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Acids and Alkalis

Salts made from an Acid and a Carbonate.

An acid can be neutralised by a metal carbonate.
A carbonate can be an alkali or a base.
The metal carbonate will bubble giving off carbon dioxide gas
and the reaction makes the salt and water.
This can be used as a test to identify carbonate ions.

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

For example

hydrochloric acid zinc carbonate arrow zinc chloride carbon dioxidewater
         2HCl(aq)      +    ZnCO3(s)      arrow     ZnCl2(aq)      +    CO2(g)   +    H2O(l)


hydrochloric acid + magnesium carbonate arrow magnesium chloride + carbon dioxide + water
2HCl(aq)       +            MgCO3(s)              arrow           MgCl2(aq)      +       CO2(g)    +     H2O(l)


sulfuric acid  copper carbonate  arrow  copper sulfate  carbon dioxide  water
H2SO4(aq)    +     CuCO3(s)           arrow       CuSO4(aq)      +    CO2(g)    +     H2O(l)


sulfuric acid  calcium carbonate  arrow  calcium sulfate  carbon dioxide  water
H2SO4(aq)    +       CaCO3(s)          arrow        CaSO4(aq)      +    CO2(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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