1. Laboratory 08
LIMITING REACTANT LAB

2. Objectives
Understand mole-to-mole ratio in a balanced chemical reaction
Identify the limiting and excess reactant in a chemical reaction based on experimental observation
Conduct limiting reactant calculations to predict theoretical yield

3. Limiting Reagent:
The reagent that is completely used up in a chemical reaction.
Excess Reagent:
Reagent not completely used up in a chemical reaction.

4. The Concept of Limiting Reactants
Stoichiometric mixture
N2(g) + 3H2(g)  2NH3(g)

5. Limiting reactant mixture
N2(g) + 3H2(g)  2NH3(g)

6. Calculations Involving a Limiting Reactant

7. Example: Find the limiting reagent when 1. 22g O2 reacts with 1
Example: Find the limiting reagent when 1.22g O2 reacts with 1.05g H2 to produce H2O.

8. Example: Find the limiting reagent when 1. 22g O2 reacts with 1
Example: Find the limiting reagent when 1.22g O2 reacts with 1.05g H2 to produce H2O.
2H2 (g) + O2 (g)  2H2O (l)
Convert mass to moles:
0.038 mol O2, mol H2
Calculate H2 moles necessary to react with O2: mol H2.
Compare mol H2 to actual mol of H2 (0.5mol H2),
Since 0.5 mol H2 is more than mol H2,
H2 is the excess reagent and O2 is the limiting reagent.