1. Class average for Exam I 70

2. Fe(OH) 3 Fe 3+ (aq) + 3 OH - (aq) [Fe 3+ ][OH - ] 3 = 1.1 x 10 -36 [y][3y] 3 = 1.1 x 10 -36 If there is another source of OH - (NaOH) that provides a higher [OH - ] then that is the value of [OH - ] to be used.

3. pH and solubility

4. CaCO 3(s) + H 3 O + (aq) Ca 2+ (aq) + HCO 3 - (aq) + H 2 O (l)

5. CaCO 3(s) + H 3 O + (aq) Ca 2+ (aq) + HCO 3 - (aq) + H 2 O (l) Net ionic equation.

6. CaCO 3(s) + H 3 O + (aq) Ca 2+ (aq) + HCO 3 - (aq) + H 2 O (l) CaCO 3 calcium carbonate, present in both limestone and marble.

7. CaCO 3(s) + H 3 O + (aq) Ca 2+ (aq) + HCO 3 - (aq) + H 2 O (l) CaCO 3 (s) + H 2 O(l) Ca 2+ (aq) + CO 3 2- (aq)

8. CaCO 3(s) + H 3 O + (aq) Ca 2+ (aq) + HCO 3 - (aq) + H 2 O (l) CaCO 3 (s) + H 2 O(l) Ca 2+ (aq) + CO 3 2- (aq) CO 3 2- (aq) + H 3 O + (aq) H 2 O(l) + HCO 3 - (aq) K sp = [Ca 2+ ][CO 3 2- ]

9. CaCO 3(s) + H 3 O + (aq) Ca 2+ (aq) + HCO 3 - (aq) + H 2 O (l) CaCO 3 (s) + H 2 O(l) Ca 2+ (aq) + CO 3 2- (aq) CO 3 2- (aq) + H 3 O + (aq) H 2 O(l) + HCO 3 - (aq) Any reaction favoring the formation of HCO 3 - favors the solution of a solid carbonate. K sp = [Ca 2+ ][CO 3 2- ]

10. Zn(OH) 2(s) Zn 2+ (aq) + 2 OH - (aq)

11. [Zn 2+ ][OH - ] 2 = K sp

12. Zn(OH) 2(s) Zn 2+ (aq) + 2 OH - (aq) [Zn 2+ ][OH - ] 2 = K sp = 4.5 x 10 -17

13. Zn(OH) 2(s) Zn 2+ (aq) + 2 OH - (aq) [Zn 2+ ][OH - ] 2 = K sp = 4.5 x 10 -17 Increase solubility of Zn(OH) 2 by lowering pH.

14. Zn(OH) 2(s) Zn 2+ (aq) + 2 OH - (aq) [Zn 2+ ][OH - ] 2 = K sp = 4.5 x 10 -17 Increase solubility of Zn(OH) 2 by lowering pH. Removal of product, OH -, shifts equilibrium to right.

15. Zn(OH) 2(s) Zn 2+ (aq) + 2 OH - (aq) [Zn 2+ ][OH - ] 2 = K sp = 4.5 x 10 -17 [Zn 2+ ] = ? @ pH = 7

16. Zn(OH) 2(s) Zn 2+ (aq) + 2 OH - (aq) [Zn 2+ ][OH - ] 2 = K sp = 4.5 x 10 -17 [Zn 2+ ] = ? @ pH = 7 [Zn 2+ ] = y

17. Zn(OH) 2(s) Zn 2+ (aq) + 2 OH - (aq) [Zn 2+ ][OH - ] 2 = K sp = 4.5 x 10 -17 [Zn 2+ ] = ? @ pH = 7 [Zn 2+ ] = y (y)(2y) 2 = K sp

18. Zn(OH) 2(s) Zn 2+ (aq) + 2 OH - (aq) [Zn 2+ ][OH - ] 2 = K sp = 4.5 x 10 -17 [Zn 2+ ] = ? @ pH = 7 [Zn 2+ ] = y (y)(2y) 2 = K sp = 4y 3 = 4.5 x 10 -17

19. Zn(OH) 2(s) Zn 2+ (aq) + 2 OH - (aq) [Zn 2+ ][OH - ] 2 = K sp = 4.5 x 10 -17 [Zn 2+ ] = ? @ pH = 7 [Zn 2+ ] = y (y)(2y) 2 = K sp = 4y 3 = 4.5 x 10 -17 [Zn 2+ ] = 2.2 x 10 -6 M[OH - ] = 4.4 x 10 -6 M

