What is z in Faraday's law?

In the context of electrolysis and Faraday's laws, z represents the electrochemical equivalent, also known as the proportionality constant.

Electrochemical Equivalent (z) Explained

The electrochemical equivalent (z) is a crucial parameter when studying electrolysis. It directly relates the amount of substance deposited or liberated at an electrode to the quantity of electric charge passed through the electrolytic cell. It is defined as the mass of a substance deposited or liberated at the electrode when one coulomb of charge passes through the electrolyte. According to the reference provided, z is the proportionality constant with unit grams per coulomb (g/C).

Key Features of the Electrochemical Equivalent

• Definition: The mass of a substance deposited or liberated at an electrode per unit charge (1 Coulomb).
• Units: Grams per Coulomb (g/C).
• Significance: It directly relates the mass of a substance produced during electrolysis to the electric charge used.

Formula

The relationship involving z is often expressed as:

m = zQ

Where:

• m is the mass of the substance deposited or liberated (in grams).
• z is the electrochemical equivalent (in g/C).
• Q is the quantity of electric charge passed (in Coulombs).

Example

If the electrochemical equivalent (z) of a metal is 0.001118 g/C, this means that for every Coulomb of charge that passes through an electrolytic solution containing ions of that metal, 0.001118 grams of the metal will be deposited at the cathode.