« Return to AACT homepage

AACT Member-Only Content

You have to be an AACT member to access this content, but good news: anyone can join!

Need Help?


In this activity, students will investigate how temperature, activation energy, initial amounts of products and reactants, and type of reaction (exo- or endothermic) effect the equilibrium position of a reaction using a simulation.

Grade Level

High school

AP Chemistry Curriculum Framework

This activity supports the following units, topics, and learning objectives:

  • Unit 5: Kinetics
    • Topic 5.6: Reaction Energy Profile
      • TRA-4.C: Represent the activation energy and overall energy change in an elementary reaction using a reaction energy profile.
  • Unit 6: Thermodynamics
    • Topic 6.2: Energy Diagrams
      • ENE-2.B: Represent a chemical or physical transformation with an energy diagram.
  • Unit 7: Equilibrium
    • Topic 7.8: Representations of Equilibrium
      • TRA-7.F: Represent a system undergoing a reversible reaction with a particulate model.
    • Topic 7.9: Introduction to Le Châtelier's Principle
      • TRA-8.A: Identify the response of a system at equilibrium to an external stress, using Le Châtelier's principle.


By the end of this lesson, students should be able to

  • See how temperature affects the value of equilibrium constants for endothermic and exothermic reactions.
  • See how activation energy affects.

Chemistry Topics

This lesson supports students’ understanding of

  • Thermodynamics
  • Equilibrium
  • Equilibrium constant
  • Activation energy


Teacher Preparation: 10 minutes

Lesson: one class period


For each group:

  • Computer with access to the internet


No safety precautions need to be observed during this activity.

Teacher Notes

For the Student



  1. Open the simulator. You can manipulate the values for each part of the curve by clicking and dragging them up or down.
  2. Determine whether you want to test an exo- or endothermic reaction, add molecules using the right side menu, and click “Start”.
  3. Allow the reaction to run until you believe equilibrium is reached. Record your information in the table below.
  4. Repeat this process several times, changing the Ea and T, one variable at a time, keeping the other variables constant.
    1. Change and evaluate the T using only the heat control, and the value on the thermometer. Do not use the Temperature on the right side menu, as that is for a different function. Record all results in the table.
  5. Repeat until you can answer the questions below.
Initial T Final T Type of reaction (endo/exo) Ea Initial A Initial B Final A Final B K (equilibrium constant)

Analysis Questions

  1. How does changing Ea affect the reaction? Explain.
  2. How do changes in T affect the value of K?
  3. Is the reaction A → B endothermic or exothermic? Explain.
  4. How do you know when equilibrium is established?
  5. Describe the conditions of a reversible reaction you conduct using the simulator. How do you know it is reversible?