20. Zn(OH) 2(s) Zn 2+ (aq) + 2 OH - (aq) [Zn 2+ ][OH - ] 2 = K sp = 4.5 x 10 -17 [Zn 2+ ] = ? @ pH = 6 [Zn 2+ ] = y buffered pH = 6, [H 3 O + ] = 10 -6 [OH - ] = KwKw [H 3 O + ]

21. Zn(OH) 2(s) Zn 2+ (aq) + 2 OH - (aq) [Zn 2+ ][OH - ] 2 = K sp = 4.5 x 10 -17 [Zn 2+ ] = ? @ pH = 6 [Zn 2+ ] = y buffered pH = 6, [H 3 O + ] = 10 -6 [OH - ] = KwKw [H 3 O + ] = 1 x 10 -14 10 -6 = 10 -8

22. Zn(OH) 2(s) Zn 2+ (aq) + 2 OH - (aq) [Zn 2+ ][OH - ] 2 = K sp = 4.5 x 10 -17 [OH - ] = 1 x 10 -8 (y)(1 x 10 -8 ) 2 = 4.5 x 10 -17

23. Zn(OH) 2(s) Zn 2+ (aq) + 2 OH - (aq) [Zn 2+ ][OH - ] 2 = K sp = 4.5 x 10 -17 [OH - ] = 1 x 10 -8 (y)(1 x 10 -8 ) 2 = 4.5 x 10 -17 y = 4.5 x 10 -17 1 x 10 -16

24. Zn(OH) 2(s) Zn 2+ (aq) + 2 OH - (aq) [Zn 2+ ][OH - ] 2 = K sp = 4.5 x 10 -17 [OH - ] = 1 x 10 -8 (y)(1 x 10 -8 ) 2 = 4.5 x 10 -17 y = 4.5 x 10 -17 1 x 10 -16 = 4.5 x 10 -1

25. Zn(OH) 2(s) Zn 2+ (aq) + 2 OH - (aq) [Zn 2+ ][OH - ] 2 = K sp = 4.5 x 10 -17 [OH - ] = 1 x 10 -8 (y)(1 x 10 -8 ) 2 = 4.5 x 10 -17 y = 4.5 x 10 -17 1 x 10 -16 = 4.5 x 10 -1 [Zn 2+ ] = 0.45 M

26. Zn(OH) 2(s) Zn 2+ (aq) + 2 OH - (aq) [Zn 2+ ][OH - ] 2 = K sp = 4.5 x 10 -17 [Zn 2+ ] = 0.45 M pH = 6 pH = 7 [Zn 2+ ] = 0.0000022 M

27. Zn(OH) 2(s) Zn 2+ (aq) + 2 OH - (aq) [Zn 2+ ][OH - ] 2 = K sp = 4.5 x 10 -17 [Zn 2+ ] = 0.45 M pH = 6 pH = 7 [Zn 2+ ] = 0.0000022 M [OH - ] = 2[Zn 2+ ]

28. Zn(OH) 2(s) Zn 2+ (aq) + 2 OH - (aq) [Zn 2+ ][OH - ] 2 = K sp = 4.5 x 10 -17 [Zn 2+ ] = 0.45 M pH = 6 pH = 7 [Zn 2+ ] = 0.0000022 M [OH - ] = 2[Zn 2+ ] = 4.4 x 10 -6 M

29. Zn(OH) 2(s) Zn 2+ (aq) + 2 OH - (aq) [Zn 2+ ][OH - ] 2 = K sp = 4.5 x 10 -17 [Zn 2+ ] = 0.45 M pH = 6 pH = 8.6 [Zn 2+ ] = 0.0000022 M [OH - ] = 2[Zn 2+ ] = 4.4 x 10 -6 M

30. Solubility of salts of weak acids

31. Solubility of salts of weak acids HA (aq) + H 2 O (l) H 3 O + (aq) + A - (aq)

32. Solubility of salts of weak acids HA (aq) + H 2 O (l) H 3 O + (aq) + A - (aq) Reduce pH, increase [H 3 O + ]

33. Solubility of salts of weak acids HA (aq) + H 2 O (l) H 3 O + (aq) + A - (aq) Reduce pH, increase [H 3 O + ] Increase [H 3 O + ] : equilibrium

34. Solubility of salts of weak acids HA (aq) + H 2 O (l) H 3 O + (aq) + A - (aq) NaA (s) Na + (aq) + A - (aq) conjugate base

