CHAPTERS 15
FAKE TEST QUESTIONS
You might need to know the following K values:
Ka = 1.8 x 10-5
Ka = 4.5 x 10-4
Ka = 7.2 x 10-4
Ka = 1.2 x 10-2
Ka = 1.8 x 10-4
CH3COOH
HNO2
HF
HSO4HCOOH
Ka = 6.5 x 10-5
Kb = 1.8 x 10-5
Ka = 5.7 x 10-8
Ka = 1.2 x 10-13
Ka = 3.0 x 10-8
Benzoic Acid
NH3
H2S
HSHOCl
SIMPLE ACIDS AND BASES
1.
According to the Brønsted–Lowry definition, which species can function both as an acid and as a base?
(A)
Cl-
2.
Which of the following species can function as both a Brønsted-Lowry acid and a Brønsted-Lowry base
in water?
(A)
HCl
3.
In this reaction, CH3COOH + H2O ⇔ H3O+ + CH3COO-, which substances are bases according to the
Brønsted–Lowry definition?
(A)
(C)
CH3COOH and H2O
H2O and CH3COO-
4.
In the reaction CN- + H2O ⇔ HCN + OH-, which is an acid–base conjugate pair?
(A)
(B)
H2O and HCN
H2O and OH-
5.
Which species is not either an Arrhenius acid or base?
(A)
HCO3-
6.
When we say an ion or a molecule is a base, we mean that it has a tendency to
(A)
(C)
(E)
combine with protons.
liberate hydroxide ions as the only anions.
Form only weakly dissociated salts.
7.
Select the pair of substances in which an acid is listed followed by its conjugate base:
(A)
(D)
NH3, NH4+
CH3COOH, CH3COOH2+
(B)
(B)
SO4-2
(C)
HPO4-2
(C)
(B)
(D)
(C)
(D)
(B)
NaOH
NH4+
(D)
NH2-
(D)
(E)
H3O+
(E)
H3O+
NaOH
CH3COOH and CH3COOH3O+ and CH3COO-
CN- and H2O
HCN and OH-
(C)
(B)
(E)
HCO3-
HIO4
(B)
(D)
HPO42-, H2PO4H2O, H3O+
1
(D)
NH3
combine with electrons.
liberate hydronium ions as the only cations.
(C)
HCO3-, CO3-2
8.
The conjugate acid of HPO42- is:
(A)
P2O5
(B)
PO43-
H2PO4-
(C)
(D)
H3O+
(E)
H3PO4
Acid/Base Strengths
9.
Given that HX is a stronger Brønsted acid than HY in aqueous solution, which is true of a 1 M solution of NaX?
(A)
(C)
It is less basic than a 1 M solution of NaY.
It yields a neutral solution.
10.
Which series is the correct order of decreasing acid strength for each group of acids?
(A)
(C)
H2S > H2Te > H2Se > H2O
HClO4 > HClO3 > HClO2 > HClO
11.
In which pair is the first member a stronger proton–donating acid than the second?
(A)
HClO4, HClO3
12.
In which pair of acids is the first member stronger than the second?
(A)
HClO > HIO
13.
Which of the following is the strongest acid:
(A) H3PO4
(B)
(B)
(B)
(D)
(B)
(D)
H2SO3, H2SO4
HClO3 > HClO4 > H2SO4 > HNO3
HF > HCl > HBr > HI
(C)
H3PO4 > HNO3
(B) H3PO3
It is more basic than a 1 M solution of NaY.
It is more concentrated than a l M solution of NaY.
(C)
(C) H3AsO4
HIO, HBrO
(D)
H2O, H2S
H2SO3 > H2SO4
(D) HBrO > HBrO2
(D) H3AsO3
(E) H3PO2
14.
Given the data in the Table on the first page, select the strongest base.
(A)
Cl-
15.
In each of the pairs below, predict which acid is stronger.
(i)
H2S and H2Se
(ii)
HNO2 and HNO3
(iii)
(A)
(B)
(C)
(D)
(E)
i)
i)
i)
i)
i)
(ii)
(ii)
(ii)
(ii)
(ii)
HNO3
HNO3
HNO3
HNO2
HNO2
H2SO3
HClO3
HClO3
H2SO3
H2SO3
16.
Which of the following groups of acids is/are in the correct order of DECREASING acid strength?
i)
ii)
iii)
HI > HBr > HCl > HF
HBrO > HBrO2 > HBrO3 > HBrO4
HClO4 > H2SO4 > H3PO4
(A) i and iii
(B)
F-
H2S
H2Se
H2S
H2Se
H2S
(B) i only
(C)
ClO-
(D)
(iii)
(iii)
(iii)
(iii)
(iii)
(C) ii only
HCOO-
(D) iii only
2
(E)
CH3COO-
H2SO3 and HClO3
(E) i and ii
17.
