Question

Assign oxidation numbers in the following corrosion reactions for copper. Tell which substances are oxidized and which are reduced. 2Cu (s) + 1⁄2 O2 (g) → Cu2O (s) Cu2O (s) + 1⁄2 O2 (g) → 2CuO (s)

Answer 1

2 Cu + 1/2 O2 --> Cu2O + Cu2O + 1/2 O2 --> 2CUO

Copper is oxidized since it went from being an oxidation number of 0 to +2.