35. Solubility of salts of weak acids HA (aq) + H 2 O (l) H 3 O + (aq) + A - (aq) NaA (s) Na + (aq) + A - (aq) A - (aq) + H 3 O + (aq) HA (aq) + H 2 O (l)

36. Solubility of salts of weak acids HA (aq) + H 2 O (l) H 3 O + (aq) + A - (aq) NaA (s) Na + (aq) + A - (aq) A - (aq) + H 3 O + (aq) HA (aq) + H 2 O (l) Reduce pH, increase [H 3 O + ]

37. Solubility of salts of weak acids HA (aq) + H 2 O (l) H 3 O + (aq) + A - (aq) NaA (s) Na + (aq) + A - (aq) A - (aq) + H 3 O + (aq) HA (aq) + H 2 O (l) Reduce pH, increase [H 3 O + ], reduce [A - ]

38. Solubility of salts of weak acids HA (aq) + H 2 O (l) H 3 O + (aq) + A - (aq) NaA (s) Na + (aq) + A - (aq) A - (aq) + H 3 O + (aq) HA (aq) + H 2 O (l) Reduce pH, increase [H 3 O + ], reduce [A - ], increase [Na + ]

39. Using common ions to separate mixtures of ions.

40. Using common ions to separate mixtures of ions. Separating ions which share a group is difficult - they have very similar chemistries.

41. Using common ions to separate mixtures of ions. I II VII Na + Ca 2+ Cl - K + Ba 2+ I -

42. M1X M1 + + X - M2X M2 + + X -

43. M1X M1 + + X - M2X M2 + + X - If the solution is not saturated for either M1X or M2X, there will be no solid present.

44. M1X M1 + + X - M2X M2 + + X - As [X - ] is increased, at some point precipitation will occur.

45. M1X M1 + + X - M2X M2 + + X - If K sp for M1X and K sp for M2X differ by a large enough amount, one will precipitate and the other will remain in solution.

46. CaF 2(s) Ca 2+ (aq) + 2 F - (aq) BaF 2(s) Ba 2+ (aq) + 2 F - (aq)

47. CaF 2(s) Ca 2+ (aq) + 2 F - (aq) BaF 2(s) Ba 2+ (aq) + 2 F - (aq) CaF 2 K sp = 3.9 x 10 -11 BaF 2 K sp = 1.7 x 10 -6

48. CaF 2(s) Ca 2+ (aq) + 2 F - (aq) BaF 2(s) Ba 2+ (aq) + 2 F - (aq) CaF 2 K sp = 3.9 x 10 -11 BaF 2 K sp = 1.7 x 10 -6 Q < K sp no precipitate

49. CaF 2(s) Ca 2+ (aq) + 2 F - (aq) BaF 2(s) Ba 2+ (aq) + 2 F - (aq) CaF 2 K sp = 3.9 x 10 -11 BaF 2 K sp = 1.7 x 10 -6 Q = [Ba 2+ ][F - ] 2 < 1.7 x 10 -6

50. CaF 2(s) Ca 2+ (aq) + 2 F - (aq) BaF 2(s) Ba 2+ (aq) + 2 F - (aq) CaF 2 K sp = 3.9 x 10 -11 BaF 2 K sp = 1.7 x 10 -6 Q = [Ba 2+ ][F - ] 2 < 1.7 x 10 -6 Q < K sp no precipitate

51. CaF 2(s) Ca 2+ (aq) + 2 F - (aq) BaF 2(s) Ba 2+ (aq) + 2 F - (aq) CaF 2 K sp = 3.9 x 10 -11 BaF 2 K sp = 1.7 x 10 -6 Q = [Ba 2+ ][F - ] 2 < 1.7 x 10 -6 Q < K sp no precipitate Q = [Ca 2+ ][F - ] 2 > 3.9 x 10 -11

52. CaF 2(s) Ca 2+ (aq) + 2 F - (aq) BaF 2(s) Ba 2+ (aq) + 2 F - (aq) CaF 2 K sp = 3.9 x 10 -11 BaF 2 K sp = 1.7 x 10 -6 Q = [Ba 2+ ][F - ] 2 < 1.7 x 10 -6 Q < K sp no precipitate Q = [Ca 2+ ][F - ] 2 > 3.9 x 10 -11 Q > K sp precipitate

53. CaF 2(s) Ca 2+ (aq) + 2 F - (aq) BaF 2(s) Ba 2+ (aq) + 2 F - (aq) CaF 2 K sp = 3.9 x 10 -11 BaF 2 K sp = 1.7 x 10 -6 Q = [Ba 2+ ][F - ] 2 < 1.7 x 10 -6 Q < K sp no precipitate Q = [Ca 2+ ][F - ] 2 > 3.9 x 10 -11 Q > K sp precipitate Adjust [F - ] so maximum Ca 2+ precipitates with no Ba 2+ precipitate.

