3) The conjugate base of HSO4– is __________.
A) OH–
B) H2SO4
C) SO42-
D) HSO4+
E) H3SO4+
4) The conjugate base of H2PO4– is __________.
A) PO4-3
B) H2PO4
C) H3PO4
D) HPO4-2
E) none of the above
5) The conjugate acid of HSO4– is __________.
A) SO42-
B) H2SO4
C) HSO4+
D) H+
E) HSO3+
6) The conjugate acid of CH3NH2 is __________.
A) CH3NH2
B) CH3NH3+
C) CH3NH3+
D) CH3NH+
E) none of the above
7) What is the conjugate base of OH–?
A) O2
B) O–
C) H2O
D) O2-
E) H3O+
8) What is the pH of an aqueous solution at 25.0 °C that contains 3.98 × 10-9 M hydronium ion?
A) 8.400
B) 5.600
C) 9.000
D) 3.980
E) 7.000
9) What is the pOH of an aqueous solution at 25.0 °C that contains 3.98 × 10–9 M hydronium ion?
A) 8.400
B) 5.600
C) 9.000
D) 3.980
E) 7.000
10) What is the pH of an aqueous solution at 25.0 °C that contains 3.98 × 10-9 M hydroxide ion?
A) 8.40
B) 5.60
C) 9.00
D) 3.98
E) 7.00
11) What is the pOH of an aqueous solution at 25.0 °C that contains 3.98 × 10-9 M hydroxide ion?
A) 8.40
B) 5.60
C) 9.00
D) 3.98
E) 7.00
12) Calculate the pOH of a solution at 25.0 °C that contains 1.94 × 10-10 M hydronium ions.
A) 1.94
B) 4.29
C) 7.00
D) 14.0
E) 9.71
13) Calculate the pH of a solution at 25.0 °C that contains 1.94 × 10-10 M hydronium ions.
A) 1.94
B) 4.29
C) 7.00
D) 14.0
E) 9.71
14) Calculate the concentration (in M) of hydronium ions in a solution at 25.0°C with a pOH of 4.223.
A) 5.98 × 10-5
B) 1.67 × 10-10
C) 1.67 × 104
D) 5.99 × 10-19
E) 1.00 × 10-7
15) Calculate the concentration (in M) of hydroxide ions in a solution at 25.0°C with a pOH of 4.223.
A) 5.98 × 10-5
B) 1.67 × 10-10
C) 1.67 × 104
D) 5.99 × 10-19
E) 1.00 × 10-7
16) An aqueous solution contains 0.100 M NaOH at 25.0°C. The pH of the solution is __________.
A) 0.100
B) 1.00
C) 13.00
D) 7.00
E) -1.00
17) An aqueous solution contains 0.150 M HCl at 25.0°C. The pH of the solution is __________.
A) 0.150
B) 1.00
C) 13.00
D) 7.00
E) 0.82
18) HZ is a weak acid. An aqueous solution of HZ is prepared by dissolving 0.020 mol of HZ in
sufficient water to yield 1.0 L of solution. The pH of the solution was 4.93 at 25.0°C. The Ka of HZ is
__________.
A) 1.2 × 10-5
B) 6.9 × 10-9
C) 1.4 × 10-10
D) 9.9 × 10-2
E) 2.8 × 10-12
19) The pH of a 0.55 M aqueous solution of hypobromous acid, HBrO, at 25.0°C is 4.48. What is the
value of Ka for HBrO?
A) 2.0 × 10-9
B) 1.1 × 10-9
C) 6.0 × 10-5
D) 3.3 × 10-5
E) 3.0 × 104
20) The pH of a 0.25 M aqueous solution of hydrofluoric acid, HF, at 25.0°C is 2.03. What is the value
of Ka for HF?
A) 2.0 × 10-9
B) 1.1 × 10-9
C) 6.0 × 10-5
D) 3.5 × 10-4
E) none of the above
21) The pH of a 0.60 M aqueous solution of formic acid, HCHO2, at 25.0°C is 1.98. What is the value
of Ka for formic acid?
A) 2.0 × 10-5
B) 1.8 × 10-4
C) 6.0 × 10-5
D) 3.5 × 10-4
E) none of the above
22) A 0.15 M aqueous solution of the weak acid HA at 25.0°C has a pH of 5.35. The value of Ka for HA
is __________.
A) 3.0 × 10-5
B) 1.8 × 10-5
C) 7.1 × 10-9
D) 1.3 × 10-10
E) 3.3 × 104
23) The Ka of hypochlorous acid (HClO) is 3.00 × 10-8. What is the pH at 25.0°C of an aqueous
solution that is 0.0200 M in HClO?
