5Fe3O4 + MnO4- + 48H+ == 15Fe3+ + Mn2+ + 24H20
Cr2O72- + 6I- + 13H+ == 2Cr3+ + 3I2 + 7H20
3H202 + 2Cr3+ + 10(OH-) == 2CrO42- + 8H20
2MnO4- + 5(H2O2) + 6H+ == 2Mn2+ + 5O2 + 8H20
基本思路是化合价升降配主要产物,电荷守恒,原字守恒配次要产物.