Chemistry 11th Edition Raymond Chang Test Bank

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Chemistry 11th Edition Raymond Chang Test Bank

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Chapter 16: Acid-Base Equilibria and Solubility Equilibria

A table of ionization constants and Ka s is required to work some of the problems in this chapter.

1. In which one of the following solutions will acetic acid have the greatest percent ionization?
A) 0.1 M CH3COOH
B) 0.1 M CH3COOH dissolved in 1.0 M HCl
C) 0.1 M CH3COOH plus 0.1 M CH3COONa
D) 0.1 M CH3COOH plus 0.2 M CH3COONa
Ans: A Category: Medium Section: 16.2

2. Which one of the following is a buffer solution?
A) 0.40 M HCN and 0.10 KCN D) 0.10 M KCN
B) 0.20 M CH3COOH E) 0.50 M HCl and 0.10 NaCl
C) 1.0 M HNO3 and 1.0 M NaNO3
Ans: A Category: Medium Section: 16.3

3. Which one of the following combinations cannot function as a buffer solution?
A) HCN and KCN D) HF and NaF
B) NH3 and (NH4)2SO4 E) HNO2 and NaNO2
C) HNO3 and NaNO3
Ans: C Category: Medium Section: 16.3

4. Which of the following is the most acidic solution?
A) 0.10 M CH3COOH and 0.10 M CH3COONa
B) 0.10 M CH3COOH
C) 0.10 M HNO2
D) 0.10 M HNO2 and 0.10 M NaNO2
E) 0.10 M CH3COONa
Ans: C Category: Medium Section: 16.2

5. Which of the following yields a buffer solution when equal volumes of the two solutions are mixed?
A) 0.10 M NH3 and 0.10 M HCl D) 0.20 M NH3 and 0.10 M HCl
B) 0.10 M NH4+ and 0.10 M KOH E) 0.20 M NH4+ and 0.10M HCl
C) 0.20 M NH3 0.10 M KOH
Ans: D Category: Medium Section: 16.3

6. Which of the following yields a buffer solution when equal volumes of the two solutions are mixed?
A) 0.10M HCl and 0.10 M NaCl D) 0.10M HClO4 and 0.10 NaClO4
B) 0.15 M HNO3 and 0.15 M NaNO3 E) 0.15M HBr and 0.15M NaBr
C) 0.10M HF and 0.10M NaF
Ans: C Category: Medium Section: 16.3

7. Which of the following yields a buffer solution when equal volumes of the two solutions are mixed?
A) 0.10M H2CO3 and 0.050M HCl D) 0.10M H2CO3 and 0.050M KOH
B) 0.10M H2CO3 and 0.10M KOH E) 0.10M K2CO3 and 0.050M KOH
C) 0.10M H2CO3 and 0.10M HCl
Ans: D Category: Medium Section: 16.3

8. Which of the following yields a buffer solution when equal volumes of the two solutions are mixed?
A) 0.050 M H3PO4 and 0.050M HCl
B) 0.050M H3PO4 and 0.025 M HCl
C) 0.050M NaH2PO4 and 0.025M NaOH
D) 0.050M Na3PO4 and 0.050M M NaOH
E) 0.050M Na3PO4 and 0.025M NaOH
Ans: C Category: Medium Section: 16.3

9. Calculate the pH of a buffer solution that contains 0.25 M benzoic acid (C6H5CO2H) and 0.15M sodium benzoate (C6H5COONa). [Ka = 6.5 105 for benzoic acid]
A) 3.97 B) 4.83 C) 4.19 D) 3.40 E) 4.41
Ans: A Category: Medium Section: 16.3

10. A solution is prepared by mixing 500. mL of 0.10 M NaOCl and 500. mL of 0.20 M HOCl. What is the pH of this solution? [Ka(HOCl) = 3.2 108]
A) 4.10 B) 7.00 C) 7.19 D) 7.49 E) 7.80
Ans: C Category: Medium Section: 16.2

11. Calculate the pH of a buffer solution prepared by dissolving 0.20 mole of cyanic acid (HCNO) and 0.80 mole of sodium cyanate (NaCNO) in enough water to make 1.0 liter of solution.
[Ka(HCNO) = 2.0 104]
A) 0.97 B) 3.10 C) 4.40 D) 3.70 E) 4.30
Ans: E Category: Medium Section: 16.3

12. Calculate the pH of a solution that is 0.410 M in HOCl and 0.050 M in NaOCl. [Ka(HOCl) = 3.2 108]
A) 0.39 B) 3.94 C) 6.58 D) 7.49 E) 8.40
Ans: C Category: Medium Section: 16.2

13. Calculate the pH of a buffer solution prepared by dissolving 0.2 mole of sodium cyanate (NaCNO) and 1.0 mole of cyanic acid (HCNO) in enough water to make 1.0 liter of solution. [Ka(HCNO) = 2.0 104]
A) 0 B) 3.0 C) 3.7 D) 4.4 E) 5.0
Ans: B Category: Medium Section: 16.3

14. You are asked to go into the lab and prepare an acetic acid sodium acetate buffer solution with a pH of 4.00 0.02. What molar ratio of CH3COOH to CH3COONa should be used?
A) 0.18 B) 0.84 C) 1.19 D) 5.50 E) 0.10
Ans: D Category: Medium Section: 16.3

15. What is the net ionic equation for the reaction that occurs when small amounts of hydrochloric acid are added to a HOCl/NaOCl buffer solution?
A) H+ + H2O H3O+ D) H+ + HOCl H2OCl+
B) H+ + OCl HOCl E) HCl + HOCl H2O + Cl2
C) HOCl H+ + OCl
Ans: B Category: Medium Section: 16.3

16. Consider a buffer solution prepared from HOCl and NaOCl. Which is the net ionic equation for the reaction that occurs when NaOH is added to this buffer?
A) OH + HOCl H2O + OCl D) H+ + HOCl H2 + OCl
B) OH + OCl HOCl + O2 E) NaOH + HOCl H2O + NaCl
C) Na+ + HOCl NaCl + OH
Ans: A Category: Medium Section: 16.3

