SALTS

Synthesising salts

Synthesising qualitative analysis

of salts

Practising to be systematic and

meticulous when carrying activities

1. Define salts2. Give 3 examples of soluble salt. 3. Give 3 examples of insoluble salt 4. Describe an experiment to prepare a

soluble salt.5. Describe an experiment to prepare an

insoluble salt

1. State the meaning of qualitative analysis.2. Describe the tests for Pb2+, Zn2+ and Mg2+.3. Describe confirmatory tests for Fe2+, Fe3+, Pb2+ and

NH4+.

4. Describe the test for SO42-

5. Plan qualitative analysis to identify a sample of salt.6. Describe the test for oxygen gas.

Chapter 8 T. 8.0

8.1

8.28.3

Method: Double decomposition

Soluble salt + soluble salt soluble salt + insoluble salt Examples

SALTS

Definition

Examples

Solubility of salts

Preparation of salt

Crystal1. Definition

2. Properties

Salts are an ionic compound whereH+ from an acid has been replace by metal ion or ammonium ion.

NaClCuI2

BaSO4

Pb(NO3)2

(NH4)2CO3

Preparation of the soluble salts

Preparation of insoluble salts

Experiment

Examples

Examples calculations involving salts Ionic equation

Experiment to build ion equation by continuous change method

*T.8.1.1

All solubleall except BaSO4 , PbSO4 , CaSO4

all except Hg2Cl2, AgCl, PbCl2

non soluble except K2CO3, Na2CO3, (NH4)2CO3

NitrateSulphateChlorideCarbonate

Solubility in waterSalt

Method:1.Acid and alkali reaction2.Acid and base reaction3.Acid and metal reaction4.Acid and carbonate reaction.

T. 8.1

Method: Double decomposition

Soluble salt + soluble salt soluble salt + insoluble

Sodium chloride

8.0 SALTS

A. What is salt?Students should be able to explain the meaning of salt.

Do you know what is salt?

1. Complete the following diagram :

Formula :

Consist

cation anion

Do you still remember that salt is formed in neutralization?

AcidBase/alkali

Comes fromComes from

Example

NaOH + HCl NaCl + H2O

Definition :Salts are _______ __________ formed when _________ ____, H+ from acid is replaced with _______ ______ or an ___________ _____, NH4

+

from base or alkali

Metal Non-metal

2. The following diagrams show the formation of salt from an acid. Fill in the box with the appropriate acid and salt produce.

a) Formation of salt from hydrochloric acid chloride salt

b) Formation of salt from _____________ nitrate salt

c) Formation of salt from sulphuric acid ____________ salt

d) Formation of salt from carbonic acid ______________ salt

H Cl

Na Cl

NH4 Cl

Na+

NH4+

H

K+

NH4+

Mg2+

NH4+

Na+

NH4+

B. Soluble and insoluble salt Students should be able to identify soluble and insoluble salts.

** All metal oxides and hydroxides are insoluble in water except Na2O, K2O, NaOH, KOH and NH4OH. Ba(OH)2 and Ca(OH)2 are slightly soluble in water.

2. Write down the chemical formula of salts:

Metal ionSulphate salt(from H2SO4)

Chloride salt(from HCl)

Nitrate salt(from HNO3)

Carbonate salt(from H2CO3)

K+

Na+

Ca2+

Mg2+

Al3+

Zn2+

Fe2+

Pb2+

Cu2+

Ag+

Ba2+

NH4+

Table 8.1

K2CO3, Na2CO3 and (NH4)2CO3

(soluble)• All carbonate salts are insoluble

SALT

soluble insoluble

• All K+, Na+ and NH4+ salts are soluble.

• All nitrate salts are soluble.

• All sulphate salts are soluble PbSO4, CaSO4 and BaSO4.

• All chloride salts are soluble PbCl2, AgCl and HgCl2

EXCEPT

EXCEPT

PCB

PAH

ANaK

3. From the above table (Table 8.1) name six examples of soluble salts and six examples of insoluble salts.

SOLUBLE SALT INSOLUBLE SALT

1. 1.

2. 2.

3. 3.

4. 4.

5. 5.

6. 6.

Table 8.2

C. Preparing SaltsStudents should be able to describe the preparation of soluble salts and insoluble salts.

1. Complete the diagram on next page…

Neutralisation

PREPARING SALT

SOLUBLE SALT INSOLUBLE SALT

NH4+, Na+, K+ Other than

NH4+, Na+, K+

Acid + alkali ______ + ______

titration

Method I

Acid + metal oxide ______ + ______

Acid + metal ______ + __________

Acid + metal carbonate ______ + ______ + _______

Method II

Acid is titrated to alkali until neutral by using an indicator. Repeat without the indicator to get _______ salt.

heatheat

heat

Add metal/ base oxide/ metal carbonate until ___________

Undissolved metal/ base oxide/ metal carbonate

_____________ the filtrate until saturated solution is formed.

Cool it at room temperature until __________ are formed.

