chemistry folio
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Chemistry Chapter 2 Form 5TRANSCRIPT
Manufacture of sulphuric acid
o Contact process produces more than 90% of the world sulphuric acid.
o Raw materials used for the manufacture of sulphuric acid :- (i) sulphur
(ii) air
(iii) water.
o Contact process consists of 3 stages:
~ Production of sulphur dioxide
~ Conversion of sulphur dioxide is sulphur trioxide.
~ Production of sulphuric acid
Stage I: Production of sulphur dioxide
(a)Sulphur is burnt in air to produce sulphur dioxide.
S(s) + O2(g) SO2(g)
(b)Burning of metal sulphides such as zinc sulphide and lead sulphide also produces sulphur dioxide.
2ZnS(s) + 3O2(g) 2SO2(g) + 2ZnO(s)
2PbS(s) + 3O2(g) 2SO2(g) + 2PbO(s)
(c)The sulphur dioxide is then mixed with excess air.The mixture is dried and purified to remove impurities such as arsenic compounds.
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(d)Arsenic compounds found in sulphur will poison the catalyst in the converter, making the catalyst ineffective.
Stage II: Conversion of sulphur dioxide to sulphur trioxide
(a)The mixture of sulphur dioxide and excess oxygen is passed through a converter.The sulphur dioxide is oxidised to sulphur trioxide.
2SO2(g) + O2(g) 2SO3(g)
(b)Optimum conditions used are as follows.
(i) Temperature : 450°C
(ii) Pressure : 1 atmosphere
(iii) Catalyst : Vanadium(V) oxide,V2O5
(c)About 97% conversion occurs under these optimum conditions.
Stage III : Production of sulphuric acid(a) The sulphur trioxide is first dissolved in concentrated sulphuric acid to form a product
called oleum, H2S2O7
SO3(g) + H2SO4(aq) H2S2O7(l)
(b) Sulphur trioxide is not dissolved in water to form sulphuric acid.This is because reaction between sulphur trioxide and water is very vigorous and produces a large amount of heat.The reaction causes the production of a large cloud of sulphuric acid mist.The mist is corrosive, pollutes the air and is difficult to condense.
(c) The oleum is then diluted with water to produce concentrated sulphuric acid of about 98%.
H2S2O7(l) + H2O(l) 2H2SO4(aq)
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Flow chart of Contact process.
burns in air
O2V2O5,450°C, 1 atm
concentrated H2SO4
water
water
Figure 1 : The manufacture of sulphuric acid through the Contact process
4 Sulphuric acid, H2SO4
Oleum, H2S2O7
Sulphur trioxide, SO3
Sulphur
Sulphur dioxide, SO2
Sulphuric acid, H2SO4
Oleum,H2S2O7
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Properties of
sulphuric acid
Chemical Formula:H2SO4 Molar
mass 98 g mol-1
Melting point 10oC
Boiling
point 340oC
Diprotic acid
Density 1.83g cm-3Soluble
in water
Dense
Viscous colourless
liquid
Non-volatile
acid
Highly corrosive
Oilyliquid
Uses of sulphuric acid
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Sulphuric acid is used as:
to manufacture
fertilisers
to manufacture
paint pigment
to manufacture detergents
to manufacture synthetic fibre
to clean metals
to manufacture plastics
as an electrolyte in car batteries
to manufacture other chemicals
There are many fertilizers that can be made of sulphuric acid. Some of them are:
a) Calcium hydrogen phosphate (superphosphate)
b) Ammonium sulphate
c) Potassium sulphate
1) To manufacture paint pigments
The white pigment in paint is usually barium sulphate, BaSO4. The neutralization of sulphuric acid and barium hydroxide produces barium sulphate.
2) To manufacture detergents
Sulphuric acid reacts with by-products of oil refining to form sulphonic acid. Neutralising the sulphonic acid with an alkali produces detergents.
3) To manufacture synthetic fibres
Synthetic fibres are polymers ( long chain molecules). Rayon is an example of a synthetic fibre that is produced by the reaction of sulphuric acid eith cellulose threads soaked in alkaline solution.
4) Cleaning metals
Before electroplating,sulphuric acid is used for cleaning metals to remove the surface oxides.
5) Other chemicals
Sulphuric acid is used as other chemicals like pharmaceuticals,insectides, tartaric acid and explosive.
