In Dumas' method of estimation of nitrogen, of an organic compound gave of nitrogen gas collected ov — Qualitative and Quantitative Analysis Chemistry Question
Question
In Dumas' method of estimation of nitrogen, $0.60 \text{ g}$ of an organic compound gave $80 \text{ mL}$ of nitrogen gas collected over $KOH$ at $350 \text{ K}$ and $695 \text{ mm Hg}$ total pressure. The aqueous tension at $350 \text{ K}$ is $20 \text{ mm Hg}$. Calculate the percentage of nitrogen in the compound. (Calculate to two decimal places and provide the exact numerical answer).
💡 Solution & Explanation
Dry pressure of $N_2 = P_{total} - \text{Aqueous Tension} = 695 - 20 = 675 \text{ mm Hg}$. Volume at STP ($V_{STP}$) = $\frac{273 \times P_1 \times V_1}{T_1 \times 760} = \frac{273 \times 675 \times 80}{350 \times 760} = 55.42 \text{ mL}$. The mass of $N_2$ at STP = $\frac{28 \times 55.42}{22400} = 0.06927 \text{ g}$. Percentage of $N = \frac{0.06927}{0.60} \times 100 = 11.54\%$.