Salt crystal

Filter the mixture to separate _____ _________

_______ the salt crystal with _________ _______

Salt solution

Double decomposition method/ Precipitation reaction

Method III

Pb(NO3)2 (aq) + 2NaCl (aq) PbCl2 (s) + 2NaNO3 (aq)

2. Preparing insoluble salts by precipitation reaction

Aqueous solution + aqueous solution precipitate + aqueous solutionorsoluble salt solution + soluble salt solution insoluble salt + soluble salt solution

examples : Preparing lead (II) chloride salt

Pb(NO3)2 (aq) + 2NaCl (aq) PbCl2 (s) + 2NaNO3 (aq)

Aqueous solution Aqueous solution

containing Pb2+ containing Cl-

Mix two ___________ __________

Stir with a ________ ________

Filter & wash with _______ ______

_____ the salts with filter paper

White precipitate of lead (II) chloride

Na+

Cl-

Pb2+

NO3- NO3

-

+

Pb2+

Cl- Cl-

Na+

NO3-

precipitate

Choose any solution containing Pb2+ ion

Choose any solution containing Cl- ion

precipitate(Insoluble salt)

3. Complete the following table and write all the possible chemical equation and ionic equation to prepare salts :

SaltType of

saltChemical equation Ionic equation

Magnesium sulphate

Soluble

MgO (s)+ H2SO4 (aq) MgSO4 (aq)+ H2O (l)MgO + 2H+ + SO4

2- Mg2+ + SO42- + H2O

MgO + 2H+ Mg2+ + H2OMg (s) + H2SO4 (aq) MgSO4 (aq) + H2 (g)

MgCO3 (s) + H2SO4 (aq) MgSO4 (aq) + H2O (l)+ CO2 (g)

Pottasium nitrate

Soluble H+ + OH- H2O

Lead (II) chloride

Insoluble

Pb(NO3)2 (aq) + 2NaCl (aq) PbCl2 (s) + 2NaNO3 (aq)

Pb2+ + Cl- PbCl2

Pb(NO3)2 (aq) + 2HCl (aq) PbCl2 (s) + 2HNO3 (aq)

Copper (II) sulphate

Lead (II) nitrate

Ammonium sulphate

SaltType of

saltChemical equation Ionic equation

Aluminium carbonate

Silver chloride

Iron (II) nitrate

Zinc chloride

Barium sulphate

Sodium carbonate

Table 8.3

4. Physical characteristics of crystals

D. Constructing ionic equation using the continuous variation method.

The ionic equation for the formation of an insoluble salt can be constructed if we know the number of _______ of cation and anion reacted together to form ______ of insoluble salt. (…Refer next page)

Examples :

1 mole of silver chromate (VI) is formed from 2 moles of Ag+ ions and 1 mole of CrO42- ions.

Ionic Equation : 2Ag+ (aq) + CrO42- (aq) Ag2CrO4 (s)

TRY THIS :

1 mole of lead (II) iodide is formed from 1 moles of Pb2+ ions and 2 mole of I- ions.

Ionic Equation :

_______ geometrical shapes

Crystals of the same substance have same

_______ but may be in different _______.

Fixed ______ between two neighbouring

surfaces

Crystals have _______ surfaces, straight

edges and ________ angles.

Height of Precipitate (cm)

5

0 5 Vol. of BaCl2 (cm3)

IONIC EQUATION(Using continuous variation method)

Writing ion equation:1.

2.

Experiment: Precipitation of barium chromate (VI)

The ratio of the number of moles of cation and anion reacted together to form 1 mole of insoluble salt.

From graph:5 cm3 of K2CrO4 reacted equivalent to 5 cm3 BaCl2

No. of mole CrO42- = MV/1000 = 0.5 x 5/1000 = 0.0025 mole

No. of mole Ba2+ = MV/1000 = 0.5 x 5/1000 = 0.0025 mole

No. of mole Ba2+: No. of mole CrO42-

0.0025 moles : 0.0025 molesOr 1 : 1

Therefore ionic equation is, Ba2+ + CrO42- BaCrO4

Chemical equation, K2CrO4 + BaCl2 BaCrO4 + 2KCl

*T. 8.1.1

5.55.55.54.43.32.21.1Height of precipitate (cm)

7654321barium chloride 0.5 M (V cm3)

5555555potassium chromate 0.5 M (V cm3)

7654321Test tube

Writing the ionic equation : 1.

2.

TRY THIS :

10 cm3 of 0.25 mol dm-3 lead(II) nitrate solutions react completely with 10cm3 of 0.5 mol dm-3 pottasium chloride solution. A white precipitate of lead (II) chloride is formed. Construct the ionic equation for the formation of lead (II) chloride.

Solution :

Number of moles of Pb2+ ions in lead (II) nitrate solution : n = MV 1000

=

= ___________ mol

Number of moles of Cl- ions in potassium chloride solution : n = MV 1000

=

= ___________ mol

From the calculation the ratio of Pb2+ ions : Cl- ions = _________ : _________

So, the simplest ratio of Pb2+ ions : Cl- ions = ________ : ________

Ionic equation :

E. Numerical problems involving stoichiometric reactions in the preparation of salts

Complete the relationship in the following diagram :

Do you still remember…..The relationship between the number of

moles, mass, the number of particles, volume of gas and concentration of

reactants and products?

Number of moles

Concentration

Volume of gasNumber of particles

Mass

HOW TO SOLVE THE NUMERICAL PROBLEM ????

