Question

An organic compound has a molecular mass of ~88 u and a mass percent composition of 54.55% C, 9.09% H and 36.36% O. What is the molecular formula of this compound?

Answer 1

they are all parts of 100

54.55% is .5455
9.09% is .0909
36.36% is .3636

These numbers are all portions of the 88 g/mol of the organic acid!

88 x .5455 = 48 g of C
88 x .0909 = 8.0g of H
88 x .3636 = 32 g of O

Now that you know what portions of the organic acid are what, we will use the atomic masses of each element to put them in perspective of moles!

48 / 12 = 4 mol of C
8 / 1 = 8 mol of H
32 / 16 = 2 mol of O

Therefore, your molecular formula is C4H8O2

We're not done though! The empirical formula is extremely easy to find from here! Since your lowest number of moles is 2 (oxygen) you divide all the coefficients by 2 as well to get your empirical formula!

4/2----> 2 mol of C
8/2----> 4 mol of H
2/2----> 1 mol of O

Therefore, your empirical formula is C2H4O

I really hope I was able to help! Good luck with everything :).