Acid Base Equilibria and Solubility Equ

August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]

Chapter 16 Acid-Base Equilibria and Solubility Equilibria
Student: ___________________________________________________________________________
NOTE: 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.
B.
C.
D.

2.

Which one of the following is a buffer solution?
A.
B.
C.
D.
E.

3.

0.40 M HCN and 0.10 KCN
0.20 M CH3COOH
1.0 M HNO3 and 1.0 M NaNO3
0.10 M KCN
0.50 M HCl and 0.10 NaCl

Which one of the following combinations cannot function as a buffer solution?
A.
B.
C.
D.
E.

4.

0.1 M CH3COOH
0.1 M CH3COOH dissolved in 1.0 M HCl
0.1 M CH3COOH plus 0.1 M CH3COONa
0.1 M CH3COOH plus 0.2 M CH3COONa

HCN and KCN
NH3 and (NH4)2SO4
HNO3 and NaNO3
HF and NaF
HNO2 and NaNO2

Which of the following is the most acidic solution?
A.
B.
C.
D.
E.

0.10 M CH3COOH and 0.10 M CH3COONa
0.10 M CH3COOH
0.10 M HNO2
0.10 M HNO2 and 0.10 M NaNO2
0.10 M CH3COONa

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August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]
5.

Calculate the pH of a buffer solution that contains 0.25 M benzoic acid (C6H5CO2H) and 0.15 M sodium benzoate (C6H5COONa). [Ka = 6.5 × 10-5 for benzoic acid]
A.
B.
C.
D.
E.

6.

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 × 10-8]
A.
B.
C.
D.
E.

7.

0.97
3.10
4.40
3.70
4.30

Calculate the pH of a solution that is 0.410 M in HOCl and 0.050 M in NaOCl. [Ka(HOCl) = 3.2 × 10-8]
A.
B.
C.
D.
E.

9.

4.10
7.00
7.19
7.49
7.80

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 × 10-4]
A.
B.
C.
D.
E.

8.

3.97
4.83
4.19
3.40
4.41

0.39
3.94
6.58
7.49
8.40

Calculate the pH of a buffer solution prepared by dissolving 0.20 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 × 10-4]
A.
B.
C.
D.
E.

0
3.0
3.7
4.4
5.0

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August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]
10. 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.
B.
C.
D.
E.

0.18
0.84
1.19
5.50
0.10

11. 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.
B.
C.
D.
E.

H+ + H2O → H3O+
H+ + OCl- → HOCl
HOCl → H+ + OClH+ + HOCl → H2OCl+
HCl + HOCl → H2O + Cl2

12. 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.
B.
C.
D.
E.

OH- + HOCl → H2O + OClOH- + OCl- → HOCl + O2Na+ + HOCl → NaCl + OHH+ + HOCl → H2 + OClNaOH + HOCl → H2O + NaCl

13. Over what range of pH is a HOCl - NaOCl buffer effective?
A.
B.
C.
D.
E.

pH 2.0 - pH 4.0 pH 7.5 - pH 9.5 pH 6.5 - pH 8.5 pH 6.5 - pH 9.5 pH 1.0 - pH 14.0

14. 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 9.2-9.3?
A.
B.
C.
D.
E.

CH3COONa/CH3COOH (Ka = 1.8 × 10-5)
NH3/NH4Cl (Ka = 5.6 × 10-10)
NaOCl/HOCl (Ka = 3.2 × 10-8)
NaNO2/HNO2 (Ka = 4.5 × 10-4)
NaCl/HCl

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August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]
15. 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 4.6-4.8?
A.
B.
C.
D.
E.

CH3COO2Na/CH3COOH (Ka = 1.8 × 10-5)
NH3/NH4Cl (Ka = 5.6 × 10-10)
NaOCl/HOCl (Ka = 3.2 × 10-8)
NaNO2/HNO2 (Ka = 4.5 × 10-4)
NaCl/HCl

16. 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 × 10-5]
A.
B.
C.
D.
E.

4.41
4.74
4.56
4.92
5.07

17. 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 × 10-5]
A.
B.
C.
D.
E.

