INTRODUCTIONIn retrospect, the definition of chemistry seems to invariably change per decade, as new discoveries and theories add to the functionality of the science. Shown below are some of the standard definitions used by various noted chemists:

Alchemy (330) – the study of the composition of waters, movement, growth, embodying and disembodying, drawing the spirits from bodies and bonding the spirits within bodies (Zosimos).Chymistry (1661) – the subject of the material principles of mixture bodies (Boyle).

Chymistry (1663) – a scientific art, by which one learns to dissolve bodies, and draw from them the different substances on their composition, and how to unite them again, and exalt them to an higher perfection (Glaser).

Chemistry (1730) – the art of resolving mixture, compound, or aggregate bodies into their principles; and of composing such bodies from those principles (Stahl).

Chemistry (1837) – the science concerned with the laws and effects of molecular forces (Dumas).

Chemistry (1947) – the science of substances: their structure, their properties, and the reactions that change them into other substances (Pauling).

Chemistry (1998) – the study of matter and the changes it undergoes (Chang).

In the study of matter, chemistry also investigates its interactions with energy and itself. Because of the diversity of matter, which is mostly composed of different combinations of atoms, chemists often study how atoms of different chemical elements interact to form molecules and how molecules interact with each other.

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FORM 4

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(H4SO4) USES OF SULPHURIC ACID

1. Sulphuric acid is used to produce chemical fertilizer such as ammonium sulphate and potassium sulphate, which are highly soluble in water and can be easily absorbed by plant.

2. Car batteries contain sulphuric acid which is used as the electrolyte.3. Sulphuric acid also used in the making of artificial silk-like fibers and rayon.4. Chemical like paints, dyes and drug use sulphuric acid as one of their component materials.

MANUFACTURE OF SULPHURIC ACID

1. Sulphuric acid is manufactured in industry though contact process 2. The process contain three stage

STAGE 1: Production Of Sulphur Dioxide From Sulphur

i. Combustion of sulphur or sulphide ores in the air produce sulphur dioxide SO2.S(s)+O2(g)SO2(g)

sulphur

ii. sulphur dioxide is dried and purified.

STAGE 2: Production Of Sulphur Trioxide From Sulphur Dioxide

i. The purified sulphur dioxide SO2 and excess air are passed over vanadium (V) oxide V2O5 at controlled optimum condition optimum condition to produce sulphur trioxide SO3.

2SO2(g)+O2(g) 2SO3(g)

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ii. The optimum used area) Temperature:450-500°Cb) Pressure: 2-3 atmospheres c) Catalyst: Vanadium(V) oxide

iii. Under controlled optimum conditions, 98% conversion is possible. Sulphur dioxide and oxygen that have not reacted are allowed to flow back again over the catalyst in the converter.

STAGE 3: Conversion of trioxide to sulphuric acid

i. Sulphur trioxide SO2 is dissolved in concentrated sulphuric acid H2SO4 to form oleum H2S2O7 which is then diluted with water to form sulphuric acid H2SO4.

SO3(g)+H2SO4(l)H2S2O7(l)

Oleum

H2S2O7(l)+ H2O(l)2H2SO4(aq)

ii. The two reactions in stage3 are equivalent to adding sulphur trioxide directly into water.

SO3(g)+H2O(l)H2SO4(aq)

iii. The addition of sulphur trioxide directly into is not carried out because the reaction is very vigorous; a lot of heat is given off. As a result, a large cloud of sulphuric acid fumes is produced, which is corrosive and causes severe air pollution.

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The Contact Process

In the converter

SULPHUR DIOXIDE AND ENVIRONMENTAL POLLUTION

1. Sulphur dioxide is one of the by-products of contact process. It is a colourless and poisonous gas with a very pungent smell.

2. Sulphur dioxide which escapes into the air causes air pollution.3. Sulphur dioxide is an acidic which dissolves in water to form sulphurous acidic, H2SO3. In the

atmosphere, sulphur dioxide dissolve in water droplets to form sulphurous acidic.

SO2 (g) + H2O (l) H2SO3 (aq)

4. Oxidation of sulphur acid by oxygen produces sulphuric acid, H2SO4, which falls to the earth as acid rain. Sulphur trioxide is also easily oxidised in the air to form sulphur trioxide. Sulphur trioxide dissolve in rainwater to produce sulphuric acid.

