Phenol is a compound that contains 76.57% carbon, 6.43% hydrogen, and 17.0% oxygen. Calculate the empirical formula.

C₆H₆O

Explanation:

The given values are the percentage in mass of each element. Empirical formula is the simplest ratio of atoms presents in a molecule. Thus, the first we need to do is convert this percentage to mass using molar mass of each element:

Moles C:

76.57C * (1mol / 12g) = 6.38 moles C

Moles H:

6.43 * (1mol / 1g) = 6.43 moles H

Moles O:

17.0% * (1mol / 16g) = 1.06 moles O

Dividing each number of moles in the moles of O (The minimum number of moles. Used to obtain "The simplest ratio..."):

C = 6.38 moles C / 1.06 moles O = 6

H = 6.43 moles H / 1.06 moles O = 6

O = 1.06 moles O / 1.06 moles O = 1

That means empirical formula of phenol is: