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Calcium carbonate

Products from calcium carbonate

For your exam, you need to know how calcium hydroxide is obtained from calcium carbonate.

Making calcium oxide

If calcium carbonate is heated strongly, it breaks down to form calcium oxide and carbon dioxide. Calcium oxide is yellow when hot, but white when cold.

Here are the equations for this reaction:

calcium carbonate right facing arrow with heat calcium oxide + carbon dioxide

CaCO3right facing arrow with heat CaO + CO2

This is a thermal decomposition reaction.

Making calcium hydroxide

Calcium oxide reacts with water to form calcium hydroxide, which is an alkali. Here are the equations for this reaction:

calcium oxide + water → calcium hydroxide

CaO + H2O → Ca(OH)2

A lot of heat is produced in the reaction, which may even cause the water to boil.

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