Chemistry Form 4

Chapter 9 :

Manufactured substances in industry

NUR FARHANA BT HASSAN

4 ALPHA

SM SAINS SABAH

9.1 Manufacture of sulphuric acid

9.1.1 Properties of sulphuric acid

1. Sulphuric acid is a strong mineral acid.

2. Its molecular formula is H2S O 4.

3. It is soluble in water.

4. Sulphuric acid is a non-volatile diprotic acid.

5. It is a highly corrosive, dense and oily liquid.

Concentrated sulphuric acid is a viscous colourless liquid

Properties of sulphuric acid

Non-volatile

acid

Diprotic acid

Soluble in water

Highly corrosive

Oily

liquid

Viscous colourless

liquid

Dense

9.1.2 The uses of sulphuric acid

1) To manufacture fertilizers

There are many fertilizers that can be made of sulphuric acid. Some of them are:

a) Calcium dihydrogen phosphate (superphosphate)

b) Ammonium sulphate

c) Potassium sulphate

2) To manufacture soaps and detergents.

3) To manufacture synthetic fibres ( nylon and rayon )

4) To manufacture paint pigments.

5) As an electrolyte in lead-acid accumulators.

6) To manufacture pesticides.

7) The uses of sulphuric acid in school laboratories are as a strong acid, drying or

dehydrating agent, as an oxidizing agent, as a sulphonating agent and catalyst.

2 H2S O 4 + Ca3(PO4) 2 → Ca(H2 PO4) 2 + 2CaSO4

sulphuric acid + tricalcium phosphate → calcium dihydrogen phosphate

H2S O 4 +2NH3 → (NH4) 2SO4

sulphuric acid + aqueous ammonia → ammonium sulphate

H2S O 4 +2NH3 → (NH4) 2SO4

sulphuric acid + aqueous ammonia → ammonium sulphate

9.1.3 Manufacture of sulphuric acid in industry

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

STAGE1: Production Of Sulphur Dioxide From Sulphur

i. Combustion of sulphur or sulphide ores in the air produce sulphur dioxide SO2.

S + O2 → SO2

ii. sulphur dioxide is dried and purified.

STAGE2: 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.

H2SO4+ SO3 → H2S2O7

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

STAGE3: 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 + H2SO4 → H2S2O7

H2S2O7+ H2O → 2 H2SO4

Figure 9.1 Flow chart of the Contact Process.

9.1.4 Environmental pollution by sulphur dioxide.

1. Sulphur dioxide is one of the by-product of contact process. It is a colourless and poisonous

gas with a vary pungent smell.

2. Sulphur dioxide which escape 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 produce 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)

Figure 9.2 Acid rain and environmental pollution.

Sources of Sulphur Dioxide

The principal source of SO2 is from the combustion of fossil fuels in domestic premises

and , more importantly, non-nuclear power stations.

Fossil fuel burning power stations account for around two thirds of total SO2 emissions in

the UK.

Other industrial processes contribute a further 20%, with vehicles, primarily diesel,

accounting for a mere 2%.

Health effects

SO2 is an irritant when it is inhaled and at high concentrations (over 1000ppb) may cause

severe problems in asthmatics such as narrowing of the airways, known as

bronchoconstriction.

Asthmatics are considerably more sensitive to the effects of SO2 than other individuals

and an effect on lung function may be experienced at levels as low as 200ppb.

Acid rain can cause many effects such as:

i. Corrodes concrete buildings and metal structure

ii. Destroys trees and plants

iii. Decrease the pH of th soil and make it become acidic

iv. Acid rain flows into the rivers and increases the acidity of water and kill aquatic living

things.

Hence, we must reduce the sulphur dioxide from the atmosphere by:

i. Use low sulphur fuels to reduce the emission of sulphur dioxide in exhaust gases

ii. Remove sulphur dioxide from waste air by treating it with calcium carbonated before it

is released.

9.2 Manufacture of ammonia and its salt.

9.2.1 Uses of ammonia

1. Ammonia that is produce commercially has many uses such as :

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 fibre and nylon.

iv. Manufacture of electrolytes in dry cells.

v. As a degreasing agent in aqueous form to remove greasy stains in the kitchen.

