Question

A sample of $0.50 \,g$ of an organic compound was treated according to Kjeldahl?? method. The ammonia evolved was absorbed in $50 \,mL$ of $0.5\, M \,H_{2}SO_{4}$. The residual acid required $60\, mL$ of $0.5 \,M$ solution of $NaOH$ for neutralisation. What would be the percentage composition of nitrogen in the compound?

• A. $50$
• B. $60$
• C. $56$
• D. $44$

Answer 1

Answer: (C)

$56$

Answer 2

Given : Mass of compound taken = $0.50\, g$ Vol. of $H_{2}SO_{4} = 50\, mL$ Molarity of $H_{2}SO_{4} = 0.5\, M$ Vol. of $NaOH$ required = $60 \,mL$ Molarity of $NaOH$ required = $0.5 \,M$ Method adopted : Kjeldahl?? method Formula Used : $\%$ of $N =\frac{1.4\times M\times2\left[V-\frac{V_{1}}{2}\right]}{m} \ldots\left(i\right)$ By substituting the values in the formula, we get, $\%$ of $N=\frac{1.4\times0.5\times2\left(50-60 /2\right)}{0.5}=56$ $\therefore\%$ of $N$ in the given compound $=56\%$