1. Kinetics Lesson 7 Catalysts

2. 1. Catalysts Participate in reaction 1.A+B→C 2.C+D→CD 3.CD+E→ABE+D Catalyst: Intermediate:

3. 1.Catalysts Participate in reaction 1.A+B→C 2.C+D→CD 3.CD+E→ABE+D Overall Equation:A +B + E →ABE Catalyst:D Intermediate: CCD

4. 2- Catalysts Reduce Ea

6. PE(kJ) 500 400 300 200 100 0 reaction path  H forward=  H reverse= Ea forward uncat= Ea reverse uncat= Ea forward cat =

7. PE(kJ) 500 400 300 200 100 0 reaction path  H forward=-300 kJ  H reverse= Ea forward uncat= Ea reverse uncat= Ea forward catalyzed =

8. PE(kJ) 500 400 300 200 100 0 reaction path  H forward=-300 kJ  H reverse=+300 kJ Ea forward uncat= Ea reverse uncat= Ea forward catalyzed =

9. PE(kJ) 500 400 300 200 100 0 reaction path  H forward=-300 kJ  H reverse=+300 kJ Ea forward uncat=100 kJ Ea reverse uncat= Ea forward catalyzed =

10. PE(kJ) 500 400 300 200 100 0 reaction path  H forward=-300 kJ  H reverse=+300 kJ Ea forward uncat=100 kJ Ea reverse uncat=400 kJ Ea forward catalyzed =

11. PE(kJ) 500 400 300 200 100 0 reaction path  H forward=-300 kJ  H reverse=+300 kJ Ea forward uncat=100 kJ Ea reverse uncat=400 kJ Ea forward catalyzed =50 kJ

12. PE(kJ) reaction path Slow rate due to high Ea

13. PE(kJ) reaction path The only way to change the PE diagram is to add a catalyst.

14. PE(kJ) reaction path The only way to change the PE diagram is to add a catalyst. Catalyst DO NOT change enthalpy change of a reaction

15. PE(kJ) reaction path Slow rate due to high Ea

16. PE(kJ) 500 400 300 200 100 0 reaction path

17. 3. Catalysts enable more molecules to jump over the hill

18. 4.Catalysts change mechanism of reaction (Introduce more steps)

19. Catalysts change mechanism of reaction (Introduce more steps)

20. Uncatalyzed reaction Catalyzed reaction

21. Catalysts change mechanism of reaction (Introduce more steps) Downhill in PE KE is produced Ea(for)(uncat)

22. Catalysts change mechanism of reaction (Introduce more steps) Ea(for)(cat) Ea(for)(uncat)

23. 4. Uncatalysed Reaction continues to occur even in the presence of Catalysts

24. 5. Inhibitors slow down reaction rate by providing mechanism (route) of high Ea. So a small fraction of collision have sufficient energy to jump over the hill.

25. 6. Reaction continues to take place even if catalyst is removed because reaction will produce catalyst. 1.A+B→C 2.C+D→CD 3.CD+E→ABE+D Catalyst:

26. Summary 1.Participate in the reaction 2.First used then made in the following step 3.Only factor that can lower Ea and change PE diagram, ΔH does not change. 4.Catalysts enable more molecules to jump over the hill 5.Change mechanism(introduce more steps) 6.Un-catalysed reaction continue to take place 7.Inhibitors slow down reaction by increasing Ea 8.Removal of all the catalyst does not stop the reaction

27. Commercial Catalysts Biological Catalysts

28. Commercial Catalysts H 2 SO 4 Many Organic Reactions PtSurface Catalyst for Diatomic Gases PdCatalytic Converter Automobile ConvertCO→CO 2 RhCatalytic Converter Automobile ConvertNO 2 →N 2 + O 2 Biological Catalysts EnzymesBiological Catalysts Amylase pepsin

29. Commercial Catalysts H 2 SO 4 Many Organic Reactions PtSurface Catalyst for Diatomic Gases PdCatalytic Converter Automobile ConvertCO→CO 2 RhCatalytic Converter Automobile ConvertNO 2 →N 2 + O 2 Biological Catalysts EnzymesBiological Catalysts Amylase pepsin

30. Pt surface HHHH HHHH Hydrogen bonds to surface of metal. Break H-H bonds Surface Catalysts

31. Pt surface HHHH Catalysts C HH C HH

32. Pt surface HHHH Catalysts C HH C HH The double bond breaks and bonds to the catalyst.

33. Pt surface HHHH Catalysts C HH C HH The hydrogen atoms bond with the carbon

34. Pt surface H Catalysts C HH C HH HHH

35. The Metal-Catalyzed Hydrogenation of Ethylene

36. Exothermic Reaction Downhill in PE KE is produced HH Ea(rev)(cat) Ea(for)(cat) Ea(for)(uncat) Ea(rev)(uncat)

37. Workbook Page 36 Question 62- 63