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Water - Solubility - Ions

Negative Ions - Carbonate.

Any carbonate will produce carbon dioxide gas
when you add a dilute acid.

For example, adding hydrochloric acid to sodium carbonate solution

HCl + sodium carbonate sodium chloride + carbon dioxide + water.
2HCl_(aq)  +  Na₂CO_3(aq)           2NaCl_(aq)      +      CO_2(g)  +     H₂O_(l)

The carbon dioxide gas is identified with the usual test
(see other examples).

Some carbonates change colour during thermal decomposition.

copper carbonate    copper oxide  +  carbon dioxide
CuCO_3(s)                  CuO_(s)       +       CO_2(g)

Copper carbonate is green and becomes copper oxide which is black.

zinc carbonate      zinc oxide  +  carbon dioxide
ZnCO_3(s)                ZnO_(s)        +      CO_2(g)

Zinc carbonate is white and becomes yellow zinc oxide.
Zinc oxide is yellow when it is hot
but becomes white again when it cools down.

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