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)

$C_{6}H_{12}O_{6}$

Answer 2

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 $=C_{6}H_{12}O_{6}$