Chemistry, 7e (McMurry/Fay)
Chapter 15 Aqueous Equilibria: Acids and Bases
15.1 Multiple-Choice Questions
1) When dissolved in water, which of the following compounds is an Arrhenius acid?
A) HCN
B) NaOH
C) NaF
D) CH3CH2OH
2) What are the Br∅nsted-Lowry bases in the following chemical reaction?
C5H5N(aq) + H2O(l) ⇌ C5H5NH+(aq) + OH-(aq)
A) C5H5N, H2O
B) C5H5N, C5H5NH+
C) C5H5N, OH–
D) C5H5N, H2O, OH–
3) What are the Br∅nsted-Lowry acids in the following chemical reaction?
HBr(sol) + CH3COOH(sol) ⇌ CH3C(OH)2+(sol) + Br–(sol)
A) HBr, CH3COOH
B) HBr, CH3C(OH)2+
C) CH3COOH, CH3C(OH)2+
D) CH3COOH, Br–
4) What are the conjugate acid-base pairs in the following chemical reaction?
NH3(aq) + H2O(l) ⇌ NH4+(aq) + OH–(aq)
A) NH3, H2O and NH4+, OH–
B) NH3, NH4+ and H2O, OH–
C) NH3, OH– and H2O, NH4+
D) NH3 and NH4+
5) Identify the conjugate acid/base pairs present in an aqueous solution of hydrogen sulfate ion, HSO4–.
A) HSO4–/SO42- and H3O+/H2O
B) H2SO4/HSO4– and H2O/OH–
C) HSO4–/H2O and H3O+/SO42-
D) HSO4–/H2O and H2SO4/OH–
6) What is the conjugate base of the Br∅nsted-Lowry acid HPO42–?
A) H3PO4
B) H2PO4–
C) HPO42-
D) PO43-
7) What is the conjugate acid of the Br∅nsted-Lowry base HAsO42-?
A) H2AsO4–
B) AsO43-
C) H2O
D) H3O+
8) Write a balanced equation for the dissociation of the Br∅nsted-Lowry acid HSO4– in water.
A) HSO4–(aq) + H2O(l) ⇌ H2SO4(aq) + OH–(aq)
B) HSO4–(aq) + H2O(l) ⇌ SO42-(aq) + H3O+(aq)
C) HSO4–(aq) + H2O(l) ⇌ SO32-(aq) + OH–(aq)
D) HSO4–(aq) + H2O(l) ⇌ SO3(g) + OH–(aq) + H2O(l)
9) Which of the following Br∅nsted-Lowry acids does not behave as a strong acid when it is dissolved in
water?
A) HBr
B) HCl
C) HNO2
D) HClO4
10) What is the strongest Br∅nsted-Lowry acid in the chemical reaction shown below?
2 HNO3(aq) + Ba(OH)2(aq) → Ba(NO3)2(aq) + 2 H2O(l)
A) HNO3
B) Ba(OH)2
C) Ba(NO3)2
D) H2O
11) From the following chemical reactions determine the relative Br∅nsted-Lowry acid strengths
(strongest to weakest).
HCl(aq) + H2O(l) → H3O+(aq) + Cl–(aq)
HCN(aq) + H2O(l) ⇌ H3O+(aq) + CN–(aq)
A) HCl > HCN > H3O+
B) HCl > H3O+ > HCN
C) H3O+ > HCl > HCN
D) HCN > H3O+ > HCl
12) From the following chemical reactions determine the relative Br∅nsted-Lowry acid strengths
(strongest to weakest).
HClO4(aq) + H2O(l) → H3O+(aq) + ClO4–(aq)
HNO2(aq) + H2O(l) ⇌ H3O+(aq) + NO2–(aq)
A) HClO4 > H3O+ > HNO2
B) HClO4 > HNO2 > H3O+
C) H3O+ > HClO4 > HNO2
D) H3O+ > HNO2 > HClO4
13) From the following chemical reactions determine the relative Br∅nsted-Lowry acid strengths
(strongest to weakest).
HClO4(sol) + CH3COOH(l) → CH3C2(OH)2+(sol) + ClO4–(aq)
H2SO4(sol) + CH3COOH(l) ⇌ CH3C(OH)2+(sol) + HSO4–(sol)
A) HClO4 > H2SO4 > CH3COOH
B) HClO4 > H2SO4 > CH3C(OH)2+
C) HClO4 > CH3COOH > H2SO4
D) HClO4 > CH3C(OH)2+ > H2SO4
14) From the following chemical reactions determine the relative Br∅nsted-Lowry base strengths
(strongest to weakest).