4.65
4.71
4.56
4.84
5.07

18. Calculate the percent ionization of cyanic acid, Ka = 2.0 × 10-4, in a buffer solution that is 0.50 M HCNO and 0.10 M NaCNO.
A.
B.
C.
D.
E.

0.02%
0.10%
0.20%
2.0%
20%

19. In which one of the following solutions will acetic acid have the greatest percent ionization?
A.
B.
C.
D.
E.

0.1 M CH3COOH
0.1 M CH3COOH dissolved in 0.1 M HCl
0.1 M CH3COOH dissolved in 0.2 M HCl
0.1 M CH3COOH plus 0.1 M CH3COONa
0.1 M CH3COOH plus 0.2 M CH3COONa

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August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]
20. On the basis of the information below, a buffer with a pH = 9 can best be made by using

A.
B.
C.
D.

pure NaH2PO4-.
H2PO4- + PO43-.
H2PO4- + HPO42-.
HPO42- + PO43-.

21. The pH at the equivalence point of a titration may differ from 7.0 due to
A.
B.
C.
D.
E.

the initial concentration of the standard solution. the indicator used. the self-ionization of H2O. the initial pH of the unknown. hydrolysis of the salt formed.

22. For which type of titration will the pH be basic at the equivalence point?
A.
B.
C.
D.
E.

Strong acid vs. strong base.
Strong acid vs. weak base.
Weak acid vs. strong base. all of the these none of these

23. 50.00 mL of 0.10 M HNO2 (nitrous acid, Ka = 4.5 × 10-4) 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.
B.
C.
D.
E.

2.17
3.35
2.41
1.48
7.00

24. A titration of an acid and base to the equivalence point results in a noticeably acidic solution. It is likely this titration involves
A.
B.
C.
D.

a strong acid and a weak base. a weak acid and a strong base. a weak acid and a weak base (where Ka equals Kb). a strong acid and a strong base.

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August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]
25. 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.
B.
C.
D.
E.

2.87
4.98
5.12
7.00
11.12

26. 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.
B.
C.
D.
E.

1.0
6.0
7.0
8.0
13.0

27. What is the pH at the equivalence point in the titration of 100 mL of 0.10 M HCN (Ka = 4.9 × 10-10) with
0.10 M NaOH?
A.
B.
C.
D.
E.

3.0
6.0
7.0
11.0
12.0

28. 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 × 10-10) solution.
A.
B.
C.
D.
E.

5.15
8.71
5.85
9.91
13.0

29. Methyl red is a common acid-base indicator. It has a Ka equal to 6.3 × 10-6. 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.
B.
C.
D.
E.

green red blue yellow violet

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August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]
30. 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 × 10-4)
A.
B.
C.
D.
E.

0.49 g
1.5g
3.4g
2.3g
0.75 g

31. 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 × 10-5)
A.
B.
C.
D.
E.

7.6 g
2.4g
5.4g
11g
3.3g

32. 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 × 10-5)
A.
B.
C.
D.
E.

0.11 M
0.022 M
0.072 M
0.050 M
0.015 M

33. 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 × 10-4)
A.
B.
C.
D.
E.

0.39 M
0.27 M
0.16 M
2.4M
0.23 M

34. For PbCl2 (Ksp = 2.4 × 10-4), will a precipitate of PbCl2 form when 0.10 L of 3.0 × 10-2 M Pb(NO3)2 is added to 400 mL of 9.0 × 10-2 M NaCl?

A.
B.
C.
D.

Yes, because Q > Ksp.
No, because Q < Ksp.
No, because Q = Ksp.
Yes, because Q < Ksp. www.kau.edu.sa/aasiri2 7

August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]
35. The solubility of lead(II) iodide is 0.064 g/100 mL at 20oC. What is the solubility product for lead(II) iodide? A.
B.
C.
D.
E.