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2 H2S O 4(aq) + Ca3(PO4) 2(s) → Ca(H2 PO4) 2 (aq)+ 2CaSO4 (s)
sulphuric acid + tricalcium phosphate → calcium hydrogen phosphate
H2S O 4(aq) +2NH3(aq) → (NH4) 2SO4(aq)
sulphuric acid + aqueous ammonia → ammonium sulphate
H2S O 4(aq) +2KOH (aq) → K2SO4(aq) + 2H2O(l)
sulphuric acid + potassium hydroxide solution→ Potassium sulphate
H2S O 4(aq) + Ba(OH)2 (aq) → BaSO4(s) + 2H2O(l)
sulphuric acid + barium hydroxide solution→ Barium sulphate + water
6) The uses of sulphuric acid in school laboratories are:
a. As a strong acid
b. As a drying or dehydrating agent
c. As an oxidizing agent
d. As a sulphonating agent
e. As a catalyst
Figure 2 : Uses of sulphuric acid
Sulphur dioxide and environmental pollution
1) Sulphur dioxide is released through:-
(a) Burning of sulphur during Contact process(b) Extraction of some metals from their sulphides ores(c) Burning of coals or fuels with high sulphur content
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Metallurgy Fertilisers Paint pigmentDetergents Synthetic Fibre PlasticsElectrolytes
2) Acid rain occurs when there is sulphurous acid,sulphuric acid and nitric acid in the rain. These strong acids will cause the pH of rain to fall between 2.4 and 5.0
3) Sulphur dioxide accounts for most of the acid rain problems. (a) When sulphur dioxide dissolves in rainwater,sulphurous acid is formed SO2(g) + H2O (l) H2SO3(aq) (b) Sulphur dioxide can react with oxygen and water to form sulphuric acid 2SO2(g) + O2(g) + 2H2O(l) 2H2SO4(aq)
Ways to control and reduce the effects of acid rain: Use low-sulphur fuels Add calcium oxide(lime), CaO; calcium hydroxide,Ca(OH)2 and powdered llimestone CaCO3 into the acidic lake or river to neutralize the acids present
CaO(s) + 2H (aq) Ca (aq) +H2O(l) Ca(OH)2(s) + 2H (aq) Ca (aq) + 2H2O(l) CaCO3(s) + 2H (aq) Ca (aq) + CO2(g) + H2O(l)
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Environmental problems cause by acid rain
corrodes buildings,monuments and statues
calcium carbonate in the marble reacts with H2SO4 from the rain to form calcium sulphate. CaCO3(s) + H2SO4(aq) CaSO4(s) + CO2(g) + H2O(l)
corrodes metallic structure
The iron from the steel bridges reacts with sulphuric acid to form iron(II) sulphate. Fe(s) + H2SO4(aq) FeSO4(aq) + H2(g)
increase the acidity of water
Acid rain disturbs the ecosystem Fish and other aquatic organisms which cannot live in acidic water may die.
increase the acidity of the soil
plants cannot grow well in acidic soil reaction of sulphuric acid with aluminium compounds in the soil forms aluminium sulphate which
can damage the roots of trees.
leaches minerals and nutrients in the soil. acid react with minerals in the soil to form double salts. dissolved salts carried by the rainwater to river. plants lack of essential nutrients for growth.
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Manufacture of ammonia in industry
Ammonia is manufactured in industries through Haber process.
Raw materials for the Haber process are (i)hydrogen (ii)nitrogen
Nitrogen gas is obtained from the fractional distillation of liquid air.
Hydrogen gas is obtained by: (i)Reaction between methane from natural gas and steam CH4(g) + 2H2O(l) 4H2(g) + CO2(g) (ii)The reaction between heated coke and steam C(s) + H2O(l) H2(g) + CO(g)
Diagram Show The Haber Process
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The manufacture of ammonia through the Haber Process .
Nitrogen and hydrogen are mixed according to the ratio 1 mole N2 : 3 moles H2.
The mixture is compressed to 200 atm and heated to a temperature of about 450°C
The mixture is then passed through layers of heated iron catalyst in a reactor.Ammonia is produced.
N2(g) + 3H2(g) 2NH3(g) The reaction is reversible and the production of ammonia gives out heat.The high pressure and iron catalyst speed up the rate of reaction.
The ammonia gas produced is liquefied ans separated to get a better yield.
