- Aligned with Big Idea 6 and Learning Objective 6.9
- Emphasizes Science Practices 3, 4, 5, 6, and 7
Investigate how temperature, concentration, and pressure affect chemical equilibrium in 3 different reactions. Teach this laboratory experience using either the guided activity or inquiry activity. In the guided activity, students perform 3 separate activities to investigate chemical equilibrium. In the first investigation, they react starch and iodine at 3 different temperatures and observe the variation in color. In the second, they react magnesium hydroxide with an acid to determine the affect a change in hydroxide-ion concentration has on solubility. For the third investigation, they pull a partial vacuum on carbonated water to show how pressure changes affect pH. Students also observe how changes in temperature and common ions affect the equilibrium between 2 complex ions. In the inquiry activity, students design experiments to show how temperature, concentration, and pressure affect the equilibria of starch-iodine, magnesium hydroxide, and carbonated water. They also design an experiment to maximize the percent yield of a reaction by adjusting temperature and reactant concentration.
Both activities include Big Idea assessment questions that follow the format of the AP® Chemistry Exam free-response questions. In the Big Idea assessment, students consider how stresses applied to the reactions of photosynthesis and the buffering of blood would affect their equilibria, and how to maximize the formation of either reactants or products using these stresses.
This kit provides the following AP® Chemistry experiences: design a procedure to collect data, analyze data, make observations, construct explanations of phenomena based on evidence,f and make predictions about natural phenomena. This experiment addresses equilibrium changes both in solution and in the gas phase, shows the reversible nature of reactions, and provides visual interest by using changes in color to monitor chemical reactions. It also includes a discussion of the Haber process. Materials are sufficient for 30 students in teams of 3. Digital teacher’s manual, included FREE with kit purchase or sold separately, is a 12-month eBook license to the Le Châtelier’s Principle and Equilibrium Shifts teacher’s manual. You can also access the digital student guide for this kit for free at
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