Question

$0.833$ mole of a carbohydrate with empirical formula $CH_{2}O$ , has $10\, g$ of hydrogen. Molecular formula of the carbohydrate is

• A. $C_{3}H_{5}O_{3}$
• B. $C_{6}H_{12}O_{6}$
• C. $C_{3}H_{10} O_{5}$
• D. $C_{3}H_{4}O_{3}$

Answer 1

Answer: (B)

Moles of carbohydrate $= 0.833$
Weight of hydrogen $= 10\, g$
$\because 0.833$ moles of carbohydrate has hydrogen
$10\,g$
$1$ mole of carbohydrate has hydrogen
$=\frac{10 \times1}{0.833}=12\,g$
Given, empirical formula of carbohydrate $=CH_{2}O$
$\because CH_{2}O$ contains hydrogen $=2\,g\,mol^{-1}$
$\therefore $ Molecular formula should contain hydrogen
$=\frac{12 \times2}{2}=12$
Molecular formula $=C_{6}H_{12}O_{6}$