1. Chemical Equilibrium

2. The state of a chemical reaction in which its forward and reverse reactions occur at equal rates so that the concentration of the reactants and products does not change with time.

3. Law of Mass Action aA + bB + cC +... pP + qQ + rR +... Equilibrium Constant [P] p [Q] q [R] r... K = --------------------- [A] a [B] b [C] c...

5. Meaning of Equilibrium Constant K>>1: reaction is product-favored; equilibrium concentrations of products are greater than equilibrium concentrations of reactants. K<<1: reaction is reactant-favored; equilibrium concentrations of reactants are greater than equilibrium concentrations of products.

6. If K = 100 = [I 2 in CCl 4 ] / [I 2 in water] for the equilibrium I 2 in water = I 2 in CCl 4 What is K for the reverse reaction, I 2 in CCl 4 = I 2 in H 2 O? 100, 1, 0.01

7. Acid-Base Equilibrium in Aqueous Solution Acid Dissociation Constant HC 2 H 3 O 2 + H 2 O H 3 O + + C 2 H 3 O 2 - [H 3 O + ][C 2 H 3 O 2 - ] K = ---------------------- [H 2 O][HC 2 H 3 O 2 ] [H 3 O + ][C 2 H 3 O 2 - ] K a = K*[H 2 O] = --------------------- - [HC 2 H 3 O 2 ]

8. Acid-Base Equilibrium in Aqueous Solution Base Dissociation Constant NH 3 + H 2 O NH 4 + + OH - [NH 4 + ][OH - ] K = ----------------- [H 2 O][NH 3 ] [NH 4 + ][OH - ] K b = K*[H 2 O] = ---------------- [NH 3 ]

9. Autoionization of Water H 2 O + H 2 O H 3 O + + OH - [H 3 O + ][OH - ] K = ----------------- [H 2 O] 2 K w = K [H 2 O] 2 = [H 3 O + ][OH - ] = 1.0 x 10 -14

10. Analogy in Semiconductors | | | | -Si:Si- -Si + :Si- + e - | | | | | | -Si:Si- h + + e - | | K = h + * e -

11. e - and h + in Semiconductors Production Recombination electrons (e ) – holes (h ) + Electron energy conduction band valence band Si e – + h E g conduction band valence band

12. Autoionization Equilibria

13. e - and h + in Semiconductors + h Si e – + h e – (–)(+)

14. Doping

15. Donors and Acceptors in Silicon conduction band } valence band donors M  M + e + – }

16. Which dopant will act as an acceptor for Si? B, Ge, As As a donor? B, Ge, As

17. Fermi Level

18. Le Chatelier's Principle If a stress, such as a change in concentration, pressure, temperature, etc., is applied to a system at equilibrium, the equilibrium will shift in such a way as to lessen the effect of the stress.

19. Gas Phase Equilibrium catalysis N 2(g) + 3 H 2(g) 2 NH 3(g) + heat high pressure and temperature

21. The Principle of Le Chatelier Changes in Concentration or Partial Pressure for N 2(g) + 3 H 2(g)  2 NH 3(g) an increase in N 2 and/or H 2 concentration or pressure, will cause the equilibrium to shift towards the production of NH 3

22. The Principle of Le Chatelier Changes in Concentration or Partial Pressure for N 2(g) + 3 H 2(g)  2 NH 3(g) likewise, a decrease in NH 3 concentration or pressure will cause more NH 3 to be produced

23. The Principle of Le Chatelier Changes in Temperature for N 2(g) + 3 H 2(g)  2 NH 3(g) + heat for an exothermic reaction, an increase in temperature will cause the reaction to shift back towards reactants

24. The cobalt complexes participating in the equilibrium below comprise a humidity sensor. From Le Châtelier's principle, when the sensor is moist (excess H 2 O), what color is the cobalt complex? pink, blue

25. A competition experiment involves O 2 and CO vying for hemoglobin (Hb) sites, defined by the equilibrium Hb(O 2 ) 4 + 4 CO = Hb(CO) 4 + 4O 2 From Le Châtelier's principle, how is CO poisoning reversed? decrease O 2 pressure, increase O 2 pressure, remove Hb

26. Heterogeneous Equilibrium CaCO 3(s) + heat CaO (s) + CO 2(g)

27. Gibbs Free Energy and Equilibrium  G Reaction ------------------------------------- NegativeSpontaneous PositiveNon-Spontaneous ZeroEquilibrium -------------------------------------

28. The Influence of Temperature on Free Energy  G,  H, &  S  G =  H - T  S  H  S  G negativepositivenegative spontaneous at all temperatures

29. The Influence of Temperature on Free Energy  G,  H, &  S  G =  H - T  S  H  S  G positivenegativepositive non-spontaneous at all temperatures

30. The Influence of Temperature on Free Energy  G,  H, &  S  G =  H - T  S  H  S  G negativenegative-------- spontaneous at low temperatures, nonspontaneous at high temperatures

31. The Influence of Temperature on Free Energy  G,  H, &  S  G =  H - T  S  H  S  G positivepositive-------- spontaneous at high temperatures, nonspontaneous at low temperatures

32. Phase Transitions H 2 O (s) -----> H 2 O (l)  H > 0;  S > 0 H 2 O (l) -----> H 2 O (g)  H > 0;  S > 0 spontaneous at high temperatures

33. Phase Transitions H 2 O (l) -----> H 2 O (s)  H < 0;  S < 0 H 2 O (g) -----> H 2 O (l)  H < 0;  S < 0 spontaneous at low temperatures