# How would you calculate the molecular formula of a compound?

Feb 18, 2016

Divide given molar mass, by "molar mass" which is calculated by you, multiply the answer with all your subscripts, voila

#### Explanation:

Its very simple actually
First, you need the empirical formula, for example, CH20, then you need, the molar mass of the compound,, which is probably stated in the question
Then, you find the "molar mass" of the compound which is given, CH2O, i.e, 12g/mol+2g/mol+16g/mol= 30g/mol
Then, divide the molar mass by the "molar mass" which YOU calculated
$M o l a r M a s s / m o l a r m a s s$= $\frac{150}{30}$= 5
Now, this 5 which you have, multiply all the subscripts in your given empirical formula by 5
i.e ${C}_{\left(1 \times 5\right)} {H}_{\left(2 \times 5\right)} {O}_{\left(1 \times 5\right)}$ - ${C}_{5} {H}_{10} {O}_{5}$
Thus, the molecular formula is ${C}_{5} {H}_{10} {O}_{5}$