Electrochemical equivalent Z of, a substance is the mass of the substance, in grams which is liberated by the passage of 1C of electricity.
Faraday's constant is a ratio of charge in coulombs to amount of substance singly changed in moles.
For the same quantity of electricity passed through different solutions, the extent of decomposition is proportional to the chemical equivalent of the element. E=PM,P being the valence of atom involved.
and Z=F1×PM=FE ⇒F=ZE