chemis folio
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1) Polymers are long chains of molecules made from
combinations of many small molecules.
2) Small molecules that combine to form polymers are called
monomers.
3) Polymerisation is a process of combining monomers to forma long of molecules.
4) Polymers can be divided into two types:
a) natural polymer
b) synthetic polymer
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Natural polymer
1) A natural polymer is a polymer that occurs naturally.
2) Natural polymers are normally made by living organisms.
Natural polymer Monomers (small molecules)
Rubber isoprene
cellulose Glucose
Starch Glucose
Protein Amino acid
Fat Fatty acids and glycerol
Nuclei acid nucleotides
Examples of natural polymers and their monomers
Synthetic polymers
1) Synthetic (artificial) polymers are man-made polymers
that are produced from chemical compounds through
polymerization.
2) Plastic, synthetic fibres and synthetic rubbers are
three examples of synthetic polymers
3) Thare are two types polymerization:
a) addition polymerization
b) Condensation polymerization
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Addition polymerization
1) Unsaturated monomers that contain double bonds
between two carbon atoms undergo addition
polymerization.
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2) Monomers undergo addition polymerisation as shown
in figure 9.14.
3) If the structure of a monomer is known, the structural
formula of its synthetic polymer can be determined as
shown below:
a) step 1
Write the symbol for two carbon atoms with double
bonds in the middle. ¶Push· the atom or molecules thet is
tied to the two carbon atoms above the two carbonatoms.
b) step 2
Change or ¶open· the double bond into single covalent
bonds and draw brackets.
c) step 3
Write the letter ¶n· at the bottom right-hand corner of the
molecule.
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4) The monomers in a polymer can be determined. The
followingguidelines are given to help you to determine
the monomers in a polymer, formed through the
addition polymerisation.
a) step 1
Determine the position of the two consecutive carbon
atoms (small repeating units) in the structure of a
polymer molecule.
b) step 2
Change or ¶close· the single bond into a double bond.
Condensation polymerisation
Small molecules such as water, H2O, and ammonia,N
H3, arereleased in condensation polymerisation.
Monomer Polymer
(a) Adpic acid and
hexanediamine
nylon
(b) 1, 2-dicarboxylbenzene and
ethane-1, 2-diol
terylene
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Uses of synthetic polymers
1) Synthetic polymers are used widely in daily life.
Type of polymer Use
Polythene Make buckets, plastic bags,
raincoats, films, bowls and
rubbish bins
Polyvinyl chloride (PVC) Make water pipes, electric
cables, mats, vinyl records and
clothes hangers
Polypropene Make ropes,bottles, chairs,drink cans and carpets
Perspex Make car windscreens, airplane
window panes and spectacle
lenses (optical instruments)
Nylon Make ropes, curtains, stockings
and clothes
Polysyrene Make packing boxes, buttons
and noticeboards
Terylene Make textile items such asclothes and cloths
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3) Synthetic polyumers such as plastic, synthetic fibers and
synthetic rubber have been used to replace various naturalitems such as cotton, silk, glass, metal, timber and rock
Natural compounds that have
been replaced by synthetic
polymers
The advantages of synthetic
polymers compared to natural
compounds
Cotton and silk Stronger, more durable,
withstands dirt, and does not
wrinkle easily
Paper Waterproof, does not wrinkle or tear easily
Timber Does not rot easily
Metal Lighter, does not corrode
easily, more easily forged and
colured
Glass and ceramics Does not break easily
Marble (rock) cheaper
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Effects of the disposal of items made from synthetic polymers
on the environment.
1) Synthetic polymers are not biodegradable (not
decomposed by microorganisms).2) The careless disposal of items made from
synthetic polymers such as plastic causes
environmental pollution.
