If a sample of aluminum oxide (Al2O3) contains 3.35 x 1024 atoms of oxygen, how many moles of aluminum oxide are present?

Question

If a sample of aluminum oxide (Al₂O₃) contains 3.35 x 10²⁴ atoms of oxygen, how many moles of aluminum oxide are present?

Answer 1

To find the answer to this question, we need to ask ourselves how many atoms of oxygen are in a molecule of aluminum oxide. This we use the subscripts of the specific elements in the compound. Here there is a subscript of 3. This means that there are 3 atoms of oxygen for every molecule of aluminum oxide. With this information we can find that there are a total of 1.12 x 10²⁴ molecules of aluminum oxide. From here we use avagadro's number (6.02 x 10²³ molecules/mole) to find that there is 1.86 moles of aluminum oxide present.