Electrolysis and the electrolytic cell

Electrolysis is the use of electrical energy to carry out a redox reaction in an electrolytic cell, which is composed of a direct current source, e.g. a battery, connected to an electrochemical cell. The term ‘electrolysis’ was coined by Michael Faraday, who developed two laws of electrolysis in 1833.

The simplest electrolytic cell consists of two electrodes dipped in an electrolyte that may be a molten or aqueous compound. The electrodes are connected to each other via a direct current source, which supplies electrical energy for the redox reaction.

The choice of electrolyte is dependent on the objective of the electrolytic process. It could be a compound that assists the extraction of a useful metal, or simply one to maintain the flow of charges in the electrochemical cell. Similarly, the choice of electrodes is dictated by the aim of the process. Atoms of active electrodes may participate directly in the redox reaction in some processes, while inert electrodes like platinum or graphite are used when we want them to function purely as conductors. For example, the diagram above shows the electrolysis of PbBr2, with molten lead bromide being the electrolyte and graphite rods as the inert electrodes.


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