Galvanic Cell
Definition and meaning of Galvanic Cell in chemistry.
A galvanic cell is an electrochemical device that converts the chemical energy of a spontaneous redox reaction into electrical energy. It is also called a voltaic cell.
In more detail
The cell consists of two half-cells, each with an electrode dipped in an electrolyte, connected by an external wire and a salt bridge (or porous partition). Oxidation occurs at the anode, which is the negative electrode in a galvanic cell, releasing electrons that travel through the external circuit to the cathode, where reduction occurs. Ions migrate through the salt bridge to maintain electrical neutrality in each half-cell. Because the overall reaction is spontaneous, the standard cell potential (E°cell) is positive and the Gibbs free energy change is negative (ΔG° = −nFE°cell).
Key facts
| Field | Physical Chemistry |
|---|---|
| Also known as | Voltaic cell |
| Daniell cell potential | E° = +1.10 V |
| Electrode polarity | Anode negative (oxidation), cathode positive (reduction) |
The Daniell cell pairs a zinc electrode in ZnSO4 solution with a copper electrode in CuSO4 solution. Zinc is oxidized (Zn → Zn2+ + 2e−) at the anode, and copper ions are reduced (Cu2+ + 2e− → Cu) at the cathode, giving E°cell = +1.10 V.
Frequently asked questions
How does a galvanic cell differ from an electrolytic cell?
A galvanic cell uses a spontaneous redox reaction to generate electrical energy, whereas an electrolytic cell uses an external electrical energy source to drive a nonspontaneous redox reaction.
Why is the anode negative in a galvanic cell?
The anode is negative because oxidation there releases electrons, which accumulate and flow out through the external circuit toward the cathode.