m = (M × I × t) / (n × F)
Electrolysis uses electric current to drive a non-spontaneous chemical reaction. Faraday's first law: the mass of substance deposited is proportional to the charge passed (Q = I × t). Faraday's second law: the mass deposited is proportional to the equivalent weight (M/n). Combined: m = MIt/(nF), where F = 96,485 C/mol (Faraday's constant). For example, electroplating copper (Cu²⁺ + 2e⁻ → Cu): with 5 A for 1 hour, mass = (63.546 × 5 × 3600)/(2 × 96485) = 5.93 g. Applications include electroplating, electrorefining of metals, production of aluminum (Hall-Héroult process), chlorine/caustic soda (chloralkali process), and water electrolysis for hydrogen production.