1. Section 2.8—Speeding Up A Reaction
How can we make those antacid reactions occur faster?

2. Video about reaction rate

3. Kinetics & Reaction Rates
Kinetics – Study of the rates of reactions
Reaction Rate – Rate at which reactants produce products

4. Collision Theory
Collision Theory – A reaction can only occur if all of the following conditions are met: 1
Reactants must collide 2
Collision must be at the correct orientation
Collision must have minimum energy for reaction to occur 3
Only a small number of collisions meet the requirements and result in a reaction

5. Collisions Must Occur
In order for two molecules to react, they must come in contact with one another N O F
There’s no way they’ll ever react if they don’t run into one another!

6. Collision with Correct Orientation
For a collision to result in a chemical reaction, it must occur with the correct orientation
A + BC AB + C

8. Collision with Enough Energy
For a collision to result in a chemical reaction, it must occur with the minimum energy for reaction

9. Activation Energy
Activation Energy = Minimal energy needed for a reaction to occur during a collision

10. Reaction Coordinate Diagram
Reaction coordinate diagrams show the energy changes throughout the reaction
Activated complex
(Also called the transition state)
Activation Energy
Products
Energy
Energy change for reaction
Reactants
Reaction proceeds

11. Activated Complex What is an “activated complex”?
Activated complex is a highly unstable arrangement of the atoms. Notice that it breaks down to form products at a much LOWER energy!

13. Factors Affecting Reaction Rates

14. Surface Area of Reactants
How does the surface area of the reactants affect the reaction rate?
As surface area increases as a result of smaller particles, reaction rate increases

15. Concentrations of Reactants
How does the concentration of reactants affect the reaction rate?
As reaction concentration increases, reaction rate increases

16. For most reactions, as temperature increases, reaction rate increases
How does temperature affect the reaction rate?
For most reactions, as temperature increases, reaction rate increases

17. Catalysts
Catalysts – Substance that increases the rate of reaction without being used up
A + B + C  D + C
“C” is the catalyst…it is present in the beginning and in the end
Enzymes are catalysts in the body

18. Catalysts
How do catalysts help speed up the reaction without being used?
Sometimes, catalysts hold one or more of the reactants in place to allow collisions to occur with the correct orientation
Once the reaction has occurred, the catalyst releases the molecule(s) and finds another one to help
Catalysts make a successful collision more likely. They lower the activation energy by allowing reactants to react in a different way, or by holding reactants in place for the reaction. Once they’ve done their job, they are released and available to “help” another reactant.

20. Catalysts & Reaction Diagrams
Reaction Path without catalyst
Reaction Path with catalyst
Energy
Reaction proceeds
Catalysts lower the activation energy of the reaction by letting it proceed in a different way.
With lower activation energy, a higher percentage of collisions will be successful (they don’t need to collide with as much energy to be successful)

21. In summary…