SO3 (g) + H2O (l) H2SO4 (aq)

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Sulphur Oxygen

S(s) + O2 (g)SO2(g)

SO2 (g) + H2SO4 (aq) H2S2O7 (l)

H2S2O7 (l) + H2O (l) 2H2SO4 (aq)

2SO (g) + O2 (g) 2SO3 (g)

Temperature: 450-500°C

Pressure: 2-3 atmospheres

Catalyst: Vanadium (V) oxideOxyge

Unreacted

2%SO2 is

flowed back

Outline of Contact process

Acid rain and environmental pollution

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(NH3) USES OF AMMONIA

1. Ammonia that is produce commercially has many uses.2. It uses:

i. In the manufacture of chemical fertilizers such as ammonium sulphate, ammonia nitric, ammonia phosphate and urea.

ii. To manufacture nitric acid and explosive.iii. In the making of synthetic fiber and nylon.iv. As a degreasing agent in aqueous form to remove greasy stains in the kitchen.

PROPERTIES OF AMMONIA GAS1. The physical properties of ammonia gas include the following:

i. It colourless and has a pungent odour.ii. It is vary soluble in water and form a weak alkaline solution.

iii. It less dense then water.iv. It easily liquefied (at about 35.5°C) when cool.

2. The chemical properties of ammonia gas:a) Ammonia gas dissolves in water to form a weak alkali.

NH3 (g) + H2O (l) NH4+ (aq) + OH-(aq)

b) The presence of hydroxide icon causes the aqueous solution to become alkaline. Thus aqueous ammonia solution:

i. Turns red litmus paper blue.ii. Reacts with acid to form only salt and waterin neutralization reaction.

NH3(aq) + HCI(aq) NH4CI(aq)

2NH3 + H2SO4(aq) (NH4)2SO4(aq)

iii. Reacts with solution of metallic cations to produce precipitates.

Fe²+(aq) + 2OH(aq) Fe (OH)2(s)

(Form ammonia solution) Dirty green precipitate

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MANUFACTURE OF AMMONIA IN INDUSTRY

1. Ammonia is manufacture on a large scale in industry through the Haber process. In this process, ammonia is formed form direct combination of nitrogen and hydrogen gas in the volume ratio 1:3.

2. The gas nitrogen obtain form the fractional distillation of liquefied air. The hydrogen gas is obtained from the cracking of petroleum or from the catalysed reaction of natural gas, CH4, with steam.

CH4 (g) + H2O (g) CO (g) + 3H2 (g)

3. The mixture of nitrogen and hydrogen gases is passed over an iron catalyst under controlled optimum condition as below to form ammonia gas.

i. Temperature: 450-500°Cii. Pressure: 200-500 atmospheres

iii. Catalyst used: Iron fillings

N2 (g) + 3H2 (g) 2NH3 (g)

4. Under these control optimum condition, only 15% of the gas mixture turn into ammonia gas. The nitrogen and hydrogen that have not reacted are then flow back over the catalyst again in the reactor chamber.

5. The ammonia product is then cooled at a low temperature so that it condenses into a liquid in the cooling chamber.

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Nitrogen Hydrogen

In the reactor chamber

The Haber process

AMMONIUM FERTILIZERS1. Nitrogen is required in large amount by plant to make proteins which are necessary for growth

and cell repair.2. Most plant are not able to get a nitrogen supply directly from the air although it is abundant in

the air (78%). Plants can only absorb soluble nitrogen compounds from soil through their roots.3. The nitrogen compounds are usually soluble nitric salt, ammonia and ammonia salt which are

manufacture as chemical fertilizer.4. Reactions of ammonia with acids produce ammonium fertilizers.

