Collision Theory and Reaction Rates

1. Mr. Chapman Chemistry 30 Collision Theory and Reaction Rates

2. Collision Theory • The collision theory states that in order for two atoms or molecules to react, they must actually collide with each other. • Surprisingly, however, only a small number of collisions between atoms and molecules result in a successful chemical reaction. There are two reasons for this:

3. Collision Theory and Rate The rate or speed of the reaction depends on the frequency of collisions or the number of collisions that occur.

4. Two Requirements for a Successful Collision • Proper Orientation • In order for two atoms or elements to react, the proper parts of them must come into contact in order to begin a reaction. • Sufficient Energy • In order for two atoms or elements to react, the molecules must actually hit each other hard enough (with enough energy) to cause a chemical reaction.

5. Listen to Mr. Chapman talk.... If you want to understand the collision theory!!! An artist rendered picture of Mr. Chapman... Notice that his man has a full head of hair, and it is wonderful.

6. Let’s do an Experiment... All you need is one crumpled up piece of paper.

7. The Intense Experiment • Find a friend, and each one of you crumple a piece of paper (sorry environment). • Now face each other with knees almost touching, and toss your pieces of paper at each other. Try to get them to collide in midair. If you do, you get a reaction! • Repeat this 10 times. How many successful collisions do you record?

8. The Intense Experiment • After repeating and recording 10 attempts at a collision, add one more person to your group. • Now: add another person to your mix, and all three of you sit close together, and try to get your papers to all hit in midair. Two out of three doesn’t count. Try 10 times! • How many successful collisions do you get?

9. The Grand Finale... • After repeating and recording 10 attempts at a collision, make a group of 5 (gasp) people! • Now: all five of you sit close together, and try to get your papers to hit in midair. To succeed you have to get all 5 at once! Do this 10 more times. • How many successful collisions do you get? Shockingly enough, Chapman’s guess is zero. I dare you to succeed even once.