1.1 × 10-8
3.9 × 10-6
1.1 × 10-11
2.7 × 10-12
1.4 × 10-3

36. The molar solubility of magnesium carbonate is 1.8 × 10-4 mol/L. What is Ksp for this compound?
A.
B.
C.
D.
E.

1.8 × 10-4
3.6 × 10-4
1.3 × 10-7
3.2 × 10-8
2.8 × 10-14

37. The molar solubility of manganese(II) carbonate is 4.2 × 10-6 M. What is Ksp for this compound?
A.
B.
C.
D.
E.

4.2 × 10-6
8.4 × 10-6
3.0 × 10-16
1.8 × 10-11
2.0 × 10-3

38. The molar solubility of tin(II) iodide is 1.28 × 10-2 mol/L. What is Ksp for this compound?
A.
B.
C.
D.
E.

8.4 × 10-6
1.28 × 10-2
4.2 × 10-6
1.6 × 10-4
2.1 × 10-6

39. The solubility of strontium carbonate is 0.0011 g/100 mL at 20oC. Calculate the Ksp value for this compound. A.
B.
C.
D.
E.

7.5 × 10-5
1.5 × 10-4
5.6 × 10-9
7.5 × 10-6
1.5 × 10-3

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August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]
40. The molar solubility of lead(II) iodate in water is 4.0 × 10-5 mol/L. Calculate Ksp for lead(II) iodate.
A.
B.
C.
D.
E.

1.6 × 10-9
6.4 × 10-14
2.6 × 10-13
4.0 × 10-5
4.0 × 10-15

41. The solubility product for chromium(III) fluoride is Ksp = 6.6 × 10-11. What is the molar solubility of chromium(III) fluoride?
A.
B.
C.
D.
E.

1.6 × 10-3 M
1.2 × 10-3 M
6.6 × 10-11 M
2.2 × 10-3 M
1.6 × 10-6 M

42. The solubility product for barium sulfate is 1.1 × 10-10. Calculate the molar solubility of barium sulfate.
A.
B.
C.
D.
E.

5.5 × 10-11 mol/L
1.1 × 10-5 mol/L
2.1 × 10-5 mol/L
1.1 × 10-10 mol/L
2.2 × 10-10 mol/L

43. The Ksp for silver(I) phosphate is 1.8 × 10-18. Calculate the molar solubility of silver(I) phosphate.
A.
B.
C.
D.
E.

1.6 × 10-5 M
2.1 × 10-5 M
3.7 × 10-5 M
7.2 × 10-1 M
1.8 × 10-1 M

44. The solubility product for calcium phosphate is Ksp = 1.3 × 10-26. What is the molar solubility of calcium phosphate? A.
B.
C.
D.
E.

1.3 × 10-26 M
1.5 × 10-7 M
2.6 × 10-6 M
4.6 × 10-6 M
6.6 × 10-6 M

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August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]
45. The Ksp value for lead(II) chloride is 2.4 × 10-4. What is the molar solubility of lead(II) chloride?
A.
B.
C.
D.
E.

2.4 × 10-4 mol/L
6.2 × 10-2 mol/L
7.7 × 10-3 mol/L
3.9 × 10-2 mol/L
6.0 × 10-5 mol/L

46. Calculate the silver ion concentration in a saturated solution of silver(I) carbonate (Ksp = 8.1 × 10-12).
A.
B.
C.
D.
E.

5.0 × 10-5 M
2.5 × 10-4 M
1.3 × 10-4 M
2.0 × 10-4 M
8.1 × 10-4 M

47. The Ksp for silver(I) phosphate is 1.8 × 10-18. Determine the silver ion concentration in a saturated solution of silver(I) phosphate.
A.
B.
C.
D.
E.

1.6 × 10-5 M
2.1 × 10-5 M
3.7 × 10-5 M
1.1 × 10-13 M
4.8 × 10-5 M

48. Calculate the silver ion concentration in a saturated solution of silver(I) sulfate (Ksp = 1.4 × 10-5).
A.
B.
C.
D.
E.

1.5 × 10-2 M
2.4 × 10-2 M
3.0 × 10-2 M
1.4 × 10-5 M none of these

49. Calculate the concentration of chloride ions in a saturated lead(II) chloride (Ksp = 2.4 × 10-4) solution.
A.
B.
C.
D.
E.

2.4 × 10-4 M
4.8 × 10-4 M
3.9 × 10-2 M
1.2 × 10-1 M
7.8 × 10-2 M

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August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]
50. Calculate the concentration of fluoride ions in a saturated barium fluoride (Ksp = 1.7 × 10-6) solution.
A.
B.
C.
D.
E.

