Finding molecular formula

[chemgal4L]

When finding the molecular formula of a compound, why is it necessary to divide all the moles, by the smallest amount of moles?

[Alex 3F]

To find the ratio of each molecule to each other

[marinah]

Yes, that is correct since you are trying to find the empirical formula, you have to divide by the smallest number to find the ratio and then write the empirical formula (which is itself the ratio of each molecule in the formula). After that, if the question asks for the molecular formula, you do (molecular molar mass/empirical molar mass) in order to get the actual number of atoms present in each molecule of the compound. Empirical= ratio, molecular=actual.