The unreacted nitrogen and hydrogen are recycled and passed back into the reactor together with the new source of nitrogen and hydrogen.About 98% of nitrogen and hydrogen are converted into ammonia.
Ammonium fertilisers
Plants need nutrients like nitrogen, phosphorus, potassium and calcium to grow.
Nitrogen-make proteins in stalks and leaves
Nitrogen is absorbed by plants in the form of soluble nitrate ions, NO3-
Ammonium fertilisers contain ammonium ions.In the soil, the ammonium ions are converted to nitrate ions by bacteria
Examples of ammonium fertilisers:
(a) Ammonium nitrate, NH4NO3
(b) Ammonium sulphate, (NH4)2SO4
(c) Ammonium phosphate, (NH4)2HPO4
(d) Urea,CO(NH2)2
Fertilisers that contain a high percentage of nitrogen are more effective.
Ammonium fertilisers can be prepared by reactions between ammonia solution and acids.
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Properties of ammonia
Chemical reaction of ammonia:(a) Reacting as a base
Ammonia ionises partially in water and therefore is a weak base. NH3(g) + H2O(l) NH4 (aq) + OH (aq)
Ammonia undergoes neutralisation with acids to form ammonium salts. Ammonia + acid ammonium salt
(b) Reacting with aqueous metal ions
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Physical properties
of ammonia
colourless gas
pungent smell
less dense
than air
very soluble in
water
alkaline gas
Ammonia solution can precipitate some metal hydroxides from their aqueous salt solutions.The metal ions combine with the hydroxide ions from aqueous ammonia to produce insoluble metal hydroxides : Mn (aq) + nOH (aq) M(OH)n(s)
Uses of ammonia To make fertilisers
- provide plants the nitrogen they need to grow- these fertilisers are ammonium salts obtained from the neutralization of ammonia with
different acids. Examples:(a) Ammonium phosphate
- reaction of ammonia with phosphoric acid produces ammonium phosphates NH3(aq) + H3PO(aq) NH4H2PO4(aq)2 NH3(aq) + H3PO(aq) (NH4)2HPO4(aq)- good fertilisers because they provide two important nutrients,phosphorus and nitrogen.
(b) Ammonium nitrate- ammonia is neutralised by nitric acid,ammonium nitrate is formed
NH3(aq) + HNO3(aq) NH4NO3(aq)
(c) Ammonium sulphate- ammonia is neutralised by sulphuric acid 2NH3(aq) + H2SO4(aq) (NH4)2SO4(aq)
(d) Urea- At a temperature of 200°C and a high pressure of 200 atm, ammonia reacts with carbon dioxide to produce urea. 2NH3(g) + CO2(g) CO(NH2)2(s) + H2O(l)
- used as a raw material for the manufacture of nitric acid in the Ostwad process.- Liquid ammonia used as cooling agent- used as an alkali to prevent the coagulation of latex- Ammonia salts is used as smelling salts to revive people who have fainted
Preparation of ammonia
-The chief commercial method of producing ammonia is by the Haber-Bosch process, which involves the direct reaction of elemental hydrogen and elemental nitrogen.N2 + 3H2 → 2NH3 This reaction requires the use of a catalyst, high pressure (100–1,000 atmospheres), and elevated temperature (400–550 °C [750–1020 °F]). Actually, the equilibrium between the elements and ammonia favours the formation of ammonia at low temperature, but high temperature is required to achieve a satisfactory rate of ammonia formation. Several different catalysts can be utilized. Normally the catalyst is iron containing iron oxide. However, both magnesium oxide on
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aluminum oxide that has been activated by alkali metal oxides and ruthenium on carbon have been employed as catalysts. In the laboratory, ammonia is best synthesized by the hydrolysis of a metal nitride.Mg3N2 + 6H2O → 2NH3 + 3Mg(OH)2
Alloys
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Arrangement of atoms in metalsPure metals
Pure metal is made up of one type of atoms,thus all atoms are of the same size.In solid state ,the atoms in a pure metal are orderly arranged and closely packed together.Thus,pure metals have high densities.
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Physical properties
of pure metals
High density
High melting & boiling points
Good conductors of heat and electricityMalleable
Ductile
Although the forces of attraction between the metal atoms are strong,they are not rigid.Therefore when a force is applied,the layers of atoms can slide over one another.Thus metals are ductile or can be stretched.
