methyl salicylate has a mass percent composition of 63.2% C, 31.6% O, and 5.26% H.The mass of one molecule of the compound is 2.53 x 10^-22.Determine the empirical formula and the molecular formula for methyl salicylate.

Answer 1

Take a 100 g sample and convert grams to moles.
63.2/12 = ??moles C
31.6/16 = ??moles O
5.26/1 = ??moles H.

Now find the ratio of these elements t one another with the smallest number being 1. The easy way to do that is to divide the smallest number by itself (which will automatically make that 1.000), then divide the other numbers by the same small number. Round to whole number unless the values are not close to whole numbers. IN this case, they are not so try multiplying all by 2, then 3, then 4, then 5, etc until all end up close to whole numbers. That will be the empirical formula. I ended up with C8H8O3.
The approximate molar mass is the mass of 1 molecule x 6.022E23.
Then molecular formula mass/empirical formula mass = n. Round n to a whole number and that will give you the molecular formula; i.e., (C8H8O3)_n