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POLYMERS and their uses.
What are polymers ?
Polymers are large molecules made up of many identical repeating sub-unit called monomerswhich are joined together by covalent bonds.
Monomers are joined into chains by a process of repeated linking known as polymerisation.
Polymerisation
Polymer
Monomer
TYPES OF POLYMER.
TYPES OF POLYMER
Natural polymer Synthetic polymer
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SYNTHETIC POLYMER.
Synthetic polymers are man-made polymers that are produced from chemical compounds throughpolymerisation.
Example of synthetic polymers , their monomers and uses.
Synthetic polymer Monomer Uses
Polythene Ethene Make plastic bags , Shopping bags ,
plastic containers and insulation for
electrical wiring.
Polypropene Propene Make piping , bottle crates , carpets ,
car batteries and ropes.
Polyvinyl chloride ,
PVC
Chloroethene Make artificial leather , water pipes
and records.Perspex Methylmethacrylate Make lenses , safety glass reflectors
and traffic signs.
Terylene Hexane-1,6-diol
Benzene-1,4-dicarboxylic
acid
Make clothing , sails and ropes.
Nylon Hexane-1,6-diamine
Hexane-1,6-dioic acid
Make ropes , clothing and carpets.
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NATURAL POLYMER.
Natural polymer is a polymer that occurs naturally.
Natural polymers are normally made by living organisms.
Natural polymer Monomers
Rubber Isoprene
Cellulose Glucose
Starch Glucose
Protein Amino acid
Fat Fatty acids and glycerol
Nucleic acid Nucleotides
Examples of natural polymers and their monomers.
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Monomer Polymer
a) H HC C
H H
Ethene
H H
C C
H H n
Polythene (polyethene)
b) Cl HC C
H H
Chloroethene (Vinyl chloride)
Cl H
C C
H H n
Polyvinyl chloride (PVC)
(Polychloroethene)
c) H HC C
CH3 HPropene
H H
C C
CH3 H n
Polypropene
d) H CH3C C
H COOCH3Methyl-2-methylpropenoate
(Methyl methacrylate)
Cl CH3
C C
H COOCH n
Perspex
(Polymethyl methacrylate)
e) H HC C
H
Styrene
H H
C C
H n
Polystyrene
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Examples of synthetic polymers (product of additionpolymerisation) and their monomers.
Structural formula of amino acid and glucose.
Polymerisation of isoprene into polyisoprene (rubber).
H R O
H N C C O H
HAmino acid (monomer of protein)
CH2OH
C O
H H
HC C
OH OH
HO OH
C C
H H
Glucose (monomer of starch and cellulose)
Monomer Polymer
H CH3 H H
n H C C C C H
Isoprene (monomer of natural rubber)
H CH3 H H
C C C C
H H
n
Polyisoprene (polymer of natural rubber)
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Polymerisation
Polymerisation is a process ofcombining monomers to form a long chain of molecules.
TYPES OFPOLYMERISATION
Addition
polymerisation
Condensation
polymerisation
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ADDITION POLYMERISATION
Unsaturated monomers that contain double bonds between two carbon atoms undergo additionpolymerisation.
Monomers undergo addition polymerisation as shown :-
H H H H H H H H H H
n C C C C or ~ C C C C C C ~
H H H H n H H H H H HEthene (monomer) Polythene (polymer)
Example of addition polymerisation.
If the structure of a monomer is known , the structural formula of its synthetic polymer can bedetermined as shown below.
Step 1
Write the symbol for two carbon atoms with double bonds in themiddle. 'Push' the atom or molecule that is tied to the two carbon
atoms above or below the two carbon atoms.
Step 2 Change or 'open' the double bond into two single covalent bonds and
draw brackets.
Step 3 Write the letter 'n' at the bottom right-hand corner of the molecule.
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CONDENSATION POLYMERISATION
Small molecules such as water , H2O and ammonia , NH3 are released in condensation polymerization.Monomer Polymer
a) Adipic acid and hexanediamine Nylonb) 1,4-dicarboxylbenzene and
ethene-1,2-diol
Terylene
Examples of synthetic polymers (products of condensation polymerisation)and their monomers.
H H O O
n H N (CH2)6 N H + nHO C (CH2)4 C OH
hexanediamine adipic acid
H H O O
N (CH2)6 N C (CH2)4 C + nH2O
Nylon n
Example of condensation polymerisation.
