Electrochemical oxidation and reduction

Abstract

The electrode reactions which occur when a solution of an ionic solute is electrolyzed involve the gain of electrons by an ion at the cathode, and the loss of electrons by an ion at the anode. The primary electrode reactions can be represented by the ionic equations

EquationSource% MathType!MTEF!2!1!+- % feaagCart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaSaaaqaabe % qaaiaadgeadaahaaWcbeqaaiabgUcaRaaakiabgUcaRiaadwgadaah % aaWcbeqaaiabgkHiTaaakiabg2da9iaadgeacaaMe8Uaamyyaiaads % hacaaMe8UaamiDaiaadIgacaWGLbGaaGjbVlaadogacaWGHbGaamiD % aiaadIgacaWGVbGaamizaiaadwgaaeaacaWGcbWaaWbaaSqabeaacq % GHsislaaGccqGHRaWkcaWGLbWaaWbaaSqabeaacqGHsislaaGccqGH % 9aqpcaWGcbGaaGjbVlaadggacaWG0bGaaGjbVlaadshacaWGObGaam % yzaiaaysW7caWGHbGaamOBaiaad+gacaWGKbGaamyzaaaabaGaamyq % amaaCaaaleqabaGaey4kaScaaOGaamOqamaaCaaaleqabaGaeyOeI0 % caaOGaeyypa0JaamyqaiabgUcaRiaadkeaaaaaaa!6854!]]</EquationSource><EquationSource Format="TEX"><![CDATA[$$\frac{\begin{gathered}{A^+}+{e^-}=A\;at\;the\;cathode\hfill\\{B^-}+{e^-}=B\;at\;the\;anode\hfill \\\end{gathered}}{{{A^+}{B^-}=A+B}}$$

This allows the generalization that oxidation occurs at the anode and reduction occurs at the cathode. Transfer of electrons by electrolysis represents the most direct, although not necessarily the most convenient, method for oxidation or reduction.