In Dumas' method 292 mg of an organic compound released 50 mL of nitrogen gas $\left(\mathrm{N}_2\right)$ at 300 K temperature and 715 mm Hg pressure. The percentage composition of ' N ' in the organic compound is ________ % (Nearest integer)
(Aqueous tension at $300 \mathrm{~K}=15 \mathrm{~mm} \mathrm{Hg}$)

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Aicharya · Accepted Answer

$\begin{aligned} & \mathrm{n}_{\mathrm{N}_2}=\frac{\mathrm{P}_{\mathrm{N}_2} \cdot \mathrm{~V}}{\mathrm{RT}} \\ & \mathrm{n}_{\mathrm{N}_2}=\frac{700}{760} \times \frac{50}{1000} \times \frac{1}{0.0821 \times 300} \\ & \mathrm{n}_{\mathrm{N}}=2 \times \mathrm{n}_{\mathrm{N}_2} \\ & \text { Mass of } \mathrm{N}=2 \times \mathrm{n}_{\mathrm{N}} \times 14 \\ & \% \mathrm{~N}=\frac{\text { mass of } \mathrm{N}}{\text { mass of organic compound }} \times 100 \\ & \% \mathrm{~N}=\frac{700}{760} \times \frac{50}{1000} \times \frac{2 \times 14}{0.0821 \times 300} \times \frac{1000}{292} \times 100 \\ & \% \mathrm{~N}=18 \%\end{aligned}$

In Dumas' method 292 mg of an organic compound released 50 mL of nitrogen gas $\left(\mathrm{N}_2\right)$ at…

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