CHEMISTRY FOLIO : CHAPTER 9 : MANUFACTURED SUBSTANCES IN INDUSTRY

PREPARED BY :

MUHAMMAD ALIF ASYRAF ZULKIFLI4 JAYA

9.1 SULPHURIC ACID9.1.1 USES OF SULPHURIC ACID

1. One of the most important industrial chemicals.2. Used in most industries ranging from agriculture fertilizers to paints, soap and the

cleaning of rust.

3. The main use of sulphuric acid is in producing fertilizers, particularly “superphosphate” and ammonium sulphate.

a. Superphosphate fertilizer:It is manufactured from the reaction between sulphuric acid and calcium phosphate.2H2SO4(l) + Ca3(PO4)2(s) → Ca(H2PO4)2(l) + 2CaSO4(s)

b. Ammonia slphate fertilizer:It is manufactured by the reaction between sulphuric acid and ammonia.2NH3(aq) + H2SO4(aq) → (NH4)2SO4(aq)

c. Potassium sulphate:It is manufactured by the neutralization of sulphuric acid and potassium hydroxide.2KOH(aq) + H2SO4(aq) → K2SO4(aq) + 2H2O(l)

4. Initially, sulphonic acid is produced by the reaction between sulphuric acid and hydrocarbon compounds.

5. Sulphonic acid the 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 and negative plates during the charging and discharging processes.

7. In the acid accumulator, sulphuric acid acts as the electrolyte.

Uses of sulphuric acid ExampleDrying 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 acid oxidizes copper to form copper(II) sulphate.2H2SO4(l) + Cu(s) →CuSO4(aq) + 2H2O(l) + SO2(g)However dilute sulphuric acid does not react with copper.

Dehydrating agent When concentrated sulphuric acis is added to sugar, a violent reaction occurs. The water content in the sugar is extracted by the acid and the sugar become carbon.C6H12O6(l) → 6H2O(l) + 6C(s)

Strong acid It reacts with the salt of the weak acid such as sodium ethanoate to form a weak acid.2CH3COONa(s) + H2SO4(l) →2CH3COOH(aq) + Na2So4(aq)

9.1.2 MANUFACTURE OF SULPHURIC ACIDToday, 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.

STAGE 1a. In the furnace, sulphur is burnt in dry air to produce sulphur dioxide.

S(l) + O2(g) → SO2(g)b. In the Contact Process, sulphur powder is sprayed inside a furnace at a

temperature of 100°C. Here sulphur is converted to sulphur dioxide.c. Sulphur dioxide can also be produced by heating metal sulphides such as zinc

sulphide.2ZnS(s) + 3O2(g) → 2ZnO(s) + 2SO2(g)

STAGE 2 (Preparation of sulphur trioxide)a. Sulphur dioxide and air are passed over a catalyst called vanadium(V) oxide,

(V2O5).b. The temperature used here is about (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.2SO2(g) + O2(g) ↔ 2SO3(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 product

called oleum, H2S2O7. This is carried out until the concentrated sulphuric acid has reached a concentration of 99.5%.

b. The product, oleum will not show any property of an acid. This is because, oleum will ‘not ionise’ without the presence of water.

c. Water is then added to the oleum to produce concentrated sulphuric acid.H2S2O7(l) + H2O(l) → 2H2SO4(l)

d. The reaction (a) and (b) is equivalent to dissolving sulphuric acid in water.SO3(g) + H2O(l) → H2SO4(aq)

e. However, this reaction is not carried out in industry. This is because the reaction is too vigorous.

f. It produces a large cloud of sulphuric acid mist. This mist is corrosive and pollutes the air.

9.1.3 SULPHUR DIOXIDE AND ENVIRONMENTAL POLLUTION1. Sulphur dioxide is present to some extent in the natural unpolluted atmosphere.

The sulphur dioxide sources are from:a. Bacterial decay of organic matter.b. Volcanic gases.c. Forest fires.However, their concentrations are low and they are normally considered as non-polluting.

2. → Sulphur is normally found in coal and petroleum. When these fossil fuels burn they produce sulphur dioxide.S(s) + O2(g) → SO2(g)→ When this gas is released to the atmosphere, they pollute the air. In fact, the burning of coal and oil is the major source of sulphur dioxide pollution in our environment.→ This gas is considered as the most serious health hazard among the pollutants. This is true especially for people with respiratory difficulties.

