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CONCEPT MAP:

Contact process

Haber process

MANUFACTURED

SUBSTANCES IN

INDUSTRY

Sulphuric Acid

Detergents Paints Fertilisers

Ammonia

Uses

Ceramics

Glass

Composite

Materials

Type

Composition

Uses

Alloys Polymers

composition characteristics

Type Of Alloys

Synthetic

Polymers

Natural

Polymers

Uses

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Sulphuric Acids

Uses Of Sulphuric Acids

1. Sulphuric acid is one of the most importand industrial chemicals. About 140 million tones are manufactured in the world every year.

2. It is used in the world industries ranging from agriculture fertilizers to paints , soap and the cleaning of rust.

3. The main uses of sulphuric acid is in producing fertilizers, particularly “superphosphate” and ammonium sulphate. a) Superphosphate fertilizers:

It is manufactured from the reaction between sulphuric acid and calcium phosphate. 2H2SO4(l) + Ca3(PO4)2 (s) Ca(H2PO4)2 (l) + 2CaSO4 (s)

b) Ammonia sulphate fertilizer: It is manufactured by the reaction between sulphuric acid and ammonia. 2NH3 (aq) + H2SO4 (aq) (NH4)2SO4 (aq)

c) Potassium Sulphate: It is manufactured by the neutralisation of sulphuric acid and potassium hydroxide. 2KOH (aq) + H2SO4 (aq) K2SO4 (aq) + 2H2O (l)

4. Initially, sulphuric acid is produced by the reaction between sulphuric acid and hydrocarbon compounds.

5. Sulphonic acid then reacts with sodium hydroxide to form sodium alkyl sulphonate which is a detergent.

6. Accumulators need an electrolyte to carry charges ad to react with the positive need negative plates during the charging and discharging processes.

7. In the acid accumulator, sulphuric acid acts as the electrolyte.

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Uses of sulphuric acid

Example

Drying agent Concentrated sulphuric acid is generally used to dry gas in laboratory. However it is not suitable to dry alkaline gases such as ammonia.

Oxidising agent

Concentrated sulphuric Oxidises copper to form copper(II) sulphate. 2H2SO4 (l) + CU(s) CuSO4(aq) +2H2O(l) + SO2(g) However dilute sulphuric acid does not react with copper.

Dehydrating agent

When concentrated sulpuric acid is added to sugar, a violent reaction occurs.The water contain the sugar is extracted by the acid and the sugar become carbon. C6H12O6 (l) 6H2O(l) + 6C(s)

Strong acid It react with salt of the weak acid such as sodium ethanoate to form a weak acid. 2CH3COONa(s) + H2SO4(l) 2CH3COOH(aq) + Na2SO4(aq)

Manufactured Of Sulphuric Acid

1. Today sulphuric acid is made from sulphuric dioxide, by the contact process. There three stages for the production of sulphuric acid by the contact process.

Stage 1:

a) In the furnace, sulphur is burnt in dry air to produce sulphur dioxide. S(l) + O2(g) SO2(g)

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b) In the contact process, sulphur powder is sprayed inside a furnace at a temperature of

100◦ C. Here sulphur is converted to sulphur dioxide.

c) Sulphhur dioxide can also be produced by heating metal sulphides such as zink sulphide 2ZnS(s) + 3O2(g) 2ZnO(s) + 2SO2(g)

Stage 2:

a) Sulphur dioxide and air are passed over a catalyst called vanadium(v) oxide, (V2O5).

b) The temperature used here is about (450-500)◦C. If the temperature is less this range , the vanadium(V) oxide may not be able to catalyse.

c) The reacting pressure is about 2 to 3 atmosphere.

