Q. 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 :
Solution:
N
H
Mass %
87.5
12.5
Mol
$\frac{87.5}{14}$
$\frac{12.5}{1}$
=6.25
=12.5
1
2
Empirical formula = $NH_{2}$
Since Vapour density = 16
$\therefore $ mol. wt. = 32
$\because$ Molecular formula = n x Emp. formula
$=2\times NH_{2}$
$=N_{2} H_{4}$
| N | H | |
|---|---|---|
| Mass % | 87.5 | 12.5 |
| Mol | $\frac{87.5}{14}$ | $\frac{12.5}{1}$ |
| =6.25 | =12.5 | |
| 1 | 2 |