# How do you calculate the molecular formula of a compound with the empirical formula C_n H_(2n) O and a molar mass of 150 g/mol?

Apr 10, 2017

Divide the empirical formula into the the molecular mass to find the number n and then put n into the chemical formula

#### Explanation:

It would help if there was an n under the O but assume the formula has an n under the O the empirical formula has the ratio of

1 $C$ : 2 $H$ : 1 $O$
We now define the mass if n=1

1x $C$ = 1 x12u = 12u (=12 gram/mol)

2x $H$ = 2 x 1u = 2u

1 x $O$ = 1 x 16u = 16u
Adding them all together gives the mass per n=1

12 + 2 + 16 = 30 g/mol

Divide 150 g/mol by 30 g/mol to find the number of empirical units (which is n).

$\frac{150}{30} = 5$

So we get n = 5, putting this back into the formula gives the solution

${C}_{5} {H}_{10} {O}_{5}$