1. Unit VI: Stoichiometry
4. Stoichiometry of Excess Quantities

2. Excess and Limiting Reactant Calculations
Excess Reactant  Too much to react with the other reactant

3. Excess and Limiting Reactant Calculations
Limiting Reactant  not enough  limits the amount of product

4. Find the Limiting and Excess Reactants

5. Find the Limiting and Excess Reactants
You are baking cakes with the Swedish Chef
For 1 Cake You need:
2 cups flour; 3 eggs; 1 pound of butter; 1 cup of milk
You have 18 cups of flour; 15 eggs; 6 pounds of butter; 8 cups of milk

6. Ca + Br2  CaBr2
If 80.2 g of Ca is mixed with g of Br2, which reactant is INXS?
Step 1 Covert to moles

7. Ca + Br2  CaBr2
If 80.2 g of Ca is mixed with g of Br2, which reactant is INXS?
Step 1 Covert to moles

8. Ca + Br2  CaBr2
If 80.2 g of Ca is mixed with g of Br2, which reactant is INXS?
Step 2 Revisit Equation

9. 2Al +3Cl2  2AlCl3
If g of Al is mixed with 400 g of Cl2 which reactant is in excess?
Directions:
Pick a product
Calculate the mass of this product starting with each reactant
(one from 108.0g Al)
(one from 400.0g Cl2)

10. 2Al +3Cl2  2AlCl3
If g of Al is mixed with 400 g of Cl2 which reactant is in excess?
Directions:
Whichever reactant gives you the larger mass of the product is the excess reactant
The reactant which is not in excess is the limiting reactant

11. 2Al +3Cl2  2AlCl3
If g of Al is mixed with 400 g of Cl2 which reactant is in excess?

12. 2Al +3Cl2  2AlCl3
If g of Al is mixed with 400 g of Cl2 which reactant is in excess?

13. 2Al +3Cl2  2AlCl3
Which mass of AlCl3 is actually formed?

14. 2C2H6 + 7O2  4CO2 + 6H2O
When g of C2H6 is mixed with g of O2 which reactant is in excess?
What volume of CO2 is produced at STP?
What mass of water is produced?
What mass of the excess reactant is actually reacted?
What mass of the excess reactant is left over?

15. 2C2H6 + 7O2  4CO2 + 6H2O
When g of C2H6 is mixed with g of O2 which reactant is in excess?
Start with C2H6

16. 2C2H6 + 7O2  4CO2 + 6H2O
When g of C2H6 is mixed with g of O2 which reactant is in excess?
Start with O2

17. 2C2H6 + 7O2  4CO2 + 6H2O What volume of CO2 is produced at STP?
Start with LR (O2)

18. 2C2H6 + 7O2  4CO2 + 6H2O
What mass of water is produced?

19. 2C2H6 + 7O2  4CO2 + 6H2O
What mass of the excess reactant is actually reacted?

20. 2C2H6 + 7O2  4CO2 + 6H2O
What mass of the excess reactant is left over?

21. Hebden
Do Exercises on page 133