3. When SO2 dissolves in water or rain, they form sulphurous acid H2SO3.4. Atmospheric SO2 can be oxidized to SO3 also. When SO3 dissolves in water, it

forms sulphuric acid H2SO4.SO3(g) + H2O(l) → H2SO4(aq)

5. Acid rain affects marine and forest ecology. In acidic environment, less fish will breeed in polluted lakes. More trees will die in the forests.

6. Sulphur dioxide is harmful to human health and property. Many of the environmental effects are actually due to the reactions of sulphuric and sulphurous acids.

7. Acids react with metals and carbonates. Thus, acid rain is corrosive both to metals and to building materials made of carbonates. For example, marble buildings and marble statures will be corroded by acid rain. This will make them less beautiful.

8. The release of SO2 gas to the atmosphere can be reduced by reacting the gas with:a. Calcium carbonate

SO2(g) + CaCO3(s) → CaSO3(s) + CO2(g)b. Calsium oxide

CaO(s) + SO(g) → CaSO3(s)4CaO(s) + 4SO2(g) +2O2(g) → 4CaSO4(g)

9. Some gases released from industries also contain sulphur dioxide. These gases are mainly produced from the burning of fossil fuels. They are also produced during the manufacture of sulphuric acid.

9.2 AMMONIA AND ITS SALTS9.2.1 USES OF AMMONIA

1. Most of the ammonia prodced are used to produce nitrogen fertilizers and nitric acid as shown in the flow chart below.

2. Ammonia is an alkaline solution. It dissolves grease. Thus, it is used in the manufacture of many household cleaning agents.

3. Ammonia is an important refrigerant (cooling agent) in refrigerators. It is suitable because it has:

a. A low boiling point andb. Is very volatile.

4. In the Ostwald Process, ammonia is used to produce nitric acid.5. Ammonia is also used to make explosive chemicals such as TNT. This explosive

is produced when ammonia reacts with toluene.6. In the rubber industry, ammonia is used to prevent the coagulation of latex. This

is because many products such as foam mattresses cannot be made from solid rubber.

7. Ammonia is widely used in the manufacture of fertilizers.

Chemical name Formula UseAmmonium chloride (sal-ammonia)

NH4Cl In dry batteries

Ammonia sulphate (NH4)2SO4 As fertilizersAmmonium nitrate NH4NO3 As explosive and fertilizers Ammonium carbonate (NH4)2CO3 As smelling salts

9.2.2 PROPERTIES OF AMMONIA1. The physical properties of ammonia gas include the following:

a. Ammonia, (NH3), is a colourless and pungent gas.b. It is less dense than air.c. It is highly soluble in water.

NH3(g) + H2O(l) → NH4OH(aq)d. A weak alkaline solution.e. It is easily liquefied (at about 35.5°C) when cool.

2. The chemical properties of ammonia gas:a. Ammonia gas dissolves in water to form a weak alkali.

NH3(g) + H2O(l) → NH4+(aq) + OH-(aq)b. The presence of hydroxide icon causes the aqueous solution to become

alkaline. Thus aqueous ammonia solution:i. Turns red litmus paper blue.

ii. React with acid to form only salt and waterin neutralization occurs.NH3(aq) + HCI(aq) → NH4CI(aq)2NH3 + H2SO4(aq) → (NH4)2SO4(aq)

iii. React with solution of metallic cations to produce precipitates.Fe²+(aq) + 2OH(aq) → Fe (OH)2(s)

9.2.3 MANUFACTURE OF AMMONIA (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).a. Methane is heated with steam over a catalyst of nickel at a high pressure.

CH4(g) + H2O(g) → CO(g) + 3H2(g)b. Carbon monoxide and hydrogen are mixed with air and again heated at

high pressure over nickel acting as a catalyst. Some of the hydrogen reacts with the oxygen in the air and leaves behind nitrogen.[CO + H2] → H2O + N2 + COThe steam (H2O) and carbon monoxide are removed, leaving just the nitrogen and hydrogen.

5. Those two gases are then mixed under 300 atmospheres of pressure and at a temperature between 450°C and 500°C.

6. This hot high-pressure mixture is then fed into a reaction chamber containing an iron catalyst.

7. The iron catalyst speeds up the reaction. Three hydrogen molecules combine with one nitrogen molecule to produce an ammonia molecule.N2(g) + 3H3(g) → 2NH3(g)

8. The temperature, pressure and catalyst help to produce as much ammonia as possible.

9. The gases from the reaction chamber are passed over the catalyst several times so as to enable more nitrogen and hydrogen to combine to form ammonia.