3) The effects of burning and careless disposal of
items made from synthetic polymers on the
environment are as follows:
a) Burning of synthetic polymers
y releases pollutants that endanger health such
as smoke, gases that are smelly, poisonous andcorrosive such as sulphur dioxide, pollutants
that cause acid rain and the greenhouse effect.
b) Careless disposal of synthetic polymers
y spoils the beauty of the environment
y causes flash floods during heavy rainfall
y endangers marine life like tutles that
accidentally eat polymers such as plastic as its
food.
4) the best way to manage used items made fromsynthetic polymers is to recycle them.
5) Plastics that are biodegradable can be used
instead to reduce environmental pollution.
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Types, composition, characteristics and uses of
glass
1) The main component of glass is silica or
silicon dioxide, Si02, which is obtained
from sand.
2) The main characteristics of glass are:
(a) brittle
(b) hard
(c) chemically inert
(d) transparent
(e) not permeable to gas and liquid (fluid)
(f) does not conduct electricity
(g) heat insulator
3) The most simple glass is the fused silica
glass. This glass mainly condiyions, Sio2.
4) Most of the glasses are produced by
mixing molten silica, SiO2, with other
compounds.
5) Glass can be recycled. Glass can also be
melted and solidified repeatedly.
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Type of glass Method of
production
Composition Properties
Fused silica glass Silica, SiO2, is
heated until
melted at 1700 c
and cooled
rapidly
Silica or silicon
dioxide, SiO2
* very high
melting point
* not easy to
change its shape
* does not easily
expand or shrink
with changes of
temperature
* transparent to
ultraviolet rays
Soda-lime glass Molten silica,
SiO2, is mixed
with sodiumcarbonate,
Na2CO3, and
calcium
carbonate, CaO3,
at 1500 c and
cooled.
Sodium silicate,
Na2SiO3, and
calcium silicate,CaSiO3
* transparents
* low melting
point*easily shaped
* easily broken
Borosilicate glass Molten silica,
SiO2, is mixed
with boron oxide,
B2O3
Silica, SiO2 and
boron oxide,
B2O3
* withstand heat
and chemical
reactions
* high melting
point* transparent to
light and infared
ray but not to
ultraviolet rays
* expands and
shrinks very little
and only whem
temperature
changes
Lead crystal
glass
Molten silica,
SiO2, is mixedwith lead(ii)
oxide, PbO, and
sodium oxide,
Na2O
Silica,Sio2,
lead(II) oxide,PbO, and sodium
oxide, Na2O
* very transparent
* shiny* high refractive
* high density
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6) Different types of glass have different uses.
Types of glass Uses
Fused silica glass Lenses, spectacles, laboratory
glassware, ultraviolet column
Soda-lime glass Bottles, glass containers, mirrors,electrical bulbs, glass windows
Borosilicate glass Bowls, plates, saucers, pots,
cookware, laboratory glassware such
as test tubes, beakers and flasks
Lead crystal glass Lenses,prisms, glasses, ornamental
items (crystals)
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Composition, properties and uses of ceramics.
1) ceramics are made from clay that has
been heated at a very high temperature.
2) The main component of ceramics is
silicate.
3) Most ceramics contain silicon, Si,
oxygen, o, and aluminium,Al.
4) Unlike glass, ceramics cannot be
recycled. Ceramics that have been
solidified cannot be melted again as they
are extremely heat resistant.
5) Common properties of ceramics are:
a) brittle
b) extremely hard
c) high melting point
d) withstand compression
e) cracks when temperature changes
drastically
f) inert to chemicals (withstand corrosion)
g) good insulators of heat and electricity
6) several uses of ceramics are as follows:
a) manufacture of computer microchips
b) make dentures (enamel)
c) make porcelain, vase and ornamental
items
d) make plates, bowls and pots
e) used in the manufacturing of car engines,
spacecraft, superconductors and nuclear
reactors
f) make construction materials such as
bricks, cement, tiles, underground piping
or roof tiles.
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1) In this modern world, the demand for items with specific
properties is high.
2) Compounds with specific properties are combined to produce a
composite material that meets the requirements of industry,
construction and transportation.
