In Dumas 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
- 16.75
- 15.76
- 17.36
- 18.20
Answer
(1) 16.75
Solution
Pressure of dry N2 = 725 - 25 = 700 mm
Volume at STP: V0 = P1 V1T1 T0P0
= 700 40300 273760
= 33.53 mL
∵ 22400 mL of N2 at STP weighs 28 g
⇒ mass of N2 = 28 33.5322400 = 0.04191 g
∴ % of N = 0.041910.25 100 = 16.76 16.75
Answer: (1)