1. Section 11.3 Limiting Reactants

2. Objectives: Identify the limiting reactant in a chemical equation.
Identify the excess reactant, and calculate the amount remaining after the reaction is complete.
Calculate the mass of a product when the amounts of more than one reactant are given.

3. Why do reactions stop?
Reactions proceed until one reactant is used up; other reactant(s) in excess.
limiting reactant – limits the extent of the reaction
determines amount of product formed.
excess reactants – leftover unused reactants.

4. Calculating Limiting Reactant
Determine how much product each reactant will form.
The reactant that produces less product is the limiting reactant.

5. Calculating Excess Reactant Leftover
To calculate excess reactant leftover:
Use the “lesser amount” of product formed to determine how much “excess reagent” was used.
Subtract the amount of excess reagent actually used from the starting amount of excess reagent.

6. Assessment
The mass of the final product in a chemical reaction is based on what?
A. the amount of excess reactant
B. the amount of limiting reactant
C. the presence of a catalyst
D. the amount of O2 present

7. Assessment
The mass of the final product in a chemical reaction is based on what?
B. the amount of limiting reactant