1. Section 2: Reaction Rates
Collision Theory
5 Factors Affecting Rates

2. A. Rates
Rate: measure of how fast any change happens over time.

3. reactants  products A. Rates Reaction Rate:
change in concentration of reactants and products over time.
(tell how fast a reaction is going)
Example: TNT & leaves changing
reactants  products
get consumed
get formed
Rate is like speed (distance changes over time). TNT explosion is immediate, leaves change color happens gradually

4. A. Rates
more reactants
more products
reactants
products

5. B. Collision Theory
Ineffective Collision
Effective Collision

6. Activation Energy B. Collision Theory
For rxn to occur, collision must have:
proper orientation
(position)
minimum energy
needed to react called
Activation Energy

7. B. Collision Theory

8. C. 5 Factors Affecting Rates
The speed that a reaction takes place can be affected by:
Temperature
Surface Area
Stirring
Concentration
Catalysts
We’ll discuss them one at a time.

9. 1) Temperature Temp. Rate Why does milk last l0nger in the fridge?
more energy, more collisions
Direct or inversely proportional

10. 2) Surface Area
Surf. Area Rate
more collisions

11. 3) Stirring
Stirring Rate
more collisions

12. 4) Concentration
Conc Rate
more collisions

13. 4) Concentration
Conc Rate

14. 5) Catalysts speed up a reaction without being consumed.
lower the activation energy.
Like a party helps people meet each other and helps build friendships

15. Like a party helps people meet each other and helps build friendships

16. Why is H2O2 stored in dark plastic bottles?
5) Catalysts
Demo: Genie in a Bottle
catalyst written above arrow
MnO2
2 H2O2  2 H2O + O2
DEMO: 40 mL 30% H2O2 in jar/bottle. tsp of MnO2 in tissue on string with cork stopper holding hanging.
Why is H2O2 stored in dark plastic bottles?

17. Quick Quiz!
1) An increase in which one of the following will NOT increase the reaction rate?
A) temperature
B) concentration of reactants
C) total mass of reactants
D) surface area of reactants

18. Quick Quiz. 2) A catalyst speeds up a reaction by
A) lowering the activation energy.
B) increasing the temperature
C) permanently changing in a reaction
D) supplying energy to a reaction