Stage 3:

a) The sulphur trioxide is dissolved in concentrated sulphuric acid to form a product called oleum , H2S2O7. This is carried out until the concentrated sulphuric acid reached a concentration of 99.5%. SO3(g) + H2SO4(aq) H2S2O7(l)

b) The product, oleum will not show any property of an acid. This because, Oluem will not ionise without the presence of water.

c) Water is then added to the oleum to produce concentrated sulphuric acid. H2S2O7(l) + H2O(l) H2SO4(aq)

d) The reaction (a) and (b) equivalent to dissolving sulphur trioxide in water. SO3(g) + H2O H2SO4(aq)

Sulphur Dioxide And Environmental Pollution

1. Sulphur dioxide is present to some extent in the natural unpolluted atmosphere. The sulphur dioxide sources are form: a) Bacterial decay of organic matter. b) Volcanic gases. c) Forest fires

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However, their concentrations are low and they are normally considered as non polluting

2. (a) Sulphur is found in coal and petroleum. When this fossil fuels burn they produce

sulphur dioxide. (b) When this gas is release to the atmosphere, they pollute the air. In fact the burning of

coal and oil is the major source of sulphur dioxide pollution in our environment (c) This gas considered as the most serious health hazard among the pollutant.

3. When SO2 desolving in water or rain , they form sulphurous acid H2SO3 4. Atmospheric SO2 can be oxidised to SO3 also. When SO3 dissolve in water it form

sulphuric acid H2SO4 . SO3(g) + H2O(l) H2SO4(aq) both type of acid will cause acid rain.

5. Acid rain are affects marin and forest ecology. In an acidic environment less fish will brred in polluted lake. More tress will die in the forest.

6. Sulphur dioxide is harmful to human health and property many of the environmental effect are actually due to the reaction of sulphuric and sulphurous acid.

7. Acid react with metal and carbonates. Thus, acid is corresive both to metal and to building material made of carbonates. For example, marble buildings and marble statures will be corroded by acid rain. This will make them less beautiful.

8. The release of SO2 gas to the atmosphere can be reduce by reacting gas with : a) Calcium carbonate

SO2(g) + CaCO3(s) CaSO3(s) + CO2(g) b) Calcium oxide

CaCO(S) + SO2(g) CaSO3 (S) 9. Some gases release from industries also contain sulphur dioxide. These gases are mainly

produced from the burning of fossil fuel.They are also produced during the manufacture of sulphuric acid.

Bad Effect of Acid Rain

1. Damage of marble structures a) The chemical compound in marble is calcium carbonate. b) The acid rain reacts with calcium carbonate to liberate carbon dioxide.

CaCO3(s) + 2H+(aq) Ca2+(aq) + CO2(g) + H2O(l) 2. Damage to metal structure:

a) All acid react with active metal such as alluminium, iron , and zinc. Fe(s) + 2H+(aq) + H2(g)

b) Therefore acids increase the rate of corrosion of metal stuructures.

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Reducing Acid Rain

1. Most acid causing acid rain are form: a) Sulphuric acid

This is formed when sulphur trioxide dissolves in water. SO3(g) + H2O(l) H2SO4(aq)

a) Sulphurous acid This is formed when sulphur dioxide dissolves in water. SO2(g) + H2O(l) H2SO3(aq)

b) Carbonic acid This is formed when carbon dioxide dissolves in water. CO2(g) + H2O(aq) H2CO3

2. A cheaper to reduce the sulphur dioxide is by directly react with calcium carbonate. CaCO3(s) +SO2(g) CaSO3(s) + CO2(g)

3. The calcium sulphite react with oxygen to form calcium sulphate. 2CaSO3(s) + O2(g) 2CaSO4(s)

4. Another chemical that can be used to react with sulphur dioxide is calcium oxide: CaO(s) + SO2(g) CaSO3(s) 2CaSO3(s) + O2(g) 2CaSO4(s)

Reducing the Acidity in the soil

1. The acidity in the soil can be reduced with the following chemicals. a) Calcium oxide

CaO(s) + 2H+(aq) Ca2+(aq) + H2O(l) b) Calcium hydroxide

Ca(OH)2(s) + 2H+(aq) Ca2+(aq) + 2H2O(l) c) Calcium carbonate

CaCO3(s) + 2H+(aq) Ca2+(aq) + H2O(l) + CO2(g)

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Ammonia And Its Salts

Uses Of Ammonia

1. Most of the ammonia produced are used to produce nitrogen fertilisers and nitric acid. 2. Ammonia is used to produce nitric acid as shown in the following series of reaction.

