A compound is 85.7% C and 14.3% H and has a molar mass of 98g/mol, what is the compounds molecular formula?

Molecular Formula => (CH₂)₇ => C₇H₁₄      

Explanation:

Empirical ratio is calculated from the sequence...

%/100wt => grams/100wt => moles => mole ratio => reduce mole ratio => Empirical Ratio

C: 85.7% => 85.7g => (85.7/12)mol = 7.14 mole

H: 14.3%  => 14.3g =>     (14.3/1)mol = 14.3 mole

C:H mole ratio => 7.14:14.3

Reduced mole ratio (divide by the smaller mole value) => (7.14/7.14):(14.3/7.14) => Empirical Ratio => 1:2 => Empirical Formula => CH₂

Molecular Wt = Whole No. Multiple of Empirical Formula Wt.

M.Wt = N(Emp Wt) => 98g = N(14g) => N = 7

∴Molecular Formula => (CH₂)₇ => C₇H₁₄