Divide the molar mass of the compound by the empirical formula mass. The result should be a whole number or very close to a whole number. Multiply all the subscripts in the empirical formula by the whole number found in step 2. The result is the molecular formula.
What does deduce the molecular formula mean?
The molecular formula is the summary of all the atoms in one individual molecule - so the molecular formula might not be the same as the empirical formula! In order to deduce the molecular formula from the empirical formula, you ALSO need to know the molecular mass of the molecule from another data source.
Can you simplify a molecular formula?
Empirical Formulas:
Empirical formulas may be molecular formulas themselves or they may be a building block or unit of a larger molecular formula. For example, C5H12cannot be simplified any further because 5 and 12 are not divisible by any common number. Therefore, C5H12 is both an empirical and molecular formula.