10. The gaseous ammonia is quickly cooled below the boiling point of ammonia. At this low temperature, ammonia gas condenses as a liquid, and is collected and stored.

11. Unconverted nitrogen and hydrogen gas are recycled through the reaction chamber.

9.2.3 PREPARATION OF AMMONIUM FERTILISERS1. 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)3NH3(aq) + H3PO4(aq) → (NH4)3PO4(aq)2NH3(aq) +H2SO4(aq) → (NH4)2SO4(aq)

9.3 ALLOYS9.3.1 MEANING OF ALLOY

1. 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 made for a certain purpose.

9.3.2 ARRANGEMENT OF ATOMS IN METALS1. In pure metals, the atoms are all of the same size.2. The atom of pure metals are packed together closely. This causes the metal to

have a high density.3. The forces of attraction between atoms (metallic bonds) are strong. More heat

energy is needed to overcome the metallic bond so that the atoms are further apart during the melting. This is why metals usually have high melting point.

4. Heat energy can be transferred easily from one atom to the next by vibration. This make metal good conduct of heat.

5. The freely moving outermost electrons within the metal’s structure are able to conduct electricity. Metal are, therefore, good electrical conductors.

6. Since atoms of pure metal are of the same size, they are arranged orderly in a regular layered pattern. When a force is applied to metal, layer of atom slide easily over one another. This make pure metals soft, malleable and ductile.

9.3.3 ARRANGEMENT OF ATOMS IN ALLOYS1. Alloys have more than one kind of atoms. These different atoms are of different

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 easily.3. The movement of atoms get jammed up. This makes them 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.

a. Solution alloys are homogenous alloys in which the different atoms are distributed uniformly throughout.

b. In heterogeneous alloys, the different atoms are not distributed uniformly.7. Homogenous alloys have definite properties and composition.

9.3.4 AIM OF PRODUCING ALLOYS1. To increase the strength and hardness of a pure metal.2. To increase the resistance to corrosion of a pure metal.3. To improve the appearance of a pure metal.

a. To increase the strength and hardness of a pure metal

In the process of making alloys, atoms of other elements are added,

usually in small amounts, into a molten pure metal. When the metal

becomes solid again, the positions of some of the atoms of the pure metal

are replaced by atoms of other elements of different sizes.

The presence of the atoms of other elements disrupts the orderly

arrangement of the pure metal. The layers of metal atoms are

prevented from sliding over one another easily. This makes alloys

stronger and harder than pure metals.

During the making of steel, carbon atoms which are smaller that

iron atoms are added into iron atoms. As a result, the uniformly of

the arrangement of iron atoms is disrupted and it is more difficult

for the layers of the iron atoms to slide over one another. This

makes steel harder and stronger than pure iron.

b. To increase the resistance to corrosion of a pure metal

Unreactive metals such as gold and silver can be found in the free

state. This is because they do not react with oxygen and water

vapour in the air.Most metals such as iron and copper corrode readily in air.

Alloying can prevent metals from corrosion. This is because alloying

helps to prevent the formation of oxide layer on the surface of the

metal.

For example, carbon, chromium and nickel are added to iron to make

stainless steel. Cutlery made from stainless steel does not corrode.

c. To improve the appearance of a pure metalMetals have lustrous surfaces. However the formation of dull metal oxide on the surface of a metal makes it quickly lose its shine. Alloying helps to keep the metal surface shiny as it prevents the formation of the metal oxide. For example, atoms of antimony and copper are added to tin to make pewter. Pewter has a more lustrous surface than tin.

