Laws of electrolysis (faraday laws)

(1) Faraday’s first law of electrolysis:-

It states that mass of any substance deposited or liberated at any electrode is directly proportional to the quantity of electricity passed.

W x q

W = Z x q

We know that q = I x t

So W = Z x I x t

W = mass or amount of sub

q = Electricity in coulomb

Z = Proportionality constant or electrochemical equivalent

I = current (in amperes)

t = time (In see)

If I = 1 ampere, t = 1 see then W = Z so electrochemical equivalent of a substance can be defined as the mass of sub. Deposited when I ampere current in passed for 1 second.

z = w/q = Eq.wt. Of sub / 96500 coulombs   

1 faraday = 96500 coulombs = 1 gm equivalent of sub

(2) Faraday’s second law of electrolysis:-

It states that when same quantity of electricity is passed through solutions of different electrolytes connected in series the weight of sub produced at electrodes are directly proportional to their equivalent weights.

e.g. - CuSO₄ and AgNo₃ Sol⁴ are connected in series, if same quantity of electricity is passed then

Weight of Cu deposited/Weight of Ag deposited = Eq. wt. of Cu / Eq. wt. of Ag

W_cu = Z_cu x I_cu x t_cu / Z_Aq x I_Aq x I_Aq         W_Aq = W_cu/W_Aq =  Z_cu/ Z_Aq

1 mole of electron = Auogaero No. = 6.023 x 10²³ e^- &

Charge on 1 mole of e^- = 1.6 x 10^-19 x 6.023 x 10²³

(Faraday constant)= 96500 coulombs = 1 faraday

If n electrons are involved in Reaction, then n faradays of electricity or charge liberate to form 1 mole of substance.

1 mole of sub = n x F

 F = 96500