The amide ion, NH2-, is a stronger base than the hydroxide ion, OH-. Which reaction will occur if sodium amide
is dissolved in water?
(A)
(C)
NH2- + H2O → H3O+ + NH-2
NH2- + H2O → OH- + NH3
18.
The H3O+ concentration in a 0.1 M solution of CH3COOH will be more than in
(A)
(D)
0.1 M HF
0.2 M CH3COOH
NH2- + H2O → NH2OH + HNH2- + H2O → no reaction
(B)
(D)
(B)
(E)
0.1 M NaHS
0.1 M NaHSO4
(C)
0.1 M HNO2
Simple pH Calculations
19.
A solution that has pH of 8 is
(A)
(D)
very acidic.
exactly neutral.
20.
The pOH of an aqueous solution is 6.0. What is the [H+]?
(A)
1 x 10-8 M
21.
At 25 °C the concentration of OH- in moles per liter in a solution that has a pH of 8 is
(A)
10-3
22.
The pH of a solution is 5. If the pH of this solution is decreased to 2, by what factor is the concentration of
hydrogen ion increased?
(A)
2 1 /2
23.
HCl is a strong acid. What is the pH of 200 mL of 0.002 M HCl?
(A)
2.0
24.
What is the pH of a 0.01 M NaOH solution?
(A)
10-12
25.
The pH of a 1.0 x 10-3 M Ba(OH)2 solution at 25 °C is
(A)
2.7
26.
When 50 mL of 0.1 M HCl is mixed with 50 mL of 0.2 M NaOH, the [H3O+] is?
(A)
0.05 M
(B)
(E)
(B)
(B)
(B)
(B)
(B)
(B)
(B)
slightly basic.
slightly acidic.
1 x 10-6 M
10-6
3
2.7
12
3.0
l x 10-7 M.
(C)
very basic.
1 x 10-7 M
(C)
10-7
(C)
(C)
10
(C)
(C)
(C)
3.4
(D)
4.0
–12
(D)
2
(D)
11.3
(D)
8M
10-8
100
0.1 M.
3
(D)
(D)
11.0
(C)
(D)
2 x 10-13
(E)
10-14
(E) 1000
(E)
–2
(E)
0.2 M.
27.
Which has the smallest concentration of OH- ions?
(A)
1 M NaOH
28.
The [OH-] and pH of a 0.035 M KOH solution are respectively:
(A)
(D)
0.035 M and 1.46
0.035 M and 12.54
29.
What is the pH of a 1.0 x 10-8 M NaOH solution?
(A)
8
30.
What is the pH of a solution made by mixing 50.0 mL of 0.125 M KOH with 50.0 mL of 0.125 M HCl.
(A)
6.3
(B)
(B)
6
(B)
0.0001 M NaOH
(B)
(E)
(C)
(C)
1 M HCl
0.035 M and -1.46
2.9 x 10-13 M and 12.54
7
7.0
(D)
(C)
a bit less than 7
(C)
8.1
(D)
1 M NH3
2.9 x 10-13 M and -12.54
(E)
(D)
water (E)
a bit more than 7
5.8
(E)
1.8
(E)
7 x 10-12
More Complex Equilibrium Calculations
31.
What is the correct equation for the ion product constant of water?
(A)
(C)
[H3O+] + [OH-] = 10-14
[H3O+] = 10-14
[OH-]
[H3O+] x [OH-] = 10-14
[H2O]2
(E)
[H3O+] x [OH-] = 10-7
[H3O+] x [OH-] = 10-14
(B)
(D)
32.
At 90 °C pure water has a [H3O+] = 1 x 10-6. What is the value of Kw at 90 °C?
(A)
1 x 10-6
33.
At 75°C, Kw = 5 x 10-14. What is the pH of neutral water at 75 °C?
(A)
7
34.
A 0.20 M solution of the hypothetical weak acid HZ was found to have a pH of exactly 3.0. The ionization
constant, Ka, of the acid is
(A)
0.6
35.
A 0.10 M C4H9COOH solution has a pH of 2.59. What is the Ka of this acid?
(A)
6.6 x 10-6
36.
The pH of a 0.55 M solution of HBrO is 4.48. What is the value of Ka for HBrO?
