CHAPTER 9 : MANUFACTURED SUBSTANCES IN INDUSTRY
Industrial products are very important nowadays. There are
manufactured purposely for our comfort.
These products are :
1. Sulphuric acid
4. synthetic polymers
7. composite materials
1. Manufacture of : Detergents, artificial fabres and paint.
2. As electrolyte in car batteries
3. production of fertilizer
The process called Contact Process
The raw materials used are sulphur, air and water.
The stages of process:
STAGE 1:Formation Of Sulphur Dioxide
Molten sulphur is burnt in dry air to produce sulphur dioxde
S + O2 SO2
Sulphur dioxide alsa can be produced by roasting sulphide ores
( lead )II sulphide) in air.
STAGE 2: Formation Of Sulphur Trioxide
Sulphur dioxide and access oxygen gas pass over vanadium (V)
oxide catalyst at 450 C to produce sulphur trioxide , SO3.
2 SO2 + O2 2SO3
Optimum condition used are:
Temperature: 450 C
Pressure: 1 atm
Catalyst : Vanadium(V) oxide
About 97 % conversion occurs under this condition.
STAGE 3 : Formation Of Sulphuric Acid
Consists of 2 steps:
Step 1 : SO3 is dissolved with concentrated sulphuric acid to
SO3 + H2SO4 H2S2O7
Step 2 : Oleum is then diluted with water to produce
concentrated sulphuric acid.
H2S2O7 + H2O 2 H2SO4
H2SO4 can be formed if react SO3 directly to water:
SO3 + H2O H2SO4
But it is not done in industry because SO3 reacts too violently.
A lot of heat and large cloud of sulphuric acid mist are
produced which are corrosive and can pollute the environment.
It is difficult to condense.
SO2 And Environment Pollution
SO2 is released into atmosphere from:
1. burning of fossil fuels containing sulphur
2. The burning of sulphur (Contact process)
3. The extraction of certain metals from their sulphide ores
1. acid rain
3. chest pain
4. shortness of breath
5. bronchitis and lung disease
AMMONIA ANND ITS SALTS
Uses Of Ammonia
To make fertilizers which is important to provide nitrogen for the
healthy growth of plants.
Can be converted to nitric acid which used to synthetic fibres,
explosives, wood pulp, paints, varnishes, lacquers rocket propellants.
The Properties of Ammonia
Less dense than water
Burns in oxygen gas but not in air
Is very soluble in water
Gives a white fume when a reacted with hydrogen chloride gas, HCl.
Manufacture of Ammonia
Through Haber Process
This process combines nitrogen gas from the air with hydrogen gas
derived mainly from natural gas to form Ammonia, NH3.
Nitrogen gas is obtained from the fractional distillation of liquid air.
Hydrogen gas obtained from natural gas.
1. The ratio of one volume of nitrogen gas to three volumes of hydrogen is
passed through the reactor.
2. The mixture is compressed to high temperature ( 200 atm) at 450 C.
3. Iron is used as catalyst in this process.
N2 + 3H2 2 NH3
Preparation Of Ammonium Fetilisers :
Ammonium fertilizers contain ammonium ions. In the soil, the ammonium
ions are oxidised to nitrate ions.
Example of ammonium fertilisers:
1. Ammonium sulphate ( (NH4)2SO4 )
2. Ammonium nitrate ( NH4NO3 )
3. Ammonium phosphate ( (NH4)3PO4 )
Example : What is the percentage by mass of nitrogen in ammonium
Is mixture of two or more elements with a certain fixed composition in
which the major component is metal.
Pure metals are make up of the same type and same size of atoms.
The orderly arrangement of atoms make the metal ductile and malleable.
Orderly arrangement of atoms in metal enables the layer of atoms to
slide on one another when force is applied.
Arrangement of atom in
pure Metal: Closely packed
& In an orderly manner
Force Layers of atoms slide
over each other.
Most pure metals are weak and soft.
The properties of pure metal can be improved by making them into
Alloys are stronger, harder, and resistant to corrosion, have a better
furnish and luster.
The example of alloy. ( refer text book page 160 )
Why make alloys ?
1. To improve the appearance of the pure metal
2. to increase the strength and hardness of the pure metal
3. to increase the resistance to corrosion of the pure metal.