54. CaF 2(s) Ca 2+ (aq) + 2 F - (aq) BaF 2(s) Ba 2+ (aq) + 2 F - (aq) K sp (BaF 2 ) = [Ba 2+ ][F - ] 2 = 1.7 x 10 -6

55. Q < K sp no precipitate CaF 2(s) Ca 2+ (aq) + 2 F - (aq) BaF 2(s) Ba 2+ (aq) + 2 F - (aq)

56. K sp (BaF 2 ) = [Ba 2+ ][F - ] 2 = 1.7 x 10 -6 Q < K sp no precipitate [F - ] 2 < 1.7 x 10 -6 [Ba 2+ ] CaF 2(s) Ca 2+ (aq) + 2 F - (aq) BaF 2(s) Ba 2+ (aq) + 2 F - (aq)

57. K sp (BaF 2 ) = [Ba 2+ ][F - ] 2 = 1.7 x 10 -6 Q < K sp no precipitate [F - ] 2 < 1.7 x 10 -6 [Ba 2+ ] = 1.7 x 10 -6 0.10 CaF 2(s) Ca 2+ (aq) + 2 F - (aq) BaF 2(s) Ba 2+ (aq) + 2 F - (aq)

58. K sp (BaF 2 ) = [Ba 2+ ][F - ] 2 = 1.7 x 10 -6 Q < K sp no precipitate [F - ] 2 < 1.7 x 10 -6 [Ba 2+ ] = 1.7 x 10 -6 0.10 = 1.7 x 10 -5 CaF 2(s) Ca 2+ (aq) + 2 F - (aq) BaF 2(s) Ba 2+ (aq) + 2 F - (aq)

59. K sp (BaF 2 ) = [Ba 2+ ][F - ] 2 = 1.7 x 10 -6 Q < K sp no precipitate [F - ] 2 < 1.7 x 10 -6 [Ba 2+ ] = 1.7 x 10 -6 0.10 = 1.7 x 10 -5 [F - ] < 4.1 x 10 -3 CaF 2(s) Ca 2+ (aq) + 2 F - (aq) BaF 2(s) Ba 2+ (aq) + 2 F - (aq)

60. K sp (BaF 2 ) = [Ba 2+ ][F - ] 2 = 1.7 x 10 -6 Q < K sp no precipitate [F - ] 2 < 1.7 x 10 -6 [Ba 2+ ] = 1.7 x 10 -6 0.10 = 1.7 x 10 -5 [F - ] < 4.1 x 10 -3 All Ba 2+ remains in solution. CaF 2(s) Ca 2+ (aq) + 2 F - (aq) BaF 2(s) Ba 2+ (aq) + 2 F - (aq)

61. K sp (CaF 2 ) = [Ca 2+ ][F - ] 2 = 3.9 x 10 -11 Q > K sp precipitate CaF 2(s) Ca 2+ (aq) + 2 F - (aq) BaF 2(s) Ba 2+ (aq) + 2 F - (aq) [Ba 2 +] = [Ca 2+ ] = 0.10 M

62. K sp (CaF 2 ) = [Ca 2+ ][F - ] 2 = 3.9 x 10 -11 Q > K sp precipitate [F - ] 2 > 3.9 x 10 -11 0.10 CaF 2(s) Ca 2+ (aq) + 2 F - (aq) BaF 2(s) Ba 2+ (aq) + 2 F - (aq)

63. K sp (CaF 2 ) = [Ca 2+ ][F - ] 2 = 3.9 x 10 -11 Q > K sp precipitate [F - ] 2 > 3.9 x 10 -11 0.10 = 3.9 x 10 -10 [F - ] > 2.0 x 10 -5 CaF 2(s) starts to precipitate CaF 2(s) Ca 2+ (aq) + 2 F - (aq) BaF 2(s) Ba 2+ (aq) + 2 F - (aq)

64. [F - ] > 2.0 x 10 -5 CaF 2(s) starts to precipitate [F - ] < 4.1 x 10 -3 All Ba 2+ remains in solution. CaF 2(s) Ca 2+ (aq) + 2 F - (aq) BaF 2(s) Ba 2+ (aq) + 2 F - (aq)

