Question

Explain giving equation, what happens when:

ZnCO₃ is heated in the absence of air?

Answer 1

When zinc carbonate is heated in the absence of air, it is converted to zinc oxide with the evolution of carbon dioxide gas. This is one of the methods used to convert concentrated metal carbonates into metal oxides during metal extraction. This method is called calcination. The given zinc carbonate is nothing but calamine ore of zinc, which gets converted to zinc oxide on calcination.

\[\ce{\underset{(Calamine ore)}{\underset{Zinc carbonate}{ZnCO3_{(s)}}} ->[Calcination] \underset{Zinc oxide}{ZnO_{(s)}} + \underset{Carbon dioxide}{CO2_{(g)}}}\]