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.
   `"ZnCO"_3("s") overset("Heat")(->)"ZnO"("s") + "CO"_2("g")`
2. When a mixture of Cu₂O and Cu₂S is heated we get the pure copper. 
   `2"Cu"_2"O"("s") + "Cu"_2("s") overset("Heat")(->) 6"Cu"("l") + "SO"_2("g")`