Limiting Reactant and Percentage Yield – Stoichiometry with Particles

What it shows

Reactants always combine in the fixed mole ratio given by the balanced equation. Divide the amount of each reactant in moles (or particles) by its coefficient: the smaller result marks the limiting reactant, which is used up first and decides how much product forms, while the other reactant is in excess. The simulation shows this in two ways, as particles meeting in groups and as a mole–mass table. Comparing the actual yield with the theoretical yield gives the percentage yield. The model assumes each reaction goes to completion with no side reactions.

How to use

Pick a Reaction and a Unit, then drag the two sliders to set the starting amounts. Press React (or tap the particle box) and watch which reactant runs out; Reset puts the reactants back. Read the table row by row. Type a value in the “obtained (actual)” box to see the percentage yield, and check that the total mass is conserved.

Parameters you can change

• Reaction 2H₂ + O₂ → 2H₂O, N₂ + 3H₂ → 2NH₃, CH₄ + 2O₂ → CO₂ + 2H₂O, Fe + S → FeS
• Unit of amount Particles, Moles, Mass (g)
• Amount of the first reactant (in the chosen unit) 0–100
• Amount of the second reactant (in the chosen unit) 0–100
• Actual yield of product (in the chosen unit, 0 = not entered) 0–1000

Questions to explore

1. Mixing 4 g of H₂ with 16 g of O₂, why does O₂ run out first even though there is less H₂ by mass?
2. For N₂ + 3H₂ → 2NH₃, how many moles of H₂ react exactly with 2 mol of N₂?
3. Why is the actual yield of ammonia in industry far below the theoretical yield?