Question

3 moles of nitrogen and 5 moles of hydrogen react to form ammonia. Use the balanced equation below to determine which is the limiting reactant.
N2 + 3H2 --> 2NH3

Answer 1

Answer:

H₂ is the limiting reactant

Explanation:

Balanced equations demonstrate the ratios of all reactants and products in terms of the number of atoms/molecules or moles;

In the given reaction:

1 mol of N₂ reacts with 3 mol of H₂ to produce 2 mol of NH₃

So the ratio of N₂ to H₂ to NH₃ will be 1:3:2

If we have 3 moles of N₂, we can apply the ratio to find that it will react with 9 moles of H₂ (3× the moles of N₂) to produce 6 moles of NH₃ (2× the moles of N₂);

Similarly, if we have 5 moles of H₂, then applying the ratio, we find that ⁵/₃ or 1.66... moles of N₂ (¹/₃× the moles of H₂) react with 5 moles of H₂ to produce ¹⁰/₃ or 3.33... moles of NH₃ (²/₃× the moles of H₂);

In order for all of the 3 moles of N₂ to react, it would require 6 moles of H₂;

There is only 5 moles of H₂ available, meaning there will be an excess of N₂;

5 moles of H₂ will react with 1.66... moles of the N₂, leaving 1.33... or ⁴/₃ moles of N₂ unreacted;

If the N₂ is in excess, then the H₂ is limited (i.e. the limiting reactant)