When a current is passed through the aqueous solution of a substance, the substance undergoes the chemical change. This effect of current is known as chemical effect of current or electrolysis.
Faraday’s Laws of Electrolysis
Faraday’s First Law
The mass of ions deposited or liberated on an electrode is directly proportional to the amount of charge passing through it.
If ‘m’ be the mass of ions deposited or liberated on an electrode when ‘q’ amount of charge is passed through it, then
m ∝ q
q = I t
i.e. m = z I t,
where ‘z’ is proportionality constant called electrochemical equivalent (e.c.e.) of a substance. Its value depends on the nature of substance.
Faraday’s Second Law
The mass of ions deposited or liberated on different voltameters is directly proportional to their chemical equivalence.
If ‘m1‘ and ‘m2‘ be the masses of ions deposited or liberated on different voltameters whose chemical equivalence are E1 and E2, then
m1 / m2 = E1 / E2