Galvanic Cell Definition (Voltaic Cell)

What Is a Galvanic Cell?

General schematic of a galvanic cell.
General schematic of a galvanic cell. Todd Helmenstine

A galvanic cell is a cell where chemical reactions between dissimilar conductors connected through an electrolyte and a salt bridge produce electric energy. A galvanic cell can also be powered by spontaneous oxidation-reduction reactions. Essentially, a galvanic cell channels the electrical energy produced by the electron transfer in a redox reaction. The electrical energy or current may be sent to a circuit, such as in a television or light bulb.

The electrode of the oxidation half-cell is the anode (-), while the electrode of the reduction half-cell is the cathode (+). The mnemonic "The Red Cat Ate an Ox" may be used to help remember reduction occurs at the cathode and oxidation occurs at the anode.

A galvanic cell is also called a Daniel cell or a voltaic cell.

How to Set Up a Galvanic Cell

There are two main setups for a galvanic cell. In both cases, the oxidation and reduction half-reactions are separated and connected via a wire, which forces electrons to flow through the wire. In one setup, the half-reactions are connected using a porous disk. In the other setup, the half-reactions are connected via a salt bridge.

The purpose of the porous disk or salt bridge is to allow ions to flow between the half-reactions without much mixing of the solutions. This maintains charge neutrality of the solutions. The transfer of electrons from the oxidation half-cell to the reduction half-cell leads to a buildup of negative charge in the reduction half-cell and of positive charge in the oxidation half-cell.

If there were no way for ions to flow between the solution, this charge build-up would oppose and half the electron flow between the anode and cathode.