H2O
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Synthetic polymers such as plastic Synthetic fibres and synthetic rubber have been used to replace
various natural items 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 coloured
Glass and ceramics Does not break easily
Marble (rock) Cheaper
Advantages of synthetic polymers used to replace natural compounds
Effects of the disposal of items made from synthetic polymers on the environment
Synthetic polymers are not biodegradable (not decomposed by microorganisms). The careless disposal of items made from synthetic polymers such as plastic causes environmental
pollution.
The effects of burning and careless disposal of items made from synthetic polymers on theenvironment as follows :
The best way to manage used items made from synthetic polymers is to recycle them. Plastics that are biodegradable can be used instead to reduced environmental pollution.
Burning of synthetic polymers
Releases pollutants that endanger
health such as smoke , gases that are
smelly , poisonous and corrosive such
as sulphur dioxide , pollutants that
cause acid rain and the greenhouse
effect.
Careless disposal of syntheticpolymers
spoils the beauty of the environment.
causes flash floods during heavy
rainfall.
endangers marine life like turtles that
accidentally eat polymers such asplastic as its food.
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GLASS AND CERAMICS.
GLASS The main component of glass is silica or silicon dioxide , SiO2 ,which is obtained from sand. The most simple glass is the fused silica gas.This glass mainly contains silica , SiO2. Most of the glasses are produced by mixing molten silica , SiO2 , with other compounds. Glass can be recycled . Glass can also be melted and solidified repeatedly.
The main characteristics of glass.
GLASS
BrittleNot permeable
to gas and liquid
(fluid)
Heat
insulator
Does not
conduct
electricity
Trasnparent
Chemically
inert
Hard
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Different types of glass have different properties and uses.
Types of glass Properties Uses
1) Fused silicaglass
Very high melting point Not easy to change its shape Does not easily expand or
shrink with changes of
temperature Transparent to ultraviolet rays
Make lenses Make spectacles Make laboratory
glassware
Make ultravioletcolumn
2) Soda-limeglass
Transparent Low melting point Easily shaped Easily broken Cannot withstand heat and
chemical reactions
Make bottles Make glass containers Make mirrors Make electrical bulbs Make glass windows
3) Borosilicateglass
Withstand heat and chemicalreactions
High melting point Transparent to light and
infrared ray but not ultraviolet
rays
Expands and shrinks verylittle and only when
temperature changes
Make bowls Make plates Make saucers Make pots Make cookware Make laboratory
glassware such as testtubes, beakers and
flasks.
4) Lead crystalglass
Very transparent Shiny High refractive index High density
Make lenses Make prisms Make glasses Make ornamental items
(crystals)
TYPES OFGLASS
Fused silica
glass
Soda-lime
glass
Borosilicate
glass
Lead crystal
glass
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CERAMICS
Ceramics are made from clay that has been heated at a very high temperature. The main component of ceramics is silicate. Most ceramics contain silicon , Si , oxygen , O and aluminium , Al. Unlike glass , ceramics cannot be recycled. Ceramics that have been solidifiedcannot bemelted
again as they are extremely heat resistant.
The common properties of ceramics.
CERAMICS
BrittleCracks when
temperature
change
drastically
Inert to
chemicals
(withstandcorrosion)
Good
insulators of
heat and
electricity
Withstand
compression
Highmelting
point
Extremely
hard
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Several uses of ceramics.
Uses of ceramics :
Manufacture of computer microchips
Make dentures (enamel)
Make porcelain , vase and ornamental items
Make plates , bowls and pots
Used in manufacturing of car engines , spacecraft superconductors and nuclear
reactors
Make construction materials such as bricks , cement , tiles , underground piping
or roof tiles
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COMPOSITE MATERIALS.
Composite materials are produced from the combination of two or more different compounds such asalloys , metals , glass , polymers and ceramics.
The characterists of the produced material are much more superior than those original components.
The Uses of Composite Materials :
In this modern world , the demand for this items with
spesific properties is high.
Compounds with spesific properties are combined to produce a
composite material that meets the requirements of industry ,
construction and transportation.
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Examples of composite materials are :-
Made from a mixture of cement , gravel , sand , water , iron or
steel to produce nets , rods or bars.
Strong , high tensile strength and cheap.
Construction material for buildings bridges highways and dams.
ReinforcedConcrete
Made from various components such as the mixture of
niobium and germanium.
Compound that has no electrical resistance ( zero resistance ).
can function only under extremely low temperatures.
Used in the transportation , telecomunications andastronomy industries and in the medical field.
