CHAPTER 13: EQUILIBRIUM

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• CHAPTER 13 EQUILIBRIUM
• Outline
• 1. introduction definition examples
• 2. KC, KP, example
• 3. heterogeneous equilibria examples
• 4. size of K, extent of reaction
• 5. predicting the direction of a reaction Q
• 6. calculations with K
• determining K from data
• determining equilibrium concentrations from K
• 7. factors that affect equilibrium LeChateliers
  Principle

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• review topics
• yields of chemical reactions Chapter 3 Section 5
• stoichiometry Chapter 3 Section 4
• partial pressure Chapter 9 Section 5

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EQUILIBRIUM PART 1
1. A reaction that proceeds to completion a. has
a theoretical yield greater than the actual
yield. b. has a theoretical yield less than the
actual yield. c. has a theoretical yield equal
to the actual yield. 2. True/False All chemical
reactions proceed to completion assuming the
experimenters technique is perfect.
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• Demonstration
• phenolphthalein added to 0.1M NaOH (solution A)
• 0.1M HCl added to 0.1M NaOH w/ phenolphthalein
  (solution B)
• 0.1M NaOH added to solution B (solution C)
• 0.1M HCl added to solution C

observations
phenolphthalein, C20H14O4
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solution A C20H14O4(colorless) OH1- ?
C20H13O41-(pink) H2O
solution B C20H13O41-(pink) H1 ?
C20H14O4(colorless)
or C20H14O4(colorless) OH1- ? C20H13O41-(pink)
H2O
or C20H13O41-(pink) H1 ? C20H14O4(colorless)
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3. What physiological reaction in blood is
reversible?
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Thought experiment 1. Add solid sodium iodide to
water till no more sodium iodide dissolves.
Filter. 2. Purchase radioactively-labeled
NaI(s). 3. Add the solid radioactively-labeled
NaI(s) to the saturated solution of NaI(aq).
Wait one day. Filter. What would you observe?
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• chemical equilibrium
• the concentrations of reactants products in a
  chemical reaction remain constant
• chemical reactions are reversible
• chemical equilibrium is dynamic

• Questions
• How do we predict the concentrations of products
  and reactants at equilibrium? (Chapters 13, 15,
  16)
• Why is it important to be able to predict
  equilibrium concentrations?
• Why do some reactions proceed nearly to
  completion but others result in a mixture of
  products and reactions? (Chapter 17) entropy