# A compounds empirical formula is HO. If the formula mass is 34 amu, what is the molecular formula?

Nov 23, 2016

$\text{Molecular formula}$ $=$ ${H}_{2} {O}_{2}$.

#### Explanation:

The molecular formula is always a whole number mulitple of the empirical formula, and of course the multiple might be $1$.

So here, $\left(\text{Molecular formula}\right)$ $=$ $\left(\text{Empirical formula} \times n\right)$

And thus,

$\left(\text{Molecular mass}\right) = 34 \cdot g \cdot m o {l}^{-} 1 = n \times \left(1.008 + 15.999\right) \cdot g \cdot m o {l}^{-} 1$

Clearly $n = 2$, and the molecular formula of hydrogen peroxide is ${H}_{2} {O}_{2}$.

What is the oxidation number of oxygen in this molecule?