Cu(s) Cu 2+ (aq) + SO 4 2- (aq) Zn(s) Zn 2+ (aq) + SO 4 2- (aq) A COM I I I I >0 e-e- e-e- e-e- Zn (s) = Zn 2+ (aq) + 2 e - Cu 2+ (aq) + 2 e - = Cu (s) Cu 2+ (aq) 2 Cu (s) Zn (s) Zn 2+ (aq) oxydation réduction 2 e - Zn 2+ (aq) Zn (s) Cu (s) Cu 2+ 2 e - NH 4 + NO 3 -