7.6 × 10-3 M
1.5 × 10-2 M
3.4 × 10-5 M
1.7 × 10-6 M
3.4 × 10-6 M

51. Which of the following would decrease the Ksp for PbI2?
A.
B.
C.
D.

Lowering the pH of the solution
Adding a solution of Pb(NO3)2
Adding a solution of KI
None of these—the Ksp of a compound is constant at constant temperature.

52. 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 × 10-9.)
A.
B.
C.
D.
E.

1.4 × 107 M
6.9 × 10-9 M
6.9 × 10-8 M
1.7 × 10-7 M
6.9 × 10-7 M

53. 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 × 10-11.)
A.
B.
C.
D.
E.

0.023 M
0.032 M
7.7 × 10-8 M
2.9 × 10-9 M
6.9 × 10-10 M

54. Will a precipitate form (yes or no) when 50.0 mL of 1.2 × 10-3 M Pb(NO3)2 are added to 50.0 mL of 2.0 ×
10-4 M Na2S? If so, identify the precipitate.
A.
B.
C.
D.
E.

Yes, the precipitate is PbS.
Yes, the precipitate is NaNO3.
Yes, the precipitate is Na2S.
Yes, the precipitate is Pb(NO3)2.
No, a precipitate will not form.

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August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]
55. Will a precipitate of magnesium fluoride form when 300. mL of 1.1 × 10-3 M MgCl2 are added to 500. mL of 1.2 × 10-3 M NaF? (Ksp (MgF2) = 6.9 × 10-9)
A.
B.
C.
D.

Yes, Q > Ksp
No, Q < Ksp
No, Q = Ksp
Yes, Q < Ksp

56. Will a precipitate of magnesium fluoride form when 200. mL of 1.9 × 10-3 M MgCl2 are added to 300. mL of 1.4 × 10-2 M NaF? (Ksp (MgF2) = 6.9 × 10-9)
A.
B.
C.
D.

Yes, Q > Ksp
No, Q < Ksp
No, Q = Ksp
Yes, Q < Ksp

57. Will a precipitate (ppt) form when 300. mL of 5.0 × 10-5 M AgNO3 are added to 200. mL of 2.5 × 10-7 M
NaBr? Answer yes or no, and identify the precipitate if there is one.
A.
B.
C.
D.
E.

Yes, the ppt is AgNO3(s).
Yes, the ppt is AgBr(s).
Yes, the ppt is NaBr(s).
Yes, the ppt is NaNO3(s).
No, a precipitate will not form.

58. Will a precipitate (ppt) form when 20.0 mL of 1.1 × 10-3 M Ba(NO3)2 are added to 80.0 mL of 8.4 × 10-4
M Na2CO3?
A.
B.
C.
D.
E.

Yes, the ppt is Ba(NO3 )2.
Yes, the ppt is NaNO3.
Yes, the ppt is BaCO3.
Yes, the ppt is Na2CO3.
No, a precipitate will not form.

59. Will a precipitate (ppt) form when 300. mL of 2.0 × 10-5 M AgNO3 are added to 200. mL of 2.5 × 10-9 M
NaI? Answer yes or no, and identify the precipitate if there is one.
A.
B.
C.
D.
E.

Yes, the ppt is AgNO3(s).
Yes, the ppt is NaNO3(s).
Yes, the ppt is NaI(s).
Yes, the ppt is AgI(s).
No, a precipitate will not form.

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August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]
60. 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 × 10-12) What is the concentration of the silver ion remaining in solution?
A.
B.
C.
D.
E.

Yes, [Ag+] = 2.9 × 10-6 M.
Yes, [Ag+] = 0.060 M.
Yes, [Ag+] = 1.3 × 10-4 M.
No, [Ag+] = 0.060 M.
No, [Ag+] = 0.105 M.

61. 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? [Given: Ka(C6H5COOH) =
6.5 × 10-5]
A.
B.
C.
D.
E.