17. What pH range is a HOCl NaOCl buffer effective?
A) pH 2.0 pH 4.0 D) pH 6.5 pH 9.5
B) pH 7.5 pH 9.5 E) pH 1.0 pH 14.0
C) pH 6.5 pH 8.5
Ans: C Category: Medium Section: 16.3

18. Assuming equal concentrations of conjugate base and acid, which one of the following mixtures is suitable for making a buffer solution with an optimum pH of 9.29.3?
A) CH3COONa / CH3COOH (Ka = 1.8 105)
B) NH3 / NH4Cl (Ka = 5.6 1010)
C) NaOCl / HOCl (Ka = 3.2 108)
D) NaNO2 / HNO2 (Ka = 4.5 104)
E) NaCl / HCl
Ans: B Category: Medium Section: 16.3

19. Assuming equal concentrations of conjugate base and acid, which one of the following mixtures is suitable for making a buffer solution with an optimum pH of 4.64.8?
A) CH3COO2Na / CH3COOH (Ka = 1.8 105)
B) NH3 / NH4Cl (Ka = 5.6 1010)
C) NaOCl / HOCl (Ka = 3.2 108)
D) NaNO2 / HNO2 (Ka = 4.5 104)
E) NaCl / HCl
Ans: A Category: Medium Section: 16.3

20. You have 500.0 mL of a buffer solution containing 0.20 M acetic acid (CH3COOH) and 0.30 M sodium acetate (CH3COONa). What will the pH of this solution be after the addition of 20.0 mL of 1.00 M NaOH solution? [Ka = 1.8 105]
A) 4.41 B) 4.74 C) 4.56 D) 4.92 E) 5.07
Ans: E Category: Difficult Section: 16.3

21. You have 500.0 mL of a buffer solution containing 0.30 M acetic acid (CH3COOH) and 0.20 M sodium acetate (CH3COONa). What will the pH of this solution be after the addition of 20.0 mL of 1.00 M NaOH solution? [Ka = 1.8 105]
A) 4.65 B) 4.71 C) 4.56 D) 4.84 E) 5.07
Ans: B Category: Difficult Section: 16.3

22. Starting with 0.250L of a buffer solution containing 0.250 M benzoic acid (C6H5COOH) and 0.20 M sodium benzoate (C6H5COONa), what will the pH of the solution be after the addition of 25.0 mL of 0.100M HCl? (Ka (C6H5COOH) = 6.5 x 10-5)
A) 4.19 B) 4.10 C) 4.28 D) 4.05 E) 3.78
Ans: D Category: Difficult Section: 16.3

23. Starting with 0.750L of a buffer solution containing 0.30 M benzoic acid (C6H5COOH) and 0.35 M sodium benzoate (C6H5COONa), what will the pH of the solution be after the addition of 340.0 mL of 0.350M HCl? (Ka (C6H5COOH) = 6.5 x 10-5)
A) 4.19 B) 4.25 C) 3.81 D) 0.45 E) 6.54
Ans: C Category: Difficult Section: 16.3

24. Calculate the percent ionization of cyanic acid, Ka = 2.0 104, in a buffer solution that is 0.50 M HCNO and 0.10 M NaCNO.
A) 0.02% B) 0.10% C) 0.20% D) 2.0% E) 20%
Ans: C Category: Difficult Section: 16.3

25. In which one of the following solutions will acetic acid have the greatest percent ionization?
A) 0.1 M CH3COOH
B) 0.1 M CH3COOH dissolved in 0.1 M HCl
C) 0.1 M CH3COOH dissolved in 0.2 M HCl
D) 0.1 M CH3COOH plus 0.1 M CH3COONa
E) 0.1 M CH3COOH plus 0.2 M CH3COONa
Ans: A Category: Medium Section: 16.2

26. Acid dissociation constants for phosphoric acid are given below.
Ka1 Ka2 Ka3
H3PO4 7.5 103 6.2 108 4.8 1013
A buffer with a pH = 7.4 can best be made by using
A) H3PO4 and NaH2PO4. D) only NaH2PO4.
B) NaH2PO4 and Na2HPO4. E) only Na2HPO4.
C) Na2HPO4 and Na3PO4.
Ans: B Category: Medium Section: 16.3

27. The pH at the equivalence point of a titration may differ from 7.0 due to
A) the initial concentration of the standard solution.
B) the indicator used.
C) the self-ionization of H2O.
D) the initial pH of the unknown.
E) hydrolysis of the salt formed.
Ans: E Category: Medium Section: 16.4

28. For which type of titration will the pH be basic at the equivalence point?
A) Strong acid vs. strong base. D) All of the above.
B) Strong acid vs. weak base. E) None of the above.
C) Weak acid vs. strong base.
Ans: C Category: Easy Section: 16.4

29. For which type of titration will the pH be neutral at the equivalence point?
A) Strong acid vs. strong base. D) All of the above.
B) Strong acid vs. weak base. E) None of the above.
C) Weak acid vs. strong base.
Ans: A Category: Easy Section: 16.4

30. 25.0 mL of a 0.100 M solution of NH3 is titrated with 0.150M HCl. After 10.0 mL of the HCl has been added, the resultant solution is:
A) Basic and before the equivalence point
B) Basic and after the equivalence point
C) Acidic and before the equivalence point
D) Acidic and after the equivalence point
E) Neutral and at the equivalence point
Ans: A Category: Medium Section: 16.4

31. 25.0 mL of a 0.100 M solution of NH3 is titrated with 0.250M HCl. After 10.0 mL of the HCl has been added, the resultant solution is:
A) Basic and before the equivalence point
B) Basic and after the equivalence point
C) Acidic and before the equivalence point
D) Basic and at the equivalence point
E) Acidic and at the equivalence point
Ans: E Category: Medium Section: 16.4

