Answer:
The correct answer is C18H20O2.
Explanation:
Based on the given information, one hundred grams of equilin contains 80.56% Carbon, 7.51% Hydrogen, and 11.95% Oxygen. Thus, by mass it comprises 80.56 g Carbon, 7.51 g Hydrogen, and 11.92 g Oxygen.
The molecular mass of carbon, hydrogen, and oxygen are 12.01 g/mol, 1.008 g/mol, and 16.00 g/mol.
The moles of the elements present can be determined by using the formula,
Moles = Weight/Molecular mass
Moles of C = 80.56 g/12.01 g/mol = 6.708 mol
Moles of H = 7.51 g/1.008 g/mol = 7.45 mol
Moles of O = 11.92 g/16 g/mol = 0.745 mol
This gives the formula of C6.708H7.45O0.745. By dividing the subscripts from the smallest value, the possible whole numbers obtained will be,
6.708/0.745 = 9, 7.45/0.745 = 10, 0.745/0.745 = 1. Now the empirical formula obtained will be, C9H10O
Now dividing the molar mass of equilin, that is, 268 g/mol from the empirical formula mass, that is, 9*12.01 g/mol + 10*1.008 g/mol+ 16.00 g/mol = 134.2 g/mol, we get,
268/134.2 = 2
Now by multiplying the subscripts in the empirical formula with 2, the molecular formula obtained will be,
C18H20O2.