Force
Layers of atoms slide over one another
Figure 3 : Metals are ductile
The arrangement of atoms in pure metals are not perfect.There are some empty spaces in between the atoms.When a metal is knocked or pressed,groups of atoms may slide and then settle into new position.So,metals are malleable.
Force
Figure 4 : Metals are malleable
Pure metals are weak and soft due to their ductility and malleability
What are alloys? An alloy is a mixture of two or more elements with a certain fixed composition in which the
major component is a metal.
Pure metals are normally soft and easily oxidised.This is the reason why monuments or statues are made of bronze(an alloy) and not copper(a pure metal).
Alloy are stronger,harder,resistant to corrosion,have a better finish and lustrous.
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Why make alloys?
The aim of making alloy is:
(a) to increase the strength and hardness of a pure metal(b) to increase the resistance to corrosion of a pure metal(c) to improve the appearance of a pure metal
Figure 5 : Making alloy
Composition, properties and uses of alloys
Alloy Composition Properties UsesBronze 90% copper,
10% tinHard,strong,does not corrode easily,shiny surface
Medals,statues,monuments,art objects
Brass 70% copper30% zinc
Harder than copper Musical instruments,kitchenware, door knobs,bullet cases,electric parts,ornaments
Cupro-nickel 75% copper25% nickel
Beautifulsurface,shiny,hard,does not corrode easily
Coins
Steel 99% iron1% carbon
Hard,strong Buildings,bridges,body of cars, railway tracks
Stainless steel 74% iron,8% carbon18%chronium
Shiny,strong,does not rust Cutlery,surgical instruments,sinks,pipes
Duralumin 93%aluminium3% copper3%magnesium1%manganese
Light,strong Body of aircraft and bullet trains
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Pewter 96% tin3% copper1% antimony
Shiny, strong,does not corrode
Art objects,souvenirs
9-carat gold 37.5% gold11% silver51.5 % copper
Shiny, strong,does not corrode
Jewellery
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What are polymers?
Polymers are large long-chain molecules formed by joining together many identical repeating sub-units called monomers.
Polymerisation is a process by which the monomers are joined together into chain-like molecule called polymer.
Formation of polymer
Polymers can be divided into 2 types.
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Polymers
Natural PolymersExist in living things in natureEx:Protein,cellulose,wool,silk, starch,natural rubber & DNA
Synthetic PolymersThey are man-made in laboratory through chemical processes.Ex: Plastics, nylon
Natural Polymers
NATURAL POLYMER MONOMERRubber Isoprene
Cellulose GlucoseStarch GlucoseProtein Amino acid
Fat Fatty acid and glycerolNucleic acid Nucleotides
Examples of natural polymers and their monomers
i) Natural polymers and their uses
NATURAL POLYMER USERubber Tyres, eraser, condom, electric insulation, elastic bands
and belts.Cellulose Paper, textiles, pharmaceuticals, and explosivesStarch To stiffen cloth (as in laundering), used in cooking to
thicken foods, manufactured of adhesives, paper, textiles and as a mold in the manufacture of sweets.
Protein Essential in the diet of animals for the growth and repair of tissue,
Fat Maintaining healthy skin and hair, insulating body organs against shock, promoting healthy cell function and serve as energy stores for the body
Synthetic Polymer
Synthetic polymers are prepared through 2 types of polymerisation processes: (a)Addition polymerisation (b)Condensation polymerisation
Addition polymerisation- involves monomers with double bonds between the carbon atoms.
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- During addition polymerisation, the double bonds between pairs of carbon atoms break and the carbon atoms pf adjacent ethene molecules join together to form a molecule of poly or polythene.
Condensation polymerisation- involves the joining up of monomers with the formation of other smaller and simple
molecules.
Plastics
Plastics are the largest group of synthethic polymers with the following properties: (a)Can be easily moulded (b)Low density (c)Strong (d)Inert to chemicals (e)Insulator of heat and electricity (f)Can be coloured
Name of polymer Equation for polymerisation
Properties Uses
Polyethylene(polythene)
H H H H n C=C C–C H H H H n Ethene Polythene
Durable,light,impermeable,Inert to chemicals,easily melted,insulator
Shopping bags,Plastic cups and plates,toys
Polypropylene(polypropene)
H CH3 H CH3
n C=C C–C H H H H nPropene Polypropene
Durable,light,impermeable,Inert to chemicals,easily melted,insulator,can be moulded and coloured
Bottles,furniture,battery casing, pipes,toys
Teflon F F F F n C=C C–C F F F F nTetrafluo- Teflonroethene
Durable,non-stick,Chemically inert,strong,impermeable
Coating for non-stick pans, electrical insulators
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Synthetic fibre
Synthetic fibre are long-chain polymers which are not easily stretched and have high strength.
