Limiting reagents and theoretical yield
≈ 48 minLimiting reagents and theoretical yield
When reactants are not supplied in exact coefficient ratio, one reactant runs out first. This limiting reagent fixes the maximum, or theoretical, yield of product. The excess reagent is left over. To identify the limiting reagent, calculate how much product each starting amount could produce, or compare each amount to its coefficient demand after converting all quantities to moles. Never choose the limiting reagent merely because it has the smaller mass; substances have different molar masses and equation coefficients.
Work it through
For 2H₂ + O₂ → 2H₂O, suppose 3.0 mol H₂ and 1.0 mol O₂ are available. One mole O₂ needs 2.0 mol H₂, so O₂ can react while 1.0 mol H₂ remains. O₂ is limiting and produces 2.0 mol H₂O. The answer should name both the limiting reagent and the excess amount when the question asks.
Mastery target
Identify a limiting reagent from mole evidence, calculate theoretical yield and state which reactant remains in excess.
For 2H₂ + O₂ → 2H₂O, which reagent is limiting if 3.0 mol H₂ reacts with 1.0 mol O₂?
Name the key chemistry term from Limiting reagents and theoretical yield that best fits the explanation and visual model.
For 2H₂ + O₂ → 2H₂O, how many moles of H₂O can 1.0 mol O₂ produce when H₂ is in excess?
Which statement corrects a common misunderstanding in Limiting reagents and theoretical yield?