Question

The insulating and packing material Styrofoam is a dating and packing material Styrofoam is a polymer of styrene. Find the molecular formula of sy ene given its percent composition: 922 775 H The approximate molar mass of styrene is 104 g/mol. A) CHE BỊ CH C)C12H D) CH12 E) C8Hg

Answer 1

Explanation:

In order to find the molecular formula, we have to find the empirical formula first of all.

It is known that is a styrofoam, elements present are carbon and hydrogen atoms.

Element     %         Atomic mass       Molar ratio           Simple ratio

    C        92.25          12.01              $\frac{92.25}{12.01}$ = 7.68                 $\frac{7.68}{7.68}$ = 1

     H        7.75            1.008            $\frac{7.75}{1.008}$ = 7.68                 $\frac{7.68}{7.68}$ = 1

As empirical formula of styrofoam is C_{x}H_{x}.

Hence, empirical mass = (12.01 + 1.008) g/mol = 13.018 g/mol = 13.0 g/mol (approx)

Molar mass given is 104 g/mol.

So,     $\frac{\text{molar mass}}{\text{empirical formula mass}}$ = $\frac{104}{13.0}$ = 8

Thus, we can conclude that molecular formula of the given styrene is $C_{8}H_{8}$.