A) +2.45
B) -2.45
C) -9.22
D) +9.22
E) +4.61
24) The Ka of acetic acid (HC2H3O2) is 1.8 × 10-5. What is the pH at 25.0°C of an aqueous solution
that is 0.100 M in acetic acid?
A) +2.87
B) -2.87
C) -11.13
D) +11.13
E) +6.61
25) The acid-dissociation constants of sulfurous acid (H2SO3) are Kal = 1.7 × 10-2 and
Ka2 = 6.4 × 10-8 at 25.0°C. Calculate the pH of a 0.163 M aqueous solution of sulfurous acid.
A) 4.53
B) 1.28
C) 1.86
D) 6.21
E) 1.93
26) The acid-dissociation constants of phosphoric acid (H2PO3) are Kal = 7.5 × 10-3, Ka2 = 6.2 × 10-8,
and Ka3 = 4.2 × 10-13 at 25.0°C. What is the pH of a 2.5 M aqueous solution of phosphoric acid?
A) 1.82
B) 0.40
C) 2.51
D) 0.86
E) 0.13
27) The pH of a 0.55 M aqueous solution ammonia, NH3, at 25.0°C is 11.50. What is the value of Kb
for NH3?
A) 2.0 × 10-9
B) 1.1 × 10-9
C) 6.0 × 10-5
D) 1.8 × 10-5
E) none of the above
28) A 0.15 M aqueous solution of the weak base B at 25.0°C has a pH of 8.88. The value of Kb for B is
__________.
A) 3.0 × 10-5
B) 1.8 × 10-5
C) 3.9 × 10-10
D) 1.3 × 10-10
E) none of the above
29) The pH of a 0.30 M solution of a weak acid is 2.67. What is the Ka for this acid?
A) 2.1 × 10-4
B) 4.4 × 10-4
C) 1.5 × 10-4
D) 6.6 × 10-4
E) none of the above
30) Z– is a weak base. An aqueous solution of NaZ is prepared by dissolving 0.350 mol of NaZ in
sufficient water to yield 1.0 L of solution. The pH of the solution was 8.93 at 25.0°C. The Kb of Z– is
__________.
A) 1.2 × 10-5
B) 6.9 × 10-9
C) 2.1 × 10-10
D) 9.9 × 10-2
E) 2.8 × 10-12
31) The pH of a 0.10 M solution of a weak base is 9.82. What is the Kb for this base?
A) 2.1 × 10-4
B) 4.4 × 10-8
C) 8.8 × 10-8
D) 6.6 × 10-4
E) 2.0 × 10-5
32) Determine the pH of a 0.35 M aqueous solution of CH3N H2 (methylamine). The Kb of
methylamine is 4.4 × 10-4.
A) 10.00
B) 3.86
C) 12.09
D) 1.96
E) 13.24
33) An aqueous solution contains 0.050 M of methylamine. The concentration of hydroxide ion in this
solution is __________ M. Kb for methylamine is 4.4 × 10-4.
A) 0.050
B) 2.2 × 10-5
C) 2.9 × 10-3
D) 4.5 × 10-3
E) 4.7 × 10-3
34) An aqueous solution contains 0.050 M of methylamine. The concentration of H+ in this solution is
__________ M. Kb for methylamine is 4.4 × 10-4.
A) 0.050
B) 2.2 × 10-13
C) 2.9 × 10-13
D) 4.5 × 10-13
E) none of the above
35) The acid-dissociation constant, Ka, for gallic acid is 4.57 × 10-3. What is the base-dissociation
constant, Kb, for the gallate ion?
A) 4.57 × 10-3
B) 2.19 × 10-12
C) 5.43 × 10-5
D) 7.81 × 10-6
E) 2.19 × 102
36) The base-dissociation constant, Kb, for pyridine, C5H5N, is 1.4 × 10-9. The acid-dissociation
constant, Ka, for the pyridinium ion, C5H5NH+, is __________.
A) 1.0 × 10-7
B) 1.4 × 10-23
C) 7.1 × 10-4
D) 1.4 × 10-5
E) 7.1 × 10-6
37) The Ka for HCN is 4.9 × 10-10. What is the value of Kb for CN–?
A) 2.0 × 10-5
B) 4.0 × 10-6
C) 4.9 × 104
D) 4.9 × 10-24
E) 2.0 × 109
38) Ka for HF is 7.0 × 10-4. Kb for the fluoride ion is __________.
