Empirical formula is the simplest ratio of whole numbers of components in a compound calculating for 100 g of compound C H O mass 64.27 g 7.19 g 28.54 g number of moles 64.27 g / 12 g/mol 7.19 g/1 g/mol 28.54 g / 16 g/mol = 5.356 mol = 7.19 mol = 1.784 mol divide by least number of moles 5.356 / 1.784 7.19 / 1.784 1.784 / 1.784 = 3.002 4.03 = 1.000 rounded off to nearest whole number C - 3 H - 4 O - 1 empirical formula - C₃H₄O
mass of empirical formula = 12 g/mol x 3 + 1 g/mol x 4 + 16 g/mol x 1 = 56 g molecular mass = 168.19 g/mol molecular formula is the actual ratio of elements making up the compound number of empirical units = molar mass of molecule / empirical mass empirical units = 168.19 g/mol / 56 g = 3.00 there are 3 empirical units making up the molecular formula molecular formula = 3 x C₃H₄O
