# The empirical formula of a compound is CH. The experimental molar mass is 78.12 g/mol. How do you determine the molecular formula of the compound?

Jan 19, 2017

The $\text{molecular formula}$ is always a whole number multiple of the $\text{empirical formula}$.

#### Explanation:

And thus: $\text{molecular formula"=nxx"(empirical formula)}$.

We take the given empirical formula, work out its mass, and then solve for $n$.

So $78.23 \cdot g \cdot m o {l}^{-} 1 = n \times \left(12.011 + 1.00794\right) \cdot g \cdot m o {l}^{-} 1$

Where of course, $12.011$ and $1.00794$ are the atomic masses of carbon and hydrogen in $g \cdot m o {l}^{-} 1$,

$n = \frac{78.23 \cdot g \cdot m o {l}^{-} 1}{\left(12.011 + 1.00794\right) \cdot g \cdot m o {l}^{-} 1} = 6$

And thus the molecular formula $\equiv$ ${\left(C H\right)}_{6}$ or ${C}_{6} {H}_{6}$. What is the likely name of this molecule?