A) 2.0 × 10-8
B) 1.4 × 10-11
C) 7.0 × 10-18
D) 7.0 × 10-4
E) 1.4 × 103
39) Ka for HCN is 4.9 × 10-10. What is the pH of a 0.068 M aqueous solution of sodium cyanide?
A) 0.74
B) 2.96
C) 11.07
D) 13.24
E) 7.00
40) Ka for HX is 7.5 × 10–12. What is the pH of a 0.15 M aqueous solution of NaX?
A) 7.97
B) 1.96
C) 6.00
D) 8.04
E) 12.10
41) The pH of a 0.15 M aqueous solution of NaZ (the sodium salt of HZ) is 10.7. What is the Ka for
HZ?
A) 1.6 × 10-6
B) 6.0 × 10-9
C) 8.9 × 10-4
D) 1.3 × 10-12
E) 3.3 × 10-8
26
16.3 Algorithmic Questions
1) An aqueous solution at 25.0°C contains [H+] = 0.080 M. What is the pH of the solution?
A) 1.10
B) -1.10
C) 13.0
D) 0.0800
E) 1.30 × 10-13
2) The pH of an aqueous solution at 25.0 °C is 10.30. What is the molarity of H+ in this solution?
A) 5.0 × 10-11
B) 2.0 × 10-4
C) 3.70
D) 1.0 × 10-13
E) 2.0 × 1010
3) Calculate the molarity of hydroxide ion in an aqueous solution that has a pOH of 5.00.
A) 1.0 × 10-5
B) 9.00
C) 1.0 × 10-9
D) 5.0 × 10-14
E) 9.0 × 10-14
4) What is the pH of an aqueous solution at 25.0°C in which [H+] is 0.0025 M?
A) 5.99
B) 2.60
C) -2.60
D) -5.99
E) none of the above
5) What is the pOH of an aqueous solution at 25.0°C in which [H+] is 0.0025 M?
A) 8.01
B) 11.40
C) -11.40
D) -8.01
E) none of the above
6) What is the pH of an aqueous solution at 25.0 °C in which [OH–] is 0.0050 M?
A) 5.30
B) -11.70
C) 2.30
D) -2.30
E) 11.70
7) What is the pOH of an aqueous solution at 25.0 °C in which [OH–] is 0.0040 M?
A) 11.60
B) -2.40
C) 2.40
D) -11.60
E) 5.52
8) What is the concentration (in M) of hydronium ions in a solution at 25.0 °C with pH = 4.153?
A) 4.15
B) 9.85
C) 1.42 × 10-10
D) 7.03 × 10-5
E) none of the above
9) What is the concentration (in M) of hydroxide ions in a solution at 25.0 °C with pH = 4.153?
A) 4.15
B) 9.85
C) 1.42 × 10-10
D) 7.03 × 10-5
E) none of the above
10) A 7.0 × 10-3 M aqueous solution of Ca(OH)2 at 25.0°C has a pH of __________.
A) 12.15
B) 1.85
C) 1.4 × 10-2
D) 7.1 × 10-13
E) 11.85
11) What is the pH of a 0.035 M aqueous solution of barium hydroxide?
A) 12.85
B) 12.54
C) 1.46
D) 10.41
E) 1.15
12) What is the pOH of a 0.035 M solution of barium hydroxide?
A) 12.85
B) 12.54
C) 1.46
D) 1.15
E) 10.41
13) The acid-dissociation constant at 25.0°C for hypochlorous acid (HClO) is 3.0 × 10-8. At
equilibrium, the molarity of H3O+ in a 0.010 M solution of HClO is __________.
A) 1.7 × 10-5
B) 0.010
C) 5.8 × 10-10
D) 4.76
E) 2.00
14) The Ka of hypochlorous acid (HClO) is 3.0 × 10-8 at 25.0°C. Calculate the pH of a 0.0335 M
hypochlorous acid solution.
A) 3.02
B) 9.50
C) 4.50
D) 6.52
E) -3.02
15) The Ka of hydrofluoric acid (HF) at 25.0 °C is 6.8 × 10-4. What is the pH of a 0.15 M aqueous
solution of HF?
A) 4.60
B) 2.00
C) 3.64
D) 0.82
E) 1.17
16) The Ka of hydrazoic acid (HN3) is 1.9 × 10-5 at 25.0°C. What is the pH of a 0.40 M aqueous
solution of HN3?
