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Acids and Alkalis

Salts made from an acid and a carbonate.

An acid can be neutralised by a metal carbonate.
The metal carbonate will bubble giving off carbon dioxide gas
and leaving the metal salt and water.
This can be used as a test to identify carbonate ions.

Any chloride or sulfate can be made
by reacting the appropriate metal carbonate
with hydrochloric acid to make the chloride
or sulfuric acid to make the sulfate.

For example

hydrochloric acid + zinc carbonate zinc chloride + carbon dioxide + water
2HCl_(aq)    +       ZnCO_3(s)                  ZnCl_2(aq)      +    CO_2(g)    +     H₂O_(l)

sulfuric acid+copper carbonate    copper sulfate+carbon dioxide+water
H₂SO_4(aq)    +       CuCO_3(s)                  CuSO_4(aq)      +    CO_2(g)    +     H₂O_(l)

sulfuric acid+calcium carbonate calcium sulfate+carbon dioxide+water
H₂SO_4(aq)    +       CaCO_3(s)                  CaSO_4(aq)      +    CO_2(g)    +     H₂O_(l)

Calcium carbonate is limestone. This reaction occurs with acid rain.

The carbonate can be added a little at a time to the acid.
It will bubble and dissolve to form the soluble salt.
When no more carbonate dissolves, the acid has been neutralised.
The undissolved carbonate can be removed from the solution by filtration.
Pure salt crystals can then be crystallised from the neutral solution.

You can also use a metal oxide to make salts in the same way.

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