Name: ________________________ Class: ___________________ Date: __________
Practice test Chapters 15 and 16: Acids and Bases
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1. Which of the following pairs of species is not a conjugate acid–base pair?
A) HOCl, OCl–
B) HNO2, NO2+
C) O2–, OH–
D) HSO4–, SO42–
E) H2CO3, HCO3–
____
2. Which of the following is the strongest acid?
A) HClO2
B) HCl
C) HClO4
D) HClO
E) HClO3
____
3. The concentration of H3O+ in a solution is 7  10–4 M at 25°C. What is its hydroxide-ion
concentration?
A) 7  10–4 M
B) 1  10–10 M
C) 2  10–10 M
D) 3  10–10 M
E) 1  10–11 M
____
4. What is the pH of a 0.051 M HClO4 solution?
A) 15.29
B) 2.98
C) 12.71
D) 1.29
E) 11.02
____
5. A solution has a pOH of 5.36. What is its hydroxide-ion concentration?
A) 1.8  10–4 M
B) 5.4 M
C) 2.3  10–9 M
D) 4.4  10–6 M
E) 4.7  10–3 M
1
ID: A
Name: ________________________
____
ID: A
6. Consider the Ka values for the following acids:
Cyanic acid, HOCN, 3.5  10–4
Formic acid, HCHO2, 1.7  10–4
Lactic acid, HC3H5O3, 1.3  10–4
Propionic acid, HC3H5O2, 1.3  10–5
Benzoic acid, HC7H5O2, 6.3  10–5
Which has the strongest conjugate base?
A) propionic acid
B) benzoic acid
C) lactic acid
D) formic acid
E) cyanic
____
7. At a temperature of 25°C an initally 0.048 M solution of a weak monoprotic acid is 2.7 % ionized
once equilibrium is established. What is the acid-ionization constant, Ka , for this acid? (assume
Ca/Ka 3 102)
5
A) 3.5  10
6
B) 1.7  10
1
C) 2.3  10
2
D) 1.5  10
7
E) 1.7  10
____
8. The equilibrium hydronium ion concentration of an initially 0.150 M solution of a monoprotic weak
3
5
acid is 1.4  10 M. The acid dissociation constant is 1.31  10 at 25°C. What is the pH of this
solution?
A) 2.85
B) 7.00
C) 11.15
D) 5.71
E) 0.82
____
9. Which of the following reactions is associated with the definition of Kb ?
A) CN–(aq) + H+(aq)
HCN(aq)
–
B) F (aq) + H2O(l)
HF(aq) + OH–(aq)
C) Zn(OH2)62+(aq)
[Zn(OH2)5OH]+(aq) + H+(aq)
D) Cr3+(aq) + 6H2O(l)
Cr(OH2)63+(aq)
E) none of these
2
Name: ________________________
ID: A
____
10. What is the pH of a 0.24 M solution of methylamine (CH3NH2, Kb = 4.4  10–4) at 25oC?
A) 5.63
B) 0.62
C) 12.00
D) 13.38
E) 2.00
____
11. Which of the following salts is most likely to form an aqueous solution having the pH shown in the
figure below?
A)
B)
C)
D)
E)
____
NH4Cl
NaBr
K2CO3
RbCN
LiNO3
12. What is Ka at 25°C for the following equilibrium?
C6H5NH3+(aq) + H2O(l)
C6H5NH2(aq) + H3O+(aq)
Kb (C6H5NH2) = 4.2  10–10 at 25°C.
A) 4.2  10–4
B) 2.4  103
C) 4.2  10–10
D) 4.2  104
E) 2.4  10–5
____
13. Suppose a buffer solution is made from formic acid (HCHO2) and sodium formate (NaCHO2).
What is the net ionic equation for the reaction that occurs when a small amount of hydrochloric acid
is added to the buffer?
A) H3O+(aq) + HCHO2(aq)  H2O(l) + H2CHO2+(aq)
B) H3O+(aq) + CHO2–(aq)  HCHO2(aq) + H2O(l)
C) HCl(aq) + CHO2–(aq)  HCHO2(aq) + Cl–(aq)
D) HCl(aq) + OH–(aq)  H2O(l) + Cl–(aq)
E) H3O+(aq) + OH–(aq)  2H2O(l)
3
Name: ________________________
ID: A
____
14. What is the hydrogen-ion concentration of a solution that is 0.052 M in acetic acid and 0.052 M in
sodium acetate at 25°C? The acid-ionization constant of acetic acid is 1.8  10–5 at 25°C.
A) 1.8  10–3 M
B) 1.8  10–6 M
C) 1.8  10–7 M
D) 1.8  10–5 M
E) 1.8  10–4 M
____
15. What is the hydronium-ion concentration of a solution that is formed by combining 600. mL of 0.10
M NaOH with 400. mL of 0.80 M HNO3 at 25°C?
