Electrochemistry: Galvanic & Electrolytic Cells

Redox reactions, cell potential, and Faraday's laws

Electrochemistry links chemical reactions to electrical energy. In galvanic (voltaic) cells, spontaneous redox reactions generate electric current. Oxidation occurs at the anode (loses electrons); reduction at the cathode (gains electrons). Electrons flow through the external circuit; ions migrate through the salt bridge to maintain electrical neutrality. Standard reduction potentials (E°) are measured vs the standard hydrogen electrode (SHE). E°cell = E°cathode - E°anode; positive E° → spontaneous. ΔG = -nFE°cell. The Nernst equation adjusts for non-standard concentrations. Electrolytic cells use external voltage to drive non-spontaneous reactions: water splitting (2H₂O → 2H₂ + O₂), electroplating (Cu²⁺ + 2e⁻ → Cu at cathode), and chloralkali process. Faraday's law: mass deposited ∝ charge passed.