16
(KNO2). The acid dissociation constant of nitrous acid is 4.50 × 10-4.
A) 3.093
B) 3.607
C) 14.26
D) 10.91
E) 4.589
5) Calculate the percent ionization of nitrous acid in a solution that is 0.241 M in nitrous acid (HNO2) and
0.195 M in potassium nitrite (KNO2). The acid dissociation constant of nitrous acid is 4.50 × 10-4.
A) 44.7
B) 0.229
C) 13.5
D) 2.11 × 10-3
E) 3.258
6) Calculate the percent ionization of nitrous acid in a solution that is 0.260 M in nitrous acid. The acid
dissociation constant of nitrous acid is 4.50 × 10-4.
A) 1.17 × 10-4
B) 0.0450
C) 4.16
D) 0.314
E) 5.78
7) Of the following solutions, which has the greatest buffering capacity?
A) 1.15 M HF and 0.624 M NaF
B) 0.574 M HF and 0.312 M NaF
C) 0.287 M HF and 0.156 M NaF
D) 0.189 M HF and 0.103 M NaF
E) They are all buffer solutions and would all have the same capacity.
8) The addition of hydrofluoric acid and ________ to water produces a buffer solution.
A) NaF
B) HF
C) NaNO3
D) NaBr
E) KI
9) What is the pH of a buffer solution that is 0.266 M in lactic acid and 0.111 M in sodium lactate? The Ka
of lactic acid is 1.4 × 10-4.
A) 14.38
B) 10.53
C) 5.38
D) 3.47
E) 4.23
10) What is the pH of a buffer solution that is 0.172 M in hypochlorous acid (HClO) and 0.131 M in
sodium hypochlorite? The Ka of hypochlorous acid is 3.8 × 10-8.
A) 14.12
B) 6.70
C) 9.07
D) 7.54
E) 7.30
11) A solution is prepared by dissolving 0.23 mol of hypochlorous acid and 0.27 mol of sodium
hypochlorite in water sufficient to yield 1.00 L of solution. The addition of 0.05 mol of HCl to this buffer
solution causes the pH to drop slightly. The pH does not decrease drastically because the HCl reacts with
the ________ present in the buffer solution. The Ka of hypochlorous acid is 1.36 × 10–3.
A) H2O
B) H3O+
C) hypochlorite ion
D) hypochlorous acid
E) This is a buffer solution: the pH does not change upon addition of acid or base.
12) A solution is prepared by dissolving 0.23 mol of benzoic acid and 0.27 mol of sodium benzoate in
water sufficient to yield 1.00 L of solution.The addition of 0.05 mol of NaOH to this buffer solution causes
the pH to increase slightly. The pH does not increase drastically because the NaOH reacts with the
________ present in the buffer solution. The Ka of benzoic acid is 6.3 × 10-5.
A) H2O
B) H3O+
C) benzoate
D) benzoic acid
E) This is a buffer solution: the pH does not change upon addition of acid or base.
13) The pH of a solution that contains 0.800 M acetic acid (Ka = 1.76 × 10-5) and 0.172 M sodium acetate is
________.
A) 4.087
B) 5.422
C) 8.578
D) 8.370
E) 9.913
14) Consider a solution containing 0.100 M fluoride ions and 0.126 M hydrogen fluoride. The
concentration of fluoride ions after the addition of 9.00 mL of 0.0100 M HCl to 25.0 mL of this solution is
________ M.
A) 0.0735
B) 0.0762
C) 0.0980
D) 0.0709
E) 0.00253
15) Consider a solution containing 0.100 M fluoride ions and 0.126 M hydrogen fluoride. The
concentration of hydrogen fluoride after addition of 9.00 mL of 0.0100 M HCl to 25.0 mL of this solution is
________ M.
A) 0.0953
B) 0.0900
C) 0.130
D) 0.122
E) 0.00976
19
16) The Ka of acetic acid is 1.76 × 10-5. The pH of a buffer prepared by combining 15.0 mL of 1.00 M
potassium acetate and 50.0 mL of 1.00 M acetic acid is ________.
A) 1.705
B) 0.851
C) 3.406
D) 4.232
E) 2.383
17) The Kb of ammonia is 1.76 × 10-5. The pH of a buffer prepared by combining 50.0 mL of 1.00 M
ammonia and 45.0 mL of 1.00 M ammonium nitrate is ________.
A) 4.632
B) 9.291
C) 4.742
D) 9.372
E) none of the above
18) Calculate the pH of a solution prepared by dissolving 0.270 mol of formic acid (HCO2H) and 0.260
mol of sodium formate (NaCO2H) in water sufficient to yield 1.00 L of solution. The Ka of formic acid is
1.77 × 10-4.
A) 2.099
B) 10.264
C) 3.736
D) 2.307
E) 3.952
19) Calculate the pH of a solution prepared by dissolving 0.850 mol of NH3 and 0.300 mol of NH4Cl in
water sufficient to yield 1.00 L of solution. The Kb of ammonia is 1.77 × 10-5.