9.2.2 Properties of ammonia

1. Very soluble in water.

2. Produces thick white fumes with hydrogen chloride, HCL gas.

3. Less dense than air.

4. Have characteristics of weak alkali when dissolved in water.

5. Pungent smell.

6. Colorless gas.

9.2.3 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 form 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.

4. Temperature: 450-500°C

5. Pressure: 200-500 atmospheres

6. Catalyst used: Iron fillings

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

7. 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.

8. The ammonia product is then cooled at a low temperature so that it condenses into a liquid

in the cooling chamber.

Figure 9.3 The Haber process

Figure 9.4 Flow chart of Haber process.

9.2.4 Preparation of ammonium fertilizers in laboratory

1 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 phospate

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

9.3 Alloys

9.3.1 Arrangement of atoms in pure metal

Nitrogen Hydrogen

N2 and H2 are mixed in the proportion of 1:3

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

Temperature: 450-500°C

Pressure: 200-500 atmospheres

Liquid ammonia

In cooling chamber

Unreacted N2 and H2 gases

In the reactor chamber

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 cause 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 to be malleable that is it can be knocked or passed into

various desired shapes.

Metals are ductile.

Metals are malleable.

9.3.2 Alloy

1. An alloy is a compound formed from a mixture of metal and other elements.

Force

Layer of atom slide

Force

The shape of the metal change

2. An impurity atom (foreign atom) may be atoms of other metals or non-metals such as

carbon.

3. The process of mixing atoms of impurities with atoms of pure metal by melting is called

alloying.

4. The aims of alloying are to increase the strength and hardness of the metal, prevent

corrosion of the metal, improve the appearance of the metal to be more attractive.

Alloy Composition Properties Uses

High carbon steel 99% iron

1% carbon

Strong,hard and high wear resistance

Making of cutting tools, hammers and chisels

Stainless steel 80.6% iron

0.4% carbon,

18%chromium,

1% nickel

Do not rust and tarnish, strong and durable

Making of surgical instrument, knives forks and spoons

Brass 70% copper

30% zinc

Hard, do not rust, bright appearance

Making of ornaments, electrical wiring and plug.

Bronze 90% copper

10% tin

Hard, do not corrode easily and durable

For casting bells, medals, swords and statues

Pewter 90% tin

2.5% copper, 0.5% antimony

Ductile and malleable, white silvery appearance

Making of ornaments, souvenirs and mugs

Duralumin 95% aluminium

4% copper, 1%magnesium

Light, strong and durable

Making part of aircrafts and racing cars

Cupronickel 75%copper

25%nickel

Attractive, silvery appearance, hard and

tough

Making of silver coins

9.3.3 Arrangement of atoms in alloys

1. 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 metals from sliding along one another easily.

4. Due to this, an alloy is harder and stronger than pure metal.

5. For example, steel is harder than iron.

9.4 Synthetic polymers and their uses

9.4.1 Polymer

1. Polymers are long chain of molecules made from combination of many small molecules.

2. Small molecules that combine to form polymers are called monomers.

3. Polymerization is a process of combining monomers to form a long chain of molecules.

4. Polymers can be divided into two types: natural polymer & synthetic polymer.

9.4.2 Natural polymer

1. A natural polymer is a polymer that occurs naturally.

2. Natural polymers are normally made by living organisms.

NATURAL POLYMER MONOMER (small molecules)

Rubber Isoprene

Cellulose Glucose

Starch Glucose

Protein Amino acid

Fat Fatty acid and glycerol

Nucleic acid Nucleotides

9.4.3 Synthetic polymers

Synthetic polymers are man-made polymers that are produced from chemical compunds through

polymerisation. Plastic, synthetic fibres and synthetic rubbers are three examples of synthetic

polymers.

There are two types of polymerisation:

a) Additon polymerisation

b) Condensation polymerisation

Addition polymerisation

Unsaturated monomers that contain double bonds between two carbon atoms undergo

addition polymerisation.

Polymerisation by addition involves monomers with >C = C< bonding, where the

monomers join together to make a long chain without losing any simple molecules from

it. Examples of polymers produced through this process are polythene, PVC perspex and

other plastics.

Condesation polymerisation

Small molecules such as water, H2O, and ammonia, NH3, are released in condensation

polymerisation.

