Question

Balance the following equation.
$HN{O}_3+H_{2}S⟶N{O}_2+H_{2}O+S$

Answer 1

Oxidation: $H_2{S}^{2-}⟶S+2e^{-}....\left(1\right)$

Reduction: $\stackrel{+5}{HN{O}_3}+e^{-}⟶\stackrel{+4}{N}{O}_2+H_{2}O....\left(2\right)$

Balancing $H$ atoms in $\left(1\right)$,

$H_{2}S⟶S+2H^{+}+2e^{-}....\left(3\right)$

Balancing $H$ atoms in $\left(2\right)$,

$H^{+}+HN{O}_3+e^{-}⟶N{O}_2+H_{2}O....\left(4\right)$

Multiplying $\left(4\right)$ by $2$ & adding with $\left(3\right)$,

$2HN{O}_3+H_{2}S⟶2N{O}_2+S+2H_{2}O$

This is the balanced equation.