32. 25.0 mL of a 0.100 M solution of NH3 is titrated with 0.250M HCl. After 25.0 mL of the HCl has been added, the resultant solution is:
A) Basic and before the equivalence point
B) Basic and after the equivalence point
C) Acidic and before the equivalence point
D) Acidic and after the equivalence point
E) Neutral and at the equivalence point
Ans: D Category: Medium Section: 16.4

33. 35.0 mL of a 0.250 M solution of KOH is titrated with 0.150 M HCl. After 35.0 mL of the HCl has been added, the resultant solution is:
A) Basic and before the equivalence point
B) Basic and after the equivalence point
C) Acidic and before the equivalence point
D) Acidic and after the equivalence point
E) Neutral and at the equivalence point
Ans: A Category: Medium Section: 16.4

34. 40.0 mL of a 0.65 M solution of HF is titrated with 0.100 M NaOH. After 0.400 L of the NaOH solution has been added, the resultant solution is:
A) Basic and before the equivalence point
B) Basic and after the equivalence point
C) Acidic and before the equivalence point
D) Acidic and after the equivalence point
E) Neutral and at the equivalence point
Ans: B Category: Medium Section: 16.4

35. 24.00 mL of a 0.25 M NaOH solution is titrated with 0.10M HCl. What is the pH of the solution after 24.00 mL of the HCl has been added?
A) 13.40 B) 13.17 C) 11.56 D) 12.88 E) 7.00
Ans: D Category: Medium Section: 16.4

36. 35.00 mL of a 0.30 M HCl solution is titrated with 0.35 M NaOH. What is the pH of the solution after 40.00 mL of the NaOH has been added?
A) 2.46 B) 11.54 C) 7.00 D) 12.72 E) 12.67
Ans: E Category: Medium Section: 16.4

37. 50.00 mL of 0.10 M HNO2 (nitrous acid, Ka = 4.5 104) is titrated with a 0.10 M KOH solution. After 25.00 mL of the KOH solution is added, the pH in the titration flask will be
A) 2.17 B) 3.35 C) 2.41 D) 1.48 E) 7.00
Ans: B Category: Medium Section: 16.4

38. A titration of an acid and base to the equivalence point results in a noticeably acidic solution. It is likely this titration involves
A) a strong acid and a weak base.
B) a weak acid and a strong base.
C) a weak acid and a weak base (where Ka equals Kb).
D) a strong acid and a strong base.
Ans: A Category: Easy Section: 16.4

39. Calculate the pH at the equivalence point for the titration of 0.20 M HCl with 0.20 M NH3 (Kb = 1.8 105).
A) 2.87 B) 4.98 C) 5.12 D) 7.00 E) 11.12
Ans: C Category: Medium Section: 16.4

40. What is the pH at the equivalence point in the titration of 100 mL of 0.10 M HCl with 0.10 M NaOH?
A) 1.0 B) 6.0 C) 7.0 D) 8.0 E) 13.0
Ans: C Category: Medium Section: 16.4

41. What is the pH at the equivalence point in the titration of 100 mL of 0.10 M HCN (Ka = 4.9 1010) with 0.10 M NaOH?
A) 3.0 B) 6.0 C) 7.0 D) 11.0 E) 12.0
Ans: D Category: Medium Section: 16.4

42. Calculate the pH of the solution resulting from the addition of 10.0 mL of 0.10 M NaOH to 50.0 mL of 0.10 M HCN (Ka = 4.9 1010) solution.
A) 5.15 B) 8.71 C) 5.85 D) 9.91 E) 13.0
Ans: B Category: Medium Section: 16.4

43. Calculate the pH of the solution resulting from the addition of 75.0 mL of 0.15 M KOH to 35.0 mL of 0.20 M HCN (Ka (HCN) = 4.9 1010).
A) 9.31 B) 9.18 C) 9.52 D) 11.63 E) 12.59
Ans: E Category: Medium Section: 16.4

44. Calculate the pH of the solution resulting from the addition of 25.0 mL of 0.20 M HCl to 50.0 mL of 0.10 M aniline (C6H5NH2). Kb (C6H5NH2) = 3.8 x 10-10
A) 9.42 B) 9.12 C) 7.00 D) 2.30 E) 2.88
Ans: E Category: Medium Section: 16.4

45. Calculate the pH of the solution resulting from the addition of 85.0 mL of 0.35 M HCl to 30.0 mL of 0.40 M aniline (C6H5NH2). Kb (C6H5NH2) = 3.8 x 10-10
A) 1.75 B) 0.81 C) 4.64 D) 4.19 E) 9.09
Ans: B Category: Medium Section: 16.4

46. Methyl red is a common acid-base indicator. It has a Ka equal to 6.3 106. Its un-ionized form is red and its anionic form is yellow. What color would a methyl red solution have at pH = 7.8?
A) green B) red C) blue D) yellow E) violet
Ans: D Category: Medium Section: 16.5

47. What mass of sodium fluoride must be added to 250. mL of a 0.100 M HF solution to give a buffer solution having a pH of 3.50? [Ka(HF) = 7.1 104]
A) 0.49 g B) 1.5 g C) 3.4 g D) 2.3 g E) 0.75 g
Ans: D Category: Difficult Section: 16.3

48. What mass of ammonium nitrate must be added to 350. mL of a 0.150 M solution of ammonia to give a buffer having a pH of 9.00? (Kb(NH3) = 1.8 105)
A) 7.6 g B) 2.4 g C) 5.4 g D) 11 g E) 3.3 g
Ans: A Category: Difficult Section: 16.3

49. 40.0 ml of an acetic acid of unknown concentration is titrated with 0.100 M NaOH. After 20.0 mL of the base solution has been added, the pH in the titration flask is 5.10. What was the concentration of the original acetic acid solution? [Ka(CH3COOH) = 1.8 105]
A) 0.11 M B) 0.022 M C) 0.072 M D) 0.050 M E) 0.015 M
Ans: C Category: Difficult Section: 16.4