Composite materials
1) Composite materials are produced from the combination of two
or more different compounds such as alloys, metals, glass,
polymers and ceramics
2) The characterists of the produced material are much more
superior than those original components.
3) Several uses of composite materials are:a) Reeinforced concrete
y Made from a mixture of cement, gravel, sand, water,
iron or steel to produce nets, rods or bars
y Stron, high tensile strength and cheap
y Construction material for buildings, bridges,
highways and dams
b) Superconductor
y Made from various components such as the mixture
of niobium and germanium
y Compound that has no electrical resistance (zero
resistance)
y Can function only under extremely low temperature
y Used in the transportation, telecommunications and
astronomy industries and in the medical field.
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c) Fibre class
y Made from silica, SiO2, sodium carbonate, Na2CO3
and calcium carbonate, CaCO3
y Good insulator of heat and electricity
y Used to make protective apparel for astronauts and
firefighters
d) fibre optics
y made from glass, copper and aluminium
y enables information to be transmitted in light form at
high speeds (speed of light)
y used in the field of communications to make
electrical cables and in the field of medicine to
observe internal organs without performing surgery.
e) Photochromic glass
y Produced from molten silica that is mixed with a
little silver chloride AgCl
y Dark in colour when exposed to bright light
(ultraviolet ray) and bright when in the dark
y Used to make optical lenses and glass windows
(windshields) of certain vehicles
f) Ceramic class
y Produced by exposing glass that contains certain
amount of metals to ultraviolet rays and heating it at
high temperaturesy Withstand heat
y Used to make cooking materials and rocket heads
g) Plastic strengthened with glass fibres
y Made of plastic and glass fibres
y Composite plastics that are very strong, light, easily
formed and can withstand corrosion
y Used to make helmets, the body of cars and
aeroplanes, rods and other parts of aeroplanes
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The uses of sulphuric acid in daily life
Sulphuric acid,H2SO4 is a non-volatile diprotic acid and is also
one of the most important chemical used in chemical industries.
Sulphuric acid is used to make :
E.g: Calcium hydrogen phosphate is formed when sulphuric acid
reacts with calcium phosphate.2H2SO4+Ca3(PO4)2 Ca(H2PO4)2 +2CaSO4
Ammonium sulphate is prepared from sulphuric acid andaqueous ammonia.H2S04+2NH3 (NH4)2SO4
Pottasium sulphate is prepared from sulphuric acid andpotassium hydroxide.H2SO4+2KOH K2SO4+2H2O
Artificial synthetic fibres are polymers.
Detergents are synthetic cleansing agents.
Sulphuric acid reacts with hydrocarbon to produce sulphonicacid which then neutralized with sodium hydroxide to producedetergent.
Fertilisers
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Neutralisation of sulphuric acid with barium hydroxide produces
barium sulphate which is the white pigment in paint
Environmental pollution by sulphur dioxide
Burning of fossil fuels
Fossil fuel such as petroleum.It contains sulphur.Sulphur dioxide is produced when fossil fuels are burned.
Affects the respiratory system
Sulphur is a poisonous and acidic gas.It cause coughing,chest pains,shortness of breath,lung diseases and bronchitis.
Burning of sulphur in industrial area
The contact process and the burning of coals or fuels producehigh sulphur dioxide content.
Affect of acid rain
Sulphur dioxide gas dissolve in atmospheric water to producesulphurous acid, H2SO3 and sulphuric acid, H2SO4.These acidscauses acid rain.
Acid rain corrodes concrete buildings and metal structures.Acidrain increases the acidity of soil, unsuitable for growth anddestroys the roots of plants.Acid rain reacts with minerals in thesoil to produce salts which are leashed out of the top soil;essential nutrients for plants growth are depleted (plants die of malnutrition and diseases).Acid rain increases the acidity of water in lake and rivers, causes aquatic organisms die anddisturb the ecosystem.
