It is important to Know that the zinc electrode gradually gets smaller, as it reacts to form zinc ions in solution. Similarly, the copper electrodes grows as copper ions in solution read to form more copper metal.
Half-cell redox reactions
The two half-cell reactions in the Zn/Cu cell are as follows:
- Zn (s) → Zn2+ (aq) +2e– (oxidation half-reaction)
- Cu2+ (aq) + 2e– → Cu (s) (reduction half-reaction)
In the first reaction, electrons are lost by zinc atoms in an oxidation half-reaction. The electrode at which oxidation occurs is the anode.
The two half-cell reactions in the Zn/Cu cell are as follows:
- Zn (s) → Zn2+ (aq) + 2e–
- Cu2+ (aq) + 2e– → Cu (s)
In the second reaction, electrons are gained by copper ions in a reduction half- reaction. The electrode at which reduction occurs is the cathode.
Anode and Cathode
ANODE: The anode is the electrode in a voltaic cell which has a negative sign because electrons flow from it.
CATHODE: The cathode in a voltaic cell has a positive sign.
