# Question #b984f

##### 1 Answer

Jan 23, 2014

A mole ratio consists of whole numbers because atoms and molecules react as whole particles.

If we have a reaction such as

N₂ + 3H₂ → 2NH₃

we know that 1 molecule of N₂ reacts with three molecules of H₂. The molecular ratio is 1:3.

If we multiply everything by Avogadro’s number *N*, we find that *N* molecules of N₂ react with 3 *N* molecules of H₂. The molecular ratio is *N*:3 *N* = 1:3.

But *N* molecules = 1 mol. Therefore

1 mol N₂ reacts with 3 mol H₂. The molar ratio is 1:3.

The molar ratio consists of small whole numbers because it is the same as the ratio of the numbers of reacting molecules.