The device in which conversion of electrical energy into chemical energy is done is known as electrolytic cell. An electrolytic cell consists of a vessel for electrolytic solution or molten electrolyte in which two metallic electrodes connected to a source of electric current are immersed. If an electrolytic solution consists of more than two ions then during electrolysis all the ions are not discharged simultaneously but certain ions are liberated at the electrode in preference to the others. This is based on the principle of preferential discharged theory which states that the ion which requires least energy is discharged first.
