LR/ER/Theoretical Yield/Percent Yield Ch. 9 Conversions LR/ER/Theoretical Yield/Percent Yield Kierston Margetts

Chapter Vocabulary / Topics Limiting Reactant- what you run out of first Excess Reactant- what you have left over Theoretical Yield- what you should make according to the math Percent Yield- percentile comparison between experimental yield and theoretical yield

Real Life Problems Cooking recipes are comparable to chemical equations 3 cups flour + 1 stick butter + 2 cups sugar + 1 can pumpkin → 2 pumpkin pies (available ingredients: 80 cups flour, 17 sticks butter, 65 cups sugar, 20 cans pumpkin) Always find limiting reactant first Do this with each ingredient, the ingredient that makes the least # of pies is the Limiting reactant. 80 cups flour 2 pies X = 53 pies 3 cups flour

Real Life Problems Cont. With the limiting reactant you can now find the excess of each ingredient Subtract this number from given number in available ingredient list You can also find the % yield Amount of LR available Amt. of excess ingredient used in eqn Amt. of LR used in eqn X Actual # of pies made Theoretical # of pies made X 100

Chemical Problems Grams A → Mol A → Mol B → Grams B

How to Find the LR of Chemical Problems 50.0 g Al₂(SO₄)₃ and 100. CaCl₂ Al₂(SO₄)₃ (aq) + 3CaCl₂ (aq) → 2AlCl₃ (aq) + 3CaSO₄ (s) g gR₁ → gP₁ gR₂ → gP₁

How to Find the LR of Chemical Problems 50.0 g Al₂(SO₄)₃ 1 mol Al₂(SO₄)₃ 2 mol AlCl₃ 133.34 g AlCl₃ X X X 342.15 g Al₂(SO₄)₃ 1 mol Al₂(SO₄)₃ 1 mol AlCl₃ = 38.9 g AlCl₃ 100. g CaCl₂ 1 mol CaCl₂ 2 mol AlCl₃ 133.34 g AlCl₃ X X X 110.98 g CaCl₂ 3 mol CaCl₂ 1 mol AlCl₃ = 80.1 g AlCl₃

How to Find Amount of Excess Reactant Left Over Al₂(SO₄)₃ (aq) + 3CaCl₂ (aq) → 2AlCl₃ (aq) + 3CaSO₄ (s) gLR → gER used

How to Find Amount of Excess Reactant Left Over 50.0 g Al₂(SO₄)₃ 1 mol Al₂(SO₄)₃ 3 mol CaCl₂ 110.98 g CaCl₂ X X X 342.15 g Al₂(SO₄)₃ 1 mol Al₂(SO₄)₃ 1 mol CaCl₂ = 48.7 g CaCl₂ used 100. g available - 48.7 g used = 51.3 g CaCl₂ left

How to Find Theoretical Yield TIP: After reading the problem questions, if one question asks for the theoretical yield of a certain product, this should be the product you use to find the LR. Process is the exact same as finding the LR EX: the theoretical yield of AlCl₃ is 38.9 g

How to Find the Percent Yield Actual (given in ?) X 100 Theoretical

How to Find the Percent Yield Question: If I make 35.0 g of AlCl₃ what is the percent yield? 35.0 g 38.9 g X 100 = 89.9 %

How to find Joules Al₂(SO₄)₃ (aq) + 3CaCl₂ (aq) → 2AlCl₃ (aq) + 3CaSO₄ (s) + 250kJ 50.0 g Al₂(SO₄)₃ 1 mol Al₂(SO₄)₃ 250 kJ 1000 J X X X 342.15 g Al₂(SO₄)₃ 1 mol Al₂(SO₄)₃ 1 kJ gLR → energy =36533 J