Electrolysis, applications, Faraday’s laws of electrolysis

1. Electrolysis is a process where electrical energy is used to drive a non-spontaneous chemical reaction.
2. Occurs in an electrolytic cell, which consists of two electrodes immersed in an electrolyte solution.
3. The anode is the site of oxidation (loss of electrons), and the cathode is the site of reduction (gain of electrons).

2. Faraday’s Laws of Electrolysis

1. Faraday's First Law: The amount of substance deposited or liberated at an electrode is directly proportional to the quantity of electricity passed through the electrolyte.
2. Mathematically: m = Z × Q, where:
   • m = mass of the substance (g).
   • Z = electrochemical equivalent (g/C).
   • Q = total charge (Coulombs).
3. Faraday's Second Law: When the same amount of electricity is passed through different electrolytes, the masses of substances deposited or liberated are proportional to their equivalent weights.
4. Faraday's constant (F) is approximately 96,485 C/mol, representing the charge of one mole of electrons.

3. Applications of Electrolysis

1. Electroplating: Coating a metal surface with another metal to prevent corrosion and enhance appearance.
2. Electrorefining: Purification of metals like copper, silver, and gold.
3. Electrolysis of water: Produces hydrogen and oxygen gases for industrial and energy applications.
4. Chlor-alkali process: Produces chlorine, hydrogen, and sodium hydroxide by electrolyzing brine.
5. Electrolytic production: Metals like aluminum are extracted using electrolysis.

4. Key Equations and Relationships

1. The total charge (Q) is calculated as: Q = I × t, where:
   • I = current (amperes).
   • t = time (seconds).
2. Number of moles of electrons (n_e) transferred: 
   n_e = Q / F
3. The equivalent mass (E) is determined using the formula: 
   E = M / n
   • M = molar mass of the substance.
   • n = number of electrons involved in the reaction.

5. Important Points

1. Electrolysis is a key process in industries for metal extraction and refining.
2. Faraday’s Laws establish the quantitative relationship between electricity and chemical change.
3. The anode is positively charged in an electrolytic cell, while the cathode is negatively charged.
4. Applications include electroplating, water electrolysis, and the chlor-alkali process.
5. Faraday’s constant (96,485 C/mol) is fundamental in calculating electrochemical reactions.
6. The mass of a substance deposited or liberated depends on the current, time, and equivalent weight.