H2O First half reaction MnO4−⟶Mn2+.... (i) On balancing MnO4−+8H++5e−⟶Mn2++4H2O..... (ii) Second half reaction C2O42−⟶2CO2 . . . . .(iii) On balancing C2O42−⟶2CO2+2e−... (iv) On multiplying eqn. (ii) by 5 and (iv) by 2 and then adding we get 2MnO4−+5C2O42−+16H+⟶2Mn2++10CO2+8H2O