1. Unit 1: Reaction Kinetics
Lesson 9: Energy Diagrams of Reaction Mechanisms

2. Warm Up!
10 min

3. Energy Diagram of a Reaction Mechanism
HBr + O2 → HOOBr (slow) HOOBr + HBr → 2 HOBr (fast) 2 HOBr + 2 HBr → 2 H2O + 2 Br2 (fast)
Notes, then have students add in the forward activation energies to the diagram and go over answers – 10 min

4. Practice Time!
Pg. 30 #54-55
5 min

5. Brain Break!
5 min

6. You know that catalysts speed up reactions, but how?
A catalyst is properly defined as a substance that provides an overall reaction with an alternative mechanism having a lower activation energy.

7. E.g.

8. The Catalyzed Reaction Mechanism
Looking at the previous diagram, we can see that the catalyzed mechanism lowers the activation energy for both the forward and reverse reaction.
It is important to note that the uncatalyzed mechanism is still available, and some particles may still follow it. However, most will react via the catalyzed mechanism.

9. Flashback! Factors Affecting Reaction Rate
While watching the video, note the five ways mentioned of increasing reaction rate. Have we covered all of these in class?
Watch “How to speed up chemical reactions” video, then discuss answer to question – 10 min

10. Homework:
Make a list of five examples of catalysts that play a role in our daily lives.
5 min