HNO3(aq) + H2O(l) → H3O+(aq) + NO3–(aq)
HF(aq) + H2O(l) ⇌ H3O+(aq) + F–(aq)
A) HNO3 > H3O+ > HF
B) NO3– > H2O > F–
C) F– > H2O > NO3–
D) F– > NO3– > H2O
15) From the following chemical reactions determine the relative Br∅nsted-Lowry base strengths
(strongest to weakest).
2 NaH(s) + H2O(l) → 2 NaOH + H2(g)
NH3(aq) + H2O(l) ⇌ NH4+(aq) + OH–(aq)
A) H– > OH– > NH3
B) H– > NH3 > OH–
C) OH–> H– > NH3
D) OH– > NH3 > H–
16) The equilibrium constant, K, for the reaction shown below has a value 1.8 × 10-5. In this reaction
which is the strongest acid and which is the strongest base?
CH3CO2H(aq) + H2O(l) ⇌ H3O+(aq) + CH3CO2–(aq)
A) CH3CO2H and CH3CO2–
B) CH3CO2H and H2O
C) H3O+ and H2O
D) H3O+ and CH3CO2–
The following pictures represent aqueous solutions of binary acids of the type HA where the water
molecules have been omitted for clarity.
17) Determine the strongest acid of the set.
A) A
B) B
C) C
D) D
18) Arrange the acids in order of increasing acid strength.
A) D < C < A < B
B) D < C < B < A
C) D < B < A < C
D) D < A < C < B
19) Using the conjugate acid-base pairs listed below, complete the following equation with the pair that
gives an equilibrium constant Kc > 1.
________ + HSO3– ⇌ ________ + H2SO3
A) CH3CO2H/ CH3CO2–
B) HCO2H/ HCO2–
C) HNO2/NO2–
D) HNO3/NO3–
20) Using the conjugate acid-base pairs listed below, complete the following equation with the pair that
gives an equilibrium constant Kc > 1.
________ + H2CO3 ⇌ ________ + HCO3–
A) HF/F–
B) HCl/Cl–
C) HOCl/OCl–
D) HSO42-/SO42-
21) What is the strongest acid among the following?
A) HF
B) HCl
C) HBr
D) HI
22) What is the strongest acid among the following?
A) H2O
B) H2S
C) H2Se
D) H2Te
23) What is the weakest acid among the following?
A) SiH4
B) PH3
C) H2S
D) HCl
24) What is the strongest acid of the following?
A) HOI
B) HOBr
C) HOCl
D) All are equivalent.
25) Which of the following should have the lowest bond strength?
A) HOI
B) HOCl
C) HOAt
D) HOBr
26) An acidic solution at 25°C has
A) [H3O+] > [OH–] > 1 × 10-7 M.
B) [H3O+] > 1 × 10-7 M > [OH–].
C) [H3O+] = [OH–] > 1 × 10-7 M.
D) [H3O+] < 1 × 10-7 M > [OH–].
27) At 50°C the value of Kw is 5.5 × 10–14. A basic solution at 50°C has
A) [H3O+] < [OH–] < 2 × 10-7 M.
B) [H3O+] < 2 × 10-7 M < [OH–].
C) [H3O+] = [OH–] < 2 × 10-7 M.
D) [H3O+] > 2 × 10-7 M < [OH–].
28) Calculate the hydronium ion concentration in an aqueous solution that contains 2.50 × 10-4 M in
hydroxide ion.
A) 4.00 × 10-9 M
B) 4.00 × 10–10 M
C) 4.00 × 10–11 M
D) 5.00 × 10–11 M
29) Calculate the hydroxide ion concentration in an aqueous solution that contains 3.50 × 10-3 M in
hydronium ion.
A) 2.86 × 10-4 M
B) 2.86 × 10–11 M
C) 2.86 × 10–12 M
D) 3.50 × 10–12 M
30) A solution with a hydrogen ion concentration of 3.25 × 10-2 M is ________ and has a hydroxide
concentration of ________.
A) acidic, 3.08 × 10–12 M
B) acidic, 3.08 × 10–13 M
C) basic, 3.08 × 10–12 M
D) basic, 3.08 × 10–13 M
31) A solution with a hydroxide ion concentration of 4.15 × 10-4 M is ________ and has a hydrogen ion
concentration of ________.
A) acidic, 2.41 × 10–10 M
B) acidic, 2.41 × 10–11 M
C) basic, 2.41 × 10–10 M
D) basic, 2.41 × 10–11 M
32) If the ionization constant of water, Kw, at 40°C is 2.92 × 10–14, then what is the hydronium ion
concentration for a neutral solution?
