Double Cheeseburgers and Stoichiometry

1. Double Cheeseburgers and Stoichiometry • 1 Double Cheeseburger needs 1 bun, 2 patties, 2 slices of cheese, 4 strips of bacon • For 5 Double Cheeseburgers how many units of each ingredient do I need? • Fill in the final column below with how many complete burgers I can make:

2. Objectives • To understand the concept of limiting reactants • To learn to recognize the limiting reactant in a reaction • To learn to use the limiting reactant to do stoichiometric calculations • To learn to calculate percent yield

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

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

5. A. The Concept of Limiting Reactants • For a Limiting reactant mixture the number of moles are not balanced to match the reaction equation • N2(g) + 3H2(g) 2NH3(g) • Limiting reactant is the reactant that runs out first • When the limiting reactant is exhausted, then the reaction stops

6. B. Calculations Involving a Limiting Reactant

7. B. Calculations Involving a Limiting Reactant

8. C. Percent Yield • Theoretical Yield • The maximum amount of a given product that can be formed when the limiting reactant is completely consumed. • The actual yield (amount produced) of a reaction is usually less than the maximum expected (theoretical yield). • Percent Yield • The actual amount of a given product as the percentage of the theoretical yield.

9. According to his pre-lab theoretical yield calculations a student’s experiment should have produced 1.44g of magnesium oxide. When he weighed his product after reaction, only 1.23g of magnesium oxide was present. What is the student’s percent yield?