SO2+H2O H2SO3
2SO2+O2+2H2O 2H2SO4
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The industrial process in the manufacture of sulphuric acid
The contact process
Production of sulphur
dioxide gas
Conversion of sulphur
dioxide to sulphur
trioxide.
Production of sulphuric
acid
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*Burning of sulphur in dry
air in the furnace
*Burning of metal sulphidessuch as zinc sulphide andlead sulphide alsoproduces sulphur dioxide.
*The sulphur dioxide is mixedwith excess air.The mixtureis then dried and purified toremove impurities such as
arsenic compounds.
*Arsenic compounds found insulphur will poison the catalystin the converter, make the catalystineffective.
*Mixture of sulphur dioxide
and excess dry oxygen ispassed through a converter.
*Sulphur dioxide is oxidised tosulphur trioxide.
*98% conversion from sulphur
dioxide to sulphur trioxide isachieved under conditions:
a) Catalyst : vanadium( V )oxide,V2O5
b) Pressure : 1 atmosphere
c) Temperature : 450 c ² 550 c
*In the absorber, sulphur
trioxide is dissolved inconcentrated sulphuricacid to produce oleum,
H2S2O7, a viscousliquid.
*Oleum is then diluted with
equal volume of water to
produce concentratedH2SO4 ( 98% )2ZnS+3O2 SO2+2ZnO
2PbS+3O2 2SO2+2PbO
2SO2+O2 2S03
SO3+H2SO4 H2S2O7
H2S2O7+H2O 2H2SO4
S+O2 SO2
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The flow chart of contact process
o The two reaction in stage 3 are equivalent to add sulphur trioxide to water.
SO3+H2O H2SO4
o SO3 is not dissolved directly in water to produce H2SO4 because :
~ SO3 has low solubility in water ~ SO3 reacts violently in water , produce large amount of heat
which will vaporise sulphuric acid to form acid mist which is
corrosive, pollutes the air and is difficult to condense
o The SO2 gas is dried and purified before added to dry air toproduce SO3 gas.This is
a) to remove water vapour in the air b) to remove contaminants such as arsenic
compounds
Sulphur
Sulphur dioxide, SO2
Sulphur trioxide, SO3
Oleum,H2S2O7
Sulphuric acid, H2SO4
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Ammonia and its salt
The uses of ammonia in industry
Nitric acid ~ can be produced through oxidation o
ammonia when latinum is used as a catal st
Detergents ~ when ammonia reacts with oil from the
plants, detergents is produced
Prevent coagulation of latex ~ latex can be stored f
longer period of time before exporting
Paint and colouring ~ reaction of nitric acid and
organic compound can produce various type color
Synthetic fabric ~ ammonia is used to synthesis the
synthetic fabric
Explosive ~ reaction of nitric acid and toluena produce
explosive material
Cooling agent ~ ammonia is used as cooling agent in th
refrigerator.It has low point and therefore is very volat
Synthetic fertilizers ~ synthetic fertilisers can be produ
through neutralisation between ammonia gas and acid
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The manufacture of nitrogenous fertilisers
2NH3 + H2SO4 ( NH4 )2 SO4
o Ammonia reacts with sulphuric acid through neutralisation to produceammonium sulphate.
NH3 + HNO3 NH4NO3
o Ammonia reacts with nitric acid through neutralisation to produceammonium nitrate.
Ammonium sulphate
Ammonium nitrate
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2NH3+CO2 CO( NH2 )2 ( S ) +H2O
o Ammonia reacts with carbon dioxide at temperature of 200 C and apressure of 200 atmosphere to produce urea.
Ostwald process : In the Ostwald process, ammonia is covered into nitric acid by three
stages.
Stage 1
Ammonia is oxidised to nitrogen monoxide gas in the presence of platinum as catalyst.
