1. 4.14.4- reaction coordinate graphs
AP Chem Kinetics
reaction coordinate graphs

2. Collision theory
The number of collisions does not accurately predict reaction rate…
There has to be something about these collisions…
Molecules have to have adequate energy
Molecules have to be at right orientation

3. We increase these two items when…
Increase temp
Increase concentration

4. Activation energy
Gases have high KE, but do not produce as many products between reactants as the collision model would predict
Arrhenius proposed that there must be something else going on: activation energy

5. Activation Energy
A threshold energy that must be overcome to produce a chemical reaction Ea

6. Reaction coordinate graph

7. Is there a way to lower activation energy of a rxn to make it easier to occur?

8. Answer: Catalysts Another way to make a reaction more likely to occur
Lowers the activation energy of a reaction
Catalysts do not increase the rate of reaction- like intermediates, they are NEVER part of rate law

9. Catalysts Lower Activation Energy

10. Example Identify the catalyst and the intermediates Cl- + O3 ClO- + O2
ClO- +O Cl O2
Intermediates –
Catalyst –

12. Reaction Coordinates
Transition state/activated complex: an intermediate, unstable species that is formed before the products are formed
Highest point on the graph
Activation energy: energy needed to get from reactants to transition state
DH: distance between energy of products and energy of reactants

15. Summary Factors Affecting Reaction Rates
Physical state reactants- more rapidly the reactants collide – the more readily they react (ex. grind solid increase surface area)
Reactant concentration- increase 1 or all reactants
Reaction temp- hi temp, more energy, ,ore colliding, reaction rate increases
Presence of catalyst

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