Page 100 - Science Coursebook

7.3 Metal carbonates and acids

Carbonates – such as calcium carbonate – are salts. Carbonates can be formed by the
reaction of a metal with carbonic acid.
We can use carbonates to form other salts by reacting them with an acid.
For example:

sulfuric acid + calcium carbonate → calcium sulfate + water + carbon dioxide
hydrochloric acid + calcium carbonate → calcium chloride + water + carbon dioxide

nitric acid + calcium carbonate → calcium nitrate + water + carbon dioxide
You may remember about the reactions of acids and carbonates from Stage 7, where
you learnt about limestone. Limestone is composed of calcium carbonate. It is damaged
when it reacts with acid rain and erodes.
The general equation for these reactions is:

acid + carbonate → salt + water + carbon dioxide

Questions
A+I 1 Write the word equation for the reaction between
magnesium carbonate and nitric acid.
2 How could you check that the gas given off in these

reactions is carbon dioxide?

Coral skeletons are made of calcium
carbonate. This piece of coral is
reacting in hydrochloric acid. How can
you tell that a reaction is taking place?

Activity 7.3

Preparation of a salt from acid and carbonate

SE You are going to prepare copper chloride, using
the reaction between copper carbonate and copper carbonate
hydrochloric acid.

1 Place 25 cm of hydrochloric acid in a
3
small beaker.
2 Add a spatula of copper carbonate. dilute
hydrochloric
acid

continued ...

98 7 Salts

A+E