Answer:
CH₃ is the empyrical formula for the hydrocarbon, a methyl group
Explanation:
Centesimal composition of hydrocarbon (X g / 100g of compound)
79.89 % C and 20.11 % H
We divide the mass of the composition, by the molar mass of the element:
79.89 g / 12 g/mol = 6.66 moles C
20.11 g / 1 g/mol = 20.11 moles H
We divide again, by the lowest value of each. In this case, 6.66
6.66 moles of C / 6.66 = 1 mol C
20.11 moles of H / 6.66 = 3 mol H
Molecular formula is CH₃
In this case, molecular formula matches the empyrical one.
