Chapter 2 Acids and Bases
Multiple Choice
1. Identify the Brønsted-Lowry acids in the following reactions. (Sec. 2.3)
CH3OH
+
I
C2H5OH
+
CH3OH2
II
III
NaH
V
a)
b)
c)
d)
HCl
Cl
+
IV
C2H5ONa
H2
+
VII
VI
VIII
I, III,VI, VII
II, VI
I, IV, V, VIII
II, III, V, VIII
2. Identify the conjugate bases in the following reactions. (Sec. 2.3)
CH3NH2
+ H3CCO2H
CH3NH3
+
I
C2H5OH
+
C2H5ONa
NaH
II
+
+
CH3OH2
HCl
V
a)
b)
c)
d)
II, III, VI
I, IV, V
I, III, V
II, IV, VI
12
H2
IV
III
CH3OH
CH3CO2
+
Cl
VI
Chapter 2 Acids and Bases
3. Identify the conjugate acids in the following reactions. (Sec. 2.3)
CH3NH2
+ CH3CO2H
CH3NH3
+
CH3CO2
I
CH3OH
+
II
CH3OH2
HCl
Cl
+
IV
III
C2H5OH
+
C2H5ONa
NaH
H2
+
VI
V
a)
b)
c)
d)
I, IV, VI
I, III, VI
II, IV, V
I, III, V
4. Which are acid-base reactions according to Brønsted-Lowry theory? (Sec. 2.3)
O
O
I.
CH3
II.
III.
IV.
a)
b)
c)
d)
C
C
+
H3CNH3
AlCl3
+
Cl
AlCl4
CH3NH2
+
HCl
CH3NH3Cl
CH3Li
+
H2O
O
CH3
CH4
I, III
I, II, II, IV
I, II, III
I, III, IV
13
OH
+
CH3NH2
+
LiOH
Chapter 2 Acids and Bases
5. Which are acid-base reactions according to the Brønsted-Lowry theory? (Sec. 2.3)
I.
(CH3)3COH
+
H2SO4
(CH3)3C
+
H2O
II.
Br2
+
FeBr3
FeBr4
+
Br
III.
CH3NH2
+
BF3
CH3NH2BF3
IV.
CH3NH2
+
HCl
CH3NH3Cl
a)
b)
c)
d)
+
I
I, III, IV
II, III
I, IV
6. Which are acid-base reactions according to Lewis theory but not according to the Brønsted-Lowry theory?
(Sec. 2.7)
O
O
I.
H3C
C
CH3
+
H3C
CH3
C
CH3
O
O
II.
III.
IV.
H3C
C
O
+
H2O
+
BF3
+
BF3
OH
NH3
H3C
CH3
H3C
C
O
NH3BF3
H3C
O
H3C
a)
b)
c)
d)
CH3
I, II
III, IV
I, III, IV
I, II, III, IV
14
BF3
+
H3O
HSO4
Chapter 2 Acids and Bases
7. Which acid has the highest pKa? (Sec. 2.4)
a)
b)
c)
d)
CH3COOH
H2O
NH4+
HCl
8. Arrange the following in order of increasing basicity (weakest to strongest). (Sec. 2.4)
I. OH-
II. Cla)
b)
c)
d)
III. H2O
IV. NH3
II, III, IV, I
III, I, IV, II
IV, I, II, III
III, IV, I, II
9. Arrange the following ions in the order of increasing acidity (weakest to strongest). (Sec. 2.4)
II. H3O+
I. H2O
a)
b)
c)
d)
III. NH4+
II, III, I
I, II, III
III, II, I
I, III, II
10. Which ion is the strongest base? (Sec. 2.4)
O
a)
CH3CH2O
b)
CH3
C
O
c) Cl
15
d) CH3CH2
Chapter 2 Acids and Bases
11. Which equilibria lie considerably toward the right? (Sec. 2.5)
O
O
C
I.
+
OH
H3C
NH3
C
H3C
O
II.
C
H3C
NH4
+
O
O
+
O
C
H2O
H3C
OH
+
OH
III.
NH4
+
OH
NH3
+
H2O
IV.