50. 25.0 mL of a hydrofluoric acid solution of unknown concentration is titrated with 0.200 M NaOH. After 20.0 mL of the base solution has been added, the pH in the titration flask is 3.00. What was the concentration of the original hydrofluoric acid solution. [Ka(HF) = 7.1 104]
A) 0.39 M B) 0.27 M C) 0.16 M D) 2.4 M E) 0.23 M
Ans: A Category: Difficult Section: 16.4

51. For PbCl2 (Ksp = 2.4 104), will a precipitate of PbCl2 form when 0.10 L of 3.0 102 M Pb(NO3)2 is added to 400 mL of 9.0 102 M NaCl?
A) Yes, because Q > Ksp. . C) No, because Q = Ksp
B) No, because Q < Ksp. D) Yes, because Q < Ksp. Ans: B Category: Medium Section: 16.6 52. The solubility of lead(II) iodide is 0.064 g/100 mL at 20C. What is the solubility product for lead(II) iodide? A) 1.1 108 B) 3.9 106 C) 1.1 1011 D) 2.7 1012 E) 1.4 103 Ans: A Category: Medium Section: 16.6 53. The molar solubility of magnesium carbonate is 1.8 104 mol/L. What is Ksp for this compound? A) 1.8 104 B) 3.6 104 C) 1.3 107 D) 3.2 108 E) 2.8 1014 Ans: D Category: Medium Section: 16.6 54. The molar solubility of manganese(II) carbonate is 4.2 106 M. What is Ksp for this compound? A) 4.2 106 B) 8.4 106 C) 3.0 1016 D) 1.8 1011 E) 2.0 103 Ans: D Category: Medium Section: 16.6 55. The molar solubility of tin(II) iodide is 1.28 102 mol/L. What is Ksp for this compound? A) 8.4 106 B) 1.28 102 C) 4.2 106 D) 1.6 104 E) 2.1 106 Ans: A Category: Medium Section: 16.6 56. The solubility of strontium carbonate is 0.0011 g/100 mL at 20C. Calculate the Ksp value for this compound. A) 7.5 105 B) 1.5 104 C) 5.6 109 D) 7.5 106 E) 1.5 103 Ans: C Category: Medium Section: 16.6 57. The molar solubility of lead(II) iodate in water is 4.0 105 mol/L. Calculate Ksp for lead(II) iodate. A) 1.6 109 B) 6.4 1014 C) 2.6 1013 D) 4.0 105 E) 4.0 1015 Ans: C Category: Medium Section: 16.6 58. The solubility product for chromium(III) fluoride is Ksp = 6.6 1011. What is the molar solubility of chromium(III) fluoride? A) 1.6 103 M D) 2.2 103 M B) 1.2 103 M E) 1.6 106 M C) 6.6 1011 M Ans: B Category: Medium Section: 16.6 59. The solubility product for barium sulfate is 1.1 1010. Calculate the molar solubility of barium sulfate. A) 5.5 1011 mol/L D) 1.1 1010 mol/L B) 1.1 105 mol/L E) 2.2 1010 mol/L C) 2.1 105 mol/L Ans: B Category: Medium Section: 16.6 60. The Ksp for silver(I) phosphate is 1.8 1018. Calculate the molar solubility of silver(I) phosphate. A) 1.6 105 M D) 7.2 101 M B) 2.1 105 M E) 1.8 101 M C) 3.7 105 M Ans: A Category: Medium Section: 16.6 61. The solubility product for calcium phosphate is Ksp = 1.3 1026. What is the molar solubility of calcium phosphate? A) 1.3 1026 M D) 4.6 106 M B) 1.5 107 M E) 6.6 106 M C) 2.6 106 M Ans: C Category: Medium Section: 16.6 62. The Ksp value for lead(II) chloride is 2.4 104. What is the molar solubility of lead(II) chloride? A) 2.4 104 mol/L D) 3.9 102 mol/L B) 6.2 102 mol/L E) 6.0 105 mol/L C) 7.7 103 mol/L Ans: D Category: Medium Section: 16.6 63. Calculate the silver ion concentration in a saturated solution of silver(I) carbonate (Ksp = 8.1 1012). A) 5.0 105 M D) 2.0 104 M B) 2.5 104 M E) 8.1 104 M C) 1.3 104 M Ans: B Category: Medium Section: 16.6 64. The Ksp for silver(I) phosphate is 1.8 1018. Determine the silver ion concentration in a saturated solution of silver(I) phosphate. A) 1.6 105 M D) 1.1 1013 M B) 2.1 105 M E) 4.8 105 M C) 3.7 105 M Ans: E Category: Medium Section: 16.6 65. Calculate the silver ion concentration in a saturated solution of silver(I) sulfate (Ksp = 1.4 105). A) 1.5 102 M D) 1.4 105 M B) 2.4 102 M E) None of the above. C) 3.0 102 M Ans: C Category: Medium Section: 16.6 66. Calculate the concentration of chloride ions in a saturated lead(II) chloride (Ksp = 2.4 104) solution. A) 2.4 104 M D) 1.2 101 M B) 4.8 104 M E) 7.8 102 M C) 3.9 102 M Ans: E Category: Medium Section: 16.6 67. Calculate the concentration of fluoride ions in a saturated barium fluoride (Ksp = 1.7 106) solution. A) 7.6 103 M D) 1.7 106 M B) 1.5 102 M E) 3.4 106 M C) 3.4 105 M Ans: B Category: Medium Section: 16.6 68. Which of the following would decrease the Ksp for PbI2? A) Lowering the pH of the solution B) Adding a solution of Pb(NO3)2 C) Adding a solution of KI D) None of the abovethe Ksp of a compound is constant at constant temperature. Ans: D Category: Medium Section: 16.6 69. Calculate the minimum concentration of Mg2+ that must be added to 0.10 M NaF in order to initiate a precipitate of magnesium fluoride. (For MgF2 , Ksp = 6.9 109.) A) 1.4 107 M D) 1.7 107 M B) 6.9 109 M E) 6.9 107 M C) 6.9 108 M Ans: E Category: Medium Section: 16.6 70. Calculate the minimum concentration of Cr3+ that must be added to 0.095 M NaF in order to