1. CHEMICAL KINETICS: REACTION RATES

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

3. Collision Theory In order for reactants to form products…
The reactant molecule must collide at the correct angle with enough energy to start the reaction (activation energy)

4. What makes some rxns occur quickly, some more slowly and some not at all?

5. Factors affecting rxn rates
Nature of the Reactants
This includes
physical states of the reactants
Complexity of bonds
Types of bonds

6. Factors affecting rxn rates
Temperature
The higher the temperature, the faster the molecules are moving.
The faster the molecules are, the more collisions there are.

7. Factors affecting rxn rates
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.

8. Factors affecting rxn rates
Concentration:
The more particles there are within a given space, the more likely a collision is to occur.
This increases the frequency of collisions.

9. Factors affecting rxn rates
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.

10. Factors affecting rxn rates
Catalysts: a substance that increases the rate of the reaction without itself being used up
A catalyst lowers the activation energy.
The opposite of a catalyst is an inhibitor.

11. Factors affecting rxn rates
Catalysts cont,
Enzymes are biological catalysts.
Catalysts are not used up and can be recovered fully in the end.

12. So…how can you speed up a reaction?
Increase the temperature. For each 10-degree increase in temperature, the reaction rate is doubled or tripled.

13. So…how can you speed up a reaction?
Stir the mixture. This allows for the concentration of reactants to be at a maximum. More reactants will come in contact with one another.

14. So…how can you speed up a reaction?
Break the reactants into smaller pieces (grinding or making it a powder). This increases the surface area of the reactants.

15. So…how can you speed up a reaction?
Add a catalyst. For example, in making aspirin, add sulfuric acid. This speeds up the reaction.

16. Which reaction rate factor determines the rate of each reaction?
Using kindling to start a fire
Why forest fires are particularly dangerous when weather conditions include high winds.
Grain elevator explosions
Using Goody’s headache powder, rather than an aspirin tablet

17. Which reaction rate factor determines the rate of each reaction?
Accidentally leaving a gallon of milk on the counter overnight.
Baking a cake
Digesting a cookie
Catalytic converter in your car
Termites destroying the foundation of a house.

18. Which reaction rate factor determines the rate of each reaction?
Using kindling to start a fire
Surface area
Why forest fires are particularly dangerous when weather conditions include high winds.
concentration
Grain elevator explosions
Using Goody’s headache powder, rather than an aspirin tablet

19. Which reaction rate factor determines the rate of each reaction?
Accidentally leaving a gallon of milk on the counter overnight.
temperature
Baking a cake
Digesting a cookie
catalyst
Catalytic converter in your car
Termites destroying the foundation of a house.