How do you determine the empirical and molcular formulas of a compound?

Question

stmoney · Answer

Depends on the information given. If given %'s of each element, convert the percents into grams of each element. Convert the grams of each element into the moles of each element. Looking at the moles of each element, divide the smallest number of moles by all the other moles - this will find you your subscripts for your empirical formula. 

For molecular formula, you will likely be given an experimental molar mass. The experimental molar mass divided by the molar mass of the empirical formula gives you a "factor". multiply the subscripts of your empirical formulas by this factor to find the molecular, or true, formula. Your molecular formula can be the same as your empirical.