Electrolytic cell is the type of a cell in which current drive a non-spontaneous redox reaction. Redox reactions are reactions in which the oxidation number of the reactants are changed. To change oxidation number, electrons must either be added to or removed from the reactants. However, to observe the law of conservation of mass, all the electrons removed from one reactant or atom must be added to another one, therefore, the number of species lost by one substance is equal to the number of electrons gained by the other.
