Question

$0.833$ mole of a carbohydrate with empirical formula $C{H}_{2}O$ , has $10g$ 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 $=10g$
$\because 0.833$ moles of carbohydrate has hydrogen
$10g$
$1$ mole of carbohydrate has hydrogen
$=\frac{10\times 1}{0.833}=12g$
Given, empirical formula of carbohydrate $=C{H}_{2}O$
$\because C{H}_{2}O$ contains hydrogen $=2gmo{l}^{-1}$
$\therefore$ Molecular formula should contain hydrogen
$=\frac{12\times 2}{2}=12$
Molecular formula $=C_6{H}_{12}{O}_6$