Topic overview

Start with the big picture

A redox reaction couples oxidation with reduction, and the OIL RIG mnemonic helps track electron loss and gain. Identifying oxidizing and reducing agents, assigning oxidation numbers, and recognizing disproportionation or comproportionation provide ways to interpret reaction changes. The ion–electron method balances redox equations through half-reactions. Electrochemical principles then connect electron transfer to standard electrode potentials, spontaneity, free energy, and the Nernst equation. Comparing galvanic and electrolytic cells clarifies how spontaneous and externally driven reactions differ while oxidation remains at the anode. The topic also introduces redox titrations, indicators, and the use of the electrochemical series.