Kinetics Lesson 3 Collision Theory

1. Kinetics Lesson 3 Collision Theory

2. The Collision Theory Link to Simulation of Molecular Motion 1. Matter is moving particles. 2. Temperature increases- particles move faster -more collisions -more collision energy. 3.Chemical reactions -bondsbreak -new bonds form 4. Collisions provide the energy.

3. Collision Theory You need a collision to have a reaction. Collisions provide the energyrequired to break bonds. Most collisions are not successful 

4. Collision Theory A successful collisionrequires: 1. Favourable Geometry Poor Geometry no products products

5. 2. Sufficient Energyto break the chemical bonds Activation energyis the minimum amount of energy required for a successful collision.

6. TheCollision Theory can be used to explain how the rate of a reaction can be changed. Reaction rates can increase due to 1. More collisions 2. Harder collisions- greater collision energy 3. Lower activationenergy or Ea- low energy collisions are more effective. And that’s it!

7. The Collision Theory can be used to explain how the rate of a reaction can be changed. 1. Increasing the temperature increases the rate because there are: Morecollisions Hardercollisions

8. 2. Increasing the reactantconcentration increases the rate because there are: More frequent collisions

9. The Collision Theory can be used to explain how the rate of a reaction can be changed. 3. Adding a catalyst Lowers the activationenergy or Ea- allowing low energy collisions to be successful The catalyst KI is added to H2O2, food colouring, and dishwashing detergent. The O2 produced makes foam. Movie

10. The Collision Theory can be used to explain how the rate of a reaction can be changed. 4. Changing the nature of the reactant for a more reactive chemical increases the rate Lower activationenergy or Ea- allowing low energy collisions to be successful

11. The Collision Theory can be used to explain how the rate of a reaction can be changed. 5. Increasing the surface area of a solid reactant increases the rate because: More frequent collisions

12. Explain each Scenario Using the Collision Theory 1. A balloon full of H2 and O2do not reactat room temperature. Ea is too highfor the room temperature collisions A small spark ignites causes an explosion. The spark provides the Eaand it explodes because it is exothermic

13. Explain each Scenario Using the Collision Theory 2. A candle does not burnat room temperature Eais too highfor the room temperature collisions A match causes the candle to burn The match provides the Ea The candle continues to burn It burns because it is exothermic

14. Explain each Scenario Using the Collision Theory 3. H2O2 decomposes very slowlyat room temperature. 2H2O2(aq) → O2(g) + 2H2O(l) KI increases the reaction rate dramatically. KI is a catalyst as it is not a reactant and it speeds up the rate. Lowers the Ea- allows low energy collisions to be successful

15. Describe and Graph the Relationship between the Following  Ea and the rate Rate Ea Decreasingthe Eaincreasesthe rate- inverse.

16. Describe and Graph the Relationship between the Following Temperature and the rate Increasingthe temperatureincreasesthe rate- direct. Rate Temp

17. Describe and Graph the Relationship between the Following Concentration and the rate Increasingthe concentration increases the rate- direct. Rate Conc

18. Describe and Graph the Relationship between the Following Ea and the temperature The only way to change the Ea is by adding a catalyst! No relationship! Temp Ea

19. Which factors increase the percentage of successful collisions? • Increasing temperature • Increasing concentration • Increasing surface area • IV. Adding a catalyst