What is the empirical formula for a substance containing 37.5 grams of carbon, c, 12.5 grams of hydrogen, h, and 50.0 grams of oxygen, o?

CH4O First, look up the atomic weights of the involved elements Atomic weight carbon = 12.0107 Atomic weight hydrogen = 1.00794 Atomic weight oxygen = 15.999 Now determine the number of moles of each element you have moles carbon = 37.5 / 12.0107 = 3.1222 mol moles hydrogen = 12.5 / 1.00794 = 12.4015 moles oxygen = 50 / 15.999 = 3.1252 So we have the ratio 3.1222 : 12.4015 : 3.1252 We need to find a ratio of small integers that closely matches the above ratio. First, divide all values by 3.1222 (selected because it's the smallest), giving 1 : 3.972 : 1.001 All of the above values are close to integers, so the ratio is 1 : 4 : 1 This indicates that the empirical formula is CH4O