2. Limiting Reactants

3. Limiting Reactant  When chemists carry out reactions, the reactants are not usually present in stoichiometric amounts, therefore,  One reactant will be used up before the other  This one is called the limiting reactant

4. Limiting Reactant  Limits the extent of the reaction  Gets used up during the reaction  Determines the amount of product  Determines the theoretical yield  Once the limiting reactant is used up, no more product can form

5. Excess Reactant  The reactant that is left over after the reaction is complete  Insures that one of the reactants is all used up  Speeds up the reaction

6. One Banana Split

7. Recipe for 1 Banana Split  1 banana  3 cherries  3 scoops ice cream  1/2 c hot fudge  1/2 c whipped cream  1/4 c peanuts

8. What we have on hand  5 bananas  13 cherries  161/2 scooops ice cream  2 3/4 c hot fudge  2 1/2 c peanuts  3 1/4 c whipped cream

9. How many Banana Splits can you make?  What is the limiting reactant?  Compare each reactant to the number of banana splits that can be made.  The reactant that creates the LEAST amount of product is limiting.  The limiting reactant cannot be determined by simply looking at the reactant amount.

10.  5 bananas X 1 banana split = 5 banana splits 1 banana 1 banana  13 Cherries X 1 Ban Spl = 4.3 Ban Splits (LR)3 cherries(TY)  16.5 Scoops X 1 BanSpl = 5.50 Ban Splits 3 scoops 3 scoops  2.75 c. hot fudge X 1 BanSpl = 5.50 Ban Spl 0.5 c Hot Fudge

11.  2.5 c peanuts X 1 ban spl = 10 Ban Spl 0.25 c peanuts  3.25 c whipped crm X 1 Ban spl= 6.5 Ban spl 0.5 c whipped cream 0.5 c whipped cream

12. How much ice cream is in excess?  1. Identify the theoretical yield (TY)using the limiting reactant (LR).  2. Use mole equivalencies to see how much of the reactant in question is needed.  3. Determine the amount left over by subtraction.

13. 4.3 Ban spl X 3 scoops = 12.9 scoops needed 1 ban spl 1 ban spl 16.5 scoops available - 12.9 scoops needed 3.6 scoops in excess 3.6 scoops in excess

14. How much whipped cream is in excess?

15. To determine the limiting reactant:  1. Balanced chemical equation  2. Complete two separate stoichiometric calculations comparing each reactant to the amount of product formed  3. Identify the limiting reactant (LR) as the reactant that formed the LEAST amount of product  4. The theoretical yield (TY) is the amount of product formed by the limiting reactant