Calculation steps :

S1 : Write the balanced equationsS2 : Write the information from the question below the equationS3 : Write the information from the equation below the chemical involvedS4 : Change S2 information into mol using the mole conceptS5 : Compare the mole ratio between the reactants and the products involved in the reaction.S6 : Change the information into the required unit using the appropriate formula.

Example :

A student prepares copper (II) nitrate by reacting copper (II) oxide powder with 100cm3 of 1.5 mol dm-3 nitric acid. Calculate the mass of copper (II) oxide needed to react completely with the acid. [Relative atomic mass : Cu, 64; O, 16]

S1 : CuO + 2HNO3 Cu(NO3)2 + H2OS3 : 1 mol 2 mol S2 : V=100cm3

M=1.5 mol dm-3

S4 : the number of moles of HNO3 ==> n = M V 1000 = 1.5 x 100 1000 = 0.15 mol

S5 : From the chemical equation, 2 mol of HNO3 reacted with 1 mol of CuO Therefore, 0.15 mol of HNO3 reacted with 0.075 mol of CuO

S6 : The mass of CuO = 0.075 mol x (64 + 16) gmol-

= 6.0 g

TRY THIS :

1. Acid reacts with calcium carbonate in limestone to form a salt and carbon dioxide. A piece of limestone reacted completely with 50cm3 0.1moldm-3 hydrochloric acid. [Relative atomic mass : H, 1; C, 12; Cl, 35.5; O, 16; Ca, 40;Molar volume: 24dm3 mol-1 at room temperature]

a) Calculate the mass of salt produced.

b) What is the volume of carbon dioxide liberated at room conditions?

QUALITATIVE ANALYSIS OF SALTS

Early observation

Colour of salts Solubility

Effect of heat on salts

The ion test

Cation test

Anion test

Using NaOH and NH4OH in excess

Confirmation test

*T.8.2.1

Anion introduction test:Anion confirmation test:

ReferT.8.1

To know the unknown salt

Experiment

Green Fe2+, CuCO3

Brown Fe3+

Blue Cu2+

White most of salts

Gas test

Carbonate Carbonate salts metal oxide + CO2

Nitrate (i) Nitrate salts metal oxide + NO2 + O2

(ii) Potassium & sodium nitrate metal Nitrite + O2

(iii) Ammonium nitrate N2O + H2OSulphate (i) Sulphate salts metal oxide + SO3 and/ SO2

(ii)Sulphate salts of Group 1 and 2 are not decomposeChloride Not decompose except the ammonium chloride

T. 8.2

F. Qualitative Analysis

1. Qualitative analysis is a series of tests conducted on a chemical substance to________

the _________ component or components in it.

2. Through qualitative analysis, the _______ and _______ present in a salt are determined.

3. To identify the cation and anion in a salt, the following tests are usually conducted. Complete the diagram.

UNKNOWN SALT

1. Physical properties

2. Observed _______ of salts

4. Effect of ________

5. Test for gases

Soluble?

3. Add ________ water

Ion in aqueous solution

6. Confirmatory tests for ions

7. Test for anions

8. Test for ________

NoYes

9. Test for specific cations

CO2

Cl2

NO2

CO32-

SO42-

NO3 -

Reagent

Damp blue litmus paper

Inference : Presence of

Gas released

8. a)Using NaOH

8. b)Using

NH3 (aq)

4. Colour of Salts

a. Most salts are colourless or _______ salts.

b. Salts of ___________ metals are coloured because they form coloured ions.

Examples :

Ion Colour

(a) copper (II) ions, Cu2+

(b) iron (II) ions, Fe2+

(c) iron (III) ions, Fe3+

Table 8.4

c. Complete the following table :

Solid Aqueous Salts/Metal oxide

Colourless K+, Na+, Ca2+, Mg2+, Al3+, Zn2+, Pb2+, NH+

Green Insoluble

Light green Fe2+ example: FeSO4 ,FeCl2 ,Fe(NO3)2

Blue Blue

Brown Fe3+

Black CuO

__________ when hot _________ when cold

InsolubleZnO

Brown when hot yellow when cold

Insoluble

Table 8.5

5. Comfirmatory test for several gases.

a) Complete the following table :

Gas Colour SmellEffect on

damp litmus paper

Reagent used

Confirmatory test

Hydrogen

Colourless

-Lighted splinter

Method : Bring a lighted splinter to the mouth of test tube.Observation : Gives '______' sound

OxygenOdourless

-Method :

Observation :

Carbon dioxide

Odourless

Method : Bubble the gas produced into ___________. Observation :

Ammonia

Colourless

Method : Dip a glass rod into concentrated ___________ ______.Observation : White fumes formed

ChlorineGreenish yellow

PungentBlue to red, then _______

Method :

Observation :

Nitrogen dioxide

PungentMethod :

Observation :

Sulphur dioxide

Colourless

Pungent Blue to redTurns acidified __________ ______________ solution from purple to ___________.

Hydrogen chloride

Colourless

Pungent Blue to redMethod :

Observation :

Table 8.6

6. Effect of Heat on Salts

a) Most compounds which decompose leave behind oxides.

