Electrolysis and Faraday's Law – AP Chemistry College Board Revision

Electrolysis and Faraday’s Law

Electrolysis is a process of using an electric current to drive a non-spontaneous chemical reaction.
It involves breaking down compounds into components by adding electricity. This breaking down process is called decomposition.
In this process, an electric current passes through an electrolyte, causing it to decompose into its elements.
The electrolysis process takes place within an apparatus called an electrolytic cell.

An electrolytic cell contains two electrodes (an anode and a cathode) immersed in an electrolyte.
The anode is the electrode where oxidation happens, and the cathode is where reduction occurs.
During electrolysis, cations move towards the cathode and are reduced, whereas anions move towards the anode and are oxidised.
An electric power supply provides the external voltage which drives the non-spontaneous redox reaction.

Faraday’s laws of electrolysis relate the amount of chemical change at an electrode during electrolysis to the quantity of electricity that passes through the solution.

First law:

The first law of Faraday states that the mass of a substance deposited or dissolved at any electrode is directly proportional to the quantity of electricity passed.
This means the more electricity passed through the electrolytic cell, the more it causes chemical decomposition.

Second law:

The second law of Faraday states that when the same quantity of electricity is passed through different electrolytes, the mass of the substances deposited or dissolved is directly proportional to their chemical equivalent weights.
So, different substances need different amounts of electricity for decomposition.

Faraday’s laws are used in many practical applications such as electroplating and electroforming.
Electroplating is the application of a metal coating to a surface - a useful technique for preventing corrosion and producing decorative objects.
Electroforming uses a metal plating process to create free-standing objects. It’s a popular method in industries like jewellery, dentistry, and engineering.
Faraday’s laws also have significant importance in designing electrochemical cells and batteries.