A) 0.080 M
B) 0.010 M
C) 0.80 M
D) 0.45 M
E) 0.26 M
4
Name: ________________________
ID: A
Record your response on your answer sheet. (White area of full size scantron)
CLEARLY SHOW THE METHOD USED AND THE STEPS INVOLVED IN ARRIVING AT
YOUR ANSWERS.
It is to your advantage to do this, since you may obtain partial credit if you do and you will receive
little or no credit if you do not. Attention should be paid to significant figures.
This section of the exam should take approximately 20 minutes to complete
16.
5
ID: A
Practice test Chapters 15 and 16: Acids and Bases
Answer Section
1. ANS: B
PTS: 1
DIF: easy
REF: 15.2
OBJ: Identify acid and base species. (Example 15.1)
TOP: acids and bases | acid-base concepts
KEY: Brønsted-Lowry concept of acids and bases
MSC: general chemistry
2. ANS: C
PTS: 1
DIF: easy
REF: 15.5
OBJ: Understand the rules for determining the relative strengths of oxoacids.
TOP: acids and bases | acid and base strength
KEY: molecular structure and acid strength
MSC: general chemistry
3. ANS: E
PTS: 1
DIF: easy
REF: 15.7
OBJ: Calculate the concentrations of H3O+ and OH– in solutions of a strong acid or base.
(Example 15.4)
TOP: acids and bases | solutions of a strong acid or base
MSC: general chemistry
4. ANS: D
PTS: 1
DIF: easy
REF: 15.8
OBJ: Calculate the pH from the hydronium-ion concentration. (Example 15.5)
TOP: acids and bases | solutions of a strong acid or base
KEY: pH of a solution
MSC: general chemistry
5. ANS: D
PTS: 1
DIF: easy
REF: 15.8
OBJ: Calculate the hydronium-ion concentration from the pH. (Example 15.6)
TOP: acids and bases | solutions of a strong acid or base
KEY: pH of a solution
MSC: general chemistry
6. ANS: A
PTS: 1
DIF: easy
REF: 16.1
OBJ: Define acid-ionization constant and degree of ionization.
TOP: acids and bases | acid and base strength
7. ANS: A
PTS: 1
DIF: easy
REF: 16.1
OBJ: Define acid-ionization constant and degree of ionization.
TOP: acids and bases | solutions of a weak acid or base
8. ANS: A
PTS: 1
DIF: easy
REF: 16.1
OBJ: Calculate concentrations of species in a weak acid solution using Ka (approximation
method). (Example 16.2)
TOP: acids and bases | solutions of a weak acid or base
9. ANS: B
PTS: 1
DIF: easy
REF: 16.3
OBJ: Define base-ionization constant.
TOP: acids and bases | solutions of a weak acid or base
KEY: base-ionization equilibria
MSC: general chemistry
10. ANS: C
PTS: 1
DIF: easy
REF: 16.3
OBJ: Calculate concentrations of species in a weak base solution using Kb. (Example 16.5)
TOP: acids and bases | solutions of a weak acid or base
KEY: base-ionization equilibria
MSC: general chemistry
1
ID: A
11. ANS:
OBJ:
TOP:
KEY:
MSC:
12. ANS:
OBJ:
TOP:
KEY:
13. ANS:
OBJ:
TOP:
KEY:
14. ANS:
OBJ:
TOP:
KEY:
15. ANS:
OBJ:
TOP:
A
PTS: 1
DIF: easy
REF: 16.4
Predict whether a salt solution is acidic, basic, or neutral. (Example 16.6)
acids and bases | solutions of a weak acid or base
acid-base properties of salt solutions | prediction of salt solution acid-base properties
general chemistry
E
PTS: 1
DIF: easy
REF: 16.4
Obtain Ka from Kb or Kb from Ka. (Example 16.7)
acids and bases | solutions of a weak acid or base
acid-base properties of salt solutions
MSC: general chemistry
B
PTS: 1
DIF: easy
REF: 16.6
Describe the pH change of a buffer solution with the addition of acid or base.
acids and bases | solutions of a weak acid or base with another solute
buffer | adding an acid or base to a buffer
MSC: general chemistry
D
PTS: 1
DIF: easy
REF: 16.6
Calculate the pH of a buffer from given volumes of solution. (Example 16.11)
acids and bases | solutions of a weak acid or base with another solute
buffer | pH of a buffer
MSC: general chemistry
E
PTS: 1
DIF: easy
REF: 16.7
Calculate the pH of a solution of a strong acid and a strong base. (Example 16.13)
acids and bases | solutions of a strong acid or base
MSC: general chemistry
2
ID: A
16. ANS:
3
ID: A
4
ID: A
PTS:
10
5