Superconductor
Made from silica , SiO2 , sodium carbonate , Na2CO3 calcium
carbonate , CaCO3.
Good insulator of heat and electricity.
Used to make protective apparel for astronauts and firefighter.
Fibre Glass
Made from glass , copper and aluminium.
Enables information to be transmitted in light form at high
speeds ( speed of light ).
Used in the fieldof communications to make electrical cablesand in the field of medicine to observe internal organs withoutperforming surgery.
Fibre Optics
Produced from molten silica that is mixed with a little silver
chloride , AgCl.
Dark in colour when exposed to bright light ( ultraviolet ray )
and bright when in the dark.
Used to make optical lenses and glass windows ( windshields )
of certai vehicles.
PhotochromicGlass
Produced by exposing glass that contains certain amount of
metals to ultraviolet rays and heating it at high temperatures.
Withstand heat.
Used to make cooking materials and rocket heads.
Ceramic Glass
Made of plastic and glass fibres.
Composite plastics that are very strong , light , easily formed
and can withstand corrosion.
Used to make helmets , the body of cars and aeroplanes , rods
and other parts of aeroplanes.
PlasticStrengthened
with GlassFibres
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MANUFACTURE OF SULPHURIC ACID.
Uses of sulphuric acid , H2SO4 , in our daily life are as follows :
Uses of Sulphuric Acid :
Manufacture of fertilisers such as ammonia sulphate , (NH4)2SO4.
Manufacture of electrolyte in lead-acid accumulators (car battery).
Manufacture of soaps and detergents.
Manufacture of pestisides (insecticide).
Manufacture of plastic items such as rayon and nylon.
Manufacture of paints and dyes.
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Manufacture of Sulphuric Acid in Industry.
Sulphuric acid , H2SO4 , is manufactured in industry through the Contact Process. The manufacturing of sulphuric acid , H2SO4 , in industry involves three stage :-
The three stages involved in the Contact Process.
Stage Aim
Stage 1Sulphur dioxide , SO2 , gas can be produced by
burning sulphur in air.
S(s) + O2(g) SO2(g)Sulphur dioxide
To produce sulphur dioxide ,
SO2 , gas.
Stage 2
The gas mixture of sulphur dioxide , SO2 , and
oxygen , O2 , is passed over vanadium(V) oxide ,
V2O5 , (catalyst) at a temperature of 450-500oC and
under the pressure of 1 atmosphere.
2SO2(g) + O2(g) 2SO3(g)Sulphure trioxide
To produce sulphur trioxide ,
SO3 , gas.
Stage 3
Sulphur trioxide , SO3 , gas is dissolved in
concentrated sulphuric acid , H2SO4 , to form oleum ,
H2S2O7.
SO3(g) + H2SO4(l) H2S2O7(l)
Oleum
Water is then added to the oleum , H2S2O7 , to dilute
it to produce sulphuric acid , H2SO4.
H2S2O7(l) + H2O(l) 2H2SO4(l)Sulphuric acid
To produce sulphuric acid ,
H2SO4.
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Environmental pollution by sulphur dioxide.
1) Fossil fuels such as petrol and manufactured products of sulphuric acid , H2SO4 , contain sulphur , S.2) Burning of these products will oxidise sulphur , S , to form sulphur dioxide , SO2.
S(s) + O2(g) SO2(g)Sulphur dioxide
3) Sulphur dioxide , SO2 , is an acidic gas . When it dissolves in rainwater , it forms sulphurousacid , H2SO3 , and causes acid rain.
SO2(g) + H2O(l) H2SO3(aq)Sulphurous acid
4) Sulphur trioxide , SO3 , will also form when sulphur dioxide , SO2 , reacts with oxygen , O2 ,gas in air.
2SO2(g) + O2(g) 2SO3(g)Sulphure trioxide
5) When sulphur trioxide , SO3 , dissolves in rainwater , sulphuric acid , H2SO4 , is also formedcausing acid rain.
SO3(g) + H2O H2SO4(aq)Sulphuric acid
The effects of acid rain on the environment
Corrodes and destroys property such as bridges , buildings and statues.Reduces pH of soil and causes it to be unsuitable for plant life.Reduces Ph of water and causes the death of aquatic life.Destroys the beauty of the environment such as the collapse of limestone caves.
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MANUFACTURE OF AMMONIA AND ITS SALT.
Uses of ammonia , NH3 , in daily life are as follow :-
Properties of ammonia , NH3.
