1. REACTION
MECHANISMS

2. REACTION
MECHANISMS
“the step by step sequence of elementary reactions
by which overall chemical change occurs.” Wiki

3. Why are they important?

4. Why are they important?
Conditions favouring one path over another can
increase yield

5. Why are they important?
Conditions favouring one path over another can
increase yield
Can help to predict untried reactions

6. Why are they important?
Conditions favouring one path over another can
increase yield
Can help to predict untried reactions
They will be in the exam

7. How to determine

8. How to determine
Carry out rate experiments to determine orders with
respect to different reactants.

9. How to determine
Carry out rate experiments to determine orders with
respect to different reactants.
Reactants that appear in the rate equation are involved
in the rate determining step.

10. How to determine
Carry out rate experiments to determine orders with
respect to different reactants.
Reactants that appear in the rate equation are involved
in the rate determining step.
The order with respect to the reactant indicates how
many moles of that reactant are involved in the rate
determining step.

11. Example

12. Example
rate = [NO2]2

13. Example
rate = [NO2]2
So rate determining step involves two molecules of
NO2

14. Example
rate = [NO2]2
So rate determining step involves two molecules of
NO2
Reactants Products
1st Step NO2 NO2
2nd Step
Overall NO2 CO NO CO2

15. Example
rate = [NO2]2
So rate determining step involves two molecules of
NO2
Reactants Products
1st Step NO2 NO2
2nd Step CO CO2
Overall NO2 CO NO CO2

16. Example
rate = [NO2]2
So rate determining step involves two molecules of
NO2
Reactants Products
1st Step NO2 NO2
2nd Step CO NO2 CO2
Overall NO2 CO NO CO2

17. Example
rate = [NO2]2
So rate determining step involves two molecules of
NO2
Reactants Products
1st Step NO2 NO2
2nd Step NO3 CO NO2 CO2
Overall NO2 CO NO CO2

18. Example
rate = [NO2]2
So rate determining step involves two molecules of
NO2
Reactants Products
1st Step NO2 NO2 NO NO3
2nd Step NO3 CO NO2 CO2
Overall NO2 CO NO CO2

19. What was the intermediate?
Reactants Products
1st Step NO2 NO2 NO NO3
2nd Step NO3 CO NO2 CO2
Overall NO2 CO NO CO2