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 arrow sodium chloride + carbon dioxide + water.
2HCl(aq)  +  Na2CO3(aq)   arrow        2NaCl(aq)      +      CO2(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  Arrow and Heat  copper oxide carbon dioxide
CuCO3(s)          arrow        CuO(s)       +       CO2(g)

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


zinc
carbonate  
Arrow and Heat   zinc oxide carbon dioxide
ZnCO3(s)        arrow        ZnO(s)        +      CO2(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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