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Electrolysis and Faraday's Law

Electrolysis is a process that uses an electric current to drive a non-spontaneous chemical reaction. Faraday's laws of electrolysis quantify the relationship between the amount of substance produced or consumed at an electrode and the electric charge passed through the system.

Faraday's First Law​

The mass of a substance produced at an electrode is directly proportional to the total electric charge passed through the electrolyte:

m = (Q × M) / (n × F)

Where:

  • m = mass of the substance (grams)
  • Q = total electric charge (coulombs)
  • M = molar mass of the substance (g/mol)
  • n = number of electrons transferred per ion
  • F = Faraday's constant (~96485 C/mol e⁻)

Faraday's Second Law​

For the same quantity of electric charge, the masses of different substances produced are proportional to their molar masses and the number of electrons involved in the electrode reaction.

Applications of Electrolysis​

  • Electroplating: Coating a metal with a thin layer of another metal.
  • Extraction of Metals: Obtaining reactive metals like aluminum from their ores.
  • Electrorefining: Purifying metals such as copper.
  • Production of Chemicals: Such as chlorine and hydrogen from brine.

Key Points​

  • Electrolysis is a practical application of non-spontaneous redox reactions.
  • Faraday’s laws allow calculation of the mass of products or reactants from the amount of charge passed.
  • Understanding electron transfer and stoichiometry is crucial for applying these laws effectively.

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