Uses of Ammonia :
Manufacture of nitrogenous fertiliser such as ammonia phosphate , (NH4)3PO4.
Manufacture of nitric acid , HNO3 , through the Ostwald process.
Manufacture of electrolytes in dry cells.
Manufacture of cleaning agents such as washing powder and detergents.
Manufacture of explosives such as trinitrotoluene (TNT).
Manufacture of dyes.
AMMONIA ,
NH3
Very
soluble in
water.Produces thick
white fumeswith hydrogen
chloride , HCl ,
gas.
Less
densethan air.
Pungent
smell
Hascharacteristics of
weak alkaliwhen dissolved
in water , H2O.
Colourles
s gas.
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Manufacture of ammonia
Ammonia , NH3 , is manufactured on a large scale in factories through the Haber process. In the haber process , nitrogen , N2 , and hydrogen , H2 , gas are mixed in the ratio of 1:3
volumes (moles).
N2(g) + 3H2(g) 2NH3(g)
The hydrogen , H2 , gas is obtained from methane CH4 , type of natural gas , while nitrogen ,N2 , gas is obtained from air by fractional distillation of liquefied air.
The gas mixture is passed over ion (catalyst)at a temperature of 450-550 oC and compressedunder a pressure of 200-500 atmosphere.
The ammonia , NH3 , gas obtained is cooled ( temperature of 50 oC ) to become liquidammonia , NH3(l).
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Synthesis of ammonia , NH3 , in industry.
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Flow chart of the Contact Process.
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Flow chart of production of ammonia , NH3 , through the Haber process.
Preparation of Ammonia fertilisers in the laboratory
Ammonia fertilisers are nitrogenous fertilisers that can provide nitrogen elements to plants. Examples of ammonia salts used as fertilisers are ammonia nitrate , NH4NO3 , ammonia
sulphate , (NH4)2SO4 and ammonia phosphate , (NH4)3PO4.
Ammonia , NH3 , dissolves in water to form ammonia solution , NH3(aq) , (aqueous ammoniaor ammonia hydroxide , NH4OH).
Neutralisation reaction between ammonia solution NH3(aq) , and acid solution producesammonia , NH4
+, salt which is used as fertiliser.
Production of ammonia fertilisers.
Neutralisation reaction Ammonia salt (fertiliser)
Ammonia solution + phosphoric acid Ammonia phosphate
Ammonia solution + nitric acid Ammonia nitrate
Ammonia solution + sulphuric acid Ammonia sulphate
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ALLOYS
An alloy is a compound formed from a mixture of metal and other elements. A foreign atom (impurity atom) may be atoms of other metals or non-metals such as carbon. The process of mixing atoms of impurities with atoms of pure metal by melting is called
alloying.
The aims of alloying are to :i. Increase the strength and hardness of the metal.
ii. Prevent corrosion of the metal.iii. Improve the appearance of the metal so that it is more attractive.
Arrangement of atoms in pure metal
1) Pure metal is soft and not very strong.2) Atoms of pure metals have similar size and shape and are arranged closely but there is still
space between the atoms.
3) When force is applied to pure metals , the atoms slide along one another easily.4) This property causes pure metal to be ductile , that is , it can be stretched into a wire.5) When knocked or hammered , metal atoms slide along one another to fill spaces between the
metal atoms.
6) This property causes pure metal pure metal to be malleable , that is , it can be knocked orpressed into various desired shapes.
Alloy Pure metal atom Main foreign atomSteel 99% Ion 1% Carbon
Stainless steel 74% Ion 18% Chromium,8% Carbon
Bronze 90% Copper 10% Tin
Brass 70% Copper 30% Zinc
Pewter 97% Tin 2% Copper,1% Antimony
Duralumin 93% Aluminium 3% Copper,3% Magnesium ,1% Manganese
Copper nickel 75% Copper 25% Nickel
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Arrangement of alloys1)impurity atoms which are mixed may be larger or smaller than atoms of pure metal.
2)Impurity atoms fill the empty spaces between the atoms in pure metal.
3)Impurity atoms can prevent the layers of metal atoms from sliding along one onother easily.
4)Due to this ,an alloy is harder and strong than pure metal.5)For example,stell is harder than iron.
Properties of alloys and their uses
The properties of alloy such as its strength,ability to withstand corrosion and its shiny appearance
cause it to be suitable to be made into various items for daily use.
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FINISH ,
THANK YOU
MANUFACTURE
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SUBTANCES IN
INDUSTRY