NH3(aq) + HNO3(aq) NH4NO3(aq)

Ammonium nitrate

3NH3(aq) + H3PO4(aq) (NH4)3PO4(aq)

Ammonium phosphate

2NH3(aq) +H2SO4(aq) (NH4)2SO4(aq)

Ammonium sulphate

ARRANGEMENT OF ATOMS IN MATELS1. The atom of pure metals is packed together closely. This causes the metal to have a high density

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N2 and H2 are mixed in the proportion of 1:3N2(g) + 3H2(g) 2NH3(g)

Temperature: 450-500°C

Pressure: 200-500 atmospheres

Catalyst used: Iron fillings

Liquid ammonia

In cooling chamber

Unreacted N2 and H2 gases

Outline Of Habert process

2. The forces of attraction between atoms (metallic bonds) are strong. More heat energy is needed to overcome the metallic bond so that the atoms are further apart during the melting. This is why metals usually have high melting point.

3. Heat energy can be transferred easily from one atom to the next by vibration. This makes metal good conduct of heat.

4. The freely moving outermost electrons within the metal’s structure are able to conduct electricity. Metal are, therefore, good electrical conductors.

5. Since atoms of pure metal are of the same size, they are arranged orderly in a regular layered pattern. When a force is applied to metal, layer of atom slide easily over one another. This makes pure metals soft, malleable and ductile.

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Force

Layer of atom slide

Metals are ductile

Force

The shape of the metal change

Matel are malleable

WHAT ARE ALLOYS1. Pure metal are usually too soft for most uses. They also have a low resistance to corrosion. They

rush and tarnish easily.2. To improve the physical properties of metal, a small amount of another element (usually metal) is

added to form another an alloy. 3. An alloy is a mixture of two or more metals (something non-metal) in a specific proportion. For

example:a. Bronze (90% of copper and 10% of tin)b. Steel (99% of iron and 1% of carbon)

4. The purposes of making alloys include the following:a) Increase the strength

i. Pure iron is soft and vary malleable. When a small amount of carbon is added to iron, an alloy, steal is formed. The more carbon is added, the stronger the steel becomes.

ii. Pure aluminium is light but not strong. With a small amount of copper and magnesium are added to aluminium, a strong, light and durable alloy call duralumin is produced.

b) Improving the resistance to corrosioni. Iron rust easily but stainless steel which contains 80.6% of iron, 0.4% of carbon, 18% of

chromium and 1% of nickel does not rush. These properties make stainless steel suitable for making surgical instrument and cutlery.

ii. Pure copper tarnish easily. When zinc (30%) is added, the yellow alloy which is known as brass develops a high resistance to corrosion.

c) Enhancing the appearancei. Pewter, an alloy of tin (97%), antimony and copper is not only hard but also has a more

beautiful white silvery appearance.ii. When copper is mixed with nickel to form cupronickel, an alloy that has an attractive silvery,

bright appearance is formed which is suitable for making coins.

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Alloy Composition Properties UsesHigh carbon steel 99% iron

1% carbonStrong,hard and high

wear resistance Making of cutting

tools, hammers and chisels

Stainless steel 80.6% iron0.4% carbon

18%chromium1% nickel

Do not rust and tarnish, strong and durable

Making of surgical instrument, knives forks and spoons

Brass 70% copper30% zinc

Hard, do not rust, bright appearance

Making of ornaments, electrical wiring and plug.

Bronze 90% copper10% tin

Hard, do not corrode easily and durable

For casting bells, medals, swords and statues

Pewter 90% tin2.5% copper

0.5% antimony

Ductile and malleable, white silvery appearance

Making of ornaments, souvenirs and mugs

Duralumin 95% aluminium4% copper

1%magnesium

Light, strong and durable Making part of aircrafts and racing cars

Cupronickel 75%copper25%nickel

Attractive, silvery appearance, hard and

tough

Making of silver coins

Composition, properties and uses of alloys

The formation of alloy

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WHAT ARE POLYMER1. Molecule that consist of a large number of small identical or similar units joined together repeatedly

are called polymer.2. The smaller molecules that make up the repeating unit in polymer are caller monomer.3. The process of joining together a large number of monomers to form a long chain polymer is called

polymerisation.4. Polymer can be naturally occurring or man-made (synthetic). Natural polymer is found in plant and

in animals for example of natural polymers are starch cellulose, protein and rubber.5. Two type of polymerisation in producing synthetic polymer are additional polymerisation.6. Double bonds between two carbon atoms usually undergo addition polymerisation.