4NH3(g) + 5O2(g) Platinum/rhodium 4NO(g) + 6H2O(g)

2NO(g) + O2(g) catalyst 850◦ 2NO2(g) 4NO2(g) + 2H2O(l) + O2(g) 4HNO3(aq)

3. Ammonia is an alkaline solution. It dissolves grease. Thus it used in the manufacture of household cleaning agent.

4. Ammonia is important refrigerator in the refrigerator. 5. Ammonia is also used to make explosive chemicals such as TNT. This explosive is

produced when ammonia reacts with toluene. 6. In the industry ammonia is used to prevent coagulate in latex. 7. Ammonia is widely used in the manufacture of fertilizer.

Property Of Ammonia

Physical Property

1. Ammonia, NH3 is colourless and pungent gas 2. It less dense than air. 3. It highly soluble in water.

NH3(g) + H2O(l) NH4 OH(aq) 4. Ammonia melt at -77.7○C and boils at -33.35○C .

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5. Its density is 0.68

Chemical Property

1. Ammonia dissolve in water to given an alkaline solution with a pH value of 9-10 2. It turns moist red litmus paper blue. 3. Ammonia is an alkali it will neutralize acid to make ammonia salts.

NH3(g) + H2SO4(aq) (NH4)2SO4(aq) 4. Gaseous ammonia react with gaseous hydrogen chloride to form white fume of ammonia

chloride. 5. When ammonia chloride heated it change back to ammonia and hydrogen chloride. 6. Ammonia dissolve water to form ammonium hydroxide. Ammonium hydroxide NH4OH,

is strongly basic. It has similar chemical properties as compared to other hydroxides of alkali metals.

7. Ammonia react with metallic ions (except Na+, K+, and Ca2+) to form metallic hydroxides. F3+(aq) + 3NH3(aq) + 3H2O(l) Fe(OH)3 (aq) + 3NH4

+(aq) <brown precipitate> Mg(OH)2(aq) + 2NH3(aq) + 2H2O(l) Mg(OH)2(aq) + 2NH4

+ (aq) <white precipitate>

Using Catalyst To Oxidise Ammonia

1. The concentrated ammonia releases ammonia gas 2. With the help of platinum catalyst, ammonia gas burn in the presence of oxygen. Here the

ammonia is oxidize by the oxygen to give nitrogen monoxide. 4NH3(g) + 5O2(g) 4NO(g) + 6H2O(g)

3. The nitrogen monoxide reacts with oxygen again to give a brownish gas called nitrogen dioxide 2NO(g) + O2(g) 2NO2(g)

4. The nitrogen dioxide dissolves in water to form nitric acid and nitrous acid 2NO2(g) + H2O(l) HNO3(aq) + HNO2(aq) this series of reaction is used to prepare nitric acid.

Decomposition Of Ammonia

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1. When the ammonia gas is passed over heated iron wool, some of the gas decomposes into the elements nitrogen and hydrogen. 2NH3(g) N2(g) + 3H2(g)

2. This process actually is the reverse of Haber process.

Manufacture Of Ammonia ( Haber Process)

1. Ammonia is made by sysnthesis through Haber process. 2. Nitrogen and hydrogen are combined directly together to form ammonia. 3. To supply the Haber process,

a) Nitrogen gas can be distilled from liquid air . b) Hydrogen is produced by electrolyzing brine

4. Nitrogen and hydrogen can also be obtained from natural gas (methane) a) Methane is heated with steam over catalyst of nickel at a high pressure.

CH4(g) + H2O(g) CO(g) + 3H2(g) b) Carbon monoxide and hydrogen are mixed with air and again heated at high pressure

over nickel acting as catalyst. Some of the hydrogen reacts with the oxygen in the air and leaves behind nitrogen. [CO + H2 ]

N2/O2 H2O + N2 + CO The steam H2O and carbon monoxide are removed leaving just the nitrogen and hydrogen.

