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Unit 4 · 6 lessons

Chemical Systems and Equilibrium

Many reactions never run to completion: they settle into a dynamic balance that can be described with an equilibrium constant, pushed around by changing conditions, and used to calculate pH, solubility and the shape of a titration curve.

  • 62 practice questions
  • 51 flashcards
  • 3 interactive lessons
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Lessons

  1. 1Dynamic Equilibrium and the Equilibrium ConstantWhy reversible reactions in a closed system stop changing without stopping reacting, how to write the equilibrium constant expression, what the size of K tells you, and how to use ICE tables to find K or equilibrium concentrations.Interactive10 questions
  2. 2Le Chatelier's Principle and the Reaction QuotientUsing the reaction quotient Q to predict which way a system will shift, and Le Chatelier's principle to explain how concentration, pressure, temperature and catalysts affect an equilibrium, from the Haber process to the buffering of blood.Interactive9 questions
  3. 3Acid-Base EquilibriaBrønsted-Lowry acids and bases and their conjugate pairs, the ionization of water, pH and pOH, the difference between strong and weak acids and bases, and calculations with Ka, Kb and percent ionization.10 questions
  4. 4Solubility Equilibria, Buffers and TitrationUsing Ksp to find molar solubility and predict precipitation, the common ion effect, how buffers resist pH change, and how to read titration curves and find the pH at the equivalence point for strong-strong and weak-strong titrations.11 questions
  5. 5Equilibrium at Work: Industry, Body and EnvironmentApplying K, Ksp and Le Chatelier's principle to real systems: the contact process for sulfuric acid, kidney stones and gallstones, removing heavy metals by precipitation, hard water, hemoglobin carrying oxygen or carbon monoxide, buffered medications and ocean acidification.11 questions
  6. 6Measuring K in the LabHow equilibrium constants are measured: Keq for the iron(III) thiocyanate equilibrium by colorimetry with Beer's law, a calibration curve and an ICE table; Ksp of calcium hydroxide by titration; Ka of acetic acid from pH; testing Le Chatelier predictions with FeSCN²⁺ and cobalt chloride; and analyzing experimental error.Interactive11 questions