Electrochemistry

1. Electrochemical Cell: A device that converts chemical energy into electrical energy or vice versa.

   • Galvanic Cell: Spontaneous reaction generates electricity (e.g., Daniell cell).
   • Electrolytic Cell: Non-spontaneous reaction driven by external current (e.g., electrolysis of water).

2. Faraday’s Laws of Electrolysis:

   • First Law: Mass deposited charge passed.
     , where Z = electrochemical equivalent.
   • Second Law: Mass deposited equivalent weight of ions.

3. Nernst Equation:
   

   • It relates electrode potential to ion concentration.
   • Helps determine cell potential under non-standard conditions.

4. Electrochemical Series:

   • A list of elements arranged by their standard electrode potentials.
   • Predicts redox reaction feasibility: A species with a lower potential gets oxidized.

5. Kohlrausch’s Law:

   • It states that molar conductivity of an electrolyte is the sum of individual ion conductivities.
   • Used to find weak electrolyte conductivity and degree of ionization.

6. Conductivity & Molar Conductivity:

   • Conductivity (κ): Conducting power of a solution, decreases with dilution.
   • Molar Conductivity (): Conductivity per mole, increases with dilution.

7. Gibbs Free Energy & EMF:
   

   • If E > 0, reaction is spontaneous; if E < 0, non-spontaneous.

8. Lead-Acid Battery:

   • Anode:
   • Cathode:
   • Used in vehicles and UPS systems.

9. Primary vs. Secondary Batteries:

   • Primary: Non-rechargeable (e.g., dry cell).
   • Secondary: Rechargeable (e.g., lithium-ion battery).

10. Fuel Cells:

• Convert chemical energy to electrical energy efficiently.
• Hydrogen-Oxygen Fuel Cell:
  • Anode:
  • Cathode:
• Used in spacecraft and electric vehicles.