Salt → metal oxide + gas (residue identification (gas identification

refers to specific cation refers to anion) only)

b)

c) Draw the correct labeled diagram for the set-up to test carbon dioxide gas liberated when the carbonate salt is heated strongly.

heat

salt

Type og gas released

Colour of residue

Can predict the identity of

______ presence in salt

Can predict the identity of ________

presence in salt

d) Write down the chemical equations for the reactions that occur :

Ion Carbonate salt Nitrate salt Sulphate salt Chloride salt

Is not decomposed by heat Decompose into O2 gas and metal nitrite

Sulphate salts usually do not decompose

Chloride salts do not decompose except NH4Cl

K+

Na+

Decompose into metallic oxide and CO2

Decompose into metal oxide, NO2 and O2

Ca2+

Mg2+

A13+

ZnSO4, CuSO4 and Fe2(SO4)3

decompose when heated to produce metal oxide and SO3

Zn2+

Fe2+2FeSO4.7H2O(s) → Fe2O3(s) +SO2 (g) + SO3(g)+14H2O

(g)Fe3+

Pb2+

Cu2+

Decompose into metal, NO2 and O2

Ag+

Decompose into NH3, CO2 and water Decompose into N2O and water Sublimes when heated to produce NH3 (g) and H2SO4 (g)

Sublimes when heated to produce NH3 (g) and HCl (g)

NH4+

Table 8.7

IONS TEST

Cations test

Anion test

Confirmation test

Fe2+, Fe3+

Pb2+

NH4+

+ HCl, white precipitate occurs and dissolved in hot water

+ Nessler reagent, brown precipitate is form

+ NaOH a little and then in excess

+ NH4OH a little and then in excess

Pre-testConfirmation

test

Anions to be test:CO3

2- , Cl- , SO42- NO3

-

Gas evolved from the reaction with salt.

Carbonate + acid gas CO2

Chloride + H2SO4 gas HClNitrate + conc.H2SO4 gas NO2

Examples

*T. 8.2.1

Formation ofWhite precipitate& and then solublein excess

Formation ofprecipitate &Non-soluble inexcess

Noprecipitate

Zn2+ , Al3+ , Pb2+Ca2+ , Fe2+ , Fe3+

Cu2+ , Mg2+

NH4+

Red solutionNo changeKSCN

Brownsolution

Dark blueprecipitate

KFe(III)(CN)6

Blueprecipitate

Light blueprecipitate

K2Fe(II)(CN)6

Fe3+Fe2+

Precipitate is formed & dissolved in excess

Precipitate is formed & not dissolved in excess.

Noprecipitate

Zn2+ , Cu2+Fe2+ , Fe3+ , Mg2+

Al3+ , Pb2+

NH4+,

Ca2+

Brown ring is formed+ H2SO4 (dil...)+ FeSO4

+ H2SO4 (con.)

NO3-

White precipitate isformed

+ HNO3

+ AgNO3

Cl-

White precipitate isformed

+ HCl + BaCl2

SO42-

Gas form whiteprecipitate with lime water

+ HClCO32-

ObservationTestAnion

+ Kl, yellow precipitate occurs and dissolved in hot water

7. Confirmatory test for anions

H+

H+

Ag+

H+

Ba2+

H+

Fe2+

H+

Hajat Hati Agong Balik Haji Hendak Fitrah Harta

CO32-

1

Cl-

2

SO42-

3

NO3-

4

a) Complete the following diagram :

8. Confirmatory test for cations

a) The presence of cation can be detected by using two common bench alkalis namely

i) _______________________, _______ solution and

ii) ________________, _______ solution.

Unknown Salt solution

Gas turns limewater

___________

_________ precipitate

formed

________ ring formed

________ ion confirmed

SO42- ion

confirmed________ ion

confirmed_________ ion

confirmed

+ dilute acid

+ HNO3

+ ______+ ______+ ______

+ H2SO4 dilute+ _______+ _____________

The function of the alkalis is to produce a precipitate, that is __________ ________________.

Metal ion + hydroxide ion metal hydroxide

b) Write the ionic equation for the reaction of cations and sodium hydroxide :

Ion Ionic equation for the reaction of cations and sodium hydroxide

Aluminum ion

Lead (II) ion

Zinc ion

Magnesium ion

Calsium ion

Copper (II) ion

Ferum (II) ion

Ferum (III) ion

c) Complete the diagram below :

Non-soluble in excess

+ excess sodium hydroxide

__________ in excess forming

Colourless solution

__________ in excess forming

________________

__________ in excess forming

________________

d) Complete the diagram below :

c) Confirmatory tests for Fe2+, Fe3+, Pb2+ and NH4+

damp

+

d) Complete the following diagram to summarises the qualitative analysis of cations in salts.

e. If a salt X is given as zinc nitrate, how can we test the compound to confirm the presence of Zn2+ and NO3

- ions in that salt?

Conduct the experiment as follows :

Experiment Observation Inference1. Observed the colour of salt X White salt

2. _______ some solid X in a test tube and observe : (a) the colour of gases released (b) the effect on damp _____ litmus (c) the effect on _________ splintd) observed the colour of residue when hot

and cool.

_________ gas.

_____ litmus turns _____.

_________ _________ splint.

Residue colour :Hot : _________

______ gas released. Acidic gas.

O2 released.

Probably NO3- present.

Probably ______ present.

