Maqsad logo
Class 9
Forward Chevron
Chemistry
Forward Chevron
Electrochemistry
Forward Chevron
Faraday’s Second Law of Electrolysis

Electrochemistry

Faraday’s Second Law of Electrolysis

Chemistry

FARADY’S SECOND LAW OF ELECTROLYSIS:   

The masses of different substances deposited or liberated when same quantity of current is passed through different electrolytes, connected in series are proportional to their chemical equivalent masses.

Explanation:

Consider three different electrolytes AgNO3_3 , CuSO4_4 and Al2_2 (NO3_3)3_3 solutions connected in series.

Same quantity of current is passed through them and then the masses of Ag, Cu and Al deposited on their respective electrodes would be directly proportional to their equivalent masses.

Equivalent mass: Equivalent mass is a concept in electrochemistry that is used to determine the amount of a substance needed to undergo a redox reaction or to calculate the amount of electricity required to produce a given amount of product.

“Equivalent mass is defined as the mass of a substance that will either donate or accept one mole of electrons. It is expressed in grams per equivalent (g/eq).”

Equivalent mass = molar mass / n where:

  • Molar mass is the mass of one mole of the substance (in grams).

  • n is the number of electrons exchanged per molecule during the redox reaction.

For example:

By passing 96500 coulombs of charge through the electrolytic solutions; Ag deposited would be equal to 108g, that of copper is 31.75g and Al is 9g which are their equivalent masses respectively.

Equivalent mass of silver Ag+1^{+1}   = 108/1  = 108

Equivalent mass of copper Cu+2^{+2} = 63.5/2   = 31.75

Equivalent mass of copper Al+3^{+3} = 27/3       = 9

Faraday:

A Faraday is a unit of electrical charge that is used in electrolysis and electrochemical processes. It is defined as, “the amount of charge required to deposit or liberate one mole of a substance during an electrochemical reaction.” One Faraday is equal to approximately 96,500 coulombs of charge.

Relation between Faraday and Coulombs

The Faraday is related to the coulomb through Faraday's constant, which is the amount of electrical charge carried by one mole of electrons. Faraday's constant is equal to the charge of one mole of electrons, which is approximately 96,500 coulombs per mole of electrons. 1 Faraday “F” = 96500 Coulombs “C”