Unit 3: Equilibria

To assess your understanding of the material, do as many of the exercises at the end of each chapter as you have time and/or patience for.

The "course videos" were created when we were using another text, and do not line up perfectly with the organization of the material in the OpenStax text. They are still quite useful, and I have tried to include them where they fit best. (If you find one that is seriously out of place, let me know.)

A note on the Practice problems: The more of the exercises you do, the better you will do on the exams. The problems I have suggested for practice are an absolute minimum, and proficiency with these problems should indicate at least a C level understanding of the material.

Fundamental Equilibrium Concepts

13.1 Chemical Equilibria

• • Describe the nature of equilibrium systems

  • Explain the dynamic nature of a chemical equilibrium

Resources: Course video, "Introduction to Chemical Equilibria (Video 7)"

Practice: chapter 13 exercises 1, 3, 5

13.2 Equilibrium Constants

• • Derive reaction quotients from chemical equations representing homogeneous and heterogeneous reactions

  • Calculate values of reaction quotients and equilibrium constants, using concentrations and pressures

  • Relate the magnitude of an equilibrium constant to properties of the chemical system

Practice: chapter 13 exercises 15, 17, 21, 23, 25, 29

13.3 Shifting Equilibria: Le Chatelier's Principle

• • Describe the ways in which an equilibrium system can be stressed

  • Predict the response of a stressed equilibrium using Le Châtelier’s principle

Resources: Course video, "Disturbing Equilibria (Video 9)"

Practice: chapter 13 exercises 31, 36, 38, 40, 42, 48

13.4 Equilibrium Calculations

• • Identify the changes in concentration or pressure that occur for chemical species in equilibrium systems

  • Calculate equilibrium concentrations or pressures and equilibrium constants, using various algebraic approaches

Resources: Course videos, "Equilibrium Problems (Video 8)" and "Equilibrium Using the Quadratic Equation (Video 8A)"

Practice: chapter 13 exercises 52, 56, 58, 60, 70, 74, 78, 86

Acid-Base Equilibria

14.1 Bronsted-Lowry Acids and Bases

• • Identify acids, bases, and conjugate acid-base pairs according to the Brønsted-Lowry definition

  • Write equations for acid and base ionization reactions

  • Use the ion-product constant for water to calculate hydronium and hydroxide ion concentrations

  • Describe the acid-base behavior of amphiprotic substances

Review: OS chapter 4 on acid/base reactions; memorize table 4.2 Common strong acids

Resources: Course video, "Bronsted Lowry Acids and Bases (Video 10)" and "Acid Base Eqilibrium (Video 11)"

Practice: chapter 14 exercises 1, 3, 7, 9, 13

14.2 pH and pOH

• • Explain the characterization of aqueous solutions as acidic, basic, or neutral

  • Express hydronium and hydroxide ion concentrations on the pH and pOH scales

  • Perform calculations relating pH and pOH

Resources: Course videos, "Bronsted Lowry Acids and Bases (Video 10)" and "Acid Base Eqilibrium (Video 11)"

Practice: chapter 14 exercises 17, 19, 21, 25

14.3 Relative Strengths of Acids and Bases

• • Assess the relative strengths of acids and bases according to their ionization constants

  • Rationalize trends in acid–base strength in relation to molecular structure

  • Carry out equilibrium calculations for weak acid–base systems

Resources: Course videos, "Bronsted Lowry Acids and Bases (Video 10)" and "Acid Base Eqilibrium (Video 11)"

Practice: chapter 14 exercises 29, 33, 35, 37, 41, 43, 50, 54, 62, 68

14.4 Hydrolysis of Salts

• • Predict whether a salt solution will be acidic, basic, or neutral

  • Calculate the concentrations of the various species in a salt solution

  • Describe the acid ionization of hydrated metal ions

Resources: Course videos, "Types of Acid Base Reactions (Video 12)", "Acid Base Equilibrium Calculations Video 13)", and "Polyprotic Acids (Video 14)"

Practice: chapter 14 exercise 70

14.5 Polyprotic acids

• Extend previously introduced equilibrium concepts to acids and bases that may donate or accept more than one proton

Resources: Course videos, "Types of Acid Base Reactions (Video 12)", "Acid Base Equilibrium Calculations Video 13)", and "Polyprotic Acids (Video 14)"

14.6 Buffers

• • Describe the composition and function of acid–base buffers

  • Calculate the pH of a buffer before and after the addition of added acid or base

Resources: Course videos, "Common Ion Effect (Video 16)" and "Buffers (Video 17)"

Practice: chapter 14 exercises 78, 80, 84, 86, 88, 90

14.7 Acid-Base Titrations

• • Interpret titration curves for strong and weak acid-base systems

  • Compute sample pH at important stages of a titration

  • Explain the function of acid-base indicators

Resources: Course video, "Titrations (Video 18)"

Practice: chapter 14 exercise 94

Equilibria of Other Classes

15.1 Precipitation and Dissolution

• • Write chemical equations and equilibrium expressions representing solubility equilibria

  • Carry out equilibrium computations involving solubility, equilibrium expressions, and solute concentrations

Practice: chapter 15 exercises 1, 5, 7, 9, 11, 15, 27, 31, 37, 39, 45

15.2 Lewis Acids and Bases

• • Explain the Lewis model of acid-base chemistry

  • Write equations for the formation of adducts and complex ions

  • Perform equilibrium calculations involving formation constants

Practice: chapter 15 exercises 62, 68, 74, 76, 78, 84

15.3 Coupled Equilibria

• • Describe examples of systems involving two (or more) coupled chemical equilibria

  • Calculate reactant and product concentrations for coupled equilibrium systems

Practice: chapter 15 exercises 101, 103