The Arrangement Of Atom In Alloys
The presence of atoms of other metals that are of different size
disturb the orderly arrangement of atoms in the metal. This decrease
the layer of atoms from sliding.
Thus alloy is stronger and harder than its pure metal.
Polymer : Large molecules make up of many identical repeating sub-units
called monomers which are joined together by covalent bonds.
Polymerization : a process to join the monomer into chains by repeated
2 types of polymer :
1. naturally occurring polymers
2. Synthetic polymers : man-made polymer.
Ex : Polythene, polyvinyl chloride, polypropene, Perspex, nylon and
GLASS AND CERAMICS
Glass : made from sand
The major component: silica, SiO2.
There are so many types of glass; fused glass is the simplest one which
is mainly silica, SiO2.
Fused glass : Highly resistant glass. It can be heated to an extremely
high temperature and then can be plunged into icy, cold water without
It’s expensive but still widely used because of its ;
1. Great purity
2. optical transparency
3. high temperature
4. chemical durability
5. Resistance to thermal shock.
It is used as :
1. Laboratory glassware
3. Telescope mirrors
4. optical fibres.
Ex : Starch, cellulose, wool, protein, silk and natural rubber.
The most common glass : Soda lime glass
Made by heating sand with limestone/ sodium carbonate.
Can be melted at a relatively low temperature
Easy to be shaped and has a good chemical durability.
High thermal expansion coefficient.
Expands a lot when it is heated and contracts a lot too when it is
Do not withstand heat.
Used to make : flat glass, electrical bulbs, mirrors and glass
Soda lime glass + Boron oxide, B2O3 Borosilicate glass
Has a lower thermal expansion coefficient
3 times as heat resistant as soda-lime glass
More resistant to chemical attacks because it contains less alkali.
Good to use in cookware, laboratory glassware and automobile
Used in glass pipelines and applications which require superior
resistance to thermal shock and greater chemical durability.
Made from clay. Ex : Kaolin ( Aluminiumsilicate, Al2O3.2SiO2.2H2O )
When the clay is heated to a very high temperature, they undergo a
series of chemical reactions and are hardened permanently to form
Ex : clay pots, bricks, tiles and mugs.
Ceramics are very hard, brittle, chemically inert, do not corrode, high
melting point and are good insulators of electricity and heat.
Suitable for making abrasive, construction material,
tableware, insulators in electrical equipments and
Comparing properties of glass and ceramics
How are they alike:
3. strong under compression
4. do not corrode
5. good electrical insulator
6. good heat insulator
7. resistant to chemical attacks
How are they different:
Highly transparent Optical transparency Opaque
Can be melted and Moulding Cannot be melted and
Lower melting point Melting point Very high melting point
Structural material that is formed by combining two or more different
substances such as metal, alloys, glass, ceramic and polymers. These
materials are created for specific application.
The material formed has properties that are better than the original
Types of Composite Material
Concrete: Consists a mixture of stones, chips and sand bound together
by cement. It is strong but brittle and weak in tension.
Steel : Strong in tension.
Concrete reinforced with steel wires, steel bars or any polymers
fibres, the resulting combination is a very tough material with
more tensile strength.
The composites are good for the construction of large structures
like high-rise building, bridges and oil platforms.
It is also cheap and can be moulded into any shape.
Capable of conducting electricity without any electrical resistance when
they are cooled to extremely low temperature.
They are used in the bullet trains in Japan, magnetic energy-storage
systems, generators, transformers and computer parts.
Fibre optic cable consists of a bundle of glass or plastic threads that
are surrounded by a glass cladding.
They are used to replace copper wire in long distance telephone lines, in
mobile phone, video camera and to link computer within local area
Fibre optic is good to use because they have law material costs, high
transmission capacity, chemical stability and less susceptible to
Formed when glass fibres are used to reinforce plastic.
Properties : High tensile strength, can be easily coloured, low in density
easily moulded and shaped and can be made into thin layers.
Used to make household products like water storage tanks, badminton
rackets, small boats, skis and helmets.
Produced by embedding photochromic substances like silver chloride,
AgCl crystals in glass or transparent polymers.
Used for making optical lenses, car windshields, smart energy efficient
windows in buildings, information display panels, lense in cameras,
optical switches and light intensity meters.