1. Limiting Reactants, Excess Reactants and Theoretical Yield

2. Limiting Reactant
A limiting reactant in a chemical reaction is the substance that:
Is used up first.
Stops the reaction.
Limits the amount of product that can form.

3. Reacting Amounts
In a table setting, there is 1plate, 1 fork, 1 knife, and 1 spoon.
How many table settings are possible from 5 plates, 6 forks, 4 spoons, and 7 knives?
What is the limiting item?
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4. Reacting Amounts Four table settings can be made.
Initially Used Left over
plates
forks
spoons
knives
The limiting item is _______________.

5. Example of Everyday Limiting Reactant
How many peanut butter sandwiches could be made from 8 slices bread and 1 jar of peanut butter?
With 8 slices of bread, only 4 sandwiches could be made. The bread is the limiting item.

6. Example of Everyday Limiting Reactant
How many peanut butter sandwiches could be made from 8 slices bread and 1 tablespoon of peanut butter?
With 1 tablespoon of peanut butter, only 1 sandwich could be made. The peanut butter is the limiting item.

7. Limiting Reactants
When 4.00 mol H2 is mixed with 2.00 mol Cl2,how many moles of HCl can form?
H2(g) Cl2(g)  2HCl (g)
4.00 mol mol ??? mol
Calculate the moles of product from each reactant, H2 and Cl2. (Use mole ratio)
The limiting reactant is the one that produces the smaller amount of product.

8. Limiting Reactants Using Moles
HCl from H2
HCl from Cl2

9. Limiting Reactants Using Moles
If 4.80 mol Ca mixed with 2.00 mol N2, which is the limiting reactant? 3Ca(s) + N2(g)  Ca3N2(s) Moles of Ca3H2 from Ca Moles of Ca3H2 from N2

11. Limiting Reactants Using Mass
Calculate the mass of water produced when 8.00 g H2 and 24.0 g O2 react? 2H2(g) + O2(g) 2H2O(l) Step #1: Calculate the number of moles of product formed from both masses of reactants to determine the limiting reactant.

12. Limiting Reactants Using Mass
Step #2: Determine the limiting reactant. Step #3: Convert lowest # of moles of product to grams of product.

13. Limiting Reactants Using Mass
What is the maximum number of grams of copper(I) sulfide produced when 80.0-g of copper reacts with 25.0-g of sulfur? 2Cu(s) + S(s)  Cu2S(s)

14. Calculating Leftover Reactant
How much of the excess reactant is leftover after the reaction has been completed?

15. Percent Yield
Actual Yield = experimental chemical rxn Theoretical Yield = based on calculations

16. Example of Percent Yield
A piece of copper with a mass of 5.00-g is placed in a solution of silver nitrate containing excess AgNO3. The silver metal produced has a mass of 15.2-g. What is the percent yield for this reaction? Cu(s) + 2AgNO3(aq)  Cu(NO3)2(aq) + 2Ag(s)

17. One More Example…
Determine the percent yield when a solution containing g of Al(NO3)3 is mixed with a solution containing excess NaOH if g of Al(OH)3 precipitate is recovered.