3. Add _________ _________ to X to make solution.

____________ in water X is soluble salt

4. Add ________ _______ solution, followed by ________. Mix. Slowly, add 5-6 drops of _____________ ________ along test tube side. (Do not shake)

_________ _______ formed.

Confirms presence of ________, ____

5. To salt solution, ________ a little NaOH(aq), then add it to_________.

Maybe ____, ____, or Al3+.

6. To salt solution, add a little ______ (aq), then add it to _________.

________ _________, soluble in excess NH3.

Confirms presence of ______ ion.

CONCLUSION : The ions present in salt X are confirmed as _____ and _____ ions.

EXECISES

1. Among the following cation solutions, which will produce precipitate when mixed with excess ammonia solution ?

I Aqueous solution Zn 2+

II Aqueous solution Pb 2+

III Aqueous solution Mg 2+

IV Aqueous solution Al 3+

A I onlyB I and IV onlyC I,II and IV onlyD II, III, and IV only

2. Among the following compounds, which is solube in water?

A lead(II) chlorideB zinc carbonateC lead(II) nitrateD Barium sulphate

3. Among the following ions, which will produce precipitation when added with hydrochloric acid solution ?

I Ca 2+ ionII Pb 2+ ionIII Ag + ionIV Al 3+ ion

A I and II onlyB II and III onlyC I, II and III onlyD I, II, III and IV

4. Figure 3 shows a flow chart for a series of reactions.

Among the following, which may be compound X ?

A copper(II) oxideB iron(III) nitrateC copper(II) carbonateD lead(II) nitrate

5. The reaction between silver nitrate solution and potassium carbonate produces an insoluble salt X. Among

XBlack solid

Blue solution

Heated up

Hot hydrochloric acid is added

the following solutions, which can dissolve salt X ?

A ammonia solutionB sodium hydroxide solutionC dilute sulphuric acidD barium chloride solution

6. Figure 5 shows tests performed on compound G.

Figure 5

G is a mixture of two types of salts. Among the following, which is found in G ?

A silver sulphate and copper(II) carbonateB lead(II) nitrate and zinc carbonateC lead(II) nitrate and aluminium nitrateD magnesium sulphate and lead(II) carbonate

7. Which of the following ions form a white precipitate that dissolves in excess sodium hydroxide solution ?

I Al 3+

II Mg 2+

III Pb 2+

IV Zn 2+

A I and III onlyB II and IV onlyC I,II and III onlyD I,III and IV only

8. A precipitate is formed when solution X is added to solution Y. Among the following, which represents solution X and Y ?

G

Precipitation solution

Added with dilute hydrochloric acid and filtered

White precipitatedissolve

Added with ammonia solution until in excess

Solution X solution Y

A sulphuric acid sodium carbonateB silver nitrate hydrochloric acidC zinc nitrate potassium iodideD aluminium sulphate sodium chloride

9. Table 2 shows the results of tests performed on a compound Y.

Test ObservationHydrochloric acid is added. Product formed is heated up slowly

White precipitate formed dissolves when heated up

Barium hydroxide solution is added

White precipitate formed

What is compound Y ?

A zinc sulphateB lead(II) chlorideC silver nitrateD lead(II) sulphate

Test Observation

Sodium hydroxide solution is slowly added until excess.

White precipitate formed.The white precipitate dissolves in excess

sodium hydroxide solution.

A few drops of sulphuric acid is added White precipitate formed.

10. The table above shows the observations made for a test conducted on a colorless solution. Among the ions below, which ion will probably exist in the solution?

A Al 3+ B Mg 2+ C Pb 2+ D Zn 2+

11. 10 g of magnesium carbonate powder, MgCO3 is reacted with 100 cm3 of sulphuric acid, H2SO4 1 mol dm-3. What is the mass of magnesium carbonate that is not reacted?

[Relative atomic mass: Mg, 24; C, 12; O, 16] A 0.84 g B 1.60 g C 8.40 g D 9.16 g

12. Which of the following method is suitable for preparing silver chloride in the laboratory?

A Heating silver metal with chlorine gasB Adding silver powder to dilute hydrochloric acidC Adding silver oxide to dilute hydrochloric acidD Adding silver nitrate solution to dilute hydrochloric acid

13. Which of the following equations represents the reaction that can produce lead(II) iodide crystal?

A PbO + 2KI → PbI2 + K2OB PbSO4 + 2KI → PbI2 + K2SO4

C Pb(NO3)2 + 2KI → PbI2 + 2KNO3

D PbCl2 + 2KI → PbI2 + 2KCl

14. When solid R is heated strongly, the residue produced is yellow in colour when cold. What is solid R? A Lead(II) carbonate B Calcium carbonate C Sodium carbonate D Zinc carbonate

15. The table below shows the results of the tests carried out on an unknown colourless solution.

Test ObservationSodium hydroxide solution is added gradually to the solution until in excess.

A white precipitate is formed.The precipitate is soluble in excess sodium hydroxide solution.

Aqueous ammonia is added gradually to the solution until in excess.

A white precipitate is formed.The precipitate is insoluble in excess aqueous ammonia.

Sulphuric acid is added to the solution. No changes.