3.3%
12%
1.3%
0.52%
0.065%

62. To 1.00 L of a 0.100 M aqueous solution of the week base pyridine (C5H5N) is added 1.00 mL of 14.0 M
NaOH. What fraction of the pyridine molecules in the resulting solution react with water to release hydroxide ions? [Given: Kb(C5H5N) = 1.7 × 10-9]
A.
B.
C.
D.
E.

1.2 × 10-7
4.1 × 10-5
0.14
2.4 × 10-10
1.3 × 10-5

63. 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 × 10-8.]
A.
B.
C.
D.
E.

3.04 × 10-4 M
1.54 × 10-7 M
6.18 × 10-7 M
1.52 × 10-4 M
9.27 × 10-8 M

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August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]
64. 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 × 10-11.]
A.
B.
C.
D.
E.

3.16 × 10-10 M
2.53 × 10-9 M
4.29 × 10-4 M
6.32 × 10-10 M
2.15 × 10-4 M

65. A saturated sodium carbonate solution at 0°C 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.
B.
C.
D.
E.

1.2.
0.30.
3.0 × 10-4.
0.90.
1.2 × 10-3.

66. A saturated sodium carbonate solution at 100°C 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.
B.
C.
D.
E.

79.0.
0.316.
0.0790.
36.8.
316.

67. 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 × 10-4]
A.
B.
C.
D.
E.

540 mL
420 mL
80. mL
340 mL
500. mL

68. 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 × 10-5]
A.
B.
C.
D.
E.

32 mL
210mL
160mL
65mL
13mL

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August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]
69. What is the effective pH range for a sodium acetate/acetic acid buffer? (For CH3COOH, Ka= 1.8 × 10-5)

70. Calculate the pH of a solution that is 0.15 M CH3COOH and 0.75 M CH3COONa.

71. What is the optimum pH of a sodium formate/formic acid buffer? (For formic acid, Ka = 1.7 × 10-4)

72. Describe how to make a sodium formate (HCOONa)/formic acid (HCOOH) buffer that has a pH of 4.77.

73. Write an equation showing the net reaction that occurs when a strong acid is added to a CO32-/HCO3buffer solution (for carbonic acid, Ka1 = 4.2 × 10-7, Ka2 = 2.4 × 10-8).

74. Write an equation showing the net reaction that occurs when a strong base is added to a CO32-/HCO3buffer solution (for carbonic acid, Ka1 = 4.2 × 10-7, Ka2 = 2.4 × 10-8).

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August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]
75. Calculate the percent ionization of formic acid in a 0.010 M HCOOH solution. (Ka = 1.7 × 10-4)

76. 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 × 10-4)

77. Calculate the percent ionization of formic acid in a solution that is 0.010 M HCOOH and 0.050 M
HCOONa. (Ka = 1.7 × 10-4)

78. 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 × 10-5)

79. 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 .

80. 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.

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August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]
81. Write a net ionic equation for the reaction that occurs when a small amount of nitric acid is added to a
NaNO2/HNO2 buffer.

82. Write a net ionic equation for the reaction occurring when a small amount of sodium hydroxide is added to a NaNO2/HNO2 buffer.

83. 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 × 10-5)

84. Calculate the pH at the equivalence point for the titration of 0.22 M HCN with 0.22 M NaOH. (Ka = 4.9 ×
10-10 for HCN.)

85. Bromothymol blue is a common acid-base indicator. It has a Ka equal to 1.6 × 10-7. Its un-ionized form is yellow and its conjugate base is blue. What color would a solution have at pH = 5.8?

86. 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 × 10-4)

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August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]
87. Solid sodium iodide is slowly added to a solution that is 0.0050 M Pb2+ and 0.0050 M Ag+.
(Ksp (PbI2) = 1.4 × 10-8; Ksp (AgI) = 8.3 × 10-17)
What compound will precipitate first?

88. Solid sodium iodide is slowly added to a solution that is 0.0050 M Pb2+ and 0.0050 M Ag+.
(Ksp (PbI2) = 1.4 × 10-8; Ksp (AgI) = 8.3 × 10-17)
Calculate the Ag+ concentration when PbI2 just begins to precipitate.

89. Solid sodium iodide is slowly added to a solution that is 0.0050 M Pb2+ and 0.0050 M Ag+.
(Ksp (PbI2) = 1.4 × 10-8; Ksp (AgI) = 8.3 × 10-17)
What percent of Ag+ remains in solution at this point?