65. [F - ] > 2.0 x 10 -5 CaF 2(s) starts to precipitate [F - ] < 4.1 x 10 -3 All Ba 2+ remains in solution. How to reduce [Ca 2+ ] to as low a level as possible without BaF 2 precipitation? CaF 2(s) Ca 2+ (aq) + 2 F - (aq) BaF 2(s) Ba 2+ (aq) + 2 F - (aq)

66. [F - ] < 4.1 x 10 -3 All Ba 2+ remains in solution. Adjust [F - ] to 0.0041 M CaF 2(s) Ca 2+ (aq) + 2 F - (aq) BaF 2(s) Ba 2+ (aq) + 2 F - (aq)

67. [F - ] < 4.1 x 10 -3 All Ba 2+ remains in solution. Adjust [F - ] to 0.0041 M How much Ca 2+ remains in solution? CaF 2(s) Ca 2+ (aq) + 2 F - (aq) BaF 2(s) Ba 2+ (aq) + 2 F - (aq)

68. CaF 2(s) Ca 2+ (aq) + 2 F - (aq) Adjust [F - ] to 0.0041 M K sp = [Ca 2+ ][F - ] 2 = 3.9 x 10 -11 [Ca 2+ ] = 3.9 x 10 -11 [F - ] 2

69. CaF 2(s) Ca 2+ (aq) + 2 F - (aq) Adjust [F - ] to 0.0041 M K sp = [Ca 2+ ][F - ] 2 = 3.9 x 10 -11 [F - ] 2 = 3.9 x 10 -11 (4.1 x 10 -3 ) 2 2.3 x 10 -6 [Ca 2+ ] =

70. Adjust [F - ] to 0.0041 M 0.10 M CaF 2(s) Ca 2+ (aq) + 2 F - (aq) 0.10 M BaF 2(s) Ba 2+ (aq) + 2 F - (aq) [Ba 2+ ] = 1.7 x 10 -6 (4.1 x 10 -3 ) 2 = 0.10 M 2.3 x 10 -6 [Ca 2+ ] = CaF 2 K sp = 3.9 x 10 -11 BaF 2 K sp = 1.7 x 10 -6

71. Metal sulfides in acidic solution MS M 2+ (aq) + S 2- (aq) K sp = [M 2+ ][S 2- ]

72. Metal sulfides in acidic solution MS M 2+ (aq) + S 2- (aq) K sp = [M 2+ ][S 2- ] S 2- Is a strong base

73. Metal sulfides in acidic solution MS M 2+ (aq) + S 2- (aq) K sp = [M 2+ ][S 2- ] S 2- Is a strong base S -2 (aq) + H 2 O (l) HS - (aq) + OH - (aq) K b = [HS - ][OH - ] [S 2- ]

74. Metal sulfides in acidic solution MS M 2+ (aq) + S 2- (aq) K sp = [M 2+ ][S 2- ] S 2- Is a strong base S -2 (aq) + H 2 O (l) HS - (aq) + OH - (aq) K b = [HS - ][OH - ] [S 2- ]  10 5

75. Metal sulfides in acidic solution MS M 2+ (aq) + S 2- (aq) K sp = [M 2+ ][S 2- ] S 2- Is a strong base S -2 (aq) + H 2 O (l) HS - (aq) + OH - (aq) K b = [HS - ][OH - ] [S 2- ]  10 5 K sp = [M 2+ ][HS - ][OH - ]

76. Metal sulfides in acidic solution MS M 2+ (aq) + S 2- (aq) S -2 (aq) + H 2 O (l) HS - (aq) + OH - (aq) K sp = [M 2+ ][HS - ][OH - ] Lower pH, lower [OH - ], higher [M 2+ ] K sp metal sulfides < 10 -10

77. Metal sulfides in acidic solution CdS (s) Cd 2+ (aq) + S 2- (aq) S -2 (aq) + H 2 O (l) HS - (aq) + OH - (aq) K sp = [Cd 2+ ][HS - ][OH - ] = 7 x 10 -28

78. Metal sulfides in acidic solution CdS (s) Cd 2+ (aq) + S 2- (aq) S -2 (aq) + H 2 O (l) HS - (aq) + OH - (aq) K sp = [Cd 2+ ][HS - ][OH - ] = 7 x 10 -28 Buffer solution to pH = 2

79. Metal sulfides in acidic solution CdS (s) Cd 2+ (aq) + S 2- (aq) S -2 (aq) + H 2 O (l) HS - (aq) + OH - (aq) K sp = [Cd 2+ ][HS - ][OH - ] = 7 x 10 -28 Buffer solution to pH = 2 [H 3 O + ] = 1 x 10 -2