Which of the following ions may be present in that solution? A Al3+

B Mg2+

C Pb2+

D Zn2+

15. Lead(II) nitrate can be prepared by adding A lead(II) sulphate to dilute nitric acid.B lead(II) oxide to dilute nitric acid.C lead(II) chloride to potassium nitrate solution.D lead(II) carbonate to sodium nitrate solution.

16. The reaction between sulphur dioxide and potassium manganate(VII) solution can be represented by the following equation:

2KMnO4 + 5SO2 + 2H2O → K2SO4 + 2MnSO4 + 2H2SO4

What is the mass of sulfur dioxide that reacts completely with 1.0 dm3 potassium manganate(VII) solution 0.02 mol dm-3?[Relative atomic mass: O, 16; S, 12]

A g

B g C g

D g

1994

16. Solution Y contains two anions. A series of test is carried out on solution Y and the results are shown below.

Add dilute Add barium nitric acid chloride solution

Add silver nitrate solution

The ions present in solution Y are A sulphate ion and carbonate ion B nitrate ion and carbonate ion C sulphate ion and chloride ion D nitrate ion and chloride ion

17. According to the equation below, what is the volume of copper(II) sulphate solution 1 mol dm-3 required to react with 0.92 g metal Q? [Relative atomic mass: Q, 23]

2Q + CuSO4 → Q2SO4 + CuA 15 cm3

B 20 cm3

C 30 cm3

D 60 cm3

18. When aqueous ammonia is added to copper(II) sulphate solution, a blue precipitate is formed. What happens to

the blue precipitate when aqueous ammonia is added until in excess?A Cannot dissolve in excess aqueous ammoniaB Dissolves in excess aqueous ammonia to produce a dark blue solutionC Dissolves in excess aqueous ammonia to produce a colourless solutionD Cannot dissolve in excess aqueous ammonia but changes to a dark blue

precipitate

19. Which of the following schemes is used to identify sulphate ion in soluble salt?

A dissolve in dilute Add barium

hydrochloric acid chloride solution

B dissolve in dilute Add barium

Solution Y Colourlesssolution

Whiteprecipitate

Whiteprecipitate

Sulphate salt

Whiteprecipitate

Solutionformed

Sulphate salt

Whiteprecipitate

Solution formed

sulphuric acid chloride solution

C dissolve Add dilute Add barium In water sulphuric chloride acid solution

D dissolve Add dilute Add barium In water hydrochloric chloride acid solution

20. Which of the following solid salts can be prepared by double decomposition reaction?A Lead(II) nitrateB Silver chlorideC Magnesium sulphateD Sodium carbonate

21 A dilute acid Q is added to a base R until in excess and then shaken. A white precipitate is formed. Which of the following pairs of Q and R represents the reaction?

Q R A Hydrochloric acid Lead(II) oxideB Sulphuric acid Zinc oxideC Sulphuric acid Copper(II) oxideD Nitric acid Magnesium oxide

22. The reaction between barium chloride and silver nitrate can be represented by the equation below.

BaCl2(aq) + 2AgNO3(aq) → 2AgCl(s) + Ba(NO3)2(aq) Which of the following barium chloride solution can exactly react with 20.0 cm3 silver nitrate solution 0.5 mol dm-3?

A 20.0 cm3 barium chloride solution 1.0 mol dm-3

B 10.0 cm3 barium chloride solution 0.5 mol dm-3

C 20.0 cm3 barium chloride solution 0.5 mol dm-3

D 40.0 cm3 barium chloride solution 0.5 mol dm-3

23. When substance T is heated in air, a brown gas which can turn moist blue litmus paper red is produced. The residue formed is a yellow solid when hot and turn to white when cold. Substance T may be

A Lead(II) carbonate B Lead(II) nitrate C Zinc carbonate D Zinc nitrate

24. Which of the following substances are most suitable for preparing lead(II) chloride salt?A Lead(II) nitrate solution and sodium chloride solutionB Solid lead(II) sulphate and sodium chloride solutionC Solid lead(II) carbonate and hydrochloric acidD Solid lead(II) oxide and hydrochloric acid

25. The table below shows the observation of the tests carried out on an unknown solution Z.

Experiment Observation Add lead(II) nitrate solution to solution Z. A white precipitate is formed.Pass ammonia gas into solution Z until in excess.

A white precipitate is formed. The precipitate dissolves when ammonia gas is in excess.

Sulphatesalt

Solution formed

Solution formed

Whiteprecipitate

Sulphatesalt

Solution formed

Solutionformed

Whiteprecipitate

The observation shows that Z may be A zinc sulphateB calciun chlorideC magnesium nitrateD aluminium chloride

26. When copper(II) carbonate is heated, it decomposes according to the equation below. CuCO3 → CuO + CO2

What is the mass of copper(II) carbonate used to produce 600 cm3 carbon dioxide gas at room temperature and pressure?[Relative atomic mass: Cu, 64; C, 12; O, 16; 1 mol of gas occupies 24 dm3 at room temperature and pressure]

A 2.3 gB 3.1 gC 6.2 gD 25.0 g

27. Solution E contains three anions. A series of test is carried out on solution E and the results are shown below.

Add dilute Add silver nitric acid nitrate solution

Add barium chloride solution

The ions present in solution E are A nitrate ion, sulphate ion and carbonate ion B sulphate ion, carbonate ion and chloride ion C hydroxide ion, sulphate ion and chloride ion D sulphate ion, hydroxide ion and carbonate ion