9.3.5 COMPOSITION, PROPERTIES AND USES OF ALLOYS

Alloys Parent metal Other metals Special properties

Main suitable uses

Alnico Fe: (75-49)% Al: (6-12)%Ni: (14-13)%Co: (5-35)%

Strongly magnetic

Permanent magnets

Constantan Cu: 60% Ni: 40% High resistance

Thermocouple

Copper-nickel Cu: 75% Ni: 25% Hard, shining and lasting

Coins

Brass Cu: 70% Zn: 30% Does not corrode easily

Ship boilers

Bronze Cu: 90% Sn: 10% Very hard and strong

Ship propellers

Duralumin Al: 95% Cu: 3%Mn: 1%Mg: 1%

Strong and light

Aircraft bodies

Magnaleum Al: 70% Mg: 30% Hard but light Aircraft structures

Pewter Sn: 97% An and Cu: 3%

Hard and shining

Decoration items and gifts

Solder Pb: 70% Sn: 30% Low melting point

Soldering wire

Stainless steel Fe: 74% Cr: 18%Ni: 8%

Strong and does not rust

Hospital and chemical equipment, cutlery

Soft steel Fe: 99.8% C: 0.2% Malleable, ductile

Cables, nails, chains

Medium steel Fe: (99.8-99.4)%

C: (0.2-0.6)% Stronger than soft steel

Railways, cantilevers

High carbon steel

Fe: (99.4-98.5)%

C: (0.6-1.5)% Very hard Knives, springs

9.4 SYNTHETIC POLYMERS9.4.1 MEANING OF POLYMERS

1. Most of the covalent molecules we have studied are small molecules.2. However, some molecules are very big. They are called macromolecules.3. Some macromolecules are formed when a large number of small molecules join

together to form a longer or bigger molecules. The small molecules are called monomers.

4. The big molecules formed are called polymers. Thus, we define polymers as the following:Polymers are large molecules made up of identical repeating sub-units of monomers which are joined together by covalent bonds.

5. The process of forming polymers is called polymerisation.6. If the molecules simply join together, then this type of polymerisation is called

additional polymerisation.7. There are two main groups of polymers:

a. Man-made polymers or synthetic polymers.b. Natral 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 made from smaller molecules that are joined together. Thus, fats, carbohydrates and proteins are natural polymers.

9.4.3 SYNTHETIC POLYMERS1. Synthetic polymers are widely used today.2. Examples of synthetic polymers are polythene, perspex, polyvinyl chloride (PVC)

polystylene and nylon.

Polymer Monomer Use CharacteristicPVC Chloroethene,

C2H3ClDrain pipes, insulation for electric wiring, artificial leather, water-proof clothes, shoes

Tough and flexible

Polythene Ethylene, CH2CH2 Plastic bags, cups, and wrappers

Not easily torn

Polypropene (polypropylene)

Propene CH2CHCH3 Film for packaging, snap-on lids, bottles

Strong and light

Perspex Methyl 2-methyl propenoate CH2C(CH3)COOCH3

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 tapes, 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

Teflon Tetrafluoroethene As a coating for non-stick pots and pans

Non-reactive and non-stick surface

Importance of Polymers1. Polymers products play a very important part in our life. In fact, thousands of

products we use are made from polymers.2. They are used in making household objects such as toys, casing, etc. most textile

materials are mixtures of synthetic fibres and natural fibres.3. In fact, polymers have replaced many natural materials for several reasons.

a. They are relatively cheap.b. They are strong.c. They last for a long time.d. Easy to be moulded or shaped.e. They are very stable and do not corrode.

9.4.4 ENVIRONMENTAL POLLUTION FROM SYNTHETIC POLYMERS1. Land Pollution2. Air Pollution3. Green House Effect

9.5 GLASS AND CERAMICS9.5.1 GLASS

1. Sand mixed with limestone can be melted into a thick, hot liquid.2. When sand is heated to about 1600°C, it flows like a thick liquid.3. if this liquid cools, it forms a clear, solid material with no crystal structure. This

solid material is called glass.4. Glass makers add limestone and sodium carbonate to the melting sand. The

mixture melts at a lower temperature than pure sand alone. This type of glass is used to make bottles, jars and window panes.

5. If lead oxide is used to replace limestone, then the glass is able to bend light in useful ways. This kind of glass is used to make eye glasses, microscopes and telescope lenses.

Type Composition Use Properties Fused silica glass SiO2: 99%

B2O3: 1%Laboratory glass apparatus, mirrors

Very high melting point 1700°C. Transparent to ultraviolet and infrared light. Difficult to form into different shapes. Not easily cracked when temperature changes too fast. Resistant to chemicals

Soda-lime glass SiO2: 75%Na2O: 15%CaO: 10%

Windows, mirrors, bottles

Melting point: 700°C. Easily broken when temperature changes too fast. Changes shape easily with heating. Transmits visible light but absorbs UV radiation.

Borosilicate (pyrex glass)

SiO2: (60-80)%B2O3: (10-25)%Na2O: (3%)Al2O3: (1%)

Used as cooking glassware and in laboratory apparatus such as test tubes and beakers

Low thermal expansion, transparent to visible and infrared light. Not transparent to UV radiation. Can withstand heating at high temperatures.

