Question

$0.1$ mole of a carbohydrate with empirical formula $CH_2O$ contains $1\, g$ of hydrogen. What is its molecular formula ?

• A. $C_5H_{10}O_5$
• B. $C_6H_{12}O_6$
• C. $C_4H_8O_4$
• D. $C_3H_6O_3$

Answer 1

Answer: (A)

$C_5H_{10}O_5$

Answer 2

$0.1$ mol of carbohydrate with empirical formula $CH_{2}O$ contains $1\, g$ of hydrogen $\therefore$ $1$ mol of carbohydrate with empirical formula $CH_{2}O$ contains $10 \,g$ of hydrogen $= 10\, g$ atoms In $CH_{2}O$ atomic ratio of $C : H : O = 1 :2 : 1$ with $10\, g$ atoms of $H, g$ atoms of carbon $= 5$ and $g$ atoms of oxygen $= 5$ $\therefore$ The molecular formula of the carbohydrate is $C_{5}H_{10}O_{5}$