28. The reaction between barium chloride solution and sodium carbonate produces an insoluble salt. The salt produced can be dissolved by adding

A sodium hydroxide solutionB potassium chloride solution C aqueous ammoniaD nitric acid

29. The equation below represents the reaction between barium hydroxide and potassium chromate(VI) .

Ba(OH)2 + K2CrO4 → BaCrO4 + 2KOH

Barium hydroxide solution reacts with 10 cm3 of potassium chromate(VI) solution to produce 0.63 g of barium chromate. What is the concentration of potassium chromate solution? [Relative atomic mass: O, 16; Cr, 52; Ba, 137]

Solution EEffervescence

occurs. A colourless

solution is formed.

Whiteprecipitate

Whiteprecipitate

A 0.025 mol dm-3

B 0.05 mol dm-3

C 0.25 mol dm-3

D 0.50 mol dm-3

30. The figure below shows the test on X. X is a mixture of two salts with the same cation.

Add distilled water and filter

+ sodium chloride solution

when heated

Which of the following substances are present in X?A Zinc carbonate and zinc chlorideB Magnesium carbonate and magnesium nitrateC Lead(II) carbonate and lead(II) nitrateD Lead(II) sulphate and lead(II) chloride

31. Which of the following salt is not decomposed by heat?A Zinc nitrateB Lithium nitrateC Potassium carbonateD Lead(II) carbonate

32. 5.0 cm3 lead(II) nitrate solution requires 25.0 cm3 sodium chloride solution 0.2 mol dm-3 to complete the reaction according to the equation below:

Pb2+(aq) + 2Cl-(aq) → PbCl2(s) What is the molarity of lead(II) nitrate solution? A 0.01 mol dm-3

B 0.10 mol dm-3

C 0.20 mol dm-3

D 0.50 mol dm-3

33. Which of the following ions produces a precipitate when sodium sulphate solution is added ? I Al3+ ion II Ca2+ ion III Cu2+ ion IV Pb2+ ion

X

Precipitate

White precipitate

Solution

Precipitate dissolves

A I and III only B II and IV only C I, II and IV only D II, III and IV only

34. The equation below shows the action of heat on the carbonate salt of metal X.

XCO3 → XO + CO2

How many moles of XCO3 are needed to produce 4.0 g of oxide X? [Relative atomic mass: C,12; O, 16; X, 64] A 0.03

B 0.05 C 0.08 D 0.09

35. The diagram below shows the crystalline structure of salt, NaCl. Which of the following is not a characteristic of the crystal of NaCl?

A It has sharp corners. B It has flat surfaces. C It has an acute angle between the two adjacent surfaces. D It has straight edges between two adjacent surfaces.

36 Which of the following ions form a white precipitate that dissolves in excess sodium hydroxide solution?

I Al3+

II Mg2+ III Pb2+

IV Zn2+

A I and II only B II and IV only C I, II and III only D I, III and IV only

37. 3.2 g of copper(II) oxide powder is reacted with excess dilute nitric acid. What is the mass of copper(II) nitrate formed in the reaction?Use the information that the relative atomic mass of N = 14, O = 16 and Cu = 64.

A 3.76 gB 4.96 gC 5.04 gD 7.52 g

38. Gas X is passed into an acidic dichromate solution. The colour of the solution changes from orange to green. What is gas X?

A Sulphur dioxide B Hydrogen chloride C Nitrogen dioxide D Chlorine

39. The formula for a sulphate ion is SO42- and for a nitrate ion is NO3

-. If the formula of the sulphate salt of M is MSO4, what is the formula of the nitrate salt of M?

A MNO3

B M2NO3

C M(NO3)2

D M(NO3)3

40. 0.12 g of magnesium reacts with excess hydrochloric acid to produce hydrogen gas. [Given that the relative atomic mass of H=1, Mg=24, Cl=35.5 and 1 mol of gas occupies 24 dm3 at room temperature and pressure] Which of the following is true about the reaction?

I Mg + 2H+ → Mg2+ + H2

II Volume of gas released is 120 cm3

III Mass of the salt formed is 0.30 g IV This is a redox reaction

A I and II only B I and III only C I, II and IV only D II, III and IV only

41. Which of the following ions form precipitate that dissolves in excess ammonia solution?

I. Al3+ II. Cu2+III. Pb2+

IV. Zn2+

A. I and II onlyB. II and IV onlyC. I, II and III onlyD. I, III and IV only

42. You are asked by your teacher to verify the cation and anion in a sample of ammonium chloride salt solution, What substance can you use to verify the cation and anion?

Cation AnionA Nessler reagent Dilute nitric acid and silver nitrateB Nessler reagent Dilute hydrochloric acid and barium chlorideC Potassium thiocyanate Dilute nitric acid and silver nitrateD Potassium thiocyanate Dilute hydrochloric acid and barium chloride

Structural question

1. Figure 2 shows a flow chart summarizing the series of changes for a compound T.

Solid T

Solution Y Gas V+Solid U Gas V+

Solution W

White precipitate soluble in excess

Solid U Gas Y+ Gas Z+

+ dilute nitric acid

Heated up

Heated up

+ dilute hydrochloric acid

+ ammonia solution

Solid U is yellow in colour when hot and white in colour when cooled.

