Chemistry Ili

CHEMISTRY FORM 4 CHAPTER 9 : MANUFACTURED SUBSTANCES IN INDUSTRY BY ILI NADHIRAH BINTI NUR`AZMAN CLASS OF 409

CONTENTS 1. 2. 3. 4. 5. 6. 7.

The Manufacture of Sulphuric Acid The Manufacture of Ammonia and Its Salts Alloys Evaluating the Uses of Synthetic Polymers Uses of Glass and Ceramic Evaluating the Uses of Composite Materials Appreciating the Importance of Various Synthetic Industrial Materials

The Manufacture of Sulphuric Acid

1. The manufacturing of sulphuric acid is one of the most important chemical industries at the present time . 2. Sulphuric acid is a non-volatile diprotic acid . 3. Concentrated sulphuric acid is a viscous colourless liquid . The Uses of Sulphuric Acid in Daily Life Sulphuric acid is an important chemical used to make other manufactured substances .

1. To manufacture fertilizers There are many fertilizers that can be made of sulphuric acid. Some of them are: a) Calcium hydrogen phosphate (superphosphate) 2

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+ Ca3(PO4) 2 → Ca(H2 PO4) 2 + 2CaSO4

sulphuric acid + calcium phosphate → calcium hydrogen phosphate

sulphuric acid + tricalcium phosphate → calcium dihydrogen phosphate b) Ammonium sulphate

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+2NH3 → (NH4) 2 SO4

sulphuric acid + aqueous ammonia → ammonium sulphate

sulphuric acid + aqueous ammonia → ammonium sulphate

c) Potassium sulphate

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+2KOH → K2SO4+2H2O

sulphuric acid + potassium hydroxide → potassium sulphate sulphuric acid + potassium 2) To manufacture detergents Sulphuric acid reacts with hydrocarbon to produce sulphonic acid. Sulphonic acid is then neutralized with sodium hydroxide to produce detergents. Examples of sulphuric acid + aqueous ammonia → ammonium sulphate hydrocarbon

sulphuric acid + aqueous ammonia 3) To manufacture synthetic fibres → ammonium sulphate Synthetic fibres are polymers ( long chain molecules). Rayon is an example of a sulphuric acid + is aqueous ammonia → action ammonium sulphate synthetic fibre that produced from the of sulphuric acid on cellulose.

sulphuric acid + aqueous ammonia → ammonium sulphate

4) To manufacture paint pigments The white pigment in paint is usually barium sulphate, BaSO4. The neutralization of sulphuric acid and barium hydroxide produces barium sulphate.

5) As an electrolyte in lead-acid accumulators

6) To remove metal oxides from metal surfaces before electroplating

7) To manufacture pesticides

8) The uses of sulphuric acid in school laboratories are:

a.

As a strong acid

b.

As a drying or dehydrating agent

c.

As an oxidizing agent

d.

As a sulphonating agent

e.

As a catalyst

The Industrial Process in the Manufacture of Sulphuric Acid 1. Sulphuric acid is manufactured by the Contact process.

2. Sulphuric acid is produced from sulfur, oxygen and water via the contact process. 3. The Contact process involves three stages.

Sulphur

→ I

Sulphur dioxide II

→

Sulphur trioxide III

4. Stage I: Production of sulphur dioxide gas, SO2. This can be done by two methods, a)

Burning of sulphur in dry air.

→

Sulphuric acid

+ →

b)

Burning of metal sulphide such as zinc sulphide in dry air. 2ZnS + 3 → 2 + 2ZnO

5. Stage II: Conversion of sulphur dioxide to sulphur trioxide SO3. This is then oxidised to sulfur trioxide under the following conditions: a)

The presence of a vanadium(V) oxide as a catalyst.

b)

A temperature of between 450°C to 550°C.

c)

A pressure of one atmosphere 2 SO2 + O2 →

6. Stage III: Production of sulphuric acid a) Sulphur trioxide is dissolved in concentrated sulphuric acid, H2SO4 to produce oleum, H2S2O7 H2SO4+ SO3 → H2S2O7

b) Oleum is reacted with water to form concentrated H2SO4.

H2S2O7+ H2O → 2 H2SO4 7. In stage II, sulphur dioxide is dried first before being added to dry air to produce sulphur trioxide. This is: a)

To remove water vapour

b)

To remove contaminants

8. In stage III, sulphur trioxide is not dissolved directly in water to produce sulphuric acid. This is because: a)

sulphur trioxide has low solubility in water

b)

sulphur trioxide reacts violently and mists are formed instead of a liquid

Sulphur or metal sulphide

burned in air

Sulphur dioxide,

a) the presence of a vanadium(V) oxide as a catalyst. b) a temperature of between 450°C to 550°C. c) a pressure of one atmosphere , SO3

dissolved in sulphuric acid, H2SO4

, H2S2O7

diluted with equal volume of water H2O

Concentrated sulphuric acid H2SO4

Flowchart of Contact process

Environmental Pollution by Sulphur Dioxide 1. Sulphur dioxide is produced during volcanic eruptions . 2. However, the main source of sulphur dioxide is from the burning of fossil fuels such as petroleum. Most of the fossil fuels contain a certain amount of sulphur. Hence, sulphur dioxide is produced when these fuels are burned. 3. Waste gases from factories also release sulphur dioxide into the atmosphere. 4. The burning of products manufactured from sulphuric acid such as rayon will also produce sulphur dioxide gas. 5. Sulphur dioxide is a poisonous and acidic gas. This gas affects the respiratory system and can cause lung diseases and bronchitis. 6. Sulphur dioxide gas dissolves in atmospheric water to produce a mixture of sulphurous acid, H2SO3 and sulphuric acid, H2SO4. The presence of these acids in rainwater results in acid rain. 7. The effects of acid rain are as follows: a)

Corrodes concrete buildings.

b)

Makes the soil acidic.

c)

Lowers the pH of waters in rivers and lakes.

d)

Depletes essential nutrients for plant growth.

The Manufacture of Ammonia and Its Salts 1. Ammonia, NH3 is a very important compound in industry. 2. The main uses of ammonia: a) To manufacture nitrogenous fertilisers such as ammonium sulphate, ammonium nitrate and urea. b) The liquid form is used as a cooling agent in refrigerators. c) As a raw material to produce nitric acid in the Ostwald process. d) To be converted into nitric acid in order to make explosives. e) As an alkali to prevent the coagulation of latex so that latex can be stored in liquid form. f) To produce ammonium chloride as an electrolyte in dry cells. 1. The manufacture of nitrogenous fertilisers: a) Ammonium sulphate Ammonia reacts with sulphuric acid through neutralisation reaction to produce ammonium sulphate. 2NH3 +

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b) Ammonium nitrate

→ (NH4) 2 SO4