Nitrogen gas and hydrogen gas are combined in a reaction to produce ammonia. If 3.0 moles of N2 and 12.0 moles of H2 are present in the mixture, which is the limiting reactant?

The limiting reactant is the N₂

Explanation:

The reaction for production of ammonia is:

N₂ + 3H₂ → 2NH₃

Ratio is 1:3. Let's make a rule of three to solve this:

1 mol of nitrogen is needed to react with 3 moles of hydrogen.

3 moles of nitrogen may react with (3. 3) / 1 = 9 moles of H₂

It is ok because I have 12 moles, so the limiting reactant is the N₂ but let's confirm it.

3 moles of H₂ react with 1 mol of N₂

12 moles of H₂ would react with (12. 1) / 3 = 4 moles of N₂

It's ok to say the N₂ is the limiting because I don't have enough moles to react. I need 4 and I only have 3