# Question #c839f

Jan 26, 2017

and 0.9397g of water. Determine the molecular formula for beta carotene. The molar mass is 536.96

#### Explanation:

Let the molecular formula of Beta carotene be ${C}_{x} {H}_{y}$ and the balanced equation of its combustion in excess oxygen is as follows.

${C}_{x} {H}_{y} + \left(x + \frac{y}{4}\right) {O}_{2} \to x C {O}_{2} + \frac{y}{2} {H}_{2} O$

It is given that $1 g$ beta carotene produces $3.278 g \text{ } C {O}_{2}$ and $0.9397 g \text{ } {H}_{2} O$

Molar mass of BC is $536.96 g \text{/mol}$

So $1 \text{ } m o l \mathmr{and} 536.96 g$ BC will produce $3.278 \times 536.96 \approx 1760.15 g \text{ } C {O}_{2}$ and $0.9397 \times 536.96 \approx 504.58 g \text{ } {H}_{2} O$

Molar mass of $C {O}_{2} = 44 g \text{/mol}$

So number of moles of $C {O}_{2}$ produced $= \frac{1760.15 g}{44 g \text{/mol}} \approx 40 m o l$

Hence number of C-atoms in one molecule of BC is $= 40$ as one molecule of $C {O}_{2}$ contains one atom of Carbon.

Again Molar mass of ${H}_{2} I = 18 g \text{/mol}$

So number of moles of ${H}_{2} O$ produced $= \frac{504.58 g}{18 g \text{/mol}} \approx 28 m o l$

So one mole BC produces $28 m o l$ water which contain $56$ mol atom Hydrogen as one molecule of water contains two atoms of Hydrogen.Hence number of Hydrogen atom present in one molecule of BC is $56$.

Now we can say that molecular formula of BC is ${C}_{40} {H}_{56}$