Question

$0.1$g organic substance in Kjeldahi's method produced some ammonia gas which is absorbed by $40$ ml $0.2$N $H_{2}S{O}_4$ solution. This solution required $20$ ml $0.1$N $NaOH$ for complete neutralisation. Percentage of $N$ in organic compound will be:

• A. $84\%$
• B. $74\%$
• C. $36\%$
• D. $42\%$

Answer 1

The correct option is A $84\%$

$\%N=(\frac{N{H}_3}{W}\times 14)\times 100\%$

moles of $H_{2}S{O}_4=\frac{40\times 0.2}{1000}=\frac{0.8}{100}$

moles of $NaOH=\frac{20\times 0.1}{1000}=\frac{0.2}{100}$ $\therefore$ left $=\frac{1}{100}\left(0.80\right)$

Now, $N{H}_3=\frac{0.6}{100\times 0}\times 1\frac{0.56}{100\times 0.1}\times 14\times 100=84\%$