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9.1..SULPHURIC ACID
9.1.1 Uses of sulphuric acid
1. Sulphuric acid is one of the most important industrial chemicals. About 140 milliontonnes are manufactured in the world every year.
2. It is used in most industries ranging from agriculture fertilisers to paints, soap andthe cleaning of rust.
3. The main use of sulphuric acid is in producing fertilisers, particularlysuperphosphate and ammonium sulphate.
a) Superphosphate fertiliser :It is manufactured from the reaction between sulphuric acid and calcium
phosphate.
2H SO (1) + CA(PO)(s) Ca(HPO)(1) + 2CaSO(s)
b) Ammonia sulphute fertiliser :It si manufactured by the reaction between sulphuric acid and ammonia.
2NH(aq) + HSO(aq) (NH)SO(aq)
c) Potassium sulphate :It is manufactured by the neutralisation of sulphuric acid and potassium
hydroxide.
2KOH(aq) + HSO(aq) KSO(aq) + 2HO(1)
4. Initially, sulphonic acid is produced by the reaction between sulphuric acid andhydrocarbon compound.
making fertilisers
paints
chemicals
detergents
removing rust from steel
other uses
Uses of sulphuric acid, H SO
A molecule of sulphuric acid
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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 and to react with the positive andnegative plates during the charging and discharging processes.
7. In the acid accumulator, sulphuric acid acts as the electrolyte.Table 9.1 Uses of sulphuric acid in the laboratory
Uses of
Sulphuric acid
Example
Drying agent Concentrated sulphuric acid is generally used to dry gas in the
laboratory. However it is not suitable to dry alkaline gases such
as ammonia.
Oxidising agent Concentrated sulphuric oxidises copper to form copper( )
sulphate.2HSO(1) + Cu(s) CuSO(aq) + 2HO(1) + SO (g)
However dilute sulphuric acid does not react with copper.
Dehydrating agent When concentrated sulphuric acid is added to sugar, a violent
reaction accurs.
The water content in the sugar is extracted by the acid and the
sugar becomes carbon.
Strong acid It reacts with the salt of the weak acid such as sodium
ethanoate to form a weak acid.
2CHCOONa(s) + HSO(1) 2CHCOOH(aq) + NaSO(aq)
9.1.2 Manufacture of Sulphuric Acid1. Today, sulphuric acid is made from sulphur dioxide, by the Contact Process.
There are three stages for the production of sulphuric acid by the Contact
Process.
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Stage 1
a. In the furnace, sulphur is burnt in dry air to produce sulphur dioxide.S(1) + O(g) SO(g)
b. In the Contact Process, sulphur powder is sprayed inside a furnace at a temperatureof 100C. Here sulphur is converted to sulphur dioxide.
c. Sulphur dioxide can also be produced by heating metal sulphides such as zinesulphide.
Stage 2 (Preparation of sulphur trioxide)
a. Sulphur dioxide and air are passed over a catalyst called vanadium(V) oxide, (VO).b. he temperature used here is aout (450 500)C. If the temperature is less than
this range, the vanadium(V) oxide may not be able to catalyse.
c. The reacting pressure is about 2 to 3 atmospheres.d. At this stage, sulphur trioxide is produced.
2SO(g) + O(g) 2SO(g)
e. This reaction will produce about 98% sulphur trioxide.Stage 3 (Formation of sulphuric acid)
a. The sulphur trioxide is dissolved in concentrated sulphuric acid to form a productcalled oleum, HSO. his is carried out until the concentrated sulphuric acid has
reached a concentration of 99.5%.
SO(g) + HSO(1)
b. The product, oleum will not show any property of an acid. This is because, oleum willnot ionise without the presence of water.
c. Water is then added to the oleum to produce concentrated sulphuric acid.HSO(1) + HO(1) 2HSO(1)
d. The reaction of (a) and (b) is equivalent to dissolving sulphur trioxide in water.
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SO(g) + HO(1) HSO(aq)
e. However this reaction is not carried out in industry. This is because the reaction istoo vigorous.
f. It produces a large cloud of sulphuric acid mist. This mist is corrosive and pollutes theair.
Contact Process
Burnt in air
Further oxidation
Catalyst: VO
emperature: (450 500) C
Pressure: 1 atm
Dissolves in concentrated sulphuric acid, HSO
Dilute with water
Sul hur
Sulphur dioxide SO
Concentrated sulphuric acid, HSO
Sulphur trioxide SO
Oleum HSO
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9.1.3 Sulphur Dioxide and Environmental Pollution1. Sulphur dioxide is the main by product produced when sulphur-containing fuels
such as coal or oil are burned.
