1. HONORS CHEMISTRY
Feb 27, 2012

2. Brain Teaser Cu + 2 AgNO3  2 Ag + Cu(NO3)2
How many moles of silver are produced when grams of silver nitrate reacts with excess amount of copper?
How many grams of silver nitrate are needed to produce 50 grams of silver?

3. Agenda Brain Teaser Notes: Limiting Reactants
Work on Mixed Stoichiometry Practice Worksheet 2
Homework
Complete Worksheet

4. Limiting Reactants

5. Limiting Reactants
Reactant that is completely used up in a chemical reaction
Determines the maximum amount of product that can be formed.

6. Limiting Reactants Why is this important?
The quantities of products formed in a reaction are always determined by the quantity of the limiting reactant.

7. Limiting Reactants
Analogy: making cheese sandwiches

8. Limiting Reactants
What is the limiting reactants?

9. Limiting Reactants

10. What is the limiting reactant?
Limiting Reactants
2H2 + O2  2H2O
What is the limiting reactant?

11. What is the limiting reactant?
Limiting Reactants
2H2 + O2  2H2O
What is the limiting reactant?

12. Limiting Reactants
How many grams of water can I make from 22 grams of hydrogen and 195 grams of oxygen?
Write a balanced chemical equation
H2 + O2  H2O
What is the limiting reactant?
Answer: Do two stoichiometry calculations
Determine mass of product produced by each reactant
How do you know?

13. Determining the limiting reactants
The limiting reagent may not be obvious!!

14. Practice Problem
If 11.3 grams of sodium chloride are formed in the reaction described above, what is the percent yield of this reaction?

15. Can you really get out everything that goes in?
% yield = experimental yield x 100
theoretical yield
Experimental or actual yield determined in the lab
Theoretical or expected yield determined by stoichiometry

16. Practice Problem
If 35 grams of C6H10 reacts with 45 grams of oxygen, how many grams of carbon dioxide will be formed?
What is the limiting reactant?
How much of the excess reactant is left over after the reaction ?
If 35 grams of carbon dioxide are actually formed from the reaction, what is the percent yield of this reaction?

17. Partner Quiz 1) CaCl2 + Na2CO3  CaCO3 + 2NaCl
5.45 g g ? How much CaCO3 (in g) is formed? What is the percent yield for this reaction if 3.96 g of calcium carbonate was isolated from the reaction?