c3 chemicals in our lives – risks & benefits lesson 7: making alkalis

C3 Chemicals in Our Lives – Risks & Benefits

Lesson 7: Making Alkalis

ObjectivesMUST describe the first method of manufacturing alkali and the pollution problems it caused

SHOULD explain how one of the pollutants became a source of a useful substance

Key WordsYou need to be able to define the

following:

Textbook Answers1) Salt was too expensive to use industrially because

of the salt tax; an Act ended the tax in 1823.2) Raw materials – salt, coal, limestone; a factory

site; workers; buyers.3) Affected by the fumes of hydrogen chloride and

hydrogen sulphide generated by the process.4) The alkali manufacturers wouldn’t spend money

to clean up their factories if they weren’t forced to.5) Hydrogen and chlorine are gases, colourless and

green respectively; chlorine is a bleach; hydrochloric acid is a solution and is a strong acid.

6) Alkali manufacturers were encouraged to collect as much hydrochloric acid as possible to increase their profits; the factory surroundings were less polluted; people were healthier.

Worksheet AnswersActivity 3 (High demand)1) Chlorine was valuable commodity and

there was lots of waste hydrochloric acid from the alkali industry; chlorine is a green gas and a bleach; hydrochloric acid is a colourless solution and a strong acid.

2) Hydrogen in the hydrochloric acid is oxidised by gaining oxygen to form water; chlorine is oxidised by loss of hydrogen.

3) Yes and no; the Gossage method had been available for years and there was demand for chlorine; the alkali manufacturers needed the spur of the law to improve their works.

Practical Answers

Practical AnswersPart D

1)sodium carbonate + hydrochloric acid sodium chloride + carbon dioxide + water

2)hydroxide + acid salt + water; carbonate + acid salt + carbon dioxide + water

3)a) potassium hydroxide + nitric acid potassium nitrate + water

b) sodium hydroxide + sulfuric acid sodium sulfate + water

c) sodium carbonate + sulfuric acid sodium sulfate + carbon dioxide + water

d) potassium carbonate + nitric acid potassium nitrate + carbon dioxide + water

e) calcium hydroxide + hydrochloric acid calcium chloride + water