4NH3 + 5O 4NO + 6H2O
Stage 2
Nitrogen monoxide is further oxidized to nitrogen dioxide
2NO + O2 2NO2
Stage 3
Nitrogen dioxide is dissolved in water produce nitric acid,
2NO2 + H2O HNO3 + HNO2
Urea
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The properties of ammonia
Very soluble in water
~ an inverted filtr funnel is used to prevent the sucking
back of water
Alkaline gas, colourless and pungent gas~ ammonia turns the damp red litmus paper blue~ the gas is less dense than air
To test ammonia gas~ ammonia gas reacts with hydrogen chloride gas to form white fumes of
ammonium chloride
Does not burn in air~ ammonia gas burns in oxygen to produce nitrogen monoxide gas
Neutralisation~ ammonia is a week alkali which reacts with dilute acida in neutralisation to
produce salts
R eacts with aqueuos metal ions~ aqueous solutions of ammonia react with metal ions( except Na+, k+ and Ca2+ )
to produce precipitate of metal hydroxides
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The industrial process in the manufacture of ammonia
* massive production of ammonia in an industrial sector is known as
Haber process
* nitrogen gas used in Haber process is obtained from the fractionaldistillation of liquid air.
y Hydrogen gas can be obtained by two methods:
y A) reaction between steam and heated coke (carbon)
y Formula
y H2o + CCo+H2
c) Reaction between steam and naturalgas consist mainly of methane, CH4
Formula2HO + CH4 CO2 + 4H2
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Steel
99.5%iron + 0.5%carbon
y very hard
y strong
Manganese steel(hadfield steel)
85%iron + 13.8%manganese + 1.2%carbony very hard
Duralumin
95%aluminium + 3%copper + 1%mangan + 1%manganesey hard
y does not corrode
y light but strong
Pewter
97%tin + 3%antimony and copper y
shiny and attractive appearancey does not corrode
y easily cast
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Ammonium fertilizers
o Nitrogen is absorbed by plants in the form of soluble nitrates, NO3 produce protein
o Ammonium fertilisers are chemical fertilisers that are used to replaceelements in soil used up by plants
o Ammonium ions, NH4+ can be converted into nitrate ions by bacterialiving in the soil
o The fertilizer with higher percentage of nitrogen is more effective andthis can be determined as below :
Percentage of nitrogen by weight
= Mass of nitrogen X100%
R elative molecular mass of fertilisers
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Alloys
~ An alloy is a mixture of two or more elements with a certain fixed
cmpositions in which the major component is a metal.
The physical properties of pure metal
~ pure metals are weak and soft because the arrangement of
atom makes them ductile and malleable.
DuctileDuctile is the ability of a metal to be stretched
MalleableMalleable is the ability of a metal to be shaped
High melting point and boiling pointsThe strong forces of attraction between metal atoms requires highenery to overcome it. Hence, metals have high melting point
Good conductor
High densityIn solid state, the atoms in a pure metal are orderly aarranged andclosely packed, causes pure metal to have high density
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Arrangement of particles in pure metals
~ pure metals are soft and have atoms of same sizes
Meaning and purpose of making alloys
~ alloying is a process of mixing two or more metals ( or mixing metals
with elements such as carbon ) which cannot be separated by usingphysical way
Arrangement of particles in alloys
Atoms have different sizes
Disrupts the arrangement of atoms
Harder for layers of atoms tom slide over each other
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Aim of making alloy
To increase the strength and hardnessy adding a little carbon to iron metal produces steel which is
very hard alloy of iron.
y adding magnesium to aluminium metal produces an alloycalled Magnalium.
y adding tin to copper metal produces Bronze is an alloyharder than tin and copper.
To improve the appearance
y pure metals can rust and tarnish easily because of theformation of metal oxides.
y alloying can maintain the luster on the surface of metal.
To prevent corrosion
y pure metals such as iron and tin are easily corroded inpolluted, damp or acidic air
y alloying can prevent metals from corrosion due to theformation of oxide layer on the surface of the metal.
Carbon + nickel + chromium added
into iron metal produce
stainless steel