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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 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

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) 2 H2SO4 + Ca3(PO4) 2 → Ca(H2 PO4) 2 + 2CaSO4 sulphuric acid + tricalcium phosphate → calcium dihydrogen phosphate

b) Ammonium sulphate H2SO4 +2NH3 → (NH4) 2SO4 sulphuric acid + aqueous ammonia → ammonium sulphate

c) Potassium sulphate H2SO4 +2NH3 → (NH4) 2SO4 sulphuric acid + aqueous ammonia → ammonium 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.

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. a) b) c)

The optimum used are Temperature:450-500°C Pressure: 2-3 atmospheres 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 SO 2 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 Nitrogen Hydrogen

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

Unreacted N2 and H2 gases

Temperature: 450-500°C Pressure: 200-500 atmospheres

Figure 9.4 Flow chart of

9.2.4 Preparation of ammonium laboratory

Haber process.

Catalyst used: Iron fillings In cooling chamber Liquid

fertilizers in

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

9.3Alloys 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 into

various desired shapes. Layer of atom slide Force

Metals are

ductile.

Force The shape of the metal change

Metals are

malleable.

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

High carbon steel

99% iron

Stainless steel

1% carbon 80.6% iron

Strong,hard and high wear resistance

0.4% carbon,

Uses

• Making of cutting tools, hammers and chisels

Do not rust and tarnish, strong and durable

• Making of surgical instrument, knives forks and spoons

Hard, do not rust, bright appearance

• Making of ornaments, electrical wiring and plug.

18%chromium, Brass

1% nickel 70% copper

Bronze

30% zinc 90% copper

Pewter

10% tin 90% tin

Duralumin

2.5% copper, 0.5% antimony 95% aluminium

Cupronickel

4% copper, 1%magnesium 75%copper

Hard, do not corrode easily and durable Ductile and malleable, white silvery appearance

• For casting bells, medals, swords and statues • Making of ornaments, souvenirs and mugs

Light, strong and durable

• Making part of aircrafts and racing cars

Attractive, silvery

• Making of silver coins

25%nickel

appearance, hard and tough

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.

9.4Synthetic 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

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

Polythene Polyvinyl chloride (PVC) Polypropene Perspex Nylon Polystyrene Terylene

USE

Make buckets, plastic bags, raincoats, films, rubbish bins Make water pipes, electric cables, mats, vinyl records, clothes hangers Make ropes, bottles, chairs, drink cans, carpets Make car windows, plane windows, spectacle lenses (optical instruments) Make ropes, curtains, stockings, clothes Make packing boxes, buttons, notice boards 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 nonrecyclable 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

9.5Glass 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. Resistant to corrosion. d. Chemically inert. e. Not permeable to gas and liquid. f. Does not conduct electricity. Type of glass

Composition

Fused glass

SiO2: 100%

Soda-lime glass

SiO2: 75% Na2O:15% CaO: 9% Other:1%

Borosilicate glass

SiO2: 78% B2O3: 12% Na2O: 5% CaO: 3%

Properties

Uses

• • • •

Transparent High melting point Good heat insulator Low melting point, easily molded into desired shape and size • Low resistant to chemical attacks • Brittle

• • • • • •

• Resistant chemical attack and durable • High melting point • Good insulator to heat

• Cooking utensils • Laboratory glassware such as conical flaks and boiling tube

• High refractive index • High density • Attractive glittering appearance

• Lenses and prisms • Decorative glassware and art object • Imation jewellery

Lens Telescope mirrors Laboratory apparatus Drinking glass, bottles Electric bulbs Window glass

Al2O3:2% Lead crystal glass (flint glass)

SiO2: 70% Pbo/PbO2:20% Na2O: 10%

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.

9.6Composite 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

Component

Properties of component

Properties of composite

Concrete

Hard but brittle,

Stronger, higher tensile strength, not so brittle,

Steel

With low tensile strength Hard with high tensile strength but expensive

can withstand higher

and can corrode

applied forces and loads,

Glass of low

Transparent, does not

relatively cheaper Reflect light rays and

refractive index Glass of high

reflect light rays. Heavy, strong but brittle

refractive index

and non-flexible

Glass

Heavy, strong but brittle

Light, strong, tough,

and non-flexible Light, flexible, elastic but

resilient and flexible, with

Polyester plastic

material

Reinforced concrete

Fibre optics

Fibreglass

weak and inflammable

Photochromic glass

does not corrode easily,

allow light rays to travel along the fibre

high tensile strength and not flammable

Glass

Transparent and not

Sensitive to light:

sensitive to light Sensitive to light

darkness when light

Silver chloride, or silver bromide

Content 9.1 Sulphuric acid 9.1.1 Properties of sulphuric acid 9.1.2 The uses of sulphuric acid 9.1.3 The industrial process in manufacture of sulphuric acid 9.1.4 Environmental pollution by sulphuric acid 9.2 Ammonia and its salt

intensity is high, becomes clear when light intensity is low Page 1 2 3-4 5-6

9.2.1 Uses and properties of ammonia 9.2.2 The industrial process in manufacture of ammonia 9.3 Alloys 9.3.1 Arrangement of atom in pure metals 9.3.2 Alloy 9.3.3 Arrangement of atoms in alloy 9.4 Synthetic polymers 9.4.1 The meaning and types of polymers 9.4.2 Synthetic polymers 9.5 Glass and ceramics 9.5.1 Glass 9.5.2 Ceramics 9.6 Composite material

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