80. Metal sulfides in acidic solution CdS (s) Cd 2+ (aq) + S 2- (aq) S -2 (aq) + H 2 O (l) HS - (aq) + OH - (aq) K sp = [Cd 2+ ][HS - ][OH - ] = 7 x 10 -28 Buffer solution to pH = 2 [H 3 O + ] = 1 x 10 -2 [OH - ] = 1 x 10 -14 1 x 10 -2

81. Metal sulfides in acidic solution CdS (s) Cd 2+ (aq) + S 2- (aq) S -2 (aq) + H 2 O (l) HS - (aq) + OH - (aq) K sp = [Cd 2+ ][HS - ][OH - ] = 7 x 10 -28 Buffer solution to pH = 2 [OH - ] = 1 x 10 -14 1 x 10 -2 = 1 x 10 -12

82. Metal sulfides in acidic solution CdS (s) Cd 2+ (aq) + S 2- (aq) S -2 (aq) + H 2 O (l) HS - (aq) + OH - (aq) K sp = [Cd 2+ ][HS - ][OH - ] = 7 x 10 -28 Buffer solution to pH = 2 [OH - ] = 1 x 10 -12

83. Metal sulfides in acidic solution CdS (s) Cd 2+ (aq) + S 2- (aq) S -2 (aq) + H 2 O (l) HS - (aq) + OH - (aq) K sp = [Cd 2+ ][HS - ][OH - ] = 7 x 10 -28 Buffer solution to pH = 2 [OH - ] = 1 x 10 -12 H 2 S (aq) + H 2 O (l) H 3 O + (aq) + HS - (aq)

84. Metal sulfides in acidic solution CdS (s) Cd 2+ (aq) + S 2- (aq) S -2 (aq) + H 2 O (l) HS - (aq) + OH - (aq) K sp = [Cd 2+ ][HS - ][OH - ] = 7 x 10 -28 [OH - ] = 1 x 10 -12 H 2 S (aq) + H 2 O (l) H 3 O + (aq) + HS - (aq) K a = [H 3 O + ][HS - ] [H 2 S] = 9.1 x 10 -8 Buffer solution to pH = 2 [H 2 S] = 0.10 M

85. Metal sulfides in acidic solution CdS (s) Cd 2+ (aq) + S 2- (aq) S -2 (aq) + H 2 O (l) HS - (aq) + OH - (aq) K sp = [Cd 2+ ][HS - ][OH - ] = 7 x 10 -28 [OH - ] = 1 x 10 -12 H 2 S (aq) + H 2 O (l) H 3 O + (aq) + HS - (aq) K a = (0.01)[HS - ] (0.10) = 9.1 x 10 -8

86. Metal sulfides in acidic solution CdS (s) Cd 2+ (aq) + S 2- (aq) S -2 (aq) + H 2 O (l) HS - (aq) + OH - (aq) K sp = [Cd 2+ ][HS - ][OH - ] = 7 x 10 -28 [OH - ] = 1 x 10 -12 H 2 S (aq) + H 2 O (l) H 3 O + (aq) + HS - (aq) K a = (0.01)[HS - ] (0.10) = 9.1 x 10 -8 [HS - ] = (0.10)(9.1 x 10 -8 )/(0.01) = 9.1 x 10 -7

87. Metal sulfides in acidic solution CdS (s) Cd 2+ (aq) + S 2- (aq) S -2 (aq) + H 2 O (l) HS - (aq) + OH - (aq) K sp = [Cd 2+ ][HS - ][OH - ] = 7 x 10 -28 [OH - ] = 1 x 10 -12 H 2 S (aq) + H 2 O (l) H 3 O + (aq) + HS - (aq) [HS - ] = 9.1 x 10 -7 [Cd 2+ ] = (7 x 10 -28 )/(9.1 x 10 -7 )(1 x 10 -12 )

88. Metal sulfides in acidic solution CdS (s) Cd 2+ (aq) + S 2- (aq) S -2 (aq) + H 2 O (l) HS - (aq) + OH - (aq) K sp = [Cd 2+ ][HS - ][OH - ] = 7 x 10 -28 [OH - ] = 1 x 10 -12 H 2 S (aq) + H 2 O (l) H 3 O + (aq) + HS - (aq) [HS - ] = 9.1 x 10 -7 [Cd 2+ ] = (7 x 10 -28 )/(9.1 x 10 -7 )(1 x 10 -12 ) = 8 x 10 -10

