# Given the molar mass of the compound is 186.5 g and the empirical formula is C2H7, what is its molecular formula?

So ${\left(E F\right)}_{n} = M F$. All we have to do is solve for $n$.
i.e. ${\left(2 \times 12.011 + 7 \times 1.00794\right)}_{n} \cdot g \cdot m o {l}^{- 1} = 186.5 \cdot g \cdot m o {l}^{- 1}$. So solve for $n$, and then do the product $\left({C}_{2} {H}_{7}\right) \times n$ to give the molecular formula. Please repost the answer here.