Polynamides and polyester are two groups of synthetic polymers used as fibres for making tekstil.
Example of polynamide polymers is nylon.
Example of polyester polymers is terylene.
Nylon and terylene are produced through condensation polymerization
TYPE OF POLYMER USEPolythene a) Make buckets
b) Make plastic bagsc) Make raincoatsd) Make filmse) Make rubbish bins
Polyvinyl chloride (PVC) a) Make water pipesb) Make electric cablesc) Make matsd) Make vinyl recordse) Make clothes hangers
Polypropene a) Make ropesb) Make bottlesc) Make chairsd) Make drink canse) Make carpets
Perspex a) Make car windowsb) Make plane windowsc) Make spectacle lenses (optical instruments)
Nylon a) Make ropesb) Make curtainsc) Make stockingsd) Make clothes
Polystyrene a) Make packing boxesb) Make buttonsc) Make noticeboards
Terylene a) Make textile items such as clothes and cloths
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Disposal of synthetic polymers has caused environmental pollution problems:
(a) Synthetic polymers are not easily biodegradable,thus their waste will block or clog up the drainage system,thereby causing flash flood.
(b) Waste plastics pollute the lake and river,making the water not suitable for aquatic organisms to live in
Ways to solve the problems caused by the use of synthetic polymers:(a) Reuse(b) Recycle(c) Use biodegradable synthetic polymer(d) Dispose of unwanted synthetic polymers in a proper manner.
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Glass The major component of glass is silica or silicon dioxide,SiO2 which can be found in sand.
Glass can made by heating a mixture of silicon dioxide and metal carbonates to a temperature above 1500°C.
Figure 6 : Structure of silicon dioxide
Type of glass Composition Properties UsesFused glass Silicon dioxide High melting
point High temperature
and chemical durability
Resistant to thermal shock
transparent to ultraviolet and infrared light
Laboratory glassware
Arc tubes in lamps
Lenses Telescope mirrors Optical fibres
Soda-lime glass silicon dioxide Sodium oxide Calcium oxide
Low melting point
High thermal expansion coefficient
Does not withstand heat
Cracks easily with sudden change in temperature
Good chemical durability
Easy to mould and shape
Transparent to visible light
Containers such as bottles,jars.
Flat glass Windowpanes Mirrors Light bulbs Industrial and art
objects.
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Borosilicate glass Silicon dioxide Boron oxide Sodium oxide Calcium oxide
Transparent to visible light
resistant to chemicals
Lower thermal expansion coefficient
Resistant to thermal shock
Can withstand wide range of temperature changes
Cookware Laboratory
glassware Automobile
headlights glass pipelines Electrical tubes
Lead crystal glass Silicon dioxide Lead(II) oxide Sodium oxide
Soft,easy to melt Transparent to
visible light High density High reactive
index
Tableware Art objects Crystals Prisms Lenses
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Ceramics
Ceramics are made from clay such as kaolin.Kaolin is rich in kaolinite(hydrated aluminosilicate,Al2O3.2SiO2.2H2O)
Examples of ceramics are bricks,tile,mugs and clay pots.
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Properties of
ceramics
Very hard and strong
Brittle
Chemically inert and does
not corrode
Good insulator of
electricity and heat
Very high melting point
Resist compression
Property Uses ExamplesHard and strong Building materials Tiles,bricks,roofs,cement,
abrasive for grindingAttractive,easily moulded and glazed
Decorative pieces and household items
Vases,porcelain ware,sinks, bathtubs
Chemically inert and non-corrosive
Kitchenware Cooking pots,plates,bowls
Very high melting point and good insulator of heat
Insulation Lining of furnace, engine parts
Electrical insulators Insulating parts in electrical appliances
Spark plugs,insulators in ovens and electrical cables
Inert and non-compressible Medical and dental apparatus Artificial teeth and bones
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Common properties
of glass and ceramics
Hard and do not bend
strong under compression
Brittle
Good electrical insulators
Good heat insulators
Inert to chemicals
Do not corrode
3 main differences between glass and ceramic: Glass can be heated until molten repeatedly but not ceramics Glass is usually transparent whereas ceramics are not Glass has a lower melting point than ceramics.
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A composite material is a structural material that is formed by combining two or more different materials such as metals,alloys,glass,ceramics and polymers.
Some common composite materials are:a. Reinforced concreteb. Superconductorc. Fibre opticd. Fibre glasse. Photochromic glass
Reinforced concrete
Reinforced concrete is formed when concrete is reinforced with steel wire netting or steel rods.
Essential for the construction of large structures like high-rise buildings,bridges and oil platforms.
Has a greater strength than ordinary concrete and has higher resistance to impact.
Superconductors
capable of conducting electricity without any electrical resistance when they are cooled to an extremely low temperature.
most of them are alloys of metal compounds or ceramics of metal oxides
Superconductors also used in :(a) magnetic energy-storage system(b) magnetically levitated train(c) generators(d) transformers(e) computer parts(f) very sensitive devices for measuring magnetic fields, voltage or current.
Fibre Optic
consists of a bundle of glass or plastic threads that are surrounded by a glass cladding.
used to replace copper wire in long distance telephones lines,in mobile phones,video cameras and to link computers within local area networks.
used in instruments for examining internal parts of the body or inspecting the interior of manufactured structural products.
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Fibre glass
produced when glass fibres are embedded in plastic resins to produce glass fibre reinforced plastics.
has high tensile strength,can be easily coloured,moulded and shaped,inert to chemicals and is low in density.
Photochromic glass
changes from transparent to coloured when it is exposed to ultraviolet light, and reverts to transparency when the light is dimmed or blocked.
can be produced by embedding photochromic substances like fine silver chloride.
photochromic glass helps to:(a) protect our eyes from harmful ultraviolet rays and glare from the sun(b) control the amount of light that passes through it automatically(c) reduce refraction of light
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Sulphuric AcidManufactured by Contact processTemperature:450°CPressure: 1 atmCatalyst : V2O5
Uses:To make fertilizers,detergents,electrolyte, and synthetic fibre
Synthetic PolymerManufactured by polymerization.Examples and uses:Polyethylene:Shopping bagsPolyvinyl chloride:Pipespolystyrene:Packaging materialsPerspex:LensesNylon:Ropes,textile
AmmoniaManufactured by Haber processTemperature:450°CPressure: 200 atmCatalyst : FeUses:To make fertilizers,nitric acid,cooling agent, explosives
Manufactured Substances in Industry
GlassMade from sand,SiO2
Types & uses:Fused glass:LensesSoda-lime glass:mirrorBorosilicate glass:BeakerLead crystal glass: Glass crystals
Composite materialsMade by combining two or more materials.Examples:Reinforce concreteSuperconductorsFibre opticFibreglassPhotochromic glass
AlloysMade from metal and other elements.Examples and composition:Bronze:Copper & tinBrass:Copper & zincSteel:Iron & carbonPewter:Tin,Copper & AntimonyStainless Steel: Iron,carbon & chronium
CeramicMade from clay,kaolinite,Al2O3.2SiO2.2H2OProperties and uses:Hard & strong:Tiles, bricksAttractive:vases,sinksNon-corrosive:KitchenwareHigh melting point: FurnaceInert: Medical & dental apparatus
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First of all,I would like to thank the God for giving me blessings to complete this folio just in time.Even I faced a lot of difficulties when doing this project,I managed to overcome it by the God’s blessing .
Then, thanks to my chemistry teacher Puan Noorlida AB Kadir for being such a good guider while doing this project.She had given us appropriate information about this project in order to make us understand more about this project.
Also a great thanks to my friends and family members who tried their best to give their support for me, either by giving me a lot of encouragement while doing this project or helping me to gather the data required for the project.
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Eng Nguan Hong,Lim Eng Wah,Lim Yean Ching., 2009. Focus Ace SPM Chemistry., Penerbitan Pelnagi Sdn. Bhd., (page 261 – 287)
http://www.ravensdown.co.nz/Resources/Education/Properties+of+Sulphuric+Acid.htm
http://www.britannica.com/EBchecked/topic/20940/ammonia/277712/Preparation-of- ammonia
http://en.wikipedia.org/wiki/Glass
http://www.tutorvista.com/content/chemistry/chemistry-ii/metals/metalsindex.php
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