When heated, a metal carbonate decomposes into a metal oxide and carbon dioxide (CO₂) gas.

Here's a general chemical equation representing this reaction:

M₂CO₃(s) → MO(s) + CO₂(g)

Where:

* M represents the metal

* M₂CO₃ is the metal carbonate

* MO is the metal oxide

* CO₂ is carbon dioxide

Example:

Heating calcium carbonate (CaCO₃) produces calcium oxide (CaO) and carbon dioxide:

CaCO₃(s) → CaO(s) + CO₂(g)