Question

What happens when

1. ZnCO₃ is heated in the absence of oxygen?
2. a mixture of Cu₂O and Cu₂S is heated?

Answer 1

1. When ZnCO₃ is heated in the absence of oxygen, zinc oxide and carbon dioxide are liberated.
   ${\displaystyle {\text{ZnCO}}_3\left(\text{s}\right)\stackrel{\text{Heat}}{\to }\text{ZnO}\left(\text{s}\right)+{\text{CO}}_2\left(\text{g}\right)}$
2. When a mixture of Cu₂O and Cu₂S is heated we get the pure copper. 
   ${\displaystyle 2{\text{Cu}}_2\text{O}\left(\text{s}\right)+{\text{Cu}}_2\left(\text{s}\right)\stackrel{\text{Heat}}{\to }6\text{Cu}\left(\text{l}\right)+{\text{SO}}_2\left(\text{g}\right)}$