A) 5.204
B) 4.300
C) 9.700
D) 8.781
20
E) 8.796
20) Calculate the pH of a solution prepared by dissolving 0.250 mol of benzoic acid (C7H5O2H) and 0.150
mol of sodium benzoate (NaC7H5O2) in water sufficient to yield 1.00 L of solution. The Ka of benzoic
acid is 6.50 × 10-5.
A) 4.409
B) 3.965
C) 10.035
D) 9.591
E) 5.190
21) A buffer solution with a pH of 4.31 is prepared with 1.0 M HC2H3O2 and ________ M NaC2H3O2.
The Ka of HC2H3O2 is 1.8 × 10-5.
A) 0.37
B) 0.74
C) 4.2 × 10–6
D) 8.8 × 10–10
E) 0.18
22) A buffer solution with a pH of 4.63 is prepared with 0.14 M formic acid and ________ M sodium
formate. The Ka of formic acid is 1.8 × 10-4.
A) 1.1
B) 2.1
C) 5.4 × 10–6
D) 3.0 × 10-8
E) 0.54
23) A buffer solution with a pH of 4.40 is prepared with 0.78 M Na C2H3O2 and ________ M HC2H3O2.
The Ka of HC2H3O2 is 1.8 × 10-5.
A) 1.7
21
B) 3.5
C) 4.1 × 104
D) 0.35
E) 0.86
24) A buffer solution with a pH of 4.78 is prepared with ________ M formic acid and 0.90 M sodium
formate. The Ka of formic acid is 1.8 × 10-4.
A) 0.083
B) 0.17
C) 3.3 × 103
D) 9.8
E) 0.041
25) How many milliliters of 0.0839 M NaOH are required to titrate 25.0 mL of 0.0990 M HBr to the
equivalence point?
A) 29.5
B) 0.332
C) 4.57
D) 0.208
E) 21.2
26) A 25.0 mL sample of 0.150 M benzoic acid is titrated with a 0.150 M NaOH solution. What is the pH at
the equivalence point? The Ka of benzoic acid is 4.50 × 10–4.
A) 11.20
B) 9.80
C) 4.20
D) 7.00
E) 8.54
27) A 25.0-mL sample of 0.150 M hydrocyanic acid is titrated with a 0.150 M NaOH solution. What is the
pH before any base is added? The Ka of hydrocyanic acid is 4.9 × 10–10.
A) 5.07
22
B) 8.6 × 10-6
C) 9.31
D) 8.49
E) 3.1 × 108
28) A 25.0 mL sample of 0.150 M hydrazoic acid is titrated with a 0.150 M NaOH solution. What is the pH
after 26.0 mL of base is added? The Ka of hydrazoic acid is 1.9 × 10-5.
A) 2.54
B) 11.47
C) 7.00
D) 4.70
E) 4.74
29) How many milliliters of 0.120 M NaOH are required to titrate 50.0 mL of 0.0998 M hypochlorous acid
to the equivalence point? The Ka of hypochlorous acid is 3.0 × 10-8.
A) 7.60
B) 50.0
C) 41.6
D) 60.1
E) 7.35
30) Which is the correct Ksp expression for PbCl2 (s) dissolving in water?
A) Ksp = [Pb2+] [Cl–]2
B) Ksp = [Pb2+] [Cl–]
C) Ksp = [Pb2+]2 [Cl–]
D) Ksp = [PbCl+] [Cl–]
E) Ksp = [Pb+] [Cl2–]2
31) A 25.0-mL sample of 0.150 M hypochlorous acid is titrated with a 0.150 M NaOH solution. What is the
pH after 13.3 mL of base is added? The Ka of hypochlorous acid is 3.0 × 10-8.
A) 7.25
B) 1.34
C) 4.43
D) 7.58
E) 7.46
32) A 25.0 mL sample of 0.723 M HClO4 is titrated with a 0.273 M KOH solution. The H3O+ concentration
after the addition of 0.00 mL of KOH is ________ M.
A) 0.0181
B) 0.430
C) 0.723
D) 0.273
E) none of the above
33) A 25.0 mL sample of an acetic acid solution is titrated with a 0.175 M NaOH solution. The equivalence
point is reached when 10.2 mL of the base is added. The concentration of acetic acid in the sample was
________ M.
A) 0.365
B) 0.175
C) 0.119
D) 0.0714
E) none of the above
34) A 25.0 mL sample of an HCl solution is titrated with a 0.139 M NaOH solution. The equivalence point
is reached with 15.4 mL of base. The concentration of HCl is ________ M.
A) 11.7
B) 0.00214
C) 0.0856
D) 0.267
E) 0.139
35) The pH of a solution prepared by mixing 45.0 mL of 0.183 M KOH and 35.0 mL of 0.145 M HCl is
________.
A) 1.314
B) 1.403
C) 0.00824
D) 12.597
E) 12.923
36) The pH of a solution prepared by mixing 55.0 mL of 0.183 M KOH and 10.0 mL of 0.145 M HC2H3O2
is ________.
A) 9.97
B) 7.74
C) 0.878
D) 13.122
E) none of the above
37) What is the molar solubility of calcium carbonate ( CaCO3 ) in water? The solubility-product constant
for CaCO3 is 4.5 × 10-9 at 25 °C.
