In Dumas' method for estimation of nitrogen 1 g of an organic compound gave 150 mL of nitrogen collected at 300 K temperature and 900 mm Hg pressure. The percentage composition of nitrogen in the compound is % (nearest integer) (Aqueous tension at 300 K = 15 mm Hg)
Answer
20
Solution
Pressure of dry N2:
p1 = 900 - 15 = 885 mm Hg
Volume of N2 at STP (p0 = 760 mm Hg, T0 = 273 K):
V0 = p1 V1 T0p0 T1
= 885 150 273760 300
= 158.95 mL
∵ 22400 mL of N2 at STP weighs 28 g,
% of N = 28 V0 10022400 m
= 28 158.95 10022400 1
= 19.87\% 20\%
Answer: 20