Question

$0.2\, g$ of an organic compound was subjected to estimation of nitrogen by Dumas method in which volume of $N _{2}$ evolved (at STP) was found to be $22.400\, mL$. The percentage of nitrogen in the compound is_____.[nearest integer]
(Given: Molar mass of $N _{2}$ is $28\, mol ^{-1}$. Molar volume of $N _{2}$ at $STP : 22.4\, L$ )

Answer 1

weight of organic compound $=0.2\, g$
mass of $N _{2}( g )$ evolved $=\frac{22.4 \times 10^{-3}}{22.4} \times 28$
$=28 \times 10^{-3} g$
$\%$ of $N =\frac{28 \times 10^{-3}}{0.2} \times 100=14$