Some Common Addition Polymers

Name(s) Formula Monomer Properties Uses

Polyethylenelow density (LDPE)

–(CH2-CH2)n–ethyleneCH2=CH2

soft, waxy solidfilm wrap, plastic bags

Polyethylenehigh density (HDPE)

–(CH2-CH2)n–ethyleneCH2=CH2

rigid, translucent solidelectrical insulationbottles, toys

Polypropylene(PP) different grades

–[CH2-CH(CH3)]n–

propyleneCH2=CHCH3

atactic: soft, elastic solidisotactic: hard, strong solid

similar to LDPEcarpet, upholstery

Poly(vinyl chloride)(PVC)

–(CH2-CHCl)n–vinyl chlorideCH2=CHCl

strong rigid solidpipes, siding, flooring

Poly(vinylidene chloride)(Saran A)

–(CH2-CCl2)n–vinylidene chlorideCH2=CCl2

dense, high-melting solid

seat covers, films

Polystyrene(PS)

–[CH2-CH(C6H5)]n–

styreneCH2=CHC6H5

hard, rigid, clear solidsoluble in organic solvents

toys, cabinetspackaging (foamed)

Polyacrylonitrile(PAN, Orlon, Acrilan)

–(CH2-CHCN)n– acrylonitrileCH2=CHCN

high-melting solidsoluble in organic

rugs, blanketsclothing

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solvents

Polytetrafluoroethylene(PTFE, Teflon)

–(CF2-CF2)n–tetrafluoroethyleneCF2=CF2

resistant, smooth solidnon-stick surfaceselectrical insulation

Poly(methyl methacrylate)(PMMA, Lucite, Plexiglas)

–[CH2-C(CH3)CO2CH3]n–

methyl methacrylateCH2=C(CH3)CO2CH3

hard, transparent solidlighting covers, signsskylights

Poly(vinyl acetate)(PVAc)

–(CH2-CHOCOCH3)n–

vinyl acetateCH2=CHOCOCH3

soft, sticky solidlatex paints, adhesives

cis-Polyisoprenenatural rubber

–[CH2-CH=C(CH3)-CH2]n–

isopreneCH2=CH-C(CH3)=CH2

soft, sticky solidrequires vulcanizationfor practical use

Polychloroprene (cis + trans)(Neoprene)

–[CH2-CH=CCl-CH2]n–

chloropreneCH2=CH-CCl=CH2

tough, rubbery solidsynthetic rubberoil resistant

Uses of synthetic polymers

SYNTHETIC POLYMERS IN DAILY LIFE1. Synthetic polymers have many advantages over other type of materials:

a. They are cheap, light-weight and translucent.b. They are easily coloured, easily moulded and shaped.c. They are non-corrosive, waterproof and good insulator.d. They are durable and long lasting because they are resistant to decay, rusting and chemical

attacks.2. There are disadvantage using synthetic polymer:

a. Most of the synthetic polymer is flammable. When a synthetic polymer material catches fire, poisonous fumes are produce causing air pollution.

b. Synthetic polymers are non-biodegradable. When there are discharges, they cause litter problem and pollute the environment.

c. Plastic containers that are left aside in an open area collect rainwater which becomes the breeding ground for mosquitoes.

d. There are limitation in recycle have to be separated out as the addition of non-recyclable polymers in the mixture affect the properties of the recycled polymers.

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WHAT ARE GLASS1. Glass is one of the most useful but inexpensive materials in the world. Many products are made

from glass because of its specials properties.2. Glass is:

a. Transparent, hard but brittle.b. A heat and electric insulator.c. Resistant to corrosion.d. Chemical not reaction and therefore resistant to chemical attack.e. Easy to maintain.

