Balance the following redox equation without using partial ionic equations: $KNO_2$ $+$ $KMnO_4$ $+$ $H_2SO_4$ $\longrightarrow$ $KNO_3$ $+$ $MnSO_4$ $+$ $H_2O$ $+$ $K_2SO_4$ - Look for the atoms whose oxidation number changes ! -How many electrons are exchanged by each of those atoms?
o.n.($Mn$): $7$ → $2$ : $5 e^-$ exchanged by each $Mn$ atom. o.n.(N): $3$ → $5$ : $2 e^-$ exchanged by each $N$ atom.
How many electrons are exchanged by a "molecule" containing these atoms?
$5 e^-$ exchanged by each $KMnO_4$ $2 e^-$ exchanged by each $KNO_2$.
What is the ratio of these molecules? Finish the balancing!
Ratio 2:5 $5$$KNO_2$ $+$$2$$KMnO_4$ $+$ $3H_2SO_4$ $\longrightarrow$ $5KNO_3$ $+$ $2MnSO_4$ $+$ $K_2SO_4$ $+$ $3H_2O$