Some Basic Concepts Of Chemistry Question 53
Question: A gaseous compound of nitrogen and hydrogen contains 12.5% (by mass) of hydrogen. The density of the compound relative to hydrogen is 16. The molecular formula of the compound is:
Options:
A) $ NH _2 $
B) $ N _3H $
C) $ NH _3 $
D) $ N _2H _4 $
Show Answer
Answer:
Correct Answer: D
Solution:
[d] In an unknown compounds containing N and H given % of H =12.5% % of $ N=100-12.5=87.5% $ Element Percentage Atomic ratio Simple ratio Elements Percentage Atomic ratio Simple ratio H 12.5% $ \frac{12.5}{1}=12.5 $ $ \frac{12.5}{6.25}=2 $ N 87.5 $ \frac{87.5}{14}=6.25 $ $ \frac{6.25}{6.25}=1 $ 2 $ \times $ vapour density = Mol. wt = mol wt. $ =16\times 2=32. $ Molecular formula = n $ \times $ empirical formula mass $ n=\frac{32}{16}=2 $
$ \therefore $ Molecular formula of the compound will be $ ={{( NH _2 )}_2}=N _2H _4 $
