Faraday's laws of electrolysis

Faraday's laws of electrolysis are quantitative relationships based on the electrochemical research published by Michael Faraday in 1833.

[1][2][3] Michael Faraday reported that the mass (m) of a substance deposited or liberated at an electrode is directly proportional to the charge (Q, for which the SI unit is the ampere-second or coulomb).

Here, the constant of proportionality, Z, is called the electro-chemical equivalent (ECE) of the substance.

Thus, the ECE can be defined as the mass of the substance deposited or liberated per unit charge.

Faraday discovered that when the same amount of electric current is passed through different electrolytes connected in series, the masses of the substances deposited or liberated at the electrodes are directly proportional to their respective chemical equivalent/equivalent weight (E).

[3] This turns out to be the molar mass (M) divided by the valence (v) A monovalent ion requires one electron for discharge, a divalent ion requires two electrons for discharge and so on.

where Faraday's laws can be summarized by where M is the molar mass of the substance (usually given in SI units of grams per mole) and v is the valency of the ions .

where wi represents the mass fraction of the ith element.

In the more complicated case of a variable electric current, the total charge Q is the electric current I(τ) integrated over time τ: Here t is the total electrolysis time.