cl (ammonium chloride)
50
WEEK 15 LESSON 1 Worksheet Answers
Y is a mixture of two salts A student carries out a number of tests on a sample of Y The
observations are recorded in the table below You are required to fill in the inferences that can be
made based on the observations recorded
TEST OBSERVATIONS INFERENCES
(i) Heat in a test tube a
small portion of solid Y
gently at first and then
strongly
Colourless gas
evolved with a
choking odour
Turns acidified
potassium dichromate
solution from orange
to green
SO2 evolved
Presence of a sulphite
(ii) To the remaining
portion of solid Y add 20
cm3 of distilled water stir
to dissolve and filter
Collect the filtrate and
divide into 3 equal portions
Filtrate is pale green
in colour
Fe2+ ions present
(iii) To the first portion of
the filtrate from (ii) add
aqueous sodium hydroxide
slowly until in excess
A green precipitate
Insoluble in excess
sodium hydroxide
Fe2+ ions present
Fe2+ (aq) + 2 OH- (aq) Fe(OH)2 (s)
Ionic equation required
TEST OBSERVATIONS INFERENCES
(iv) To the second portion
of the filtrate from (ii) add
aqueous silver nitrate
White precipitate
Soluble in aqueous
ammonia
Cl- ions present
51
followed by aqueous
ammonia
(v) To the third portion of
the filtrate from (ii) add
aqueous barium nitrate
followed by aqueous
hydrochloric acid
White precipitate
formed
Precipitate readily
dissolves in aqueous
hydrochloric acid with
the evolution of a
colourless gas with a
choking smell
SO32- CO3
2- SO42- ions present
SO32- ions present
52
WEEK 15 LESSON 2 Worksheet Answers
A student conducts a number of tests on an aqueous solution of Compound X The observations
made are recorded in the table below Complete the table by filling in the inferences that could
be made based on the observations recorded
TEST OBSERVATION INFERENCE
To a sample of a solution of
X dilute nitric acid is added
followed by a few drops of
silver nitrate solution
A white precipitate
which went grey black
in light was formed
Chloride ions present
Ag+ (aq) + Cl- (aq) AgCl (s)
(Ionic equation is required)
To a sample of a solution of
X aqueous sodium hydroxide
is added until in excess
A pale blue gelatinous
precipitate is formed
which is insoluble in
excess
Cu2+ ions present
To a sample of a solution of
X a few drops of acidified
aqueous potassium
manganate (VII) solution
were added and the solution
heated
The potassium
manganate (VII)
solution is decolourised
X contains a reducing agent
To a sample of a solution of
X a few drops of barium
chloride followed by dilute
hydrochloric acid were added
A white precipitate
is formed
The precipitate
dissolved in acid
SO32- SO4
2- or CO32- ions are
present
SO32- ions are present
53
WEEK 15 LESSON 3 Worksheet Answers
Complete the table below for tests carried out on a solid Q
TEST OBSERVATIONS INFERENCES
(i) To solid Q add water stir
filter and then divide the
filtrate into four portions
Retain and dry the residue for
test (vi) below
(ii) To the first portion of the
filtrate from (i) above add
aqueous NaOH until in
excess
White ppt
Ppt soluble in excess
Al3+ Pb2+ Zn2+ Ca2+ present
Al3+ Pb2+ Zn2+ present
(iii) To the second portion of
the filtrate from (i) above
add aqueous NH3 until in
excess
White precipitate
Precipitate soluble in
excess aqueous NH3
Al3+ Pb2+ Zn2+ present
(iv) To the third portion of
the filtrate from (i) above
add aqueous KI
Yellow precipitate Pb2+ present
Pb2+ (aq) + 2 I- (aq) PbI2 (s)
(Ionic equation required)
(v) To the fourth portion of
the filtrate from (i) above
add aqueous AgNO3
followed by aqueous NH3
No observable change Cl- Br- I- absent
TEST OBSERVATIONS INFERENCES
(vi) To the dried residue from
(i) above add dilute HNO3
Vigorous effervescence
observed upon addition of
dilute HNO3
CO2 evolved OR
Carbonate present
54
warm filter and then divide
the filtrate into two portions
Gas evolved turns lime
water cloudy
(vii) To the first portion of
the filtrate from (vi) above
add aqueous NaOH until in
excess
Cu2+ ions present
Cu2+ (aq) + OH- (aq)
Cu(OH)2 (s)
(Ionic equation required)
(viii) To the second portion of
the filtrate from (vi) above
add aqueous NH3 until in
excess
Blue ppt
ppt dissolves in excess
NH3 to give a deep blue
solution
Cu2+ ions present
55
MINISTRY OF EDUCATION
SECONDARY ENGAGEMENT PROGRAMME
CHEMISTRY
GRADE 11
REFERENCES
Hunte-King J Maragh P Nagir F amp Norris R (2013) Chemistry for CSEC United
Kingdom Nelson Thornes Ltd
Remy C Mason L Lambert N amp Mohammed M (2007) Chemistry for CSEC England and
Wales Pearson Education Limited
Taylor M amp Chung-Harris T (2010) CXC Chemistry England Macmillan Publishers
Limited
Tindale A (2016) Chemistry A Concise Revision for CXC London HarperCollins Publishers
Limited