Question

For the estimation of nitrogen, $1.4g$ of an organic compound was digested by Kjeldahl method and the evolved ammonia was absorbed in $60mL$ of $\frac{M}{10}$ sulphuric acid. The unreacted acid required $20ml$ of $\frac{M}{10}$ sodium hydroxide for complete neutralisation. The percentage of nitrogen in the compound is :

• A. $3\%$
• B. $5\%$
• C. $6\%$
• D. $10\%$

Answer 1

The correct option is D $10\%$

$\%$ of $N=\frac{1.4\times milliequivalentsofacidconsumed}{massoforganiccompound}$

Meq. of acid consumed by $N{H}_3=$ Total Meq of $H_{2}S{O}_4-$ Meq. of acid consumed by $NaOH$

$=(60\times \frac{1}{10}\times 2)-(20\times \frac{1}{10}\times 1)$$=10$ Meq.
$\therefore \%$ of $N=\frac{1.4\times 10}{1.4}=10\%$