2. Sulphuric acid is formed by atmospheric oxidation of sulphur dioxide in thepresence of water . It also produces sulphurous acid.
3. Sulphuric acid and sulphurous acid are constituents of acid rain.4. 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 the soil and make it become acidic.IV. Acid rain flows into the rivers and increases the acidity of water and kill
aquatic living things.
5. 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 calciumcarbonated before it is released.
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Acid rain and environmental pollution
9.2..AMMONIA AND ITS
SALTS
9.2.1 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 fibre and nylon.IV. As a degreasing agent in aqueous form to remove greasy stains in the
kitchen.
9.2.2 PROPERTIES OF AMMONIA GAS1. The physical properties of ammonia gas include the following:
I. It colourless and has a pungent gas.II. It is highly soluble in water and form a weak alkaline solution.
NH(g) + HO(1) NHOH(aq)
III. It less dense than air.IV. It easily liquefied (at about 35.5C) when cool.V. Ammonia melts at -77.7C and oils at -33.35C.
VI. Its density is 0.68 (at its boiling point and at 1 atmosphere ofpressure)
2. The chemical properties of ammonia gas:I. Ammonia dissolves into water to give an alkaline solution with a pH
value of 9-10.
II. Its turns moist red litmus paper to blue.III. Ammonia is an alkali. It will neutralise acids to make ammonium salts.
NH(g) + HSO(aq) (NH)SO(aq)
Ammonia sulphuric acid ammonium sulphate
NH(g) + HNO(aq) NHNO(aq)
Ammonia + nitric acid ammonium nitrate
A molecule of ammonia
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IV. Gaseous ammonia reacts with gaseous hydrogen chloride to formwhite fumes of ammonium chloride.
NH(g) + HCI(g) NHCI(s)
Ammonia + hydrogen ammonium chloride
chloride
V. When ammonia chloride heated, it changes back into ammonia andhydrogen chloride.
VI. Ammonia dissolves in water to form ammonium hydroxide.Ammonium hydroxide, NHOH, is strongly asic. It has similar
chemical properties as compared to other hydroxides of alkali metals.
VII. Ammonia reacts with metallic ions(except Na, Kand Ca)to formmetallic hydroxides.
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9.2.3 MANUFACTURE OF AMMONIA IN INDUSTRY(Haber Process)
1. Ammonia is made by synthesis 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 electrolysing brine (sea water)
4. Nitrogen and hydrogen can also be obtained from natural gas (methane).5. 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: 450-500CII. Pressure: 200-500 atmospheres
III. Catalyst used: Iron fillings6. Under these control optimum condition, only 15% of the gas mixture turn
into ammonia gas. The nitrogen and hydrogen that have not reacted are thenflow back over the catalyst again in the reactor chamber.
7. The ammonia product is then cooled at a low temperature so that itcondenses into a liquid in the cooling chamber.
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The manufacture of ammonia, NH3 through the Haber Process
1) Gases mixed and scrubbedHaber process comines N gas from the air with H gas from natural gas to
form NH. The two gases are mixed. The mixture is scrubbed to get rid of
impurities.
2) CompressorOne volume of N gas and three volume of H gas is compressed to a
pressure of 200 500atm
N(g) + 3H(g) 2NH(g)
3) ConverterThen, it goes to the converter. It is then passed through layers of iron
catalyst with aluminium oxide as a promoter at a temperature of 450C
500C
4) CoolerA mixture of three gases leaves the converter. It is cooled until the ammonia
condenses. The nitrogen and hydrogen are pumped back to the converter
for another chance to react.
5) storage tanksNH is formed and then liquefy and separated to get a better yield. he NH
is run into tanks and stored as a liquid under pressure.
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Making Ammonia in School Laboratory
1. Ammonia can be produced in the laboratory by warming an ammonium saltwith an alkali.
2. Example: heating ammonium chloride with sodium hydroxideNHCI(s) + NaOH(aq) NaCI(aq) + NH(g) + HO(I)
3. In the laboratory, a mixture of solid ammonium chloride and dry calcumhydroxide is heated.
4. The damp ammonia gas prepared in the laboratory can be dried by passing itthrough calcium oxide.
5.
Other drying agent agents such as concentrated sulphuric acid and anhydrouscalcium chloride cannot be used. They react with ammonia.