(A)
2.0 x 10-9
(B)
(B)
14
(B)
(B)
(B)
7 x 10-14
(C)
1 x 10-14
(C)
6.65
2.0 x 10-4
2.6 x 10-3
1.1 x 10-9
(D)
(D)
7.35
(E)
1.0 x 10-3
(C)
(D)
6.6 x 10-5
(C)
6.0 x 10-5
(C)
4
1 x 10-12
(D)
(D)
2.23 x 10-7
5.0 x 10-6
2.6 x 10-2
3.3 x 10-5
(E)
4.48
37.
What is the pH of a 0.020 M solution of HOCl?
(A)
2.45
38.
What is the pH of a solution which is 0.10 M in a monoprotic acid, HA, with Ka = 1.0 x 10-6?
(A)
1.6
39.
The ionization constant of a weak acid HA is 1 x 10-5. If 0.1 mol of the acid is dissolved in water and diluted to
exactly one liter, what is the pH of the solution?
(A)
1
40.
Enough water is added to 0.35 g of benzoic acid (C6H5COOH) to make 1000 mL of solution. What is the pH?
(A)
1.9
41.
The dissociation constant for monoprotic acid HX in water is 1.34 x 10-4. What is the concentration of X- ion in
a 0.20 M solution of HX?
(A)
5.2 x 10-3
42.
The dissociation constant for a weak base B in water was found to be 1.25 x 10-6. What is the concentration of
H+ in a 3.2 M solution of B?
(A)
2.0 x 10-3 M
43.
What is the [OH-] in a 0.50 M solution of NH3(aq)?
(A)
(E)
5 x 10-1 M
3 x 10-3 M
44.
Arsenic acid (H3AsO4) has Ka values of 2.5 x 10-4, 5.6 x 10-8, and 3 x 10-13. What is the concentration of
the HAsO4-2 dianion in a solution whose initial arsenic acid concentration was 0.35 M?
(A)
(D)
9.4 x 10-3 M
5.6 x 10-8 M
45.
HCN has a Ka of 2.9 x 10-8. What is the [CN-] in 0.115 M HCN?
(A)
(E)
2.9 x 10-8 M
5.8 x 10-5 M
(B)
(B)
(B)
3.5
3
(B)
(B)
-2.45
(C)
(C)
(C)
5.0
5
2.6
(B)
(D)
9.22
(E)
4.61
6.0
(D)
7
3.4
(D)
2.0 x 10-4
(C)
1.6 x 10-11 M
1.8 x 10-5 M
(B)
(E)
(B)
(D)
(C)
4.5 x 10-4
(B)
-9.22
(D)
(C)
5
6.4 x 10-4
(C)
4.0 x 10-6 M
(D)
5.0 x 10-12 M
(C)
6 x 10-3 M
(D)
9 x 10-6 M
2.5 x 10-4 M
3 x 10-13
4.24 M
4.2
(C)
4.24 x 10-5 M
8.8 x 10-5 M
(D)
4.24 x 10-8 M
Ion Hydrolysis
46.
What is the set of products expected from the hydrolysis of CN- ion?
(A)
HCN and OH-
47.
Which substance dissolves in water to form an acidic solution?
(A)
KCl
48.
Which salt reacts with water (hydrolyzes) to produce a basic solution?
(A)
NaCH3COO
49.
Which solution has a pH less than 7.0?
(A)
1 M CH3NH3Cl
50.
What is the pH of a 0.30 M sodium acetate, Na CH3COO solution?
(A)
2.6
51.
Of the four following substances, which would form basic solutions: NH4Cl, NaNO3, K2CO3, NaF
(A)
(D)
NH4Cl and NaNO3
NaF and K2CO3
52.
Calculate the value of Kb for F- [Ka for HF is 7.2 x 10-4].
(A)
(E)
2.0 x 10-8
1.4 x 10-10
53.
What is the pH of a 0.15 M solution of KF [Ka for HF is 7.2 x 10-4].
(A)
12.01
54.
Sodium hypochlorite (NaClO) is an active ingredient in some household laundry bleach. Given that the
Ka of HClO is 2.9 x 10-8, what is the pH of a 0.015 M solution of sodium hypochlorite?
(A)
9.4
55.
What answer best describes the pH of the following 0.1 M salt solutions? (a) NaF, (b) KBr, (c)
KHCOO and (d) NH4Cl?
