Mastering Stoichiometry: Definitions, Calculations, and Limiting Reactant

Dive into the world of stoichiometry with essential concepts like limiting reactants, theoretical yield, and percent yield. Practice calculations and sharpen your skills through real-world examples like making pizza and chemical reactions. Explore the intricacies of balancing equations and determining the optimal reactants for maximum efficiency in reactions.

• Stoichiometry
• Limiting Reactant
• Theoretical Yield
• Percent Yield
• Chemistry

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1. CHE 111 Fall 2020 Lecture 7g Stoichiometry II Overview/Topics Skills to Master 1. Definitions of LR, ER, % Yield, Theoretical Yield 2. Calculations 1. HW 7g + Extra Practice Read OER 7.4

2. Review 7f Roadmap to the Future! _1_ C + _6_ D _2_ A +_3_ B MW MW mol/mol Grams A Mol A Mol B Grams B Mol to Mol Ratio from Balanced Eqn Molecular Weight g/mol Molecular Weight g/mol

3. Making Pizza _1_ crust + _25_ pepperoni slices + _3.5_ oz. cheese + _10_ pineapple slices _8_ Pizza slices In your cupboard: 10 crusts 160 pepperoni slices 24 oz. cheese 60 pineapple slices Question 2 Question 1 _____ Crusts left _____ Pepperoni left _____oz. cheese left _____pineapple left _____Theoretical Pizza Slices made _____ Percent of Pizza Slices made 1. How many pizza slicer can you make? 2. What is the Limiting Ingredient? 3. How much of each ingredient will be left over? 4. If while baking the pizza s you burn 10 slices, what is the percent of pizza slices you successfully made?

4. Making Pizza _1_ crust + _25_ pepperoni slices + _3.5_ oz. cheese + _10_ pineapple slices _8_ Pizza

7. Chemistry is a little harder Excess Reactant: Limiting Reactant: The reactant that you run out of first Zero left at end of the reaction g R1 mol R1 mol P1 g P1 g R2 mol R2 mol P1 g P1 Fewest grams of P1 determines LR The reactant that is left over g LR mol LR mol ER g ER used - Starting g ER Used g ER Left Over ER Grams of a Product or Theoretical Yield: Percent Yield: Actual Yield (Lab or Given) Theoretical Yield g LR mol LR mol P g Pmade Percent Yield = 100 Energy Released: Double Check: Energy is just like a normal product g LR mol LR kJ Energy Mass at Start = Mass at the End g R1 + g R2 = g ER + g P1 + g P2

8. _2_ Al(OH)3 + _3_ H2SO4 _1_ Al2(SO4)3+ _6_H2O 78.00 g/mol 98.08 g/mol 18.02 g/mol 342.15 g/mol At your lab bench: 50.0 g Al(OH)3 75.0 g H2SO4 Question 1 Question 2 1. How many grams Al2(SO4)3 can you make? 2. What is the Limiting Reactant? 3. How much of the Excess Reactant is Left Over? 4. How much H2O do you make 5. If in lab you only made 70.0 grams of Al2(SO4)3 what is the percent yield? 6. How much energy in kJ is released? 7. Double Check _____ g Al(OH)3 _____ g H2SO4 _____g Al2(SO4)3 _____g H2O _____ Percent Yield of Al2(SO4)3 _____ kJ Released

9. Limiting Reactant: The reactant that you run out of first Zero left at end of the reaction g R1 mol R1 mol P1 g P1 g R2 mol R2 mol P1 g P1 Fewest grams of P1 determines LR

10. Excess Reactant: - Starting g ER Used g ER Left Over ER The reactant that is left over g LR mol LR mol ER g ER used

11. Grams Product or Theoretical Yield: g LR mol LR mol P g Pmade

12. Percent Yield: Actual Yield (Lab or Given) Theoretical Yield Percent Yield = 100 Energy Released: Energy is just like a normal product g LR mol LR kJ Energy Double Check: Mass at Start = Mass at the End g R1 + g R2 = g ER + g P1 + g P2

13. Mental Roadmap MW MW mol/mol Grams A Mol A Mol B Grams B Mol to Mol Ratio from Balanced Eqn Molecular Weight g/mol Molecular Weight g/mol _1_ C + _6_ D _2_ A +_3_ B 1. Find the LR 2. Find ER used 3. Find second Product 4. kJ Energy Release 5. % Yield 6. Double Check!

14. You Try It: _3_ C + _1_ Fe2O3 _2_Fe + _3_CO + 75 kJ 12.011 g/mol 159.687 g/mol 55.845 g/mol 28.01 g/mol At your lab bench: 250.0 g C 50.0 g Fe2O3 Question 2 Question 1 1. How many grams Fe can you make? 2. What is the Limiting Reactant? 3. How much of the Excess Reactant is Left Over? 4. If in lab you only made 30.0 grams of Fe what is the percent yield? 5. kJ of energy released 6. Double Check? _____ g C left _____ g Fe2O3 left _____g Fe made _____g CO made _____ Percent Yield of Fe _____ kJ Released

18. Answers! _3_ C + _1_ Fe2O3 _2_Fe + _3_CO + 75 kJ 12.011 g/mol 159.687 g/mol 55.845 g/mol 28.01 g/mol Answers Double Check At your lab bench: 250.0 g C 50.0 g Fe2O3 238.7 g C Left Over 0 g Fe2O3 Left Over 35.0 g Fe made 26.3 g CO made 85.7% yield of Fe 23.5 kJ Energy LR = Fe2O3 Start: 250 + 50 = 300 g of Reactants End: 35.0 g Fe + 26.3 g CO + 238.7 g C 300 g Start = End therefore Lavoisier is happy! Question 2 Question 1 _____ g C left _____ g Fe2O3 left _____g Fe made _____g CO made _____ Percent Yield of Fe _____ kJ Released 1. How many grams Fe can you make? 2. What is the Limiting Reactant? 3. How much of the Excess Reactant is Left Over? 4. If in lab you only made 30.0 grams of Fe what is the percent yield? 5. How much energy in kJ is released? 6. Double Check