A) [H3O+] < 1.00 × 10-7 M
B) [H3O+] > 1.71 × 10-7 M
C) [H3O+] = 1.71 × 10-7 M
D) [H3O+] < 1.71 × 10-7 M
33) Human tears have a concentration of H3O+ that is 3.16 × 10-8. The concentration of OH– in human
tears is
A) greater than 3.16 × 10-7 and tears are acidic.
B) greater than 3.16 ×10-7 and tears are basic.
C) less than 3.16 × 10-7 and tears are acidic.
D) less than 3.16 × 10-7 and tears are basic.
34) An acidic solution at 25°C will have a hydronium ion concentration ________ and a pH value
________.
A) [H3O+] > 1 × 10-7 M, pH > 7.00
B) [H3O+] > 1 × 10-7 M, pH < 7.00
C) [H3O+] < 1 × 10-7 M, pH > 7.00
D) [H3O+] < 1 × 10-7 M, pH < 7.00
35) If the ionization constant of water, Kw, at 40°C is 2.92 × 10–14, then what is the hydronium ion
concentration and pH for an acidic solution?
A) [H3O+] > 1.71 × 10-7 M and pH > 6.77
B) [H3O+] > 1.71 × 10-7 M and pH < 6.77
C) [H3O+] < 1.71 × 10-7 M and pH > 6.77
D) [H3O+] < 1.71 × 10-7 M and pH < 6.77
36) Calculate the pH for an aqueous solution of acetic acid that contains 2.15 × 10-3 M hydronium ion.
A) 4.65 × 10–12
B) 2.15 × 10-3
C) 2.67
D) 11.33
37) Calculate the pH for an aqueous solution of pyridine that contains 2.15 × 10-4 M hydroxide ion.
A) 4.65 × 10–11
B) 2.15 × 10–4
C) 3.67
D) 10.33
38) What is the hydroxide ion concentration and the pH for a hydrochloric acid solution that has a
hydronium ion concentration of 1.50 × 10-4 M?
A) 6.67 × 10–10 M, 4.82
B) 6.67 × 10–10 M, 9.18
C) 6.67 × 10–11 M, 3.82
D) 6.67 × 10–11 M, 10.18
14
39) What is the hydronium ion concentration and the pH for an aqueous solution of NH3 that has a
hydroxide ion concentration of 2.25 × 10-3 M?
A) 4.44 × 10–11 M, 3.65
B) 4.44 × 10–11 M, 10.35
C) 4.44 × 10–12 M, 2.65
D) 4.44 × 10–12 M, 11.35
40) What is the hydronium ion concentration of an acid rain sample that has a pH of 3.15?
A) 1.41 × 10–11 M
B) 7.08 × 10-4 M
C) 3.15 M
D) 10.85 M
41) What is the hydroxide ion concentration of a lye solution that has a pH of 11.20?
A) 6.31 × 10–12 M
B) 1.58 × 10-3 M
C) 2.80 M
D) 11.20 M
42) At 25°C, the pH of a vinegar solution is 2.60. What are the values of [H3O+] and [OH–] in the solution?
A) 3.99 × 10–12 M, 2.51 × 10-3 M
B) 2.51 × 10-3 M, 3.98 × 10–12 M
C) 2.51 × 10-3 M, 11.40 M
D) 2.60 M, 11.40 M
43) Which of the following solutions has the highest concentration of hydroxide ions [OH–]?
A) pH = 3.21
B) pH = 7.83
C) pH = 10.93
D) pH = 12.04
44) Which of the following indicates the most basic solution?
A) [H+] = 1 × 10–10 M
B) pOH = 6.7
C) [OH–] = 7 × 10–5 M
D) pH = 4.2
45) What is the approximate pH of a solution X that gives the following responses with the indicators
shown?
Indicators
HIn — In–
pH range
Solution X
methyl orange
red-yellow
3.2-4.4
yellow
methyl red
red-yellow
4.8-6.0
yellow
bromothymol blue
yellow-blue
6.0-7.6
green
phenolphthalein
colorless-pink
8.2-10.0
colorless
A) 3.2 – 4.4
B) 4.8 – 6.0
C) 6.0 – 7.6
D) 8.2 – 10.0
46) What is the approximate pH of a solution X that gives the following responses with the indicators
shown?
