19133860 chemistry form 4 auto saved
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Chemistry Form 4
Chapter 9 :
Manufactured substances
in industry
NUR FARHANA BT HASSAN
4 ALPHA
SM SAINS SABAH
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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 H2SO4.
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
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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 H2SO4 + Ca3(PO4) 2 Ca(H2 PO4) 2 + 2CaSO4
sulphuric acid + tricalcium phosphate calcium dihydrogen phosphate
H2SO4 +2NH3 (NH4) 2SO4
sulphuric acid + aqueous ammonia ammonium sulphate
H2SO4 +2NH3 (NH4) 2SO4
sulphuric acid + aqueous ammonia ammonium sulphate
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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 are
a) Temperature:450-500°C
b) Pressure: 2-3 atmospheres
c) Catalyst: Vanadium(V) oxide
STAGE3: C onversion 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 2H2SO4
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Figure 9.1 Flow chart of the Contact Process.
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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.
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Sources of Sulphur Dioxide
y The principal source of SO2 is from the combustion of fossil fuels in domestic premises
and , more importantly, non-nuclear power stations.
y Fossil fuel burning power stations account for around two thirds of total SO2 emissions in
the UK .
y Other industrial processes contribute a further 20%, with vehicles, primarily diesel,
accounting for a mere 2%.
Health effects
y 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.
y 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. R emove sulphur dioxide from waste air by treating it with calcium carbonated before it
is released.
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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
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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 R eactions of ammonia with acids produce ammonium fertilizers.
NH3(aq) + HNO3(aq) NH4 NO3(aq) ammonium nitrate
3NH3(aq) + H3PO4(aq) (NH4)3PO4(aq) ammonium phospate
2NH3(aq) +H2SO4(aq) (NH4)2SO4(aq) ammonium sulphate
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
Li uid ammonia
In cooling chamber
Unreacted N2 and
H2 gases
In the reactor chamber
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9.3Alloys
9.3.1 Arrangement of atoms in pure metal
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 intovarious desired shapes.
Metals are ductile.
Metals are malleable.
Force
La er o atom slide
Force
The shape of the
metal change
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9.3.2 Alloy
1. An alloy is a compound formed from a mixture of metal and other elements.
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
y 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
y Making of surgical instrument,knives forks and spoons
Brass 70% copper
30% zinc
Hard, do not rust,
bright appearance
y Making of ornaments, electrical
wiring and plug.
Bronze 90% copper
10% tin
Hard, do not corrode
easily and durable
y For casting bells, medals,swords and statues
Pewter 90% tin
2.5% copper, 0.5%
antimony
Ductile and malleable,
white silvery
appearance
y Making of ornaments, souvenirs
and mugs
Duralumin 95% aluminium
4% copper,
1%magnesium
Light, strong and
durable
y Making part of aircrafts and
racing cars
Cupronickel 75%copper
25%nickel
Attractive, silvery
appearance, hard and
tough
y Making of silver coins
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9.4Synthetic 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
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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
y Unsaturated monomers that contain double bonds between two carbon atoms undergo
addition polymerisation.
y 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.
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C ondesation polymerisation
y Small molecules such as water, H2O, and ammonia, NH3, are released in condensation
polymerisation.
y 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
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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. R educe, reuse and recycle synthetic polymers
b. Develop biodegradable polymers
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9.5Glass 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. R esistant 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% y Transparent
y High melting point
y Good heat insulator
y Lens
y Telescope mirrors
y Laboratory apparatus
Soda-lime glass SiO2: 75%
Na2O:15%
CaO: 9%
Other:1%
y Low melting point,easily molded into
desired shape andsize
y Low resistant to
chemical attacks
y Brittle
y Drinking glass, bottles
y Electric bulbs
y Window glass
Borosilicate glass SiO2: 78%
B2O3: 12%
Na2O: 5%
CaO: 3%
Al2O3:2%
y R esistant chemical
attack and durable
y High melting point
y Good insulator to
heat
y Cooking utensils
y Laboratory glassware
such as conical flaks
and boiling tube
Lead crystal glass
(flint glass)
SiO2: 70%
Pbo/PbO2:20%
Na2O: 10%
y High refractive index
y High density
y Attractive glittering
appearance
y Lenses and prisms
y Decorative glassware
and art object
y Imation jewellery
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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.
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9.6Composite 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
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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