Final answer:
To determine a molecular formula from an empirical formula, you calculate the empirical formula mass and then find the ratio of the molecular mass to this value. A molecular formula will be a whole-number multiple of the empirical formula if the molecular mass is itself a multiple of the empirical formula mass.
Step-by-step explanation:
To determine a possible molecular formula based on an empirical formula, we must find the ratio of the molecular mass to the empirical formula mass. If the given empirical formula is C3H5ClO, we would first calculate its empirical formula mass by adding together the atomic masses of each element: (3 × atomic mass of C) + (5 × atomic mass of H) + (1 × atomic mass of Cl) + (1 × atomic mass of O).
Once we have the empirical formula mass, we compare it to the molecular mass, if known. If the molecular mass is a whole-number multiple of the empirical formula mass, the molecular formula would be a corresponding whole-number multiple of the empirical formula (e.g., if the multiple is 2, and the empirical formula is C3H5ClO, the molecular formula could be C6H10Cl2O2). Without the actual molecular mass, we cannot provide a definitive molecular formula, but we can show the approach to figuring it out once that information is available.