A 40.57 g sample of nicotine is found to be 0.2500 mol. What is the molar mass of nicotine?

1. Molar mass is the mass of a sample divided by the amount of substance it contains. 2. Substituting gives 40.57 g / 0.2500 mol. 3. The division yields 162.3 g/mol. 4. The value 81.13 g/mol is the empirical formula mass, which is half the molar mass here. 5. The value 10.14 g/mol comes from multiplying the mass by the mole count instead of dividing. _Source: OpenStax Chemistry (CC BY 4.0), Ch 3 "Composition of Substances and Solutions", section 3.2 Determining Empirical and Molecular Formulas_