(A)
(B)
(C)
(D)
(E)
(a) pH < 7
(a) pH > 7
(a) pH < 7
(a) pH = 7
(a) pH < 7
(B)
(B)
(B)
(B)
(B)
4.9
10.4
(b)
(b)
(b)
(b)
(b)
pH > 7
pH = 7
pH = 7
pH = 7
pH < 7
(C)
NaNO3
1 M NaOCl
9.1
(D)
NH4Cl
(D)
(D)
Na2CO3
HCN and H2O
NH4Cl
(D)
Ba(ClO4)2
(C)
1 M K2CO3
(D)
1 M NaOH
11.4
K2CO3 and NH4Cl
K2CO3 only
(C)
(C)
8.9
HCN and H+
(C)
1.4 x 10-11
5.84
(C)
(C)
Na3PO4
(B)
(E)
(B)
(B)
(B)
(C)
CN- and H2O
8.16
(D)
9.9
(c)
(c)
(c)
(c)
(c)
pH > 7
pH > 7
pH < 7
pH > 7
pH < 7
6
(C)
7.2 x 10-18
(D)
(E)
2.33
NaF only
(D)
7.2 x 10-4
(E)
4.1
(d)
(d)
(d)
(d)
(d)
pH > 7
pH < 7
pH > 7
pH < 7
pH < 7
9.16
Buffers
56.
Which pair constitutes a buffer in aqueous solution?
(A)
HCl and NaCl
57.
The addition of a small amount of acid or base will have very little effect on the pH value of a solution
containing equal molar concentrations of
(A)
(D)
NH4Cl and NaCl
NH3 and NaCl
58.
Which of the following pairs could be used to make a buffer solution?
(A)
(D)
NH3 + NaCH3COO
NaOH + NaCl
59.
Which of the following can form buffer systems? (a) HF/KF
Na2SO3/NaHSO3
(b) HClO4/KClO4
(c)
(A)
(b) and (c)
(D)
(a) and (b)
60.
What is the pH of a buffer system consisting of 0.15 M CH3COONa and 0.10 M CH3COOH?
(A)
2.78
61.
Kb for ammonia is 1.8 x 10-5. What is the pH of a solution prepared by combining 50.0 mL of 1.00 M
NH3 and 50.0 mL of 1.00 M NH4Cl?
(A)
4.63
62.
What is the [OH-] of a solution which is 0.18 M in ammonium ion and 0.10 M in ammonia?
(A)
1.3 x 10-3
63.
The acid HX has an ionization constant of 1 x 10-4. A solution is 0.1 M in HX and 1.0 M in the salt Na+X-. What
is a close approximation of the hydrogen ion concentration?
(A)
1 x 10-3 M
64.
A solution is 0.100 M in acetic acid and 0.100 M in NaCH3COO. What is the [H+]?
(A)
1.36 x 10-3 M
65.
What is the [H+] of a solution which is 0.2 M in NaCH3COO and 0.1 M in CH3COOH?
(A)
9.0 x 10-7
(B)
(B)
(B)
(B)
(B)
(B)
(B)
(E)
HBr and KBr
(a) and (c)
2.87
(C)
all three
5.56
(C)
1.3 x 10-5
1 x 10-5 M
(C)
NaNO3 + NH4Cl
HNO2 + NaNO2
(C)
9.26
(B)
NH3 and NH4Cl
NaOH and NaCl
CH3COOH and NaCH3COO
(B)
(E)
(B)
(C)
(D)
1.0 x 10-3
(C)
2 x 10-5 M
(C)
0.100 M
(C)
3.6 x 10-6
(C)
7
(D)
(D)
1.80 x 10-5 M
1.8 x 10-6
HNO3 and NH4NO3
NaOH and HCl
(C)
(D)
4.74
(D)
(b)
7.00
CH3COOH + HCl
(E)
(E)
9.37
4.92
(E)
7.00
1.0 x 10-5
1 x 10-8 M
(D)
(D)
0.200 M
9.0 x 10-6
66.
What is the pH of a buffer solution containing 0.10 M KNO2 and 0.20 M HNO2?
(A)
3.66
(B)
3.05
(C)
3.35
(D)
2.02
LEWIS ACIDS AND BASES
67.
SnCl4 accepts two electron pairs and acts as
(A)
a Brønsted acid.
68.
Which of these species is most likely to be a Lewis acid and is also least likely to be a Brønsted acid?
(A)
NH4+
69.
Which compound functions as a Lewis acid but not as a Brønsted acid?
(A)
BCl3
70.
According to the Lewis definition, an acid is a species
(A)
(C)
having a hydrogen ion.
accepting a pair of electrons.
71.
In the reaction, BF3 + F- → BF4-, BF3 is acting as what type of acid?
(A)
(D)
Arrhenius only
All three
(B)
(B)
(B)
an Arrhenius base.
BF3
NI3
(B)
(E)
(C)
(C)
(C)
H2O
HCl
(B)
(D)
a Lewis acid.
(D)
(D)
(D)
a Lewis base.