Optical glass SiO2: 100% Lenses in cameras, spectacles, and projectors

Low thermal expansion, transparent to wide range of wavelengths. Used in optical research.

Lead-crystal glass SiO2: 55%PbO: 30%K2O: 10%Na2O: 3%A;2O3: 2%

Bowls, vases and decorative glasses

Melting point 600°C. High density. High index of refraction. Easily refract light, thus making them shiny.

General Properties of Glass1. Glass can be transparent or translucent.2. They can refract light.3. They are:

a. Hardb. Brittlec. Non reactive to chemicalsd. Good heat insulatorse. Good electric insulators

4. Glass is easy to clean.5. They are not porous.6. However, glass is brittle and can be easily broken.

Use ExampleScientific equipment/apparatus Test tubes, beakers, burettes, flasks,

pipettes, lenses, prismsHousehold equipment Glass, bowls, lamps, bottlesIndustrial equipment Bulbs, glass tubes, optical fibres, televisionBuilding materials Window panes, mirrors

9.5.3 CERAMICS

1. Ceramics are made from clays, such as kaolin. It contains silicates such as

aluminium silicates.

2. Ceramics are hardened by heating them at high temperatures.

3. Like glass, the main component of ceramics are based on silicates.

4. Glass can be melted and remelted as often as it is desired. However, once a

ceramic has been hardened, it is resistant to extreme temperatures.

General Uses of ceramics

1. Ceramics have been used for thousand of years to:

a. Store food.

b. Protect food from moisture.

2. Ceramic are used to make:

a. Roofing tiles

b. Bricks

c. Sewer pipes

3. Ceramics are used as insulators in light fixtures and in electric equipment such as

plugs and lamp holders.

4. Ceramics tiles are the only materials that can withstand the temperature of over

1600°C. Thus, they are used:

a. As heat insulating tiles to protect space shuttles.

b. To line the wall of furnace or oven.

General Properties of Ceramic

1. Ceramics have the following properties:

a. Hard and strong

b. Brittle, (easily broken)

c. Cannot be compressed

d. Easily crack when the temperature changes too quickly

e. Resist moisture

f. Do not conduct electricity

g. Do not conduct heat

h. Can withstand very high temperatures

i. Resistant to action by chemicals

2. The strength of ceramics is due to the strong bonds between the elements in it.

Modified Properties of Ceramics

1. Some specialised ceramics can be made to conduct electricity. They are silicon

carbide SiC and aluminium carbide Al4C3.

2. Some ceramics are made to function as semiconductors. They are used in

microchips.

Properties Uses Examples

Strong and hard Building materials Tiles and pipes

Rust proof and chemical

resistance

Kitchen ware Cups and bowls

Long lasting and pleasing Decorative items Porcelain, pots souvenirs

High melting point Heat insulator Lining of oven and furnace

Sealing surface of space

shuttles

Hard and not compressible Dental and medical uses False teeth and artificial

limbs

Electric insulators Electrical items Spark plugs, insulators in

toaster and electric iron

New Uses of Ceramics

1. Superconductor

2. Engine block

9.6 USES OF COMPOSITE MATERIALS

9.6.1 MEANING OF COMPOSITE MATERIALS

1. Every substance has its advantages and disadvantages.

2. If we can take the best properties of two substances and then put them together,

we produce a composite material that is better than the two original materials.

3. Thus by combining the useful properties of two or more materials, chemists can

produce a new better material called composite material.

4. Composite materials are made p of high-strength fibres. These fibres could be

from:

a. Glass

b. Graphite

c. Ceramics

5. These fibres are usually held together by thermosetting plastics.

6. The fibres provide the support. The surrounding plastic acts to protect the fibres

from breaking.

7. The most commonly used composite materials are polyester reinforced with glass

fibres.

Composite materials Components Uses

Reinforced concrete Steel bars and concrete Used in the construction

industry such as houses,

bridges and offices

Superconductor Yttrium oxide (Y2O3),

barium carbonate (BaCO3),

copper(II) oxide (CuO)

Used in superconductors to

make magnets and

electronic chips

Optic fibres (composite of

glass fibres)

Silica SiO2, sodium

carbonate Na2CO3, calcium

oxide CaO

Used in optic fibres for

communication

Composite of glass fibres

(fibre glass)

Polyester resin glass a. Sports equipment

such as tennis

rackets

b. Boat hulls

c. Model chairs

d. Car panels

Photochromic glass Glass and silver chloride or

silver bromide

Photochromic glass used to

make spectacles