Theoretical Yield Formula
Maximum product from stoichiometry
Concept
Theoretical yield = moles of limiting reactant × (mole ratio product/reactant) × molar mass of product.
Theoretical Yield = nLR × (stoich. ratio) × Mproduct
Example
Reaction: N₂ + 3H₂ → 2NH₃
Given: 10 mol N₂, 20 mol H₂; M(NH₃) = 17 g/mol.
Check limiting reactant: N₂ needs 30 mol H₂ (have 20), so H₂ is limiting.
n(NH₃) from H₂ = 20 mol H₂ × (2 NH₃ / 3 H₂) = 13.33 mol NH₃
Theoretical yield = 13.33 mol × 17 g/mol ≈ 226.7 g
Answer: ≈ 226.7 g NH₃
Common Mistakes
Not identifying limiting reactant
Always determine which reactant runs out first.
Using wrong stoichiometric ratio
Check balanced equation carefully for mole ratios.