initiate a precipitate of chromium(III) fluoride. (For CrF3 , Ksp = 6.6 1011.) A) 0.023 M D) 2.9 109 M B) 0.032 M E) 6.9 1010 M C) 7.7 108 M Ans: C Category: Medium Section: 16.6 71. Will a precipitate form (yes or no) when 50.0 mL of 1.2 103 M Pb(NO3)2 are added to 50.0 mL of 2.0 104 M Na2S? If so, identify the precipitate. A) Yes, the precipitate is PbS. D) Yes, the precipitate is Pb(NO3)2. B) Yes, the precipitate is NaNO3. E) No, a precipitate will not form. C) Yes, the precipitate is Na2S. Ans: A Category: Medium Section: 16.6 72. Will a precipitate of magnesium fluoride form when 300. mL of 1.1 103 M MgCl2 are added to 500. mL of 1.2 103 M NaF? [Ksp (MgF2) = 6.9 109] A) Yes, Q > Ksp D) Yes, Q < Ksp B) No, Q < Ksp E) Yes, Q = Ksp C) No, Q = Ksp Ans: B Category: Medium Section: 16.6 73. Will a precipitate of magnesium fluoride form when 200. mL of 1.9 103 M MgCl2 are added to 300. mL of 1.4 102 M NaF? [Ksp (MgF2) = 6.9 109] A) Yes, Q > Ksp D) Yes, Q < Ksp B) No, Q < Ksp E) Yes, Q = Ksp C) No, Q = Ksp Ans: A Category: Medium Section: 16.6 74. Will a precipitate (ppt) form when 300. mL of 5.0 105 M AgNO3 are added to 200. mL of 2.5 107 M NaBr? Answer yes or no, and identify the precipitate if there is one. A) Yes, the ppt is AgNO3(s). D) Yes, the ppt is NaNO3(s). B) Yes, the ppt is AgBr(s). E) No, a precipitate will not form. C) Yes, the ppt is NaBr(s). Ans: B Category: Medium Section: 16.6 75. Will a precipitate (ppt) form when 20.0 mL of 1.1 103 M Ba(NO3)2 are added to 80.0 mL of 8.4 104 M Na2CO3? A) Yes, the ppt is Ba(NO3 )2. D) Yes, the ppt is Na2CO3. B) Yes, the ppt is NaNO3. E) No, a precipitate will not form. C) Yes, the ppt is BaCO3. Ans: C Category: Medium Section: 16.6 76. Will a precipitate (ppt) form when 300. mL of 2.0 105 M AgNO3 are added to 200. mL of 2.5 109 M NaI? Answer yes or no, and identify the precipitate if there is one. A) Yes, the ppt is AgNO3(s). D) Yes, the ppt is AgI(s). B) Yes, the ppt is NaNO3(s). E) No, a precipitate will not form. C) Yes, the ppt is NaI(s). Ans: D Category: Medium Section: 16.6 77. Which response has both answers correct? Will a precipitate form when 250 mL of 0.33 M Na2CrO4 are added to 250 mL of 0.12 M AgNO3? [Ksp(Ag2CrO4) = 1.1 1012] What is the concentration of the silver ion remaining in solution? A) Yes, [Ag+] = 2.9 106 M. D) No, [Ag+] = 0.060 M. B) Yes, [Ag+] = 0.060 M. E) No, [Ag+] = 0.105 M. C) Yes, [Ag+] = 1.3 104 M. Ans: A Category: Difficult Section: 16.6 78. To 1.00 L of a 0.100 M aqueous solution of benzoic acid (C6H5COOH) is added 1.00 mL of 12.0 M HCl. What is the percentage ionization of the benzoic acid in the resulting solution? [Ka(C6H5COOH) = 6.5 105] A) 3.3% B) 12% C) 1.3% D) 0.52% E) 0.065% Ans: D Category: Medium Section: 16.3 79. Calculate the molar solubility of BaCO3 in a 0.10 M solution of Na2CO3(aq). (Ksp (BaCO3) = 8.1 x 10-9) A) 8.1 x 10-9 M D) 2.8 x 10-4 M B) 9.0 x 10-5 M E) 0.10 M C) 8.1 x 10-8 M Ans: C Category: Medium Section: 16.8 80. Calculate the molar solubility of CaF2 in a 0.25 M solution of NaF(aq). (Ksp (CaF2) = 4.0 x 10-11) A) 4.0 x 10-11 M D) 1.3 x 10-5 M B) 6.4 x 10-10 M E) 2.2 x 10-4 M C) 1.6 x 10-10 M Ans: B Category: Medium Section: 16.8 81. Calculate the molar solubility of AgCl in a 0.15 M solution of NH3(aq). (Ksp (AgCl) = 1.6 x 10-10; Kf (Ag(NH3)2+) = 1.5 x 107) A) 6.7 x 10-3 M D) 7.5 x 10-2 M B) 1.3 x 10-5 M E) 3.3 x 10-5 M C) 3.9 x 103 M Ans: A Category: Difficult Section: 16.10 82. Calculate the molar solubility of AgBr in a 0.25M solution of NH3(aq) (Ksp (AgBr) = 7.7 x 10-13 ; Kf (Ag(NH3)2+) = 1.5 x 107. A) 8.8 x 10-7 M D) 2.5 x 10-1 M B) 3.4 x 10-3 M E) 9.7 x 102 M C) 8.4 x 10-4 M Ans: C Category: Difficult Section: 16.10 83. Calculate the molar solubility of Fe(OH)2 in a solution with pH = 13.15. (Ksp Fe(OH)2 = 1.6 x 10-14) A) 1.6 x 10-14 M D) 8.0 x 10-13 M B) 1.1 x 10-13 M E) 3.4 x 10-7 M C) 1.6 x 10-5 M Ans: D Category: Difficult Section: 16.9 84. Calculate the molar solubility of Mg(OH)2 in a solution with pH = 12.20. (Ksp (Mg(OH)2 = 1.2 x 10-11) A) 4.8 x 10-8 M D) 1.4 x 10-4 M B) 7.6 x 10-10 M E) 2.4 x 10-6 M C) 3.5 x 10-6 M Ans: A Category: Difficult Section: 16.9 85. Find the concentration of Pb2+ ions in a solution made by adding 5.00 g of lead(II) iodide to 500. mL of 0.150 M KI. [For PbI2, Ksp = 1.39 108.] A) 3.04 104 M D) 1.52 104 M B) 1.54 107 M E) 9.27 108 M C) 6.18 107 M Ans: C Category: Medium Section: 16.8 86. Find the concentration of calcium ions in a solution made by adding 3.50 g of calcium fluoride to 750. mL of 0.125 M NaF. [For CaF2, Ksp = 3.95 1011.] A) 3.16 1010 M D) 6.32 1010 M B) 2.53 109 M E) 2.15 104 M C) 4.29 104 M Ans: B Category: Medium Section: 16.8 87. A