Question

Nitrogen and hydrogen react to form ammonia: N₂(g) + 3H₂(g) → 2NH₃(g). Identify the limiting reactant (hydrogen or nitrogen) in each of the following combinations of starting chemicals.

a) 0.75 moles of nitrogen and 2.5 moles of hydrogen
b) 1.0 mole of nitrogen and 1.0 mole of hydrogen
c) 1.0 mole of nitrogen and 4.0 moles of hydrogen

Answer 1

To find the limiting reactant, compare the actual mole ratio of the reactants provided to the mole ratio required by the balanced equation. In cases a) and c), nitrogen is the limiting reactant, and in case b), hydrogen is the limiting reactant.

Step-by-step explanation:

To identify the limiting reactant in the reaction where nitrogen (N₂) and hydrogen (H₂) form ammonia (NH₃), we need to use the mole ratio from the balanced chemical equation N₂ + 3H₂ → 2NH₃.

• a) For 0.75 moles of nitrogen, the stoichiometry requires 3 x 0.75 = 2.25 moles of hydrogen. Since we have 2.5 moles of hydrogen, which is more than required, nitrogen is the limiting reactant.
• b) For 1.0 mole of nitrogen, we need 3.0 moles of hydrogen. With only 1.0 mole of hydrogen available, hydrogen is the limiting reactant.
• c) In the presence of 1.0 mole of nitrogen, 3.0 moles of hydrogen are required. With 4.0 moles of hydrogen available, we have an excess of hydrogen, making nitrogen the limiting reactant again.