Indicators
HIn — In–
pH range
Solution X
methyl orange
red-yellow
3.2-4.4
yellow
methyl red
red-yellow
4.8-6.0
orange
bromothymol blue
yellow-blue
6.0-7.6
yellow
phenolphthalein
colorless-pink
8.2-10.0
colorless
A) 3.2 – 4.4
B) 4.8 – 6.0
C) 6.0 – 7.6
D) 8.2 – 10.0
47) What is the approximate pH of a solution X that gives the following responses with the indicators
shown?
Indicators
HIn — In–
pH range
Solution X
methyl orange
red-yellow
3.2-4.4
yellow
methyl red
red-yellow
4.8-6.0
yellow
bromothymol blue
yellow-blue
6.0-7.6
blue
phenolphthalein
colorless-pink
8.2-10.0
pink
A) 4.8 – 6.0
B) 6.0 – 7.6
C) 7.6 – 8.2
D) > 8.2
17
48) What is the pH of a 0.020 M HClO4 solution?
A) 0.020
B) 0.040
C) 1.70
D) 12.30
49) What is the pH of a 0.020 M Ba(OH)2 solution?
A) 1.40
B) 1.70
C) 12.30
D) 12.60
50) What is the pH of a solution prepared by dissolving 0.15 gram of solid CaO (lime) in enough water to
make 2.00 L of aqueous Ca(OH)2 (limewater)?
CaO(s) + H2O(l) → Ca2+(aq) + 2 OH–(aq)
A) 2.57
B) 2.87
C) 11.13
D) 11.43
51) What is the pH of a solution prepared by diluting 25.00 mL of 0.10 M HCl with enough water to
produce a total volume of 100.00 mL?
A) 1.00
B) 1.60
C) 2.00
D) 3.20
52) What is the pH of a solution prepared by diluting 25.00 mL of 0.020 M Ba(OH)2 with enough water to
produce a total volume of 250.00 mL?
A) 2.40
B) 2.70
C) 11.30
D) 11.60
53) What is the pH of a solution made by mixing 100.00 mL of 0.20 M HCl with 50.00 mL of 0.10 M HCl?
Assume that the volumes are additive.
A) 0.15
B) 0.52
C) 0.78
D) 1.70
54) What is the pH of a solution made by mixing 100.0 mL of 0.10 M HNO3, 50.0 mL of 0.20 M HCl, and
100.0 mL of water? Assume that the volumes are additive.
A) 0.30
B) 0.82
C) 1.00
D) 1.10
55) What is the equilibrium constant expression (Ka) for the acid dissociation of hydrocyanic acid HCN?
The equation of interest is
HCN(aq) + H2O(l) ⇌ H3O+(aq) + CN–(aq).
A) Ka = ([H3O+][CN–])/([HCN][H2O])
B) Ka = ([H3O+][CN–])/([HCN])
C) Ka = ([HCN][H2O])/([H3O+][CN–])
D) Ka = ([HCN])/([H3O+][CN–])
56) What is the equilibrium constant expression (Ka) for the acid dissociation of nitrous acid HNO2? The
equation of interest is
HNO2(aq) + H2O(l) ⇌ H3O+(aq) + NO2–(aq).
A) Ka = ([H3O+][NO2–])/([HNO2][H2O])
B) Ka = ([H3O+][NO2–])/([HNO2])
C) Ka = ([HNO2][H2O])/([H3O+][NO2–])
D) Ka = ([HNO2])/([H3O+][NO2–])
57) Determine the acid dissociation constant for a 0.10 M acetic acid solution that has a pH of 2.87. Acetic
acid is a weak monoprotic acid and the equilibrium equation of interest is
CH3COOH(aq) + H2O(l) ⇌ H3O+(aq) + CH3CO2–(aq).
A) 1.3 × 10-2
B) 1.3 × 10-3
C) 1.8 × 10–5
D) 1.8 × 10-6
58) Determine the acid dissociation constant for a 0.010 M nitrous acid solution that has a pH of 2.70.
Nitrous acid is a weak monoprotic acid and the equilibrium equation of interest is
HNO2(aq) + H2O(l) ⇌ H3O+(aq) + NO2–(aq).
A) 8.0 × 10-3
B) 2.0 × 10-3
C) 5.0 × 10–4
D) 4.0 × 10-4
59) Determine the acid dissociation constant for a 0.020 M formic acid solution that has a pH of 2.74.
Formic acid is a weak monoprotic acid and the equilibrium equation of interest is
HCOOH(aq) + H2O(l) ⇌ H3O+(aq) + HCO2–(aq).
A) 1.8 × 10-3
B) 1.8 × 10-4
C) 3.6 × 10–4
D) 3.6 × 10-5