1. Chapter 17 “Reaction Rates and Equilibrium” Part 1: Reaction Rates
Activated Complex
Activation Energy is being supplied
Reaction Rates #2.ppt
Reaction Rates #2.ppt

2. Today you will learn… Effects of temperature on reaction rate
Effects of concentration on reaction rate
Effects of catalysts and inhibitors on reaction rate
How catalysts affect reation rate

3. Factors Affecting Rate
Temperature
Increasing temperature increases the rate of a reaction.
Surface Area
Increasing surface area increases the rate of a reaction
Concentration – Increasing concentration increases the rate of a reaction
Presence of Catalyst – increases the rate unless an inhibitor is present

4. Temperature
When we increase the temperature we give the particles energy
This makes them move faster
This means they collide with other particles more often
So the reaction goes faster.

5. Temperature
Increasing temperature increases KE
Increasing KE means more particles have sufficient energy to overcome the activation energy barrier

6. This makes the reaction faster.
Surface area
If we make the pieces of the reactants smaller we increase the number of particles on the surface which can react.
This makes the reaction faster.
The particles on the surface can react
When cut into smaller pieces the particles on the inside can react

7. Dissolve a sugar cube in warm water
Surface area
Dissolve a sugar cube in warm water 2 1
Dissolve granulated sugar in warm water

8. Surface Area
Demo:
Combustion of iron
Combustion of flour

9. There are more particles in the same volume to react
Concentration
There are less red particles in the same volume, so there is less chance of a collision
If we make one reactant more concentrated (like making a drink of Kool-Aid more concentrated)
There are more particles in the same volume to react
So the reaction goes faster.
There are more red particles in the same volume so there is more chance of a collision, so the reaction goes faster

10. Concentration
Demo:
Elephant’s toothpaste

11. Catalysts
Catalyst: A substance that speeds up a reaction, without being consumed itself in the reaction
Enzyme: A large molecule (usually a protein) that catalyzes biological reactions.
Human body temperature = 37o C, much too low for digestion reactions without catalysts.

12. Catalysts
Inhibitors – interfere with the action of a catalyst; reactions slow or even stop
Catalysts work by lowering the activation energy for a process

13. Endothermic Reaction with a Catalyst

14. Exothermic Reaction with a Catalyst