Question

$0.833$ mole of a carbohydrate, with empirical formula $ C{{H}_{2}}O $ , has $10 \,g$ of hydrogen. Molecular formula of carbohydrate is :

• A. $C_3H_5O_3$
• B. $C_6H_{12}O_6$
• C. $C_3H_{10}O_5$
• D. $C_3H_{4}O_3$

Answer 1

Answer: (B)

Given: moles of carbohydrate $= 0.833$
Hydrogen $= 10 \,g $
$ \because 0.833$ moles of carbohydrate has hydrogen $= 10\, g$
$ \therefore 1$ mole of carbohydrate has hydrogen $ =\frac{10}{0.833}\times 1 = 12\, g$
Given: empirical formula of carbohydrate $ =C{{H}_{2}}O $
$ \because $ $ C{{H}_{2}}O $ contains hydrogen $= 2 \,g$ hydrogen per mole Molecular formula should contain hydrogen $ =\frac{12}{2}\times 2=12 $
$ \therefore $ Molecular formula of hydro carbon $ ={{C}_{6}}{{H}_{12}}{{O}_{6}} $