90. The Ksp of CaF2 is 4 × 10-11. What is the maximum concentration of Ca2+ possible in a 0.10 M NaF solution? 91. 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+ = 1.5 × 107)

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August 28,, 2009 [PR
ROBLEM SET FROM
M R. CHA
ANG TEST BANK]
A
form when 0.050
0 mol NaCl((s) and 0.0550 mol AgN
NO3(s) are dissolved d in 500.
92. Will a preecipitate of AgCl
7
-10
+
mL of 3.00 M NH3? (K
Kf for Ag(N
NH3)2 = 1.55 × 10 ; Ksp(AgCl)
(
= 1..6 × 10 )

93. Will Fe(O
OH)3 precipiitate from a buffer soluution that is 0.60 M CH
H3COOH annd 0.10 M CH
C 3COONa, if the solution iss also madee to be 0.0011 M in Fe3+? (For Fe(O
OH)3, Ksp = 6.8 × 10-36.))

94. The conceentration off Mg2+ in seawater is 5..0 × 10-2 M.. What hydrroxide concentration is needed to remove r 2+
-11
90% of thhe Mg by precipitation p n? (For Mg g(OH)2, Ksp = 1.2 × 10 .)

95. Ammoniuum chloride solutions are a slightly acidic, a so thhey are betteer solvents tthan water for f insolublle substancees such as Ca(OH)2. Ideentify two reeactions thaat, added toggether, givee the overalll reaction beelow.
Then deteermine Kc foor the overaall reaction.
(Ksp for Ca(OH)
C
4 × 10-8; Kb for NH3 is i 1.8 × 10-55.)
2 is 4.0
Ca(O
OH)2(s) + 2N
NH4+ (aq)

Ca2+(aaq) + 2NH3((aq) + 2H2O

96. Calculate the equilibrrium constaant Kc for thhe followingg overall reaaction.
(For AgCl, Ksp = 1.6 × 10-10; forr Ag(CN)2-, Kf = 1.0 × 1021)
AgCl(s) + 2CN-(aq)

A
Ag(CN)
2 (aq) + Cl (aq))

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August 28,, 2009 [PR
ROBLEM SET FROM
M R. CHA
ANG TEST BANK] he net reactiion shown below. b 97. Calculate the equilibrrium constaant Kc for th
-17
7
+
A
(For AgI, Ksp = 8.3 × 10 ; for Ag(NH
3)2 , Kf = 1.5 × 10 .)
AgI((s) + 2NH3(aaq)

+
A
Ag(NH aq) + I-(aq)
3)2 (a

98. The solub bility of Ba(NO3)2 is 13
30.5 g/L at 0oC. How many m moles of dissolved salt are prresent in 4.0
0 L of a o saturated solution of Ba(NO3)2 at a 0 C?

99. A sample of rainwateer collected near a lead d smelter is analyzed a fo or acid conteent. Experim ments show w that a s of th he rainwaterr is neutralizzed by 22.44 milliters of 0.0122 M NaOH. Assuming thatt the
100. mL sample acid preseent is sulfuro ous acid, which w resulteed from the reaction off SO2 with w water, what is the molarrity of acid in thee rainwater??

100. A wildlifee biologist is interested d in testing the t pH of thhe water in a lake. He oobtains a 200. mL samp ple of the water and titrates this samplee with a .050 M NaOH
H solution. Neutralizatio
N
on of the lak ke water req quires 40. mL off the NaOH solution.
Estimate the t pH of th he lake.

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2

August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]
101. A wildlife biologist is interested in testing the pH of the water in a lake. He obtains a 200. mL sample of the water and titrates this sample with a .050 M NaOH solution. Neutralization of the lake water requires
40. mL of the NaOH solution.
Is the lake acidic, basic, or neutral?

102. A wildlife biologist is interested in testing the pH of the water in a lake. He obtains a 200. mL sample of the water and titrates this sample with a .050 M NaOH solution. Neutralization of the lake water requires
40. mL of the NaOH solution?
If the size of the lake can be described as 1.1 km long by 2.3 km wide, and has a depth of 10. m, estimate how many moles of acid are present in the lake water.

