Question

What happens when:
(a)copper powder is heated in a China dish
(b)hydrogen gas is passed over hot copper(ll) oxide?

Answer 1

When copper powder is heated is a China dish the surface of copper powder become coated with black colour substance coper ll oxide

Answer 2

1) When copper metal is heated in presence of oxygen, it gets oxidised to form black colour copper oxide.

2Cu + O2 → 2CuO

2) When hydrogen gas is passed over heated copper oxide, then the black copper oxide is reduced and brown copper metal is obtained.

CuO + H2 → Cu + H2O