2NH + HSO (NH)SO
4NH + CaCI CaCI.4NH
FLOW CHART FOR THE HABER PROCESS
AMMONIUM FERTILIZERS
1. Nitrogen is required in large amount by plant to make proteins which arenecessary for growth and cell repair.
2. Most plant are not able to get a nitrogen supply directly from the airalthough 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 andammonia salt which are manufacture as chemical fertilizer.
H N
450 - 500C
Refrigeration
NH
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4. Reactions of ammonia with acids produce ammonium fertilizers.
9.3..ALLOYS
9.3.1 Meaning of Alloy1. Alloys are materials that contain more than one element.2. Usually, alloys are mixtures of metallic elements two or more metals.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 frames.
4. Thus an alloy is a mixture of metals are made for a certain purpose.
9.3.2 Arrangement of Atoms in Metals
1. In pure metals, the atoms are all of the same size.2. They are arranged in layers as shown in the figure below.
3. When the pure metals are hit with a hammer, the layers of atoms can slideover each other easily.
4. Thus, pure metal can easily change its shape. They are said to be Ductile as they can be drawn into long wires Malleable as they can be hammered to form any shapes.
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9.3.3 Arrangement of Atoms in Alloys
1. Alloys have more than one kind of atoms. These different atoms are ofdifferent sizes. They are mixed when they are in the molten state (liquid).
2. The layers of atoms in an alloy cannot slide over each other as easily asshown in the figure below.
3. The movement of atoms get jammed up. This makes tem difficult to move.4. This makes the alloy not ductile and not malleable.5. However, alloys are harder and stronger than the original constituent metals.6. There are different ways of arranging the different atoms in alloys.
Solution alloys are homogeneous alloys in which the different atomsare distributed uniformly throughout.
In heterogeneous alloys, the different atoms are not distributeduniformly.
7. Homogeneous alloys have definite properties and compositions.
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9.3.4 Aim of Producing Alloys
1. The basic aim of making alloys is to modify the properties of the pure metalelements. Sometimes this is necessary to make ornaments.
2. Pure gold is too soft to be used in jewellery. However, an alloy of copper andgold is quite hard for this purpose.
3. To prevent or minimise corrosion Iron is easily corroded especially in polluted, acidic and damp
industrial areas.
An iron alloy will be less likely to rust if carbon, nickel, or chromium isadded to it.
Stainless steel is an alloy of iron. It will not rust even under extremeconditions.
The presence of chromium in it, will form chromium (III) oxide. The presence of nickel in it will form nickel (I ) oxide. The presence of layers of these oxides will prevent corrosion and
oxidation.
4. To improve the physical appearance Fresh metal surfaces are usually shinning. These shinning surfaces are usually tarnished if they are coated with
a layer of oxides.
Alloys are not easily oxidised. This is because the oxide layers are noteasily formed. Thus, surfaces of alloys will remain shinning for a
longer time.
Stainless steel utensils are more shinning then iron utensils.
9.3.5 Composition, properties and uses of alloys
1. Like metals, all alloys are conductors of Heat and Electricity
2. Like metals too, all alloys have shinning surfaces. They have a lustrousappearance. However, most alloys are more shinny than pure metals if they
are kept for a long time. This is because alloys do not corrode or oxidise
easily. Metals tend to have a layer of oxides after some time.
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3. Alloys are less malleable than metals. They are not easily hammered intosheets.
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9.4..SYNTHETIC POLYMERS
9.4.1 Meaning of Polymers1. Polymers are large molecules made up of many identical repeating sub-unitscalled monomers which are joined together by covalent bonds.
2. Monomers are joined into chains by a process of repeated linking known aspolymerisation.
3. A polymer may consists of thousands ofmonomers.4. The process of forming polymers ispolymerisation.5. If the molecules simply join together, then this type of polymerisation is
called additional polymerisation.
6. There are two main groups of polymers: Man-made polymers or synthetic polymers Natural polymers
9.4.2 Natural Polymers1. Rubber is an example of a natural polymer.2. Other natural polymers are :
a. Fat in cells;b. Carbohydrate in cells;c. Protein in cells.
3. All these substances are large molecules that are joined together. Thus, fats,carbohydrates and proteins are natural polymers.
9.4.3 Synthetic Polymers
1. Synthetic polymers are man-made polymers.2. The monomers used are usually obtained from petroleum after goingthrough the refining cracking processes.3. Examples: polythene, polyvinyl chloride (PVC) polystylene, Perspex , and
nylon.