saturated sodium carbonate solution at 0C contains 7.1 g of dissolved sodium carbonate per 100. mL of solution. The solubility product constant for sodium carbonate at this temperature is A) 1.2 B) 0.30 C) 3.0 104 D) 0.90 E) 1.2 103 Ans: A Category: Medium Section: 16.6 88. A saturated sodium carbonate solution at 100C contains 45.5 g of dissolved sodium carbonate per 100. mL of solution. The solubility product constant for sodium carbonate at this temperature is A) 79.0 B) 0.316 C) 0.0790 D) 36.8 E) 316 Ans: E Category: Medium Section: 16.6 89. Which of the following compounds is more soluble in acidic solution than in pure neutral water? A) BaCO3 B) CuI C) PbCl2 D) AgBr E) NH4NO3 Ans: A Category: Medium Section: 16.9 90. Which of the following compounds is more soluble in acidic solution than in pure neutral water? A) PbI2 B) CuBr C) KClO4 D) FeS E) NaNO3 Ans: D Category: Medium Section: 16.9 91. Which of the following compounds is more soluble in a 0.10 M NH3(aq) solution than in pure neutral water? A) CaF2 B) MgCO3 C) AgI D) SrSO4 E) Ba(NO3)2 Ans: C Category: Medium Section: 16.10 92. Which of the following compounds is more soluble in a 0.10 M NaCN solution than in pure neutral water? A) Mg(OH)2 B) Ca3(PO4)2 C) CaCO3 D) AgBr E) NH4ClO4 Ans: D Category: Medium Section: 16.10 93. What volume of 0.0500 M sodium hydroxide should be added to 250. mL of 0.100 M HCOOH to obtain a solution with a pH of 4.50? [Ka(HCOOH) = 1.7 104] A) 540 mL B) 420 mL C) 80. mL D) 340 mL E) 500. mL Ans: B Category: Difficult Section: 16.4 94. What volume of 0.200 M potassium hydroxide should be added to 300. mL of 0.150 M propanoic acid (C2H5COOH) to obtain a solution with a pH of 5.25? [Ka(C2H5COOH) = 1.34 105] A) 32 mL B) 210 mL C) 160 mL D) 65 mL E) 13 mL Ans: C Category: Difficult Section: 16.4 95. Calculate the pH of a solution that is 0.15 M CH3COOH and 0.75 M CH3COONa. Ans: 5.44 Category: Medium Section: 16.3 96. Calculate the pH of a solution that is 0.20M NH3(aq) and 0.35 M NH4Cl(aq). (Kb(NH3) = 1.8 x 10-5) Ans: 9.01 Category: Medium Section: 16.3 97. 500. mL of a solution containing 1.5 M NH3(aq) is mixed with 500. mL of a solution containing 0.50M of HCl(aq). What is the pH of the final solution? (Kb(NH3) = 1.8 x 10-5) Ans: 9.56 Category: Medium Section: 16.4 98. 500. mL of a solution containing 1.5 M NH4Cl(aq) is mixed with 500. mL of a solution containing 0.50M of NaOH(aq). What is the pH of the final solution? (Kb(NH3) = 1.8 x 10-5) Ans: 8.95 Category: Medium Section: 16.4 99. What is the optimum pH of a sodium formate/formic acid buffer? (For formic acid, Ka = 1.7 104) Ans: 3.77 Category: Medium Section: 16.3 100. Describe how to make a sodium formate (HCOONa)/formic acid (HCOOH) buffer that has a pH of 4.77. Ans: Prepare a solution having a molar ratio of 10.0 mol HCOONa to 1.0 mol HCOOH. Category: Medium Section: 16.3 101. Write an equation showing the net reaction that occurs when a strong acid is added to a CO32/HCO3 buffer solution (for carbonic acid, Ka1 = 4.2 107, Ka2 = 2.4 108): Ans: CO32 + H+ HCO3 and HCO3 + H+ H2CO3 Category: Medium Section: 16.3 102. Write an equation showing the net reaction that occurs when a strong base is added to a CO32/HCO3 buffer solution (for carbonic acid, Ka1 = 4.2 107, Ka2 = 2.4 108): Ans: HCO3 + OH CO32 + H2O Category: Medium Section: 16.3 103. Calculate the percent ionization of formic acid in a 0.010 M HCOOH solution. (Ka = 1.7 104) Ans: 13% Category: Medium Section: 16.2 104. Calculate the percent ionization of formic acid in a solution that is 0.010 M HCOOH and 0.005 M HCOONa and compare your answer to the percent ionization you would calculate if the sodium formate were not present. Explain the difference, if any. (Ka = 1.7 104) Ans: 3.4%; the addition of formate suppresses the ionization of formic acid by shifting the ionization equilibrium towards the un-ionized acid. Category: Medium Section: 16.2 105. Calculate the percent ionization of formic acid in a solution that is 0.010 M HCOOH and 0.050 M HCOONa. (Ka = 1.7 104) Ans: 0.34% Category: Medium Section: 16.2 106. What molar ratio of benzoate ion to benzoic acid would be required to prepare a buffer with a pH of 5.20? [Ka(C6H5COOH) = 6.5 105] Ans: 10.3 Category: Medium Section: 16.3 107. Write a net ionic equation for the reaction that occurs when a small amount of hydrochloric acid is added to a buffer solution containing NH4Cl and NH3. Ans: H+ + NH3 NH4+ Category: Medium Section: 16.3 108. Write a net ionic equation for the reaction occurring when a small amount of sodium hydroxide solution is added to a buffer solution containing NH4Cl and NH3. Ans: OH + NH4+ NH3 + H2O Category: Medium Section: 16.3 109. Write a net ionic equation for the reaction that occurs when a small amount of nitric acid is added to a NaNO2/HNO2 buffer. Ans: H+ + NO2 HNO2 Category: Medium Section: 16.3 110. Write a net ionic equation for the reaction occurring when a small amount of sodium hydroxide is added to a NaNO2/HNO2 buffer. Ans: OH + HNO2 NO2 + H2O Category: Medium Section: 16.3 111. 