Question

A $20.0 mL$ solution containing $0.2 g$ impure $H _{2} O _{2}$ reacts completely with $0.316 g$ of $KMnO _{4}$ in acid solution. The purity of $H _{2} O _{2}$ (in \%) is _______.(mol. wt. of $H _{2} O _{2}=34 ;$ mol. wt. of $\left. KMnO _{4}=158\right)$

Answer 1

Eq of $H _{2} O _{2}= Eq$ of $KMnO _{4}$

$x \times 2=\frac{0.316}{158} \times 5$

$x=5 \times 10^{-3} mol$

$m _{ H _{2} O _{2}}=5 \times 10^{-3} \times 34=0.17 gm$

$\% H _{2} O _{2}=\frac{0.17}{0.2} \times 100=85$