Voltaic Cell Simulation

Choose two metal electrodes. The more reactive metal is oxidized at the anode, electrons move through the wire, metal ions are reduced at the cathode, and salt bridge ions move to keep each half-cell electrically balanced.

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salt bridge: NaNO3(aq)

Anode

Cathode

Zn

Cu

Electrons: anode → cathode

Oxidation: metal atoms become ions.

Reduction: ions become metal atoms.

Salt bridge:
ions move to balance charge.

electron metal ion in solution Na+ from salt bridge NO3− from salt bridge plated atoms on cathode

At the anode

Metal atoms lose electrons and enter the solution as ions.

In the wire, electrons flow.

e− through the wire Na+ NO3−

In the salt bridge, ions flow to balance the charge.

At the cathode

Metal ions gain electrons and plate onto the electrode as atoms.

Left electrode Right electrode Reset simulation Pause animation

Zn → Cu about 1.10 V

Half-reactions

Overall reaction

Classroom noteThe anode gets smaller because atoms become ions. The cathode grows because ions become atoms and plate onto the surface.