1. Reaction Rates Reaction Rates Collision Theory
5 Factors Affecting Rates

2. A. Rates
Rate:
measure of change over time

3. reactants  products A. Rates Reaction Rate:
rate at which reactants change into products over time.
(tell how fast a reaction is going)
Example: TNT & rusting
reactants  products
get consumed
get formed

4. A. Rates
more reactants
more products
reactants
products

5. B. Collision Theory
Ineffective Collision
Effective Collision

6. Activation Energy (Eact) B. Collision Theory For reaction to occur:
reactants must collide
with proper orientation
with enough (kinetic) energy
needed to react called
Activation Energy
(Eact)

7. Reactants energy energy released (in bonds) Product Potential
Reaction progress →

8. ? Reactants energy energy released (in bonds) Product Potential
Reaction progress →

9. B. Collision Theory
break reactant bonds
Eact ΔE

10. C. 5 Factors Affecting Rates
The speed that a reaction takes place can be affected by:
Temperature
Surface Area
Stirring
Concentration
Catalysts

11. 1) Temperature Temp. Rate more energy more collisions
Direct or inversely proportional

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

13. Factors That Affect Reaction Rates
3) Surface Area (particle size)
smaller pieces, more exposed surface area for collision.

14. 3) Stirring
Stirring Rate
more collisions

15. 4) Concentration more collisions
Conc Rate
more collisions
Why do bananas ripen faster in a ziplock bag?

16. 4) Concentration
Conc Rate
more collisions

17. Factors That Affect Reaction Rates
1) Concentration of Reactants
↑ concentration, ↑ collision frequency
↑ rate
Fe(s) + O2(g)  Fe2O3(s)
20% of air is O2(g)
100% O2(g)

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

19. Surface Catalysts
H2 + H2C=CH2
Catalysts can orient reactants to help bonds break and form.
H2 + H2C=CH2  H3C–CH3
CH3CH3 19

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

21. Why is H2O2 stored in dark plastic bottles?
5) Catalysts
Demo:
catalyst written above arrow
MnO2
2 H2O2  2 H2O + O2
DEMO (Genie in a Bottle): 40 mL 30% H2O2 in 250 mL Florence flask.
1 tsp of MnO2 in tissue on string with cork stopper holding hanging.
Why is H2O2 stored in dark plastic bottles?

22. 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

23. 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