Stoichiometry - Limiting Reactants

In chemical reactions, usually one chemical is used up before the other. The chemical is known as the limiting reactant (L.R.). Once the limiting reactant is used up the reaction stops. The Limiting Reactant determines the quantity of products form+ed. To find the L.R. assume one reactant is used up. Then determine how much of this reactant is required.

Example:

1. Determine the L.R. when 1.4 of H2 reacts with 0.89mol of O2

• 2H2 + O2 -> 2H2O

1.4mol x 1 = 0.70mol of O2 needed
              1

• H2 is L.R.