A) 0.40
B) 2.16
C) 5.23
D) 2.56
E) -3.46
17) The base-dissociation constant of ethylamine (C2H5NH2) is 6.4 × 10-4 at 25.0 °C. The [H+] in
a 1.6 × 10-2 M solution of ethylamine is __________ M.
A) 3.5 × 10-12
B) 2.9 × 10-3
C) 3.1 × 10-12
D) 3.2 × 10-3
E) 11.46
18) Calculate the pH of a 0.100 M aqueous solution of NH3. The Kb of NH3 is 1.77 × 10-5.
A) 8.95
B) 11.12
C) 2.88
D) 12.12
E) 1.87
19) The acid-dissociation constant of hydrocyanic acid (HCN) at 25.0°C is 4.9 × 10-10. What is the pH
of an aqueous solution of 0.080 M sodium cyanide (NaCN)?
A) 11.11
B) 2.89
C) 1.3 × 10-3
D) 7.8 × 10-12
E) 3.9 × 10-11
20) Calculate the pOH of a 0.0627 M aqueous sodium cyanide solution at 25.0°C. Kb for CN–
is 4.9 × 10-10.
A) 9.33
B) 10.00
C) 5.25
D) 1.20
E) 8.75
21) Calculate the pH of a 0.0787 M aqueous sodium cyanide solution at 25.0 °C. Kb for CN–
is 4.9 × 10-10.
A) 9.33
B) 10.00
C) 5.21
D) 1.10
E) 8.79
22) Determine the pH of a 0.35 M aqueous solution of KF. For hydrofluoric acid, Ka = 7.0 × 10-4.
A) 0.46
B) 5.65
C) 8.35
D) 5.01
E) 1.35
23) Determine the pOH of a 0.35 M aqueous solution of KF. For hydrofluoric acid, Ka = 7.0 × 10-4.
A) 0.46
B) 5.65
C) 8.35
D) 5.01
E) 1.35
24) Calculate the pH of 0.586 M anilinium hydrochloride (C6H5NH3Cl) solution in water, given that
Kb for aniline is 3.83 × 10-4.
A) 1.82
B) 12.18
C) 5.41
D) 8.59
E) 12.42
25) Calculate the pOH of 0.716 M anilinium hydrochloride (C6H5NH3Cl) solution in water, given that
Kb for aniline is 3.83 × 10-4.
A) 1.78
B) 12.22
C) 5.37
D) 8.63
E) 12.42
26) Kb for NH3 is 1.8 × 10-5. What is the pH of a 0.45 M aqueous solution of NH4Cl at 25.0 °C?
A) 2.55
B) 11.45
C) 9.20
D) 4.80
E) 11.23
27) Kb for NH3 is 1.8 × 10-5. What is the pOH of a 0.15 M aqueous solution of NH4Cl at 25.0 °C?
A) 2.78
B) 11.22
C) 8.96
D) 5.04
E) 11.23
28) The Ka for formic acid (HCO2H) is 1.8 × 10-4. What is the pH of a 0.10 M aqueous solution of
sodium formate (NaHCO2)?
A) 11.64
B) 5.63
C) 3.39
D) 8.37
E) 4.26
16.4 Short Answer Questions
1) A solution of acetic acid is 2.0% dissociated at 25.0°C. What was the original concentration (in M) of
the acetic acid solution? The Ka at 25.0 °C for acetic acid is 1.8 × 10-5.
2) A solution of formic acid is 3.0% dissociated at 25.0°C. What is the original concentration (in M) of
the formic acid solution? The Ka at 25.0 °C for formic acid is 1.8 × 10-4.
3) A solution of ammonia is 2.0% ionized at 25.0°C. What was the original concentration (in M) of the
ammonia solution? The Kb at 25.0°C for ammonia is 1.8 × 10-5.
4) What is the pH of a sodium acetate solution prepared by adding 0.820 grams of sodium acetate to
100.0 ml of water at 25.0°C? The Ka at 25.0°C for acetic acid is 1.8 × 10-5.
5) What is the pH of a sodium formate solution prepared by adding 0.680 grams of sodium formate to
100.0 ml of water at 25.0°C? The Ka at 25.0°C for formic acid is 1.8 × 10-4.
16.5 True/False Questions
1) In the reaction
BF3 + F– → BF4–
BF3 acts as a Br∅nsted-Lowry acid.
2) An acid containing the COOH group is called a carbo-oxy acid.
3) A Lewis acid is an electron-pair acceptor, and a Lewis base is an electron-pair donor.