A compound sample contains 1.71 g of carbon and 0.287 g of hydrogen. What is its empirical formula? Use C = 12.01 and H = 1.008 g/mol.

1. Convert carbon to moles: 1.71 g / 12.01 g/mol = 0.142 mol C. 2. Convert hydrogen to moles: 0.287 g / 1.008 g/mol = 0.285 mol H. 3. Divide both by the smaller amount: carbon gives 1.00 and hydrogen gives 0.285 / 0.142 = 2.0. 4. The ratio is one carbon to two hydrogen atoms, so the empirical formula is CH2. 5. C2H4 has the same ratio but is not reduced to smallest whole numbers, so it is not the empirical formula. _Source: OpenStax Chemistry (CC BY 4.0), Ch 3 "Composition of Substances and Solutions", section 3.2 Determining Empirical and Molecular Formulas_