Q. The empirical formula of a compound is ${CH}_{2}.$ One mole of this compound has a mass of 42 g. Its molecular formula is
A) $C_{3}H_{6}$
B) $C_{3}H_{8}$
C) ${CH}_{2}$
D) $C_{2}H_{2}$
Explanation
(a)
Weight of empirical formula
$CH_{2} = 12 + (1 \times 2)$
$= 12 + 2$
$= 14$
Mass of one mole of the compound=its molecular weight
=42
$n = \frac{mol.wt.}{empirical\ formula\ wt.} = \frac{42}{14} = 3$
$\therefore$ Mol. formula=(Empirical formula$\times n$)
$= \left( CH_{2} \right) \times 3 = C_{3}H_{6}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.