Limiting and Excess Reactants

0.2 mol Pb(NO₃)₂ produces 0.5 mol gases. Volume = 11.2 dm³.

Stoichiometric coefficients always represent mole ratios.

Stoichiometric mixture. SO₂ = 1 mol. Mass = 64 g.

Na₂CO₃ is limiting. CO₂ formed = 0.5 mol. Mass = 22 g.

Potassium is limiting. KOH formed = 1 mol. Mass = 56 g.

Stoichiometry is based on these fundamental chemical laws.

O₂ is limiting. CO₂ = 3.2 mol. Volume = 71.68 dm³.

2 mol butane require 13 mol O₂, exactly the amount available.

Na = 2 mol, H₂O = 3 mol. Na is limiting. H₂ = 1 mol = 2 g.

CH₄ = 1.25 mol, O₂ = 0.625 mol. Oxygen is insufficient and is limiting.

Al = 1 mol (limiting). Cr produced = 1 mol = 52 g.

The limiting reactant determines how much of the excess reactant is consumed.

Ca = 0.5 mol, H₂O = 2 mol. Water left = 1 mol = 18 g.

245 g = 2 mol KClO₃. O₂ = 3 mol. Volume = 3 × 22.4 = 67.2 dm³.

Carbon is limiting. Si = 1.5 mol. Mass = 1.5 × 28 = 42 g.

Limiting reactants are identified by comparing available and required mole ratios.

NO = 2 mol and O₂ = 1 mol. Stoichiometric mixture. NO₂ formed = 2 mol.

Stoichiometric mixture. Cl₂ produced = 1 mol = 71 g.

NH₃ = 2 mol, O₂ = 1.5 mol. O₂ limits. NO = 1.2 mol. Mass = 1.2 × 30 = 36 g.