The empirical formula for carbohydrates is CH2O. The molecular weight for a particular carbohydrate is 90.09 grams. What is the molecular formula for that carbohydrate? (atomic masses: C =12.0107; H = 1.00794; O = 15.9994)
We find the weight of the empirical formula: 12.0107 + 2 x 1.00794 + 15.9994 = 30.03
Now, we divide the molecular weight by the weight of the empirical formula to find the number of times the empirical formula repeats: 90.09 / 30.03 = 3