5. These two gases are then mixed under 300 atmosphere of pressure and at a temperature between 450 – 500○C

6. This hot high pressure mixture then fed into the reaction chamber containing an iron catalyst.

7. The iron catalyst speed up the reaction. 8. The temperature, pressure and catalyst help to produce as much ammonia as possible. 9. The gases from the reaction chanber are passed over the catalyst several time so as to

enable more nitrogen and hydrogen to combine to form ammonia. 10. The gaseous ammonia is quickly cooled below the boiling point of ammonia. At this low

temperature ammonia gas condenses as a liquid and is collected and stored. 11. Unconverted nitrogen and hydrogen gas are recycled through the reaction chamber.

Calculation Of Percentage Of Nitrogen In Fertiliser

1. Different fertilizer contains different percentages of nitrogen.

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2. The % of nitrogen content can be calculated by using the following formula.

% � �Mass of nitrogen

Molecular mass of fertiliser

Alloys

Meaning Of Alloy

1. Alloys are materials that contain more than one elements. 2. Usually alloys are mixtures of metallic elements 3. Pure aluminium is light but not strong enough to make aeroplane bodies. If a small

amount of manganese and magnesium are added then an alloy duralumin is formed. This alloy is hard and strong for aeroplane frame.

4. Thus an alloy is mixture of metals made for a certain purpose.

Arrangement of Atoms in Metals

1. In pure metals the atom are all of the same size. 2. When the pure metals are hit with a hammer the layer of atom can slide over each other

easily. 3. Thus, pure metal can easily change it shape. They are said to be:

a) Ductile as they can be drawn into long wires. b) Malleable as they can be hammered to form any shape.

Arrangement Of Atom In Alloys

1. Alloys have more than kind of atoms. These different atoms are of different size. 2. The layers of atoms of an alloy cannot slide over each other as easily. 3. The movements of atom get jammed up. This make them difficult to move. 4. This make alloy not ductile and malleable.

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5. However, alloy are harder and stronger than the original constituent metals. 6. There are different ways of arranging the different atom alloys

a) Solution alloys are homogenous alloys in which the different atoms are distributed uniformly throughout.

b) In heterogeneous alloys, the different atoms are not distributed uniformly. 7. Homogeneous alloys have definite properties and compositions.

Aim Of Producing Alloys

1. The basic aim of making alloys is to modify the properties of the pure metal elements. Sometimes this necessary to make ornaments.

2. Pure gold are too soft to be used in the jewellery. However , an alloys of copper and gold is quite hard of this purpose.

3. To prevent or minimize corrosion. 4. To improve the physical appearance.

Composition, Properties and uses of alloys

1. like metals, all alloys are conductors of: a) heat b) electricity

2. like metals too, all alloys have shining surfaces. They have a lustrous appearance. However most alloy are more shinny than pure metal if they kept for a long time.

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Synthetic Polymers

Meaning Of Polymers

1. most of the covalent molecules we have studied are small molecule. 2. However, some molecules are very big. They are called macromolecules. 3. Some macromolecules are formed when a large number of small molecules join together

to form a longer or bigger molecules. The small molecules are called monomers. 4. The big molecules formed are called polymers. Thus we define a polymers as the

following: Polymers are large molecules made up of identical repeating sub-units of monomers which are joined together by covalent bonds.

5. The process of forming polymers is called polymerization. 6. If the molecules simply join together then this type of polymerisation is called additional

polymerisation 7. There are two main group of polymers.

a) Man-made polymers or synthetic polymers b) Natural polymers.

Natural Polymers

1. Rubber is an example of a natural polymer. 2. All these substances are large molecules made from smaller molecules that are joined

together. Thus, fat, carbohydrates and proteins are natural polymers.

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Natural Rubber Polymer

1. Natural rubber are natural polymer 2. Its monomer is called isoprene. 3. The joining of “n” molecules of isoprene will form the natural rubber polymer (C5H8)n.

