×

# An organic compound X contains 68.18% carbon 13.64%hydrogen and 18.18%oxygen .The relative formula mass of X=88.Given that C=12,O=16,H=1.Determine its molecular formula?

Jun 22, 2018

We got...${C}_{5} {H}_{12} O$

#### Explanation:

As always, we assume a $100 \cdot g$ mass of the material and interrogate its atomic composition...

$\text{Moles of carbon} \equiv \frac{68.18 \cdot g}{12.011 \cdot g \cdot m o {l}^{-} 1} = 5.68 \cdot m o l .$

$\text{Moles of hydrogen} \equiv \frac{13.64 \cdot g}{1.00794 \cdot g \cdot m o {l}^{-} 1} = 13.53 \cdot m o l .$

$\text{Moles of oxygen} \equiv \frac{18.18 \cdot g}{16.00 \cdot g \cdot m o {l}^{-} 1} = 1.14 \cdot m o l .$

We divide thru by the LOWEST molar quantity to get an empirical formula of ${C}_{\frac{5.68 \cdot m o l}{1.14 \cdot m o l}} {H}_{\frac{13.53 \cdot m o l}{1.14 \cdot m o l}} {O}_{\frac{1.14 \cdot m o l}{1.14 \cdot m o l}} \equiv {C}_{5} {H}_{12} O$...

And here the empirical formula is the SAME as the molecular formula. How do I know?