OH-
H2O
donating a pair of electrons.
accepting a hydrogen ion.
Brønsted-Lowry only
Arrhenius and Brønsted-Lowry
(C)
Lewis only
Titrations
72.
In titrating NH3(aq) with 0.1 M HCl, the equivalence point in pH units will be
(A)
(C)
lower than 7 due to hydrolysis of NH4+
higher than 7 due to hydrolysis of NH4+
73.
When titrating 25 mL of 1.0 M HNO2 with 2.0 M NaOH, which of the following statements is correct?
(A)
(B)
(C)
(D)
(E)
The pH at the start of the titration will be greater than 7.
The pH at the equivalence point will be equal to 7.
The equivalence point will occur after addition of 25 mL of NaOH
The pH at the equivalence point will be greater than 7.
HNO2 is a strong acid
74.
A 25.0-mL sample of 0.130 M HCl is mixed with 15.0 mL of 0.240 M of NaOH. The pH of the resulting
solution will be nearest
(A)
2.1
(B)
(B)
(D)
7
(C)
8
lower than 7 due to hydrolysis of Clhigher than 7 due to hydrolysis of Cl-
11.9
(D)
13.0
75.
In the titration of 50.0 mL of 0.100 M benzoic acid (a monoprotic acid) with 50.0 mL of 0.100 M Na0H, the
properties of the solution at the equivalence point will correspond exactly to the properties of
(A)
(C)
a 0.100 M sodium solution.
a 0.0500 M benzoic acid solution.
76.
Which equation best represents the net reaction that occurs when sodium hydroxide and hydrochloric acid
solutions are mixed?
(A)
(C)
Na+ + HCl → NaCl + H+
OH- + H3O+ → 2H2O
77.
Calculate the pH of a solution formed by mixing 25 mL of 0.1 M acetic acid with 12.5 mL of 0.1 M NaOH?
(A)
2.87
78.
Calculate the pH of a solution formed by mixing 25 mL of 0.1 M acetic acid with 12.5 mL of 0.2 M NaOH?
(A)
2.87
79.
What is the resultant pH when 0.6 moles of NaOH are added to 1 L of 0.90 M HCOOH solution
(A)
10.0
80.
25.0 mL of 0.10 M C2H5NH2 (ethylamine) is titrated with 9.00 mL of 0.15 M HCl. Given that the Kb of
ethylamine is 6.5 x 10-4, what is the pH of the solution?
(A)
11.08
81.
What is the pH at the equivalence point for the titration of 30.0 mL of a 0.20 M C6H5COOH solution
with 0.30 M KOH (Ka of C6H5COOH = 6.5 x 10-5)?
(A)
10.73
82.
What is the pH halfway to the equivalence point for the titration of 0.20 M CH3NH2 with 0.20 M HCl?
(Kb of CH3NH2 = 4.4 x 10-4)
(A)
10.6
83.
What is the resultant pH when 20 mL of 0.30 M HCl is added to a 30.0 mL sample of 0.20 M NH3 (Kb
for NH3 = 1.8 x 10-5)
(A)
6.0
84.
What is the resultant pH when 10.0 mL of 0.950 M NaOH is added to 100 mL of a buffer solution that
consists of 0.10 M CH3COOH and 0.10 M NaCH3COO. Ka for CH3COOH is 1.8 x 10-5.
(A)
3.2
(B)
(B)
(B)
7.00
(B)
(B)
(B)
(B)
(B)
3.4
8.9
4.7
(C)
(C)
4.74
(C)
2.55
10.88
(C)
OH- + HCl → H2O + ClNaOH + H3O+ → 2H2O + Na+
(C)
5.12
8.63
a 0.0500 M sodium hydroxide solution.
a 0.0500 M sodium benzoate solution.
(B)
(D)
3.02
(C)
(B)
(D)
5.21
(D)
4.05
(C)
(C)
9.3
11.3
10.8
(D)
(D)
(E)
10.74
5.37
(D)
(D)
4.7
(D)
2.72
(D)
9.3
9
(E)
(E)
(E)
8.79
9.95
(D)
3.26
13
(E)
10.55
(E)
3.12
7.00
7.0
5.1
6.3
ANSWERS:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
D
B
C
B
D
A
C
C
A
C
A
A
A
C
B
A
C
B
B
A
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
B
E
B
B
D
D
C
D
E
B
D
D
C
D
C
A
E
B
B
C
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
A
D
E
D
E
A
C
A
A
C
D
B
C
D
B
C
E
E
B
E
10
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
B
D
B
C
D
B
C
B
A
C
C
A
D
C
D
C
C
D
D
C
81
82
83
84
B
A
E
E