Question

In Dumas’ method for estimation of nitrogen, 0.3g of an organic compound gave 50mL of nitrogen collected at 300K temperature and 715mm pressure. Calculate the percentage composition of nitrogen in the compound. (Aqueous tension at 300K=15 mm).

Answer 1

Volume of nitrogen collected at 300K and 715mm pressure is 50 mL

Actual pressure = 715-15 =700 mm

Volume of nitrogen at STP =273 *700 *50/300 *760

= 41.9 mL

22,400 mL of N2 at STP weighs = 28 g

41.9 mL of nitrogen weighs=28 *41.9 /22400g

Percentage of nitrogen =28 *41.9* 100/22400* 0.3

=17.46%