Salicylic acid, used in the synthesis of aspirin, has mass composition 60.87% C, 4.38% H, and 34.75% O. What is the empirical formula of the compound? 1. C5H5O3 2. C6H7O3 3. C7H6O3 4. C7H3O4 5. C7H7O3 6. C8H5O2

3.

Explanation:

Firstly, what we need to know is that we will be dividing the percentage composition of each element by its relative atomic masses. The relative atomic mass of carbon is 12, the relative atomic mass of oxygen is 16 and the relative atomic mass of hydrogen is 1.

We proceed with the division as follows:

Carbon = 60.87/12 = 5.0725

Hydrogen = 4.38/1 = 4.38

Oxygen = 34.75 / 16 = 2.171875

We now divide by the smallest ratio which is that if oxygen:

Carbon = 5.0725/2.171875 = 2.33

Hydrogen = 4.38/2.171875 = 2.

Oxygen = 2.172/2.172 = 1

We can multiply through by 3

The ratio is 2.33 : 2 : 1 or 7 : 6: 3