The numerical values of “n” could be a few millions.

Fat Polymer

1. A molecules of fat is made by the combination of a glycerol molecule with carboxylic acid molecules.

2. The carboxylic acid may be of the same type or different types. For example, two molecules of stearic acid and one molecule of oleic acid have combined with one molecule of glycerol to give one molecule of fat.

3. The glycerol part of the molecule form a bridge across the three carboxylic acid parts. 4. Other type of fat molecules may have structures with different carboxylic acid molecules.

Carbohydrate Polymers

1. Carbohydrate are polymers made up of small sugar molecules joined together. 2. Starch and cellulose are two types of carbohydrate polymers. In both cases the monomer

is glucose C6H12O6. 3. When the glucose monomer join together, they will form a polymer starch chain.

Protein Polymers

1. Protein polymer made up from monomer called amino acids. 2. They are many types of amino acids, but only twenty-four of them are found in nature. 3. These naturally occurring amino acids are used to make proteins. 4. The simplest amino acid is glycine H2N-CH2-COOH. 5. When the glycine and alanine join together they form a dipeptide protein.

Synthetic Polymer

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1. Synthetic polymer are widely use today. 2. Example of synthetic polymer are polythene, Perspex, polyvinyl chloride (PVC), and

nylon.

Synthetic Rubber

1. There are two main types of synthetic rubber: a) SBR rubber or styrene-butadiene b) Neoprene

2. SBR rubber or styrene-butadiene a) This rubber is made by combining one part of styrene (IUPAC name: buta1,3-diena) b) This type of polymerization is called copolymerization. c) This polymer was developed during World War II and is used mainly to make tyres.

3. Neoprene a) This rubber is made from monomer called chloroprene. b) Its IUPAC name is 2-chloro-1,3-butadiena c) The term diena means that this molecule contains two double bonds. d) When these molecules polymerise they form the synthetic rubber polymer called

neoprene. e) This type of polymerization is called additional polymerisation.

Importance Of Polymers

1. Polymer products play a very important part in our life. In fact, thousands of products we use are made from polymer.

2. They are used in making household object such as toys,casing etc. Most textile materials are mixture of synthetic fibres and natural fibres.

3. In fact, polymers have replaced many natural materials for several reasons. a) They are relatively cheap b) They are strong c) They last for a long time d) Easy to be moulded or shaped

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Environmental Pollution From Synthetic Polymers

1. Land pollution a) The properties of polymers that make them useful causes problems. For example,

polymers are cheap. Thus, it often cheaper to throw away a polymer plate or cup then to wash one to be used again.

b) As a result, there is an increase in the volume of polymer rubbish everyday. c) Most polymer plastic do not react easily with other chemical compounds. d) This problem of polymer rubbish can be reduced if synthetic polymers are mixed with

material that can be disintegrate.

Air Pollution

1. Burning plastics causes air pollution. When PVC is burnt, it gives off corrosive acidic hydrogen chloride gas and poisonous chlorine gas. These two gases will produce acid rain

2. Plastic material contain carbon. When they are burnt, poisonous gases such as carbon monoxide are produced.

3. Some plastic materials contain carbon and nitrogen. When they are burnt, highly poisonous gas such as hydrogen cyanide is given off to the air.

Green House Effect

1. This “green House effect “ can be contributed by the carbon dioxide gas given off during burning of polymer rubbish.

2. The layer of carbon dioxide in the atmosphere reduces the amount of heat that can be radiated to outer space. Here the carbon dioxide acts as a heat trap.

3. This increase the temperature of the earth.

Reducing Pollution Of Plastic

1. Recycling plastics

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a) If you look at the bottom of a plastic container , you are likely to see a recycle symbol b) Recycling can create new product from disposed plastics. For example, bottles,

synthetic clothing and parts for new cars can be made from discarded plastics. c) A pile of empty soda bottles can be turned into synthetic wood. d) By recycling, we can help to minimize environmental pollution due to the disposal of

synthetic polymers. 2. Using biodegradable plastis

a) By mixing plastics with biodegradable materials, plastic can be decomposed like any other organic rubbish.

