Aspirin is C9H8O4 with a molar mass of 180.159 g/mol. Using C = 12.01 g/mol, what is its mass percentage of carbon?

1. Take one mole of aspirin so that molar masses can be used directly. 2. The nine carbon atoms contribute 9 x 12.01 g/mol = 108.09 g/mol. 3. Divide by the molar mass of the compound: 108.09 / 180.159. 4. Multiplying by 100 gives 60.00 percent carbon. 5. The value 4.476 percent is the hydrogen share and 35.52 percent is the oxygen share. _Source: OpenStax Chemistry (CC BY 4.0), Ch 3 "Composition of Substances and Solutions", section 3.2 Determining Empirical and Molecular Formulas_