28.2.9—Transition metal redox calculations

In acid, MnO₄⁻ is reduced to Mn²⁺; oxalate, Fe²⁺ or I⁻ are oxidised according to their half-equations. Combine half-equations so electrons, atoms and charge balance.

Use stoichiometric ratios to calculate titres or amounts. For Cu²⁺ + I⁻, iodine forms and can be titrated with thiosulfate in the full analytical method.

MnO₄⁻ + 8H⁺ + 5e⁻ → Mn²⁺ + 4H₂O; Fe²⁺ → Fe³⁺ + e⁻, so one permanganate reacts with five Fe²⁺.

Do not balance oxygen with OH⁻ in an acidic equation without converting correctly, and do not ignore the reaction medium.