Explain giving equation, what happens when: (a) ZnCO3 is heated in the absence of air? (b) a mixture of Cu2O and Cu2S is heated?

Solution:

(a) Zinc carbonate decomposes into zinc oxide and carbon dioxide when heated rapidly in the absence of air.

ZnCO₃(s) → ZnO(s) + CO₂

(b) Copper metal and sulphur dioxide are formed when copper (I) oxide interacts with copper (I) sulphide.

2Cu₂O(s) + Cu₂S → 6Cu(s) + SO₂(g)