Type of glass Composition Properties UsesFused glass SiO2: 100% Transparent

High melting point Good heat insulator

Lens Telescope mirrors Laboratory apparatus

Soda-lime glass SiO2: 75%Na2O:15%CaO: 9%Other:1%

Low melting point, easily molded into desired shape and size

Low resistant to chemical attacks

Brittle

Drinking glass, bottles Electric bulbs Window glass

Borosilicate glass SiO2: 78%B2O3: 12%Na2O: 5%CaO: 3%Al2O3:2%

Resistant chemical attack and durable

High melting point Good insulator to heat

Cooking utensils Laboratory glassware

such as conical flaks and boiling tube

Lead crystal glass (flint glass)

SiO2: 70%Pbo/PbO2:20%

Na2O: 10%

High refractive index High density Attractive glittering

appearance

Lenses and prisms Decorative glassware

and art object Imation jewellery

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CERAMICS

1. Traditional silicate ceramics are made by heating aluminosilicate clay such as kaolin to a very high temperature.

2. Ceramics have many special properties that make them one of the most useful materials in our everyday life. That:

a. Are hard, strong but brittleb. Have high melting point and remain stable at high temperature c. Are heat and electric instrumentd. Are resistant to corrosion and weare. Are chemically not reactivef. Do not readily deform under stress

3. Ceramic play important role in our daily life. They are uses as a. Construction materials

i. Ceramic are strong and hard, uses to make roof tiles, bricks cement, sinks, and toilet bowls.ii. They are also used to make refractory bricks because high resistant to heat.

b. Decorative itemsi. To make pottery, china plates, and porcelain vases since they do not tarnish easily and are

durable.ii. They are used to make bathroom fixture such as floor and wall tiles.

c. Electrical insulatori. Ceramic are used to make electrical insulator in electrical items such as toasters, fridges and

electrical plug.

Materials Melting point/ °C Density/G cm-3 Elastic modulus/ GPa

Hardness/ mohs

Oxide ceramicAlumina,AL2O3

Beryllia, BeOZirconia, ZiO

205425742710

3.973.015.68

380370210

988

Non-oxide ceramicsBoron carbide,B4C3

Silicon nitride, Si3, n4

23502830

1900

2.503.16

3.17

280400

310

99

9MetalsAluminiumSteel

6601515

2.707.86

70205

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WHAT ARE COMPOSITE MATERIALS1. A composite material (or composite) is a structure of materials that is formed by two or more

different substances such as metal, glass, ceramic and polymer.2. Some common composite materials are:

a. Reinforces concreteb. Superconductorc. Fiber opticd. Fiber glasse. Photo chromic glass

REINFORCES CONCRETE

1. Concrete is hard, fireproof, waterproof, comparatively cheap and easy to maintain. It is more important construction materials.

2. The reinforce is a combination of concrete and steel.

SUPERCONDUCTOR

1. Metal such as copper and aluminium are good conductor of electricity, but 20% of the electric energy is lost in the form of heat during transmission.

2. Super conductor is materials that have no resistance to the flow of electricity at a particular temperature. Hence, 100% electricity transmission is possible.

3. One of the most dramatic properties of a superconductor is its ability to levitate a magnet. Superconductor are used to build magnetically levitate high-speed train (at about 552 km/h).

4. Superconductors are used to make chips for smaller and faster supercomputer. Superconductor also plays an important role in high speed data processing in internet communication.

FIBRE OPTIC

1. Fiber optic is a composite material that in used to transmit signals for light wave.2. Fiber optic is used in

a. Telecommunicate where the telephone substation are liked by fiber optic cables.b. Domestic cable television networkc. Closed circuit television security system.

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3. Fiber optic also used in medical fields. It is used in a number of instruments which enable the investigation for internal body part without having to perform surgery.

FIBRE GLASS

1. Fiber glass is glass in the form of fine threads. Molten gas is dropped onto a refractory rating disc when the glass flies off the disc glass to form fiber.

2. Fiber glass is strong than steel, do not burnt, stretch or rot, resistant to fire and water but is brittle.3. When fiber glass added to a plastic, a new composite material fiber glass reinforces plastic is formed.4. Fiber glass reinforces plastic has more superior properties than glass and plastic. It is

a. Extremely strongb. Light weighc. Resistant to fire and waterd. Can be molded, shaped and twisted

PHOTOCHROMIC GLASS

1. When 0.01 to 0.1% of silver chloride (a type of photo chromic substances) and a small amount of copper (II) chloride are added to molten silicon dioxide, photo chromic glass is formed.

2. The photo chromic glass has special properties. It darkens when exposed to strong sunlight or ultraviolet.

3. Photo chromic glass is suitable for making sunglasses.

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