Presentation is loading. Please wait.

Presentation is loading. Please wait.

Percent Yield and Limiting Reactants Unit 9. Percent Yield The percent yield is the percentage of a certain product actually produced in a chemical reaction.

Similar presentations


Presentation on theme: "Percent Yield and Limiting Reactants Unit 9. Percent Yield The percent yield is the percentage of a certain product actually produced in a chemical reaction."— Presentation transcript:

1 Percent Yield and Limiting Reactants Unit 9

2 Percent Yield The percent yield is the percentage of a certain product actually produced in a chemical reaction. The theoretical yield is predicted by a stoichiometry problem.

3 A. Percent Yield calculated on paper measured in lab

4 A. Percent Yield When 45.8 g of K 2 CO 3 react with excess HCl, 46.3 g of KCl are formed. Calculate the theoretical and % yields of KCl. K 2 CO 3 + 2HCl 2KCl + H 2 O + CO g ? g actual: 46.3 g

5 A. Percent Yield 45.8 g K 2 CO 3 1 mol K 2 CO g K 2 CO 3 = 49.4 g KCl 2 mol KCl 1 mol K 2 CO g KCl 1 mol KCl K 2 CO 3 + 2HCl 2KCl + H 2 O + CO g? g actual: 46.3 g Theoretical Yield:

6 A. Percent Yield Theoretical Yield = 49.4 g KCl % Yield = 46.3 g 49.4 g 100 = 93.7% K 2 CO 3 + 2HCl 2KCl + H 2 O + CO g49.4 g actual: 46.3 g

7 Percent Yield The reaction between SO 2 and oxygen yields SO 3.. Calculate the percent yield of SO 3 if 40.0 grams of SO 3 is formed, when 32 grams of SO 2 react with an excess of oxygen. SO 2 + O 2 SO 3 2SO 2 + O 2 2SO 3

8 B. Limiting Reactants Available Ingredients Available Ingredients 4 slices of bread 1 jar of peanut butter 1/2 jar of jelly Limiting Reactant Limiting Reactant bread Excess Reactants Excess Reactants peanut butter and jelly

9 B. Limiting Reactants Limiting Reactant Limiting Reactant used up in a reaction determines the amount of product Excess Reactant Excess Reactant added to ensure that the other reactant is completely used up cheaper & easier to recycle

10 B. Limiting Reactants 1. Write a balanced equation. 2. For each reactant, calculate the amount of product formed. 3. Smaller answer indicates: limiting reactant amount of product

11 Limiting Reactant Steps (version 2) 1 Step one o Write and balance the equation for the reaction. 2 Step two o Convert known masses to grams of product. 4 Step three o Determine limiting reactant and amount that can be made. 5 Step four o Determine the grams of excess from limiting reactant.

12 B. Limiting Reactants 79.1 g of zinc react with 0.90 L of 2.5M HCl. Identify the limiting and excess reactants. How many liters of hydrogen are formed at STP? Zn + 2HCl ZnCl 2 + H g ? L 0.90 L 2.5M

13 A. Limiting Reactants 79.1 g Zn 1 mol Zn g Zn = 27.1 L H 2 1 mol H 2 1 mol Zn 22.4 L H 2 1 mol H 2 Zn + 2HCl ZnCl 2 + H g ? L 0.90 L 2.5M

14 A. Limiting Reactants 22.4 L H 2 1 mol H L 2.5 mol HCl 1 L = 25 L H 2 1 mol H 2 2 mol HCl Zn + 2HCl ZnCl 2 + H g ? L 0.90 L 2.5M

15 A. Limiting Reactants Zn: 27.1 L H 2 Limiting reactant: HCl Excess reactant: Zn Product Formed: 25 L H 2 left over zinc HCl: 25 L H 2

16 Limiting Reagent or Reactant 2 (problem #2) §How many grams of ammonia will be produced when 20.0 grams of potassium hydroxide react with 15.0 grams of ammonium sulfate? §Step 1 l 2KOH + (NH 4 ) 2 SO 4 K 2 SO 4 +2NH 3 +2H 2 O

17 (NH 4 ) 2 SO 4 is the limiting reagent because it will make the least amount of product. It is the reactant that will run out first.

18 Limiting Reagent or Reactant 2


Download ppt "Percent Yield and Limiting Reactants Unit 9. Percent Yield The percent yield is the percentage of a certain product actually produced in a chemical reaction."

Similar presentations


Ads by Google