Cr2+ -> Cr3+ + e-
Co2+ + 2e- -> Co
transferred electron을 맞추기 위해서
2Cr2+ -> 2Cr3+ + 2e-
Co2+ + 2e- -> Co
두 equation을 더합니다.
2Cr2+ Co2+ + 2e--> 2Cr3+ + 2e- + Co
2Cr2+ Co2+-> 2Cr3+ + Co
reactant side charge = (+2) * 2 + (+2) * 1 = +6
product side charge = (+3) *2 = +6
동일하지요 :)