The mass deposited or liberated in an electrolytic cell is independent of the concentration of the electrolyte, of the temperature, of the solvent or the density of the electrolyzing current, provided the conditions of the cell are such as to deposit or liberate the element. It depends only on the electric charge passed through the solution, and the valence and atomic weight of the material being deposited or liberated.

According to Faraday’s first law the chemical deposition due to flow of electric current through the electrolyte is directly proportional to the quantity of electricity passed through it.

If the mass of ions liberated is m due to w of current of I amperes for t seconded through the electrolyte then according to first law electrolysis of Faraday

M ∝ Q ∝  It                          Since Q = It

Faraday’s second law states that when the same quantity of electricity is passed through several electrolytes then mass of ions liberated are proportional to their respective chemical equivalents or equivalent weights.

i.e.  m ∝ chemical equivalents or equivalent weight
Combining expressions (i) and (ii) we get
m ∝ If x chemical equivalent

or m = Z It where Z is a constant called the electro-chemical equivalent of the substance and its value depends upon the chemical equivalent of the substance which is equal t the ratio of atomic weight and valence of a substance.

The ratio of E.C.E. to chemical equivalent is the same for all substances and is equal to 0.01036.

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