The equation is: 3 O₂ + 4 Co → 2 Co₂O₃ Oxidation half reaction: Co → Co³⁺ + 3 e Reduction half reaction: O₂ + 4 e → 2 O²⁻ To balance the equation number of electrons lost must be equal to number or electrons gained so we must multiply oxidation half time 4 and reduction half times 3
