# Why are there three moles of oxygen in one mole of potassium nitrate?

##### 1 Answer
Sep 9, 2015

Because by definition you have 1 mol of potassium nitrate. Potassium nitrate in this quantity comprises 1 mol K, 1 mol N, and 3 mol oxygen.

#### Explanation:

If I had a formula unit of $K N {O}_{3}$, clearly there would be only 1 atom of potassium, 1 atom of nitrogen, and 3 atoms of oxygen. If I had 10 formula units of $K N {O}_{3}$, I would have 10 atoms each of potassium and nitrogen, and 30 oxygen atoms. Are you with me? You specified a mole of $K N {O}_{3}$, so the quantities are multiplied by 1 mole.