chemistry help please.?

Question

what is the empirical formula of a molecule containig
65.5% carbon
5.5% hydrogen
29.0%oxygen

Answer 1

Since these are weight % and we want to know composition in terms of numbers of atoms, we need to divide each weight % by it's respective atomic weight.

65.5/12.01 = 5.45
5.5/1.01 = 5.45
29.0/16.00 = 1.81

Although these numbers are proportional to the empirical formula, they are not in whole numbers, so we will try dividing all of them by the smallest number and see if we can get the same ratio but in whole numbers.

5.45/1.81 = 3.01
5.45/1/81 = 3.01
1.81/1.81 = 1.00

These are very close to whole numbers, so the empirical formula is: C3H3O

Note that the empirical formula might not be the actual formula! The real formula could be a multiple (2 x, 3 x etc) of the emperical formula.

Answer 2

C11H11O4