Glass And Ceramics

Glass

1. Sand mixed with limestone can be melted into a thick liquid. 2. When sand is heated to about 1600○C, it flows like a thick liquid. 3. If this liquid cools, it forms a clear, solid material with no crystal structure. This solid

called glass 4. Glass maker add limestone and sodium carbonate to the melting sand. The mixture melts

at a lower temperature than pure sand alone. This type of glass is used to make bottles, jars and window pane.

5. If lead oxide is used to replace limestone, then the glass is able to bend light in useful ways. This kinds of glass is used to make eye glasses, microscopes and telescopes lenses.

6. If boron oxide is added, the glass is able to resist heat better than ordinary glass. This type of glass is used to make cooking pots and laboratory glassware.

7. Coloured glass is made by adding various metals. For example: a) Selenium and gold will produce red glass b) Cobalt makes beautiful, dark blue glass.

Special Uses Of Glass

1. Optical fibres for communication a) Light shinning at one end of a glass fibre , will continue to travel

Through the glass fibre to the other end. b) The effect is similar to electrons that travel through a copper wire. c) A pair of optical fibres each with the thickness of a human hair, can carry 625000

phone calls at one time.

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d) Unlike copper wire, glass does not corrode. Therefore, communication by using optical fibres are also clear

Photochromic Glass

1. Photochromic glasses are glasses that darken in response to very bright light. 2. This type of glass of glass is made by adding tiny silver chloride crystals into molten

glass. 3. The silver chloride crystal are trapped in the glass structure, as the glass solidifies. Some

silver bromide and copper(II) chloride are added too. 4. Silver chloride and silver bromide have the property of darkening when light passes

through them. This happens when light dissociates the silver chloride or silver bromide into silver. 2AgCl(s) 2Ag(s) + Cl2(g) 2AgBr(s) 2Ag(s) + Br2(g)

5. If the light intensity decreases then the silver chloride will restore back to original colour.

Conducting Glass

1. Glass is not a conductor of electric. However, it will conduct electricity if it is coated with a film of conducting materials.

2. This conducting film can be made of indium stannum(IV) oxide 3. This type of glass is called ITO glass and is commonly used in LCD display panels.

General Properties Of Glass

1. Glass can be transparent or translucent. 2. They can refract light

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3. They are: a) Hard b) Brittle c) Non reactive to chemicals d) Good heat insulator e) Good electric insulators

4. Glass is easy to clean 5. They are not porous. 6. The colour of glass can be changed by adding coloured oxides of metals. Additional of

a) Iron(II) oxides will colour the glass green b) Copper(II) oxide and cobalt oxide will colour it blue. c) Colloidal gold will colour it a red colour.

7. Crystals glass has a high refractive index. They are very suitable to make lenses and prisms.

Ceramics

1. Ceramics are made from clays, such as kaolin. It contain silicates such as aluminium silicates.

2. Ceramic are hardened by heating them at high temperature. 3. Like glass, the main component of ceramics are based on silicates. 4. Glass can be melted and remelted as often as it is desired. However, once a ceramic has

been hardened, it is resistant to extreme temperature.

Composition Of Ceramics

1. The main composition of kaolin is aluminosilicate (Al 2O3.2SiO2.2H2O) 2. This compound contains aluminium, silicon and oxygen. 3. Silicone is added into kaolin to harden it during the process of making porcelain.

General Uses Of Ceramic

1. Ceramic has been used for thousand of years to: a) Store food b) Protect food from moisture.

2. Ceramic are used to make:

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a) Roofing tiles b) Bricks c) Sewer pipes

3. Ceramic are used as insulator in light fixtures and in electric equipment such as plugs and lamp holders.

4. Ceramic tiles are the only materials that can withstand the temperature of over 1600○C. thus they are used: a) As heat insulating tiles to protect space shuttle. b) To line the wall of furnace or oven.

