Electrolysis and Faraday's Laws - SS2 Chemistry Lesson Note

Electrolysis is a process that uses an electric current to drive a non-spontaneous redox reaction. It involves the decomposition of a compound into its constituent ions or the deposition of ions onto an electrode. In electrolysis, an external power source, such as a battery, is used to provide the electric current that drives the reaction. Electrolytic cells are specifically designed for electrolysis and consist of an electrolyte solution, electrodes, and a power source.

Faraday's First Law of Electrolysis:

Faraday's First Law states that the amount of a substance produced or consumed during electrolysis is directly proportional to the quantity of electric charge passed through the cell. It can be mathematically represented as: moles of substance = (electric charge)/(Faraday's constant) Faraday's constant is the charge of one mole of electrons and is approximately 96,485 C/mol.

Faraday's Second Law of Electrolysis:

Faraday's Second Law states that the mass of a substance produced or consumed during electrolysis is directly proportional to its molar mass. It can be mathematically represented as: mass of substance = (moles of substance) x (molar mass of substance)

Faraday's laws provide a quantitative relationship between the amount of substance produced or consumed during electrolysis, the electric charge passed through the cell, and the molar mass of the substance.

Electrolysis can be used for various applications, including electroplating, electrolytic refining of metals, production of chemical compounds, and water electrolysis for hydrogen production.

Electrolytic cells have two electrodes:

a.    Anode: The electrode connected to the positive terminal of the power source. It attracts negatively charged ions (anions) and undergoes oxidation.

b.    Cathode: The electrode connected to the negative terminal of the power source. It attracts positively charged ions (cations) and undergoes reduction.

During electrolysis, positive ions migrate towards the cathode (where reduction occurs), and negative ions migrate towards the anode (where oxidation occurs). This migration is facilitated by the movement of electrons through the external circuit. The specific products of electrolysis depend on the nature of the electrolyte and the conditions applied, such as the voltage, current, and electrode materials.

The efficiency of electrolysis depends on factors such as the conductivity of the electrolyte, electrode materials, electrode surface area, and current density. The process of electrolysis is important for the production of many industrial chemicals, metal refining, electroplating of objects, and various research and laboratory applications.

Understanding electrolysis and Faraday's laws enables the prediction and control of the amount of substance produced or consumed during the electrolytic process. These laws provide a foundation for the quantitative analysis of electrolysis and its applications in industry and scientific research.