Electrolysis of Molten Salts

Key Concepts

Melting a salt enables it to conduct electricity.
The use of inert electrodes, electrodes made of a material that will not take part in the reactions, means the only species present that can take part in the electrolytic cell reactions are the anions and cations of which the salt is composed.
During the electrolysis of a molten salt:
- Oxidation occurs at the anode.
- Anions (negatively charged ions) migrate to the positive anode.
- Reduction occurs at the cathode.
- Cations (positively charged ions) migrate to the negative cathode.
Electrolysis is a non-spontaneous reaction: E^o for the electrolytic cell is negative^*.
Applied emf must be greater than the emf for the cell, ie greater than -E^o.
Mass of substance produced electrolytically is proportional to the quantity of electricity flowing.

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^*This discussion assumes that all species are present in their standard states so that the electrode potentials are standard electrode potentials.

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