1. Unit Equilibrium
Lundquist

2. Potential Energy diagrams (again)
Unit 10.1
Collision Theory
&
Potential Energy diagrams (again)

3. Video Time

4. Collision Theory
Reactions only occur if reactants collide with enough energy & in the correct orientation

5. Reaction Rates
Rate = change in concentration of a reactant or product per unit time
𝑀 𝑠 -or- 𝑚𝑜𝑙 𝐿×𝑠
determined experimentally
Appearance of Prod
Concentration of rxts
Change in temp.

6. Factors that effect reaction rates
Notes
p. 1
Factors that effect reaction rates
GENERALLY: 10oC increase doubles speed
Nature of Reactants
Concentrations
Surface Area
Temperature
Catalysts

7. Note Quiz Questions (Unit 10.1)1. a. b c. d. 2.

8. Note Quiz Questions (Unit 10.1)3. 4. a. b c. d.

9. DO p. 6-8

10. Potential energy Measure of the energy (“heat”) in something
Enthalpy (H)
ASTONOMICALLY MASSIVE (E=mc2)
So to keep things understandable we measure the difference in enthalpy (DH)

11. Potential Energy (continued)
Law of Conservation of Energy
Energy cannot be created or destroyed
Bonds must break
Bonds must form
+ 92 𝑘𝐽 𝑚𝑜𝑙

12. Potential Energy (continued)
Breaking a bond requires energy
Breaking a bond releases energy

13. Potential Energy (continued)
Heat of Reaction (DHRxn)
The change in enthalpy from reactants to products in a chemical reaction
𝛥 𝐻 𝑅𝑥𝑛 =𝛥 𝐻 𝑝𝑟𝑜 −𝛥 𝐻 𝑟𝑥𝑡
Enthalpy (heat) of the reactants (J)
-bonds broken-
Enthalpy (heat) of the products(J) -bonds formed-
Enthalpy (heat) of the reaction (J)

14. Potential Energy (continued)
Exothermic
Energy is released
-DH
C8H18 + O2 4 CO2 + H2O DH = -32 𝑀𝐽 𝑚𝑜𝑙

15. Potential Energy (continued)
Endothermic
Requires energy
+DH

16. Potential Energy (continued)

17. Potential Energy

18. Potential Energy Diagrams
Ea – Activation Energy
Energy needed to start the Rxn
DHrxn = DHprod – DHrxt
DHrxt
DHprod

19. Note Quiz Questions (Unit 10.1)5.

20. Note Quiz Questions (Unit 10.1)
Which shows the activation energy of the reaction?
Which letter is the enthalpy of the reaction?
Which letter shows the potential energy of CH4 and O2?
Is the reaction endo/exothermic?

21. Thermodynamics
Potential energy Diagrams
Catalysts – lower the activation energy by rearranging the reactants, or providing an alternative pathway.

22. Note Quiz Questions (Unit 10.1)

23. DO p. 9-10

24. Le Châtelier's principle Equilibrium Expressions (Keq)
Unit 10.2
Le Châtelier's principle
&
Equilibrium Expressions (Keq)

25. Henry Louis Le Châtelier
1850 – 1936
French Chemist
Trained as an engineer, but chose to teach chemistry
Had a great interest in industrial engineering
The formation of ammonia

26. Le Châtelier (continued)
1901 he attempted to create ammonia from H2 and N2 gas at a high temperature and pressure
Explosion due to the presence of excess air
Nearly killed an assistant
Abandoned the project

28. Haber Process
Mass production of ammonia
Equilibrium

29. Video Time

30. Equilibrium
When the rate of the forward reaction is equal to the rate of the reverse reaction
Dynamic – constantly in motion
Will stay the same FOREVER unless something changes

31. Note Quiz Questions (Unit 10.1)1. 2. 3.

32. Equilibrium (continued)
Le Châtelier’s Principle
A system at equilibrium will stay at equilibrium

33. Stresses circumstances that shift equilibrium
Concentrations of Prod/rxts
Surface Area
Temperature
Catalysts – affects both the forward and reverse reaction equally

34. What would happen if more N2 (g) was added?

35. What would happen if NH3 (g) was added?

36. What would happen if NH3 (g) was removed?

37. What would happen if H2 (g) was removed?

38. Note Quiz Questions (Unit 10.1)5. 4. 6.
2SO2 + O2  2SO3

39. + 92 𝑘𝐽 𝑚𝑜𝑙
What would happen if the reaction was heated?

40. + 92 𝑘𝐽 𝑚𝑜𝑙
What would happen if the reaction was cooled?

41. Note Quiz Questions (Unit 10.1)7.
Cooling the equilibrium mixture

42. What would happen if the pressure increased (volume decreases)?

43. What would happen if the pressure decreased?

44. Note Quiz Questions (Unit 10.1)8. 9.

45. Equilibrium expression
On the loose sheet I gave you
Equilibrium expression
Mass action expression (K)
Mathematical expression of WHEN equilibrium occurs
Ratio of products to reactants

46. Equilibrium Constant 5. 1.

47. Equilibrium Constant (K)
ONLY INCLUDES GASES & SOL’Ns
The concentration of solids & pure liquids is so massive that they rarely change
Not in notes!
BUT YOU NEED TO KNOW IT

48. ZnCl2(s)  Zn2+(aq) + 2 Cl-(aq)
Equilibrium Constant
Write the equilibrium expression for:
ZnCl2(s)  Zn2+(aq) + 2 Cl-(aq)
What is the value of the equilibrium constant (K) if at equilibrium the concentrations are as follows:
ZnCl2 90M
Zn M
Cl M

49. Note Quiz Questions (Unit 10.1)

50. THE END Test NEXT PERIOD! 25 MC you will need to 21 to get a 100
Multiple Choice homework due NEXT PERIOD!
Test NEXT PERIOD!
25 MC you will need to 21 to get a 100
1 free response worth 10 points, you will need to earn 5 to get a 100