Aspirin is C9H8O4 with a molar mass of 180.159 g/mol. Using H = 1.008 g/mol, what is its mass percentage of hydrogen?

1. Work with one mole of aspirin so molar masses apply directly. 2. The eight hydrogen atoms contribute 8 x 1.008 = 8.064 g/mol. 3. Divide by the compound molar mass: 8.064 / 180.159. 4. Multiplying by 100 gives 4.476 percent hydrogen. 5. The value 0.560 percent counts only one hydrogen atom, and 8.064 percent quotes the gram figure as a percentage. _Source: OpenStax Chemistry (CC BY 4.0), Ch 3 "Composition of Substances and Solutions", section 3.2 Determining Empirical and Molecular Formulas_