(a) What is solid U? [ 1 mark ](b) Name the cation and anion in solid T. [ 2 marks ](c ) (i) Name gas V. [ 1 mark ]

(ii) What is observed when gas V is passed through limewater? [ 1 mark ](iii) Write the chemical equation for reaction between gas T with limewater.

[ 3 marks](d) Write the chemical equation to represent the effect of heat on solid T. [ 1 mark ]

(e) (i) Name solution Y. [ 1 mark ](ii) Describe briefly a chemical test to identify the anion in solution Y.

[ 3 marks ](f) Name the type of reaction which occurs when solid U reacts with dilute hydrochloric acid to form

solution W. [ 1 mark ](g) (i) What are gas Y and gas Z ? [ 2 marks ]

(ii) Write the balance chemical equation for the effect of heat on solution Y.[ 1 mark ]

2. Figure 3 summarises the series of reactions that involves lead compounds.

Lead(II)nitrate Solid J + Mix of gases K and L

Heated up

Figure 3

(a) What is solid J ? [ 1 mark ](b) What is the colour of solid J when hot and cooled ? [ 1 mark ](c ) Write a balance chemical equation to represent the effect of heat on lead(II) nitrate to form solid J and a

mixture of gas K and N. [ 3 marks ](d) (i) Name precipitate M. [ 1 mark ]

(ii) State a way to test compound M. [ 1 mark ](iii) Write the ionic equation to show then formation of precipitate M.

[ 1 mark ](e) Sodium hydroxide solution is added little by little into solution N until there is no more change. What can be

observed ? [ 1 mark ](f) How can you obtain dry crystal salt, N , from solution N ? [ 3 marks ](g) A piece of zinc is put into solution N.

(i) Predict the observation. [ 1 mark ](ii) Write the chemical equation to represent the reaction which has occurred.

[ 1 mark ]

White precipitate M Solution N

Add dilute hydrochloric

acid

Add dilute nitricacid

Compound J

Gas K[Brown colour and acidified]

+

Gas L[Colourless]

+

Solid M

Heat

Figure 3

3. Figure 3 shows a series of process done by a student to identify a compound J.

(a) With refer to reaction I, white precipitate Q is formed which is soluble in excess sodium hydroxide solution. Name all the ions which are probably presence in solution J.

[ 1 mark ]

(b) Referring to reaction I and II, name the cation presence in solution J.[ 1 mark ]

(c ) Write down the ionic equation for the reaction forming the white precipitate, R.[ 3 marks ]

(d) (i) Name two cations which produced white precipitate that will not dissolve in excess sodium hydroxide solution. [ 1 mark ]

(ii) State one confirmatory test for one cation presence in (d)(i). [ 3 marks ]

Essay questions1. (a) What is the meaning of salt ? [ 1 mark ]

(b) (i) State four types of preparation reaction for insoluble iron(II) chloride. [ 4 marks ]

(ii) For each type of reaction in (b)(i), write a chemical equation for salts prepared through the reactions mentioned. [ 4 marks ]

(c ) You are required to prepare zinc sulphate salt. Chemical compounds provided are listed as follows:

Dissolved in

water

Colourless J solution

White precipitate R

Reaction II

+ Na2SO4 (aq)

White precipitate Q Dissolved in

excess sodium

hydroxide solution

Reaction I

+ NaOH (aq)

Describe a laboratory experiment how you can prepare zinc sulphate salt that is dry. In your description, include the chemical equations involved.

[ 11 marks ]

2. (a) What is meant by precipitation reaction ? [ 1 mark ](b) Describe how you can use ammonia solution to differentiate the

following solutions.

(c ) A solution contains iron(II) ion cation. Decribe briefly three laboratory experiment for you to confirm the presence of iron(II) ion in the solutions.

[ 6 marks ](d) Describe a laboratory experiment to prepare lead(II) nitrate crystal salt in the laboratory. In your

description, write the chemical equations for the reactions involved.[ 9 marks ]

3 .(a) The following information is about hydrochloric acid and ethanoic acid.* the pH of 1 mol dm-3 hydrochloric acid is 1* the pH of 1 mol dm-3 ethanoic acid is 4

[4 marks]Explain why these two solution have different pH values(b) Two bottles of reagent each containing hydrochloric acid and ammonium chloride solution.

Qualitative analysis can be used to determine the presence of cations and anions in solutions.Describe chemical tests that can be used to verify the ions in each solution.

[10 marks]© The chemical equation of reaction P is as follows:

CuCl2 + Na2CO3 2NaCl + CuCO3

Excess sodium carbonate is added to 50cm3 of 0.5 mol dm-3 copper(II) chloride. Given that the relative molecular mass of CuCO3 = 124. Calculate the mass of copper(II) carbonate precipitate formed.

[2 marks] (d) When copper(II) carbonate is heated, it produces solid X and gas Y.

(i) Name solid X and state its colour. [2 marks]

(ii) Name gas Y and describe a method to verify its identity. [2 marks]

Dilute sulphuric acid Sodium carbonate solution Zinc nitrate solution

Potassium nitrate solution Zinc sulphate solution Magnesium chloride solution