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Stoichiometry in the Real World

Stoichiometry in the Real World. Stoichiometry – Ch. Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem. Limiting Reactants. Available Ingredients 4 slices of bread 1 jar of peanut butter 1/2 jar of jelly. Limiting Reactant bread. Excess Reactants

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Stoichiometry in the Real World

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  1. Stoichiometry in the Real World Stoichiometry – Ch. Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  2. Limiting Reactants • Available Ingredients • 4 slices of bread • 1 jar of peanut butter • 1/2 jar of jelly • Limiting Reactant • bread • Excess Reactants • peanut butter and jelly Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  3. Limiting Reactants • Limiting Reactant • used up in a reaction • determines the amount of product • Excess Reactant • added to ensure that the other reactant is completely used up • cheaper & easier to recycle Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  4. 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 Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  5. 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  ZnCl2 + H2 ? L 79.1 g 0.90 L 2.5M Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  6. Limiting Reactants Zn + 2HCl  ZnCl2 + H2 ? L 79.1 g 0.90 L 2.5M 79.1 g Zn 1 mol H2 1 mol Zn 1 mol Zn 65.39 g Zn 22.4 L H2 1 mol H2 = 27.1 L H2 Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  7. Limiting Reactants Zn + 2HCl  ZnCl2 + H2 ? L 79.1 g 0.90 L 2.5M 0.90 L 2.5 mol HCl 1 L 1 mol H2 2 mol HCl 22.4 L H2 1 mol H2 = 25 L H2 Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  8. left over zinc Limiting Reactants Zn: 27.1 L H2 HCl: 25 L H2 Limiting reactant: HCl Excess reactant: Zn Product Formed: 25 L H2 Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  9. measured in lab calculated on paper Percent Yield Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  10. Percent Yield • When 45.8 g of K2CO3 react with excess HCl, 46.3 g of KCl are formed. Calculate the theoretical and % yields of KCl. K2CO3 + 2HCl  2KCl + H2O + CO2 45.8 g ? g actual: 46.3 g Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  11. Percent Yield K2CO3 + 2HCl  2KCl + H2O + CO2 Theoretical Yield: 45.8 g ? g actual: 46.3 g 45.8 g K2CO3 1 mol K2CO3 138.21 g K2CO3 2 mol KCl 1 mol K2CO3 74.55 g KCl 1 mol KCl = 49.4 g KCl Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  12. 46.3 g 49.4 g Percent Yield K2CO3 + 2HCl  2KCl + H2O + CO2 Theoretical Yield = 49.4 g KCl 45.8 g 49.4 g actual: 46.3 g  100 = 93.7% % Yield = Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

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