Question

What is the relation between Faraday and electrochemical equivalent?

Answer 1

The relation between Faraday and electrochemical equivalent is rooted in the way electricity interacts with matter, particularly in electrolysis.

Faraday's Laws of Electrolysis describe the amount of substance (in grams) that gets deposited or dissolved at an electrode during electrolysis. These laws are linked to the electrochemical equivalent (denoted as \( z \)), which represents the mass of a substance deposited per unit charge (typically in grams per coulomb).

Faraday’s First Law of Electrolysis:

It states that the amount of substance deposited or dissolved is directly proportional to the amount of electric charge passed through the electrolyte.

Faraday’s Second Law of Electrolysis:

This law states that the amount of substance deposited or dissolved is inversely proportional to the equivalent weight of the substance.

Electrochemical Equivalent (\( z \)):

The electrochemical equivalent (z) is defined as the mass (in grams) of a substance deposited or dissolved by 1 coulomb of charge passed through the electrolyte.

The formula relating Faraday’s constant \( F \) (the amount of charge per mole of electrons, approximately 96,485 C/mol) to the electrochemical equivalent is:

\[
z = \frac{M}{F \times n}
\]

Where:

1. \( M \) is the molar mass of the substance (in grams per mole),
   

1. \( n \) is the number of electrons involved in the reaction (valency of the ion),
   

1. \( F \) is Faraday's constant.
   

Key Relationship:

1. Faraday's constant tells us how much charge is needed to transfer one mole of electrons, and the electrochemical equivalent tells us how much mass of a substance is deposited or dissolved per unit charge.
   

  
In essence, the electrochemical equivalent gives a practical way of relating the total charge passed in an electrochemical process to the amount of substance involved, with Faraday’s constant providing the necessary link between charge and mole of electrons.