89. Metal sulfides in acidic solution CdS (s) Cd 2+ (aq) + S 2- (aq) S -2 (aq) + H 2 O (l) HS - (aq) + OH - (aq) K sp = [Cd 2+ ][HS - ][OH - ] = 7 x 10 -28 [OH - ] = 1 x 10 -7 H 2 S (aq) + H 2 O (l) H 3 O + (aq) + HS - (aq) K a = (1 x 10 -7 )[HS - ] (0.10) = 9.1 x 10 -8 [HS - ] = (0.1)(9.1 x 10 -8 )/(1 x 10 -7 ) = 9.1 x 10 -2 pH = 7

90. Metal sulfides in acidic solution CdS (s) Cd 2+ (aq) + S 2- (aq) S -2 (aq) + H 2 O (l) HS - (aq) + OH - (aq) K sp = [Cd 2+ ][HS - ][OH - ] = 7 x 10 -28 [OH - ] = 1 x 10 -7 H 2 S (aq) + H 2 O (l) H 3 O + (aq) + HS - (aq) [HS - ] = 9.1 x 10 -2 [Cd 2+ ] = (7 x 10 -28 )/(9.1 x 10 -2 )(1 x 10 -7 ) = 8 x 10 -20

91. Complex ions

92. Metals coordinated to ligands which can exist independantly as molecules or ions.

93. Ammonia, NH 3, and water are common ligands in complex ions.

94. Cobalt(II) chloride

95. CoCl 2. 6H 2 O CoCl 2. 2H 2 O

96. Cobalt(II) chloride CoCl 2. 6H 2 O [Co(H 2 O) 6 ] 2+ (Cl - ) 2 CoCl 2. 2H 2 O blue purple magenta

97. 2+ [Co(H 2 O) 6 ] 2+

98. Solubilities of complex ions Equilibria involving complex ions may involve multi-step processes in which individual ligands are added or removed.

99. Cobalt(II) chloride CoCl 2. 6H 2 O [Co(H 2 O) 6 ] 2+ (Cl - ) 2 CoCl 2. 2H 2 O blue purple magenta These species are quite soluble.

100. Ag + (aq) + NH 3(aq) Ag(NH 3 ) +

101. Ag + (aq) + NH 3(aq) Ag(NH 3 ) + (aq) [Ag(NH 3 ) + ] [Ag + ][NH 3 ] = 2.1 x 10 3 K 1 =

102. [Ag(NH 3 ) + ] [Ag + ][NH 3 ] = 2.1 x 10 3 K 1 = Ag(NH 3 ) + (aq) + NH 3(aq) Ag(NH 3 ) 2 + (aq) Ag + (aq) + NH 3(aq) Ag(NH 3 ) + (aq)

103. [Ag(NH 3 ) + ] [Ag + ][NH 3 ] = 2.1 x 10 3 K 1 = Ag(NH 3 ) + (aq) + NH 3(aq) Ag(NH 3 ) 2 + (aq) Ag + (aq) + NH 3(aq) Ag(NH 3 ) + (aq) K 2 = [Ag(NH 3 ) 2 + ] [Ag(NH 3 ) + ][NH 3 ] = 8.2 x 10 3

104. K 1, K 2 > 10 3 - large

105. Ag + in the presence of excess NH 3 is converted to  100% Ag(NH 3 ) 2 +

106. K 1, K 2 > 10 3 - large Ag + in the presence of excess NH 3 is converted to  100% Ag(NH 3 ) 2 +. Add 0.1 M AgNO 3 to 1 L of 1 M NH 3

107. K 1, K 2 > 10 3 - large Ag + in the presence of excess NH 3 is converted to  100% Ag(NH 3 ) 2 +. Add 0.1 M AgNO 3 to 1 L of 1 M NH 3 Initial condition: [Ag(NH 3 ) 2 + ] = 0.10 M [NH 3 ] = 0.80 M

108. Ag(NH 3 ) 2 + ( aq) Ag(NH 3 ) + (aq) + NH 3(aq) K = 1 K2K2 [Ag(NH 3 ) 2 + ] [Ag(NH 3 ) + ] [NH 3 ] = Init 0.100 M 0 0.80

109. Ag(NH 3 ) 2 + ( aq) Ag(NH 3 ) + (aq) + NH 3(aq) K = 1 K2K2 [Ag(NH 3 ) 2 + ] [Ag(NH 3 ) + ] [NH 3 ] = Init 0.100 M 0 0.80  -y +y + y Eq 0.100-y y 0.80 + y

