In a compound C , H and N are present in 9 : 1 : 3 . 5 by weight. If molecular weight of compound is 108 , the molecular formula of compound is

Question

In a compound C , H and N are present in 9 : 1 : 3 . 5 by weight. If molecular weight of compound is 108 , the molecular formula of compound is, C 2 H 6 N 2, C 3 H 4 N, C 6 H 8 N 2, C 9 H 12 N 3

MARKS App · Accepted Answer

Element Ratio (by weight) Atomic weight Mol Ratio Simplest Mol Ratio C 9 12 9 12 = 0 . 75 0 . 75 0 . 25 = 3 H 1 1 1 1 = 1 . 00 1 . 00 0 . 25 = 4 N 3 . 5 14 3 . 5 14 = 0 . 25 0 . 25 0 . 25 = 1 ∴ Empirical formula = C 3 H 4 N The empirical formula mass = 3 × 12 + 4 × 1 + 14 = 54 g Given, molecular mass = 108 g Thus, n = 108 54 = 2 Hence, molecular formula = (Empirical formula) × 2 C 3 H 4 N × 2 = C 6 H 8 N 2

Element	Ratio (by weight)	Atomic weight	Mol Ratio	Simplest Mol Ratio
$C$	$9$	$12$	$\frac{9}{12} = 0.75$	$\frac{0.75}{0.25} = 3$
$H$	$1$	$1$	$\frac{1}{1} = 1.00$	$\frac{1.00}{0.25} = 4$
$N$	$3.5$	$14$	$\frac{3.5}{14} = 0.25$	$\frac{0.25}{0.25} = 1$

Search any question & find its solution

Looking for more such questions to practice?