Chemistry class 12th Galvanic_Cells_Explanation

Galvanic Cells: Explanation and Working Principle


A galvanic cell (or voltaic cell) is an electrochemical cell that generates electrical energy from
spontaneous redox reactions occurring within the cell. It consists of two half-cells connected by a
salt bridge,
allowing electron flow through an external circuit.


Components of a Galvanic Cell
1. Electrodes: Two metal electrodes (anode and cathode) where oxidation and reduction occur.
2. Electrolyte: Ionic solution that facilitates ion movement.
3. Salt Bridge: Maintains charge balance by allowing ion exchange.
4. External Circuit: Conducts electrons between electrodes.


Working Principle
- Oxidation occurs at the anode, releasing electrons.
- Electrons travel through an external circuit to the cathode.
- Reduction occurs at the cathode, gaining electrons.
- The salt bridge maintains electrical neutrality by allowing ion exchange.


Standard Electrode Potential
The potential difference between an electrode and its solution is called the electrode potential.
Standard electrode potential (E°) is measured under standard conditions (1M concentration, 25°C, 1
atm pressure).
The cell potential is calculated as:
E°cell = E°cathode - E°anode


Example: Daniell Cell
The Daniell cell consists of a Zn electrode in ZnSO4 solution and a Cu electrode in CuSO4 solution.
- Zn oxidizes at the anode: Zn -> Zn2+ + 2e- (oxidation)
- Cu2+ reduces at the cathode: Cu2+ + 2e- -> Cu (reduction)
- The electron flow from Zn to Cu generates an electric current.


Applications of Galvanic Cells
- Used in batteries (e.g., dry cells, lead-acid batteries)