4. Synthetic polymers are very stable and do not corrode or decay, and alsodifficult to dispose.
5. They may cause pollution, blockage of drainage systems and flash floods.
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Polythene
Open up of double bonds of ethene molecules
1. Double bonds of ethene molecules, open up to form single bonds.
Formation of polyethylene polymer
2. Opened molecules of ethene, join together to form polyethylene polymera. If ethene gas is heated under pressure, it will polymerise to form a
waxy white solid as shown in figure below.
b. This process is called man-made polymerisation.c.
Ethene is called a monomer and the product polythene is a syntheticpolymer.
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Perspex
PVC..
Polystyrene
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Synthetic polymers and their users
Synthetic Rubber
1. There are two main types of synthetic rubber :a. SBR rubber or styrene butadience.b. Neoptene.
2. SBR rubber or styrene- butadiencea. This rubber is made by combining one part of styrene (IUPAC name :
phenylethene) with three parts of butadience (IUPAC name : 1 , 3
diena).
Polymers Monomer Uses Characteristic
PVC Chloroethene, C H CI Drain pipes, insulation for
electric wiring, artificial
leather, water-proof
clothes, shoes
Tough and flexible
Polythene Ethylene, CH CH Plastic bags, cups and
wrappers
Not easily torn
Polypropene
(polypropylene)
Propene CH CHCH Film for packaging, snap-on
lids, bottles
Strong and light
Perspex Methyl 2-methyl
Propenoate
CH C(CH )COOCH
Lenses, window glass Light, strong and
stable to sunlight
Nylon
(polyamide)
Carboxylic acid Curtain rails, hinges, fibres
for clothes, ropes, stocking,
parachutes, fishing line
Strong and long
lasting, easy to wash.
Can be drawn into
threads
Terylene
(polyester)
Ethylene glycol and
terephthalic acid
Fibres for clothes, video
tape, plastic bottles
Keep in shape after
washing, light and
soft but strong
Polystyrene Styrene Foam drinking cups,
insulation, furniture,
packing materials
Strong and light. Can
be made into foam
Styrene and
butadience
undergo addition
reaction..
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b. This type of polymerisation is called copolymerisation.c. This polymer was developed during World War II and it used mainly to
make tyres.
3. Neoprenea. 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.
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9.5..GLASS AND CERAMICS
9.5.1 Glass
o The major component of glass is silica or silicon dioxide, SiO2 which found insand.
o Properties of glass: Transparent, hard but brittle, chemically inert, heatinsulator, electrical insulator, impermeable to liquid.
Glass
Fused glass (SiO)
Highly heat-resistant
glass
High transparency
High melting point
Resistant to chemical
attack
Uses : Laboratory
glassware, lenses,
telescope, mirrors
Lead crystal glass
(SiO, NaO, PbO, KO,
AlO)
Soft and easy to
melt.
High density
High refractive index
Uses- Lead crystal
glassware, art
objects, lens, prisms
and chandeliers
Borosilicate glass
(SiO, NaO, CaO,
AlO,BO)
Low thermal
expansion
coefficient
Resistant to heat and
chemical attack High melting point
Uses : Cooking
utensils, laboratory
glassware,
automobile
headlights
Soda-lime glass
(SIO, NA, CaO)
Good chemical
durability
High thermal
expansion
coefficient
Easy to make into
different shapes
Low melting point
Uses Bottles,
window panes,
mirrors, electrical
bulbs, flat glass
and all kind of glass
containers
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9.5.3 Ceramics Ceramics are made from clay, for example kaolin, a hydrated aluminium
silicate, AlO.2SiO.2HO.
When the clay is heated to a very high temperature, they undergo a series ofchemical reaction and are hardened permanently to form ceramics.
Ceramics are very hard, brittle, have a very high melting point, chemicallyinert and do not corrode.
The are good insulators of electricity and heat. Uses of ceramics: construction materials bricks, tiles, cement and pipes Ornamental articles bowls, cups, plates, vase and porcelain Electrical insulators spark plugs, fuses, insulators in electric iron and oven Superconductors
9.5 Uses of Composite Materialso Composite materials is a structural material that is formed by combining two or
more different substance such as metal, alloys, glass, ceramics and polymers.
o The resulting material has properties that are superior than those of the originalcomponents.
o Composite materials are created for specific application.
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