Q. Number of hydrogen atoms per molecule of a hydrocarbon A having $85.8 \%$ carbon is_____ (Given: Molar mass of $A =84 \,g \,mol ^{-1}$ )
Solution:
Element
Percentage
Mole
Mole ratio
C
85.8
$\frac{85.8}{12}=7.15$
1
H
14.2
$\frac{14.2}{1}=14.2$
2
Empirical formula $\left( CH _2\right)$
$14 \times n =84$
$n =6$
$\therefore$ Molecular formula $C _6 H _{12}$
| Element | Percentage | Mole | Mole ratio |
|---|---|---|---|
| C | 85.8 | $\frac{85.8}{12}=7.15$ | 1 |
| H | 14.2 | $\frac{14.2}{1}=14.2$ | 2 |