1. Reaction Theories

2. Rate of Reaction Change of concentration per unit time
[department of education definition]

3. Collision Theory 1. Particles must collide
2. Collision only results in formation of products if a certain Minimum Energy is exceeded in the collision.
Minimum Energy is called Activation Energy
Called an Effective Collision

4. Maxwell-Boltzmann Distribution
People walking on street
Some very quickly
Some very slowly
Most moderately fast - near the average
Particles in a gas at 15oC have a roughly similar distribution
Draw a graph

5. Graph at 15oC
Particles in shaded area have Activation Energy

6. Graph at 25oC and 15oC

7. Activation Energy
Minimum energy two colliding particles must have in order to react [or to have an Effective Collision]
Higher the temperature the more energy each particle has
Thus the greater the proportion of particles that have activation energy

8. Size of Activation Energy depends on nature of the reactants
Some have large Activation Energies so are slow or do not happen at all, because only a small fraction of the particles have sufficient energy to react
Some have low Activation Energies and so react quickly

9. Reaction Profile Diagrams #1
Exothermic reaction ∆H

10. Reaction Profile Diagrams #2

11. Effect of catalyst on activation energy

12. Ea ∆H