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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) + Na2CO3(aq) 2NaCl(aq) + CO2(g) + H2O(l)
dioxide gas is identified with the usual
(see other examples).
Some carbonates change colour during thermal decomposition.
oxide + carbon dioxide
CuCO3(s) CuO(s) + CO2(g)
Copper carbonate is green and becomes copper oxide which is black.
zinc carbonate zinc oxide + carbon dioxide
ZnCO3(s) ZnO(s) + CO2(g)
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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