Polymerisation by condensation involves the elimination of small molecules like water,

methanol, ammonia or hydrogen chloride during the process. Examples of products of

this process are terylene and nylon-66

Uses of synthetic polymers:

TYPE OF POLYMER USE

Polythene Make buckets, plastic bags, raincoats, films, rubbish bins

Polyvinyl chloride (PVC) Make water pipes, electric cables, mats, vinyl records, clothes hangers

Polypropene Make ropes, bottles, chairs, drink cans, carpets

Perspex Make car windows, plane windows, spectacle lenses (optical instruments)

Nylon Make ropes, curtains, stockings, clothes

Polystyrene Make packing boxes, buttons, notice boards

Terylene Make textile items such as clothes and cloths

1. Synthetic polymers have many advantages over other type of materials:

a. They are cheap, light-weight and translucent.

b. They are easily colored, easily molded 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 polymers are flammable. When a synthetic polymer material

catches fire, poisonous fumes are produce causing air pollution.

b. Synthetic polymers are non-biodegradable. When there are discharge , 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.

3. Methods to overcome the environmental pollution caused by synthetic polymers

a. Reduce, reuse and recycle synthetic polymers

b. Develop biodegradable polymers

9.5 Glass and Ceramics

9.5.1 Glass

1. 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. Chemically inert.

e. Not permeable to gas and liquid.

f. Does not conduct electricity.

Type of glass Composition Properties Uses

Fused 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

9.5.2 Ceramics

1. Ceramics are made from clay that has been heated at a very high temperature.

2. The main component of ceramics is silicate.

3. Most ceramics contain silicon, oxygen and aluminium.

4. Ceramics cannot be recycled. Ceramics that have been solidified cannot be melted again as

they are extremely heat resistant.

5. Properties of ceramics:

a) very hard and strong but brittle

b) inert to chemical reaction

c) has a very high melting point

d) good electric and heat insulator

e) able to withstand compression

6. Ceramic play important role in our daily life. They are uses as

a) Construction materials

Ceramic are strong and hard, uses to make roof tiles, bricks cement, sinks, and toilet

bowls.

They are also used to make refractory bricks because high resistant to heat.

b) Decorative items

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

durable.

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

c) Electrical insulator

Ceramic are used to make electrical insulator in electrical items such as toasters, fridges

and electrical plug.

9.6 Composite materials

1. A composite material (or composite) is a structure of materials that is formed by two or

more different substances such as alloys, metal, glass, ceramic and polymer.

2. The composite material produced will have different properties far more superior to the

original materials.

3. The composite material produced is harder, stronger, lighter, more resistant to heat and

corrosion and also for specific purposes.

Composite material Component Properties of component Properties of composite

Reinforced

concrete

Concrete Hard but brittle,

With low tensile strength

Stronger, higher tensile

strength, not so brittle, does not

corrode easily, can withstand

higher applied forces and loads,

relatively cheaper

Steel Hard with high tensile strength

but expensive and can corrode

Fibre optics

Glass of low

refractive index

Transparent, does not reflect

light rays.

Reflect light rays and allow light

rays to travel along the fibre

Glass of high

refractive index

Heavy, strong but brittle and

non-flexible

Fibreglass

Glass Heavy, strong but brittle and

non-flexible

Light, strong, tough, resilient

and flexible, with high tensile

strength and not flammablePolyester plastic Light, flexible, elastic but weak

and inflammable

Photochromic glass

Glass Transparent and not sensitive

to light

Sensitive to light: darkness when

light intensity is high, becomes

clear when light intensity is lowSilver chloride, or

silver bromide

Sensitive to light

Content Page

9.1 Sulphuric acid

9.1.1 Properties of sulphuric acid 1

9.1.2 The uses of sulphuric acid 2

9.1.3 The industrial process in manufacture of sulphuric acid 3 - 4

9.1.4 Environmental pollution by sulphuric acid 5 - 6

9.2 Ammonia and its salt

9.2.1 Uses and properties of ammonia 7

9.2.2 The industrial process in manufacture of ammonia 8 - 9

9.3 Alloys

9.3.1 Arrangement of atom in pure metals 10

9.3.2 Alloy 11

9.3.3 Arrangement of atoms in alloy 12

9.4 Synthetic polymers

9.4.1 The meaning and types of polymers 13

9.4.2 Synthetic polymers 14 - 16

9.5 Glass and ceramics

9.5.1 Glass 17

9.5.2 Ceramics 18

9.6 Composite material 19