Question

0.1 mole of carbohydrate with empirical formula CH2O contains 1 gram of hydrogen what is its molecular formula

Answer 1

Given that the empirical formula of the carbohydrate is C $H_{2}$ O, its molecular formula can be written as n(C $H_{2}$ O)

= $C_{n}$ $H_{2n}$ $O_{n}$,

It is given that 0.1 moles of the compound contains 1 gram of H i.e 0.1 mol -> 1 gram of H,

This means (2n)(0.1) moles of H in the compound contains 1 gram of H i.e (2n)(0.1) -> 1 g,

(2n)(0.1) = 1,

2n = 10 or n = 5,

So the molecular formula of CH2O is $C_{5}$ $H_{10}$ $O_{5}$

Answer 2

Given that number of moles of carbohydrate = 0.1 moles.

We know that 1 mole of carbohydrate contains 2n moles of H.

Then 0.1 mole of carbohydrate = 2n * 0.1 moles.

Given that molar mass of hydrogen in 0.1 moles = 1g.

So, 2n * 0.1 = 1

= > 2n = 10

= > n = 5.

Therefore, the molecular formula of the carbohydrate is (C5H10O5).

Hope this helps!