Answer
Empirical: $CH$
Molecular: $C_8H_8$
Work Step by Step
Assume a 100 gram sample. Since Carbon $C$ makes up 92.3% of the mass of styrene, we can now say that there is $92.3 g$ of $C$ in the sample and $7.7 g$ of $H$ in the sample. We can now multiply each of those values by the respective atomic mass of their elements (1/12) and (1/1), getting $7.691 mol C$ and $7.7 mol H$. Through dividing each result by the lowest of the mole values, we get $1$ and $1.0011$. Via this mole ratio, we can accurately surmise the empirical formula will be 1:1 Carbon and Hydrogen.
To get molecular formula, we first get the empirical formula mass of the compound. We add $1 atom \times 12 g/mol = 12 g/mol$ and $1 atom \times 1 g/mol = 1 g/mol$ to get the empirical mass of $13 g/mol$. We can now divide the molar mass $104 g/mol$ by the empirical mass $13 g/mol$ to get the value $8$. If we continue the 1:1 ratio in the empirical formula, we retrieve $C_8H_8$.
