Electrolytic Cell: Plating Zinc on Copper Demonstration ...
Connecting the negative lead to the copper electrode supplies electrons to the copper electrode. The Zn 2+ ions in solution near the copper electrode gain electrons to form zinc atoms. The zinc atoms are platted out as metallic zinc, Zn 2 + (aq) + 2e--> Zn (s), on the copper electrode.. Connecting the positive lead to the zinc electrode removes electrons form the zinc electrode.