Unit VI: Stoichiometry 4. Stoichiometry of Excess Quantities

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

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

Find the Limiting and Excess Reactants

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

Ca + Br2  CaBr2 If 80.2 g of Ca is mixed with 475.2 g of Br2, which reactant is INXS? Step 1 Covert to moles

Ca + Br2  CaBr2 If 80.2 g of Ca is mixed with 475.2 g of Br2, which reactant is INXS? Step 1 Covert to moles

Ca + Br2  CaBr2 If 80.2 g of Ca is mixed with 475.2 g of Br2, which reactant is INXS? Step 2 Revisit Equation

2Al +3Cl2  2AlCl3 If 108.0 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)

2Al +3Cl2  2AlCl3 If 108.0 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

2Al +3Cl2  2AlCl3 If 108.0 g of Al is mixed with 400 g of Cl2 which reactant is in excess?

2Al +3Cl2  2AlCl3 If 108.0 g of Al is mixed with 400 g of Cl2 which reactant is in excess?

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

2C2H6 + 7O2  4CO2 + 6H2O When 108.0 g of C2H6 is mixed with 360.8 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?

2C2H6 + 7O2  4CO2 + 6H2O When 108.0 g of C2H6 is mixed with 360.8 g of O2 which reactant is in excess? Start with C2H6

2C2H6 + 7O2  4CO2 + 6H2O When 108.0 g of C2H6 is mixed with 360.8 g of O2 which reactant is in excess? Start with O2

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

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

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

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

Hebden Do Exercises 26-28 on page 133