103. 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 × 10-7, 1.8 × 10-10, and 2.0 × 10-13, respectively. Which compound will precipitate first?

104. A 50.0 mL sample of 2.0 × 10-4 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? www.kau.edu.sa/aasiri2 21

August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]
105. How many moles of NaF must be dissolved in 1.00 liter of a saturated solution of PbF2 at 25°C to reduce the [Pb2+] to 1.0 × 10-6 M? (Ksp of PbF2 at 25 °C = 4.0 × 10-8)

106. At 25°C, the base ionization constant for NH3 is 1.8 × 10-5. Determine the hydroxide ion concentration in a
0.150 M solution of ammonia at 25°C.

107. At 25°C, the base ionization constant for NH3 is 1.8 × 10-5. Determine the pH of a solution prepared by adding 0.0500 mol of solid ammonium chloride to 100. mL of 0.150 M ammonia.

108. At 25°C, the base ionization constant for NH3 is 1.8 × 10-5. Determine the percentage ionization of a 0.150
M solution of ammonia at 25°C.

109. At 25°C, the base ionization constant for NH3 is 1.8 × 10-5. 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 × 10-11.]

110. 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.
True False

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August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]
111. A mixture made from 10 mL of 1 M HCl and 20 mL of 1 M CH3COONa would be classified as a buffer solution. True False
112. All indicators are weak acids that are one color in acidic solution and another color in basic solution.
True False
113. For any conjugate acid-base pair, it is true that Kb = KaKw.
True False
114. 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.
True False

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August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]

Chapter 16 Acid-Base Equilibria and Solubility Equilibria Key

1.A
2.A
3.C
4.C
5.A
6.C
7.E
8.C
9.B
10.D
11.B
12.A
13.C
14.B
15.A
16.E
17.B
18.C
19.A
20.C
21.E
22.C
23.B
24.A
25.C
26.C
27.D

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August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]
28.B
29.D
30.D
31.A
32.C
33.A
34.B
35.A
36.D
37.D
38.A
39.C
40.C
41.B
42.B
43.A
44.C
45.D
46.B
47.E
48.C
49.E
50.B
51.D
52.E
53.C
54.A
55.B
56.A
57.B
58.C
59.D

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August 28, 2009 [PROBLEM SET FROM R. CHANG TEST BANK]
60.A
61.D
62.A
63.C
64.B
65.A
66.E
67.B
68.C
69.3.7-5.7
70.5.44
71.3.77
72.Prepare a solution having a molar ratio of 10.0 mol HCOONa to 1.0 mol HCOOH.
73.CO32- + H+ → HCO3- and HCO3- + H+ → H2CO3
74.HCO3- + OH- → CO32- + H2O
75.13%
76.3.4%; the addition of formate suppresses the ionization of formic acid by shifting the ionization equilibrium towards the un-ionized acid.
77.0.34%
78.10.3
79.H+ + NH3 → NH4+
80.OH- + NH4+ → NH3 + H2O
81.H+ + NO2- → HNO2
82.OH- + HNO2 → NO2- + H2O
83.8.92
84.11.18
85.Yellow
86.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. 87.AgI
88.5.0 × 10-14 M
89.1.0 × 10-9 %
90.4 × 10-9 M

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August 28,, 2009 [PR
ROBLEM SET FROM
M R. CHA
ANG TEST BANK]
91.8.4 × 10-6 M
92.Yes
93.Yes
94.4.9 × 10-5 M
95. Ca(OH)
C
2(s)
2NH4+(aq) + 2OH-(aaq)
Kc = 120

Ca2+(aq) + 2OH-(aq)
2NH
H3(aq) + 2H2O

96. 1.6 × 1011
97. 1.2 × 10-9
98.2.0 moles
99.1.37 × 10-3 M
100.22
101.aacidic
102.22.5 × 108 mol
103.A
AuCl
104.11.3 × 10-14 M
105.00.20 mol
106.11.6 × 10-3 M
107.88.73
108.11.1%
109.Y
Yes
FALSE
110.F
111.T
TRUE
FALSE
112.F
FALSE
113.F
TRUE
114.T

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