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

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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 LIMITING REACTANT EXCESS REACTANT

5  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 + Br 2  CaBr 2  If 80.2 g of Ca is mixed with g of Br 2, which reactant is INXS?  Step 1 Covert to moles

7 Ca + Br 2  CaBr 2  If 80.2 g of Ca is mixed with g of Br 2, which reactant is INXS?  Step 1 Covert to moles

8 Ca + Br 2  CaBr 2  If 80.2 g of Ca is mixed with g of Br 2, which reactant is INXS?  Step 2 Revisit Equation

9 2Al +3Cl 2  2AlCl 3  If g of Al is mixed with 400 g of Cl 2 which reactant is in excess? Directions: 3. Whichever reactant gives you the larger mass of the product is the excess reactant 4. The reactant which is not in excess is the limiting reactant

10 2Al +3Cl 2  2AlCl 3  If g of Al is mixed with 400 g of Cl 2 which reactant is in excess? Directions: 1. Pick a product 2. Calculate the mass of this product starting with each reactant (one from 108.0g Al) (one from 400.0g Cl 2 )

11 2Al +3Cl 2  2AlCl 3  If g of Al is mixed with 400 g of Cl 2 which reactant is in excess?

12 2Al +3Cl 2  2AlCl 3  If g of Al is mixed with 400 g of Cl 2 which reactant is in excess?

13 2Al +3Cl 2  2AlCl 3  Which mass of AlCl 3 is actually formed?

14 2C 2 H 6 + 7O 2  4CO 2 + 6H 2 O a. When g of C 2 H 6 is mixed with g of O 2 which reactant is in excess? b. What volume of CO 2 is produced at STP? c. What mass of water is produced? d. What mass of the excess reactant is actually reacted? e. What mass of the excess reactant is left over?

15 2C 2 H 6 + 7O 2  4CO 2 + 6H 2 O a. When g of C 2 H 6 is mixed with g of O 2 which reactant is in excess? Start with C 2 H 6

16 2C 2 H 6 + 7O 2  4CO 2 + 6H 2 O a. When g of C 2 H 6 is mixed with g of O 2 which reactant is in excess? Start with O 2

17 2C 2 H 6 + 7O 2  4CO 2 + 6H 2 O b. What volume of CO 2 is produced at STP? Start with LR (O 2 )

18 2C 2 H 6 + 7O 2  4CO 2 + 6H 2 O c. What mass of water is produced?

19 2C 2 H 6 + 7O 2  4CO 2 + 6H 2 O d. What mass of the excess reactant is actually reacted?

20 2C 2 H 6 + 7O 2  4CO 2 + 6H 2 O e. What mass of the excess reactant is left over?

21 Hebden  Do Exercises on page 133

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