Question

$0.8g$ of an organic compound was analysed by Kjeldahl's method for the estimation of nitrogen. If the percentage of nitrogen in the compound was found to be $42\%$, then_____ $mL$ of $1M{H}_{2}S{O}_4$ would have been neutralized by the ammonia evolved during the analysis.

Answer 1

Answer: 12

Organic compound: $0.8gm$
wt. of $N=\left(\frac{42}{100}\times 0.8\right)gm$
mole of $N=\frac{42\times 0.8}{100\times 14}=\frac{2.4}{100}mol$
moles of $N{H}_3=\frac{2.4}{100}$
$\underset{\frac{2.4}{100}mole}{2N{H}_3}+\underset{\frac{1.2}{100}mole}{H_{2}S{O}_4}\to {\left(N{H}_4\right)}_{2}S{O}_4$
$\frac{1.2}{100}=1\times V(l)$
$\Rightarrow V_{H_{2}S{O}_4}=\frac{1.2}{100}l=12ml$