Faraday's Laws and Applications of Electrolysis

Understanding Electrolysis

Electrolysis is a chemical process that uses electricity to drive a non-spontaneous chemical reaction. It involves the movement of ions in an electrolyte solution to the electrodes, where they undergo chemical changes.

Faraday's Laws of Electrolysis

• First Law: The mass of a substance deposited or liberated at an electrode during electrolysis is directly proportional to the quantity of electricity (charge) passed through the electrolyte.
• Second Law: The mass of different substances deposited or liberated by the same quantity of electricity is proportional to their equivalent weights.

Mathematically, Faraday's first law can be expressed as:

$$m = Z \times Q$$

Where:

• $m$ = mass of substance (in grams)
• $Z$ = electrochemical equivalent (in grams per coulomb)
• $Q$ = total electric charge (in coulombs)

The total electric charge $Q$ can be calculated using:

$$Q = I \times t$$

Where:

• $I$ = current (in amperes)
• $t$ = time (in seconds)

Applications of Electrochemical Cells

Electrochemical cells have various applications in everyday life and industry:

• Electroplating: A process used to coat a metal object with a thin layer of another metal using electrolysis. This improves appearance and resistance to corrosion.
• Extraction of Metals: Electrolysis is used to extract metals from their ores, such as aluminum from bauxite.
• Purification of Metals: Impure metals can be purified by electrolysis, such as refining copper.

Worked Example: Calculating Mass Deposited