Final answer:
To determine the empirical formula for a compound, calculate the moles of each element from their percent composition, divide them by the smallest mole value, and write the ratio as subscripts.
Step-by-step explanation:
To determine the empirical formula for a compound, you need to know the percent composition of each element in the compound. In this case, you have been given the percent composition of carbon (C), hydrogen (H), and oxygen (O). To find the empirical formula, you first convert the percentages to grams. Then, calculate the moles of each element by dividing the grams by the molar mass.
Next, divide each element's moles by the smallest mole value. This will give you the simplest, whole-number ratio of the elements in the compound. Finally, write the empirical formula using the ratios as subscripts.
For a compound that contains 40.0% C, 6.71% H, and 53.28% O, the empirical formula would be C2H4O.