550. mL of a 0.40M solution of NaOH is titrated with 0.25 M HCl. Calculate the pH of the solution after 650. mL of the HCl has been added. Ans: 12.68 Category: Medium Section: 16.4 112. 550. mL of a 0.40M solution of NaOH is titrated with 0.25 M HCl. Calculate the pH of the solution after 1.10 L of HCl has been added. Ans: 1.48 Category: Medium Section: 16.4 113. Calculate the pH at the equivalence point for the titration of 0.25 M CH3COOH with 0.25 M NaOH. (For CH3COOH, Ka= 1.8 105) Ans: 8.92 Category: Medium Section: 16.4 114. Calculate the pH at the equivalence point for the titration of 0.22 M HCN with 0.22 M NaOH. (Ka = 4.9 1010 for HCN) Ans: 11.18 Category: Medium Section: 16.4 115. 340. mL of a 0.150 M solution of NH3(aq) is titrated with 0.100 M HCl. Calculate the pH of the solution after 350. mL of HCl has been added. (Ka(NH4+) = 5.6 x 10-10) Ans: 8.91 Category: Medium Section: 16.4 116. 340. mL of a 0.150M solution of NH3(aq) is titrated with 0.100 M HCl. Calculate the pH of the solution after 750. mL of the HCl has been added. . (Ka(NH4+) = 5.6 x 10-10) Ans: 1.66 Category: Medium Section: 16.4 117. Bromothymol blue is a common acid-base indicator. It has a Ka equal to 1.6 107. Its un-ionized form is yellow and its conjugate base is blue. What color would a solution have at pH = 5.8? Ans: Yellow Category: Medium Section: 16.5 118. Describe how to prepare 500. mL of a cyanic acid (HCNO)/sodium cyanate (NaCNO) buffer having a pH of 4.80. [Ka(HCNO) = 2.0 104] Ans: Dissolve amounts of the two compounds equal to a molar ratio of 12.6 mol NaCNO to 1.0 mol HCNO in enough water to yield 500. mL of solution. (Note: the buffer capacity will be limited if the concentrations of HCNO and NaCNO are too low.) Category: Medium Section: 16.3 119. Calculate the molar solubility of silver carbonate (Ksp (Ag2CO3 = 8.1 x 10-12)) Ans: 1.3 x 10-4 M Category: Medium Section: 16.6 120. Calculate the molar solubility of lead (II) fluoride (Ksp (PbF2 = 4.1 x 10-8)) Ans: 2.2 x 10-3 M Category: Medium Section: 16.6 121. Solid sodium iodide is slowly added to a solution that is 0.0050 M Pb2+ and 0.0050 M Ag+. [Ksp (PbI2) = 1.4 108; Ksp (AgI) = 8.3 1017] What compound will precipitate first? Ans: AgI Category: Medium Section: 16.7 122. Solid sodium iodide is slowly added to a solution that is 0.0050 M Pb2+ and 0.0050 M Ag+. [Ksp (PbI2) = 1.4 108; Ksp (AgI) = 8.3 1017] Calculate the Ag+ concentration when PbI2 just begins to precipitate. Ans: 5.0 1014 M Category: Medium Section: 16.7 123. Solid sodium iodide is slowly added to a solution that is 0.0050 M Pb2+ and 0.0050 M Ag+. [Ksp (PbI2) = 1.4 108; Ksp (AgI) = 8.3 1017] What percent of Ag+ remains in solution at this point? Ans: 1.0 109 % Category: Medium Section: 16.7 124. The Ksp of CaF2 is 4 1011. What is the maximum concentration of Ca2+ possible in a 0.10 M NaF solution? Ans: 4 109 M Category: Medium Section: 16.8 125. 5.0 mL of 12 M NH3 is added to 500. mL of 0.050 M AgNO3. What concentration of silver ion will exist after equilibrium is established? [Kf for Ag(NH3)2+ is 1.5 107] Ans: 8.4 106 M Category: Difficult Section: 16.10 126. Will a precipitate of AgCl form when 0.050 mol NaCl(s) and 0.050 mol AgNO3(s) are dissolved in 500. mL of 3.0 M NH3? [Kf for Ag(NH3)2+ is 1.5 107; Ksp(AgCl) = 1.6 1010] Ans: Yes Category: Difficult Section: 16.10 127. Will Fe(OH)3 precipitate from a buffer solution that is 0.60 M CH3COOH and 0.10 M CH3COONa, if the solution is also made to be 0.001 M in Fe3+? For Fe(OH)3, Ksp = 6.8 1036. Ans: Yes Category: Difficult Section: 16.9 128. The concentration of Mg2+ in seawater is 5.0 102 M. What hydroxide concentration is needed to remove 90% of the Mg2+ by precipitation? (For Mg(OH)2, Ksp = 1.2 1011.) Ans: 4.9 105 M Category: Difficult Section: 16.9 129. Ammonium chloride solutions are slightly acidic, so they are better solvents than water for insoluble substances such as Ca(OH)2. Identify two reactions that when added together, give the overall reaction below, and determine Kc for the overall reaction. Ca(OH)2(s) + 2NH4+(aq) Ca2+(aq) + 2NH3(aq) + 2H2O Given: Ksp for Ca(OH)2 is 4.0 108; Kb for NH3 is 1.8 105. Ans: Ca(OH)2(s) Ca2+(aq) + 2OH(aq) Ksp(Ca(OH)2) 2NH4+(aq) + 2OH(aq) 2NH3(aq) + 2H2O Kb(NH3) Kc = 120 Category: Difficult Section: 16.9 130. Calculate the equilibrium