$5\times| 2\mathop{O}\limits^{-1}\to \mathop{O_2}\limits^0+2e$
$2\times| \mathop{Mn}\limits^{+7}+5e\to \mathop{Mn}\limits^{+2}$
Thăng bằng e:
$5H_2O_2+ 2KMnO_4+3H_2SO_4\to 5O_2+K_2SO_4+2MnSO_4+8H_2O$
Cân bằng: $Mn, K, O$ (trong $H_2O_2$, $O_2$), $S, H$. Kiểm tra $O$