General Properties Of Ceramics

1. Ceramics have the following properties: a) Hard and strong b) Brittle c) Cannot be compressed d) Easily crack when the temperature change too quickly e) Resist moisture f) Do not conduct electricity g) Do not conduct heat h) Resist to action by chemical

2. The strength of ceramic is due to the bonds between the element in it.

Modified Properties Of ceramics

1. Some specialized ceramics can be made to conduct electricity. They are cilicon carbide SiC and aluminium carbide Al3C3.

2. Some ceramics are made to function as semiconductors. They are used in microchips.

New Uses Of Ceramics

1. Superconductor a) This type of conductor has almost no resistance .thus, superconductor will not lose

energy while conducting electricity. b) This conductor is called perovskite

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c) It contain the mixture of yttrium oxide, barium oxide and copper(II) oxide. d) Ceramic superconductor can be used to make lighter but stronger magnets than

conventional magnets. 2. Engine block

a) Additional of magnesium oxide into ceramics can be used to make engine blocks that can withstand very high temperatures.

b) In this type of engine, the fuel can burn at higher temperature. This increases the efficiency of engines.

Uses Of Composite Material

Meaning Of Composite Material

1. Every substance has its advantages and disadvanges. 2. If we can take the best properties of two substances and then put them together, we

produce a composite material that is better than the two original materials. 3. Thus by combining the useful properties of two or more material , chemists can produce a

new better material called a composite material. 4. Composite materials are made up of high-strength fibres could be form:

a) Glass b) Graphic c) Ceramics

5. These fibres are usually held together by thermosetting plastics. 6. The fibres provide the support. The surrounding plastic acts to protect the fibres from

breaking. 7. The most commonly used composite materials are polyester resins reinforced with glass

fibres.

The Needs For New Materials

1. Most of the material used today have their own weakness. Example :

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a) Iron is a good material to use in construction industry. However iron rust easily. b) Common plastics are long lasting. However, most of them melt or soften if heated.

2. New materials are needed today to supply the high demand for the new industries. 3. With the knowledge of science on materials, chemists are able to produce new composite

material for general and specific needs of technology development.

Natural Composite Material

1. Wood is made of long fibres of cellulose. 2. These fibres are held together by another plant polymer called lignin. 3. a) cellulose fibres are flexible. It cannot support tree branches.

b) lignin is brittle and would crack under the weight of tree branches c) But a combination of cellulose and lignin make a tree branch strong.

Justify the use Of Composite Material

1. Engines a) With the shortage and high cost of fuel, car and jet engines have to operate with

maximum fuel efficiency. This type of engines needs to perform efficiently at high temperature.

b) Thus, ceramics, might be a better material for these engines because ceramics can withstand very high temperature.

c) However ceramic are brittle. They tend to break rather than bend. This limits their usefulness.

2. The new organoceramics can also be used to produce: a) Superconducting wire b) Microelectronic devices.

3. In future, these organoceramics can be developed to build prothestic devices such as artificial bones.

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Appreciating Synthetic Materials

Handling Synthetic Materials And Their Wastes

1. We should grateful to scientists who use their ideas and creativity to develop new materials.

2. Sources of materials are limited in this world. We should use them carefully so as not to waste them.

3. Many of the synthetic materials are non biodegradable. We should minimize their use or make them biodegradable.

4. Many of the used synthetic materials are inflammable and give out toxic gases when burnt. We should find a safe way to dispose them.

5. We should be responsible in using new products invented. This includes finding a suitable way to dispose of their waste product. This is because new materials can cause environmental pollution.

The Importance Of Doing Research And Development Continuously

1. The understanding of the interaction among materials enables various new materials to be developed

2. We need new materials to improve the quality of human life. 3. Development of new materials requires us to do research and development continuously.

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Justify The Importance Of Synthetic Materials In Daily Life

1. Society’s need increase from day to day. Our present needs are more complex as compared to the old days. Thus, it is important for us to do research and development continuously.

2. Research and development that are carried out can create new materials and products for us to use.