Q65 / 180 · NEET 2015 (Phase 1) · Chemistry

In Duma's method for estimation of nitrogen, 0.25 g of an organic compound gave 40 mL of nitrogen collected at 300 K temperature and 725 mm pressure. If the aqueous tension at 300 K is 25 mm, the percentage of nitrogen in the compound is:

  • A
    17.36
  • B
    18.20
  • Correct answer
    C
    16.76
  • D
    15.76

Solution

\(\begin{aligned} & n_{N_2}=\frac{P V}{R T} \\ & =\frac{(725-25) 40 \times 10^{-3}}{760 \times 0.082 \times 300} \\ & n_{N_2}=\frac{28}{760 \times 24.6} \\ & w_{N_2}=\frac{28 \times 28}{760 \times 24.6} \mathrm{~g} \text { of } N_2 \\ & \text {Weight of } \mathrm{N}_2=\frac{28 \times 28}{760 \times 24.6} \mathrm{gm} \\ & \% N_2=\frac{28 \times 28}{\frac{1}{660 \times 24.6}} \times \frac{1}{0.25} \times 100 \\ & =16.77 \% \end{aligned}\)

Hence, the correct answer is option: 'C'.

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