Browse Questions

A compound of carbon ,hydrogen and nitrogen contains these elements in the ratio 9 : 1 : 3.5.Calculate the empirical formula.If its molecular mass is 108,what is the molecular formula ?

$\begin{array}{1 1}(a)\;C_6H_8N_2&(b)\;C_4H_6N\\(c)\;C_2H_2N&(d)\;CH_4N\end{array}$

The empirical formula =$C_3H_4N$
Empirical formula mass=$(3\times 12)+(4\times 1)+14=54$
$n=\large\frac{Mol.Mass}{Emp.mass}$
$\;\;\;=\large\frac{108}{54}$
$\;\;\;=2$
Thus,molecular formula of the compound =$2\times Empirical\;formula$
$\Rightarrow 2\times C_3H_4N$
$\Rightarrow C_6H_8N_2$
Hence (a) is the correct answer.