constant Kc for the following overall reaction: AgCl(s) + 2CN(aq) Ag(CN)2(aq) + Cl(aq) For AgCl, Ksp = 1.6 1010; for Ag(CN)2, Kf = 1.0 1021. Ans: 1.6 1011 Category: Difficult Section: 16.10 131. Calculate the equilibrium constant Kc for the net reaction shown below. AgI(s) + 2NH3(aq) Ag(NH3)2+(aq) + I(aq) For AgI, Ksp = 8.3 1017; for Ag(NH3)2+, Kf = 1.5 107. Ans: 1.2 109 Category: Difficult Section: 16.10 132. The solubility of Ba(NO3)2 is 130.5 g/L at 0C. How many moles of dissolved salt are present in 4.0 L of a saturated solution of Ba(NO3)2 at 0C? Ans: 2.0 moles Category: Medium Section: 16.6 133. A sample of rainwater collected near a lead smelter is analyzed for acid content. Experiments show that a 100. mL sample of the rainwater is neutralized by 22.4 milliters of 0.0122 M NaOH. Assuming that the acid present is sulfurous acid, which resulted from the reaction of SO2 with water, what is the molarity of acid in the rainwater? Ans: 1.37 103 M Category: Medium Section: 16.4 134. An environmental chemist obtained a 200. mL sample of lake water believed to be contaminated with a single monoprotic strong acid. Titrating this sample with a 0.0050 M NaOH(aq) required 7.3 mL of the NaOH solution to reach the endpoint. What is the concentration of H+ in the lake? Ans: 1.8 104 M Category: Medium Section: 16.4 135. An environmental chemist obtained a 200. mL sample of lake water believed to be contaminated with a single monoprotic strong acid. Titrating this sample with a 0.0050 M NaOH(aq) required 7.3 mL of the NaOH solution to reach the endpoint. What is the pH of the lake? Ans: 3.74 Category: Medium Section: 16.4 136. An environmental chemist obtained a 200. mL sample of lake water believed to be contaminated with a single monoprotic strong acid. Titrating this sample with a 0.0050 M NaOH(aq) required 7.3 mL of the NaOH solution to reach the endpoint. If the size of the lake can be approximated as 1.1 km long by 2.3 km wide, and has an average depth of 10. m, estimate how many moles of the strong acid are present in the lake? Ans: 4.6 106 moles of acid Category: Medium Section: 16.4 137. NaCl is added slowly to a solution that is 0.010 M each in Cu+, Ag+, and Au+. The Ksp's for CuCl, AgCl, and AuCl are 1.9 107, 1.8 1010, and 2.0 1013, respectively. Which compound will precipitate first? Ans: AuCl Category: Easy Section: 16.7 138. A 50.0 mL sample of 2.0 104 M CuNO3 is added to 50.0 mL of 4.0 M NaCN. The formation constant of the complex ion Cu(CN)32 is 1.0 109. What is the copper(I) ion concentration in this system at equilibrium? Ans: 1.3 1014 M Category: Difficult Section: 16.10 139. How many moles of NaF must be dissolved in 1.00 liter of a saturated solution of PbF2 at 25C to reduce the [Pb2+] to 1.0 106 M? The Ksp for PbF2 at 25 C is 4.0 108. Ans: 0.20 mol Category: Medium Section: 16.8 140. At 25 C, the base ionization constant for NH3 is 1.8 105. Determine the hydroxide ion concentration in a 0.150 M solution of ammonia at 25 C. Ans: 1.6 103 M Category: Medium Section: 16.2 141. At 25 C, the base ionization constant for NH3 is 1.8 105. Determine the pH of a solution prepared by adding 0.0500 mol of solid ammonium chloride to 100. mL of 0.150 M ammonia. Ans: 8.73 Category: Difficult Section: 16.2 142. At 25 C, the base ionization constant for NH3 is 1.8 105. Determine the percentage ionization of a 0.150 M solution of ammonia at 25 C. Ans: 1.1% Category: Medium Section: 16.2 143. At 25 C, the base ionization constant for NH3 is 1.8 105. If 0.0800 mole of solid magnesium chloride is dissolved in a solution prepared by adding 0.0500 mol of solid ammonium chloride to 100. ml of 0.150 M ammonia, will a precipitate of magnesium hydroxide form? (Assume the volume of the solution is unchanged. The solubility product constant for magnesium hydroxide is 1.5 1011.) Ans: Yes Category: Difficult Section: 16.9 144. The percent ionization of a weak acid HA is greater in a solution containing the salt NaA than it is in a solution of the weak acid only. Ans: False Category: Medium Section: 16.2 145. A mixture made from 10 mL of 1 M HCl and 20 mL of 1 M CH3COONa would be classified as a buffer solution. Ans: True Category: Medium Section: 16.3 146. All indicators are weak acids that are one color in acidic solution and another color in basic solution. Ans: False Category: Medium Section: 16.5 147. The solubility of a salt increases as its Ksp increases. Ans: True Category: Easy Section: 16.6 148. The pH of a solution that is 0.20 M CH3COOH and 0.20 M CH3COONa should be higher than the pH of a 0.20 M CH3COOH solution. Ans: True Category: Medium Section: 16.2

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