110. Ag(NH 3 ) 2 + ( aq) Ag(NH 3 ) + (aq) + NH 3(aq) K = 1 8.2 x 10 3 (0.100-y) (y)(0.80+y) = Init 0.100 M 0 0.80  -y +y + y Eq 0.100-y y 0.80 + y

111. K = 1 8.2 x 10 3 (0.100-y) (y)(0.80+y) = Assume y is small 8y = 1.2 x 10 -4 y = 1.5 x 10 -5 M/L

112. Ag(NH 3 ) 2 + ( aq) Ag(NH 3 ) + (aq) + NH 3(aq) Init 0.100 M 0 0.80  -y +y + y Eq 0.100 1.5 x 10 -5 0.80

113. Ag(NH 3 ) + ( aq) Ag + (aq) + NH 3(aq) [Ag + ][NH 3 ] [Ag(NH 3 ) + ] = 1 K1K1 = 4.8 x 10 -4 Eq 0.100 1.5 x 10 -5 0.80

114. Ag(NH 3 ) + ( aq) Ag + (aq) + NH 3(aq) [Ag + ][NH 3 ] [Ag(NH 3 ) + ] = 1 K1K1 = 4.8 x 10 -4 Eq 0.100 1.5 x 10 -5 0.80 [Ag + ] = (1.5 x 10 -5 )(4.8 x 10 -4 ) 0.80

115. Ag(NH 3 ) + ( aq) Ag + (aq) + NH 3(aq) [Ag + ][NH 3 ] [Ag(NH 3 ) + ] = 1 K1K1 = 4.8 x 10 -4 Eq 0.100 1.5 x 10 -5 0.80 [Ag + ] = (1.5 x 10 -5 )(4.8 x 10 -4 ) 0.80 = 9 x 10 -9 M/L

116. Ag + (aq) + NH 3(aq) Ag(NH 3 ) + (aq) Ag(NH 3 ) + (aq) + NH 3(aq) Ag(NH 3 ) 2 + (aq) 9 x 10 -9 0.80 1.5 x 10 -5 1.5 x 10 -5 0.80 0.10

117. Formation of complex ions starting with AgCl.

118. AgCl (s) Ag + (aq) + Cl - (aq) K sp = 1.6 x 10 -10 By adding NaCl, increase in [Cl - ] (common ion effect) causes shift to AgCl (s)

119. K sp = 1.6 x 10 -10 Ag + (s) + 2 Cl - (aq) AgCl 2 - (aq) AgCl (s) Ag + (aq) + Cl - (aq) [AgCl 2 - ] [Ag + ][Cl - ] 2 K = 1.8 x 10 5 =

120. K sp = 1.6 x 10 -10 Ag + (s) + 2 Cl - (aq) AgCl 2 - (aq) AgCl (s) Ag + (aq) + Cl - (aq) [AgCl 2 - ] [Ag + ][Cl - ] 2 K = 1.8 x 10 5 = [Ag + ] = [Cl - ] = 1.3 x 10 -5

121. K sp = 1.6 x 10 -10 Ag + (s) + 2 Cl - (aq) AgCl 2 - (aq) AgCl (s) Ag + (aq) + Cl - (aq) [AgCl 2 - ][Ag + ][Cl - ] 2 = (1.8 x 10 5 ) [Ag + ] = [Cl - ] = 1.3 x 10 -5

122. K sp = 1.6 x 10 -10 Ag + (s) + 2 Cl - (aq) AgCl 2 - (aq) AgCl (s) Ag + (aq) + Cl - (aq) [Ag + ] = [Cl - ] = 1.3 x 10 -5 [AgCl 2 - ](1.3 x 10 -5 ) 3 = 4 x 10 -10 = (1.8 x 10 5 ) [AgCl 2 - ][Ag + ][Cl - ] 2 = (1.8 x 10 5 )

123. K sp = 1.6 x 10 -10 Ag + (s) + 2 Cl - (aq) AgCl 2 - (aq) AgCl (s) Ag + (aq) + Cl - (aq) [Ag + ] = 1.3 x 10 -5 [AgCl 2 - ](1.3 x 10 -5 ) = 2.34 M = (1.8 x 10 5 ) [AgCl 2 - ][Ag + ][Cl - ] 2 = (1.8 x 10 5 ) Change [Cl - ] 1 M

124. Hydrolysis by complex ions

125. + H 2 O (l) + H 3 O +

126. + H 2 O (l) + H 3 O + K a = [H 3 O + ][Fe(H 2 O) 5 OH 2+ ] [Fe(H 2 O) 6 3+ ] = 7.7 x 10 -3