1. 23.4 Notes – Reaction Rates and Energy
Part B

2. Objectives Describe the factors that affect reaction rate.
Discuss the effects of catalysts and inhibitors on the speed of chemical reactions

3. Reaction rate How quickly a reaction occurs
The time it takes reactants to turn into products
The change in concentration of reactants and products over time

4. Factors affecting reaction (rxn) rates
Temperature
Concentration
Surface area/size
Catalyst

5. Temperature
The higher the temperature, the faster the molecules are moving
The faster the molecules are, the more collisions there are

6. Temperature
Increasing the temperature increases the kinetic energy of each particle.
The more energy, the more likely the particles will have enough energy to achieve the activation energy.

7. Concentration
The more particles there are within a given space, the more likely a collision is to occur
This increases the frequency of collisions
Video info

8. Surface Area How much of a material is exposed
The larger the surface area of a reactant, the greater the number of particles that are exposed for reaction
This increases the frequency at which particles collide

9. Catalyst
Speeds up a chemical reaction without itself being permanently changed
Lowers the activation energy
An inhibitor prevents or slows a chemical reaction

10. So…how can you speed up a reaction?
Increase the temperature
Stir the mixture
Break the reactants into smaller pieces
Higher concentration
Add a catalyst

11. Let’s Practice
Identify which factor determines the rate of each reaction.
Temp, Concentration, Surface Area, or Catalyst

12. Answers Using kindling to start a fire
Why forest fires are particularly dangerous when weather conditions include high winds.
Using Goody’s headache powder, rather than an aspirin tablet
Accidentally leaving a gallon of milk on the counter overnight.
Surface Area
Concentration
Surface Area
Temperature

13. Answers Baking a cake Digesting a cookie
Catalytic converter in your car
Termites destroying the foundation of a house.
Temperature
Catalyst
Catalyst
Catalyst

14. In-Class Assignment/Homework
23.4 WKT