Neet Solved Paper 2015 Question 31
Question: In Duma’s method for estimation of nitrogen, 0.25g 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
Options:
A) 17. 36
B) 18.20
C) 16.76
D) 15.76
Show Answer
Answer:
Correct Answer: C
Solution:
Experimental values $ {P _{N _2}}\ =P _{total}\ -{P _{H _2O}}\ =725\ -25\ =700\ mm $
According to Duma’s method for estimation of N,
Weight of nitrogen $ =\frac{pVM}{RT} $
where, p is pressure = 700 mm V of nitrogen = 40mL M molecular mass of
$ N _2=28 $ $ R-0.0821 $ $ T-300K=\frac{700\times 40\times 28}{760\times 1000,\times 300,\times 0.0821}=0.042g $
$ \therefore $ % of nitrogen $ =\frac{0.042}{0.25}\times 100=16.573% $
