Question

How does Cu₂O act as both oxidant and reductant? Explain with proper reactions showing the change of oxidation numbers in each example.

Answer 1

Cu₂O undergoes disproportionation to form Cu²⁺ and Cu.

2Cu²⁺(aq) > Cu²⁺(aq) + Cu(s)

Thus, Cu₂O acts both as an oxidant as well as a reductant.

(i) When heated in air, Cu₂O is oxidized to CuO;

and Cu₂O acts as a reductant and reduces O₂ to O^2-

(ii) When heated with Cu₂S it oxidizes S^2- to SO₂ and hence Cu₂O acts as an oxidants