GCSE CHEMISTRY - What are the Properties and Uses of Alkalis?

What are the Properties of Alkalis?

All alkalis have a pH greater than 7 and make hydroxide ions in water.

All alkalis will make litmus paper turn from red to blue
and universal indicator will turn blue or purple.

All alkalis react with acids to form a salt and water, see neutralisation.

What are the Uses of Alkalis?

1) Sodium hydroxide is used in the manufacture
of paper, soap and ceramics.
Ceramics include plates, cups, bricks and tiles.
Sodium hydroxide is used as an alkali cleaner and to treat aluminium
before anodising. It is also used to neutralise acids to make salts.

2) Calcium oxide or calcium carbonate is used to remove acidic gases
from a power station chimney to reduce acid rain.
Calcium carbonate has many other uses.

3) Calcium hydroxide (called 'slaked lime', or just 'lime'),
is added to soils or lakes to make them less acidic (see acid rain).
Calcium hydroxide solution (lime water)
is used in the test for carbon dioxide).

4) Ammonia is used in the Haber process to make fertiliser.

5) Indigestion may be caused by
too much hydrochloric acid in the stomach.
Indigestion tablets contain a base such as
magnesium oxide or calcium carbonate to neutralise the acid.

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