A) 2.3 × 10-9
B) 9.0 × 10-9
C) 8.35
D) 9.5 × 10-5
E) 6.7 × 10-5
38) What is the molar solubility of silver carbonate (Ag2CO3) in water? The solubility-product constant
for Ag2CO3 is 8.1 × 10–12 at 25 °C.
A) 1.4 × 10-6
B) 2.0 × 10-4
C) 4.0 × 10–6
D) 1.3 × 10-4
E) 2.7 × 10–12
25
39) In which aqueous system is CaF2 least soluble?
A) H2O
B) 0.5 M HF
C) 0.2 M HF
D) 1.0 M HNO3
E) 0.8 M KF
40) In which of the following aqueous solutions would you expect AgBr to have the lowest solubility?
A) 0.040 M SrBr2
B) pure water
C) 0.040 M NaBr
D) 0.040 M KBr
E) 0.010 M AgNO3
41) In which of the following aqueous solutions would you expect AgI to have the highest solubility?
A) pure water
B) 0.050 M BaI2
C) 0.050 M NaI
D) 0.050 M KI
E) 0.010 M AgNO3
42) In which of the following aqueous solutions would you expect AgF to have the lowest solubility?
A) 0.030 M LiF
B) pure water
C) 0.023 M NaF
D) 0.015 M KF
E) 0.0075 M AgNO3
43) In which of the following aqueous solutions would you expect AgF to have the highest solubility?
A) 0.00750 M LiF
B) 0.030 M AgNO3
26
C) 0.023 M NaF
D) 0.015 M KF
E) AgF will have the same solubility in all solutions.
44) In which of the following aqueous solutions would you expect CuBr to have the highest solubility?
A) 0.0100 M KBr
B) 0.040 M CuNO3
C) 0.030 M NaBr
D) 0.020 M LiBr
E) CuBr will have the same solubility in all solutions.
45) In which of the following aqueous solutions would you expect PbCl2 to have the lowest solubility?
A) 0.020 M BaCl2
B) 0.020 M Pb(NO3)2
C) 0.020 M NaCl
D) 0.020 M KCl
E) pure water
46) Of the substances below, ________ will decrease the solubility of Pb(CN)2 in a saturated solution.
A) Pb(MnO4)2
B) NaMnO4
C) HMnO4
D) H2O2
E) NaCl
47) A solution of NaF is added dropwise to a solution that is 0.0122 M in Ba2+. When the concentration of
F– exceeds ________ M, BaF2 will precipitate. Neglect volume changes. For BaF, Ksp = 1.7 × 10-6.
A) 7.0 × 10-5
B) 1.2 × 10-2
C) 2.1 × 10-8
D) 3.0 × 10–3
E) 1.4 × 10-4
17.4 Short Answer Questions
1) Calculate the pH of a buffer that contains 0.270 M hydrofluoric acid (HF) and 0.180 M cesium fluoride
(CsF). The Ka of hydrofluoric acid is 6.80 × 10-4.
2) Calculate the pH of a buffer solution that contains 0.820 grams of sodium acetate and 0.010 moles of
acetic acid in 100 ml of water. The Ka of acetic acid is 1.77 × 10-5.
3) Suppose you have just added 100.0 ml of a solution containing 0.5000 moles of acetic acid per liter to
400.0 ml of 0.5000 M NaOH. What is the final pH? The Ka of acetic acid is 1.77 × 10-5.
4) Suppose you have just added 200.0 ml of a solution containing 0.5000 moles of acetic acid per liter to
100.0 ml of 0.5000 M NaOH. What is the final pH? The Ka of acetic acid is 1.77 × 10-5.
5) 200.0 ml of a solution containing 0.5000 moles of acetic acid per liter is added to 200.0 ml of 0.5000 M
NaOH. What is the final pH? The Ka of acetic acid is 1.77 × 10-5.
6) In general, the solubility of a slightly soluble salt is ________ by the presence of a second solute that
furnishes a common ion.
7) Although CaCO3 has a relatively small solubility product, it is quite soluble in the presence of
________.
8) An assembly of a metal ion and the Lewis bases bonded to it is called a(n) ________.
9) Metal oxides and hydroxides that are relatively insoluble in neutral water, but are soluble in both
strongly acidic and strongly basic solutions are said to be ________.
10) ________ analysis determines only the presence or absence of a particular metal ion, whereas
________ analysis determines how much of a given substance is present.
17.5 True/False Questions
1) The extent of ionization of a weak electrolyte is increased by adding to the solution a strong electrolyte
that has an ion in common with the weak electrolyte.
2) For any buffer system, the buffer capacity depends on the amount of acid and base from which the
buffer is made.
3) The solubility product of a compound is numerically equal to the product of the concentration of the
ions involved in the equilibrium, each multiplied by its coefficient in the equilibrium reaction.
4) The solubility of a slightly soluble salt is decreased by the presence of a second solute that provides a
common ion to the system.
5) The solubility of slightly soluble salts containing basic anions is proportional to the pH of the solution.