Name: Gibbs Free Energy, EMF and Equilibrium Constant
Uploaded: 2019-07-19
Duration: 6 min 15 s
Description: There are various thermodynamic parameters that are to be considered while studying the working of an electrochemical cell. Let's learn about them here!

Question

State and explain Faraday's laws of electrolysis.

Accepted Answer

First Law of Electrolysis It is one of the primary laws of electrolysis. It states, during electrolysis, the amount of chemical reaction which occurs at any electrode under the influence of electrical energy is proportional to the quantity of electricity passed through the electrolyte.

$On passing Q electricity amount W of substance is deposited, which is direct proportional to each other . W \infty Q [amount of charge = Q, current = I in amperes passed for time = t \sec .] W \infty It W = ZIt {z = electrochemical equivalent}$

Second Law of Electrolysis During electrolysis, when the same quantity of electricity passes through the electrolytic solution, a number of different substances liberated are proportional to their chemical equivalent weights (Equivalent weight is defined as the ratio of the atomic mass of metal and the number of electrons required for reducing the cation).

From these laws of electrolysis, we can deduce that the amount of electricity needed for spontaneous redox reaction in a cell depends on the stoichiometry of the electrode reaction.

For example, oxidation of metal into their stable ion forms in an aqueous solution will require the amount of electricity as $M \to M^{n +} + {ne}^{-} for one mole of metal n mole of electrons are released and consequently amount of charges will be consumed . So, amount of charges required Q = N_{A} x q_{e} \Rightarrow Q = 6.023 X 10^{23} X 1.6021 X 10^{- 19} c The charge of one mole of electrons is called Faraday' s Constant and is denoted by F; Faraday' s constant is equal to \Rightarrow 96485 C = 1 F, The unit of F is Coulombs per mole for sodium Na \to {Na}^{+} + 1 e^{-}; 1 F electricity is required for Copper Cu \to {Cu}^{2 +} + 2 e^{-}; 2 F electricity is required for aluminium Al \to {Al}^{3} + 3 e^{-}; 3 F electricity is required .$

This quantity of electricity is defined as one Faraday and is denoted by F. Hence; one Faraday is defined as the charge carried per unit mole of electrons.

State and explain Faraday's laws of electrolysis.

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