Final answer:
To find the empirical formula of a compound, the percentages of elements are first converted to grams, assuming a 100g sample, then to moles by dividing by atomic weights, and finally to the simplest whole number ratio to get the empirical formula.
Step-by-step explanation:
To determine the empirical formula of a compound with a given percentage composition, we start by assuming we have a 100 gram sample of the compound. This simplifies the math because the percentages can directly be converted into grams. For a compound with 52.2% carbon (C), 13.0% hydrogen (H), and 34.8% oxygen (O), we can express this as having 52.2 grams of carbon, 13.0 grams of hydrogen, and 34.8 grams of oxygen.
We then convert these masses into moles by dividing by the respective atomic weights: carbon (12.01 g/mol), hydrogen (1.008 g/mol), and oxygen (16.00 g/mol). For carbon, we have 52.2g / 12.01 g/mol, for hydrogen, 13.0g / 1.008 g/mol, and for oxygen, 34.8g / 16.00 g/mol.
Once we have the moles for each element, we divide all by the smallest number of moles to find the simplest whole number ratio. This ratio gives us the empirical formula. For precise calculations, the exact number of moles should be used and rounded properly to obtain the most simplified whole number mole ratios.