HCN
+
OH
CN
+
H2O
a)
b)
c)
d)
II, III
I, III, IV
III, IV
I, II, III
12. Which equilibria lie considerably toward the left? (Sec. 2.5)
O
O
C
I.
OH
H3C
+
CN
C
H3C
O
II.
C
H3C
O
+
+
C
NH4
H3C
OH
a)
b)
c)
d)
C
H3C
OH
NH3
O
IV.
+
HCN
O
NH4
III.
O
+
NH3
+
H2O
+
CH3OH
O
OH +
C
CH3
H3C
II
I, IV
III, IV
I
16
O
Chapter 2 Acids and Bases
13. List the bonds in order of increasing acidity (least to most). (Sec. 2.6)
C H
O H
I
II
a)
b)
c)
d)
F
H
N H
III
IV
II, III, IV, I
III, I, II, IV
I, IV, II, III
IV, III, II, I
14. List the bonds in order of decreasing acidity (most to least). (Sec. 2.6)
F
Br
H
I
a)
b)
c)
d)
H
II
Cl
H
I
H
III
IV
I, III, II, IV
IV, II, III, I
II, III, IV, I
I, II, III, IV
15. Which substances are Lewis bases? (Sec. 2.7)
H2O
AlCl3
I
II
a)
b)
c)
d)
CH
H3C
F
CH3
III
IV
I, II
I, III
III, IV
I, IV
16. What is the stronger acid in the following reaction if the equilibrium constant is approximately 10 8. (Sec. 2.5)
+ NH2
HC CH
a)
b)
HC C
+
c)
NH3
d)
17. What is the stronger acid in the following reaction if the equilibrium constant is much less than 0.01? (Sec. 2.5)
HNO3
a)
+
H2SO4
b)
H2NO3 +
c)
HSO4
d)
17
Chapter 2 Acids and Bases
18. Which is the stronger base if the equilibrium lies considerably to the right? (Sec. 2.5)
O
O
C
H3C
OH
CN
+
C
H3C
a)
b)
+
O
c)
HCN
d)
19. What is the role of diethyl ether in the following reaction? (Sec. 2.7)
CH3CH2OCH2CH3
a)
b)
c)
d)
+
BF3
(CH3CH2)2O BF3
Lewis acid
Lewis base
Brønsted acid
Brønsted base
20. What is the role of water in the following reaction? (Sec. 2.3)
NH3
a)
b)
c)
d)
+
H3O
H2O
+
NH4
acid
base
conjugate acid
conjugate base
21. What is the role of methanol in the following reaction? (Sec. 2.7)
CH3
CH3
H3C C
+ CH3OH
H3C C O
CH3
CH3
a)
b)
c)
d)
CH3
H
Lewis acid
Lewis base
Brønsted acid
Brønsted base
22. Which statements about acid-base equilibria are true? (Sec. 2.4)
I. The pKa is the negative log10 of the acid equilibrium constant.
II. A stronger acid has a pKa with a smaller value than a weaker acid.
III. A stronger base has a conjugate acid which has a pKa with a smaller value than a weaker base.
IV. The Ka = K [HA].
a)
b)
c)
d)
I, III
I, II
I, II, III
II, III, IV
18
Chapter 2 Acids and Bases
23. Which is the order of decreasing acid strength of the following compounds (greatest first)? (Sec. 2.6)
O
Cl
C
H2
C
O
Br
OH
C
H2
C
O
F
OH
C
H2
II
I
a)
b)
c)
d)
C
O
H
OH
C
H2
III
C
OH
IV
II, I, III, IV
III, IV, I, II
III, I, II, IV
IV, II, I, III
24. Which is the order of increasing acid strength of the following compounds (least first)? (Sec. 2.6)
O
O
F
OH
O
OH
OH
F
I
a)
b)
c)
d)
O
F
OH
F
II
III
I, III, II, IV
IV, III, II, I
II, I, III, IV
IV, III, I, II
19
IV
Chapter 2 Acids and Bases
25. Which is the proper reaction mechanism for the reaction of borontrifluoride and diethyl ether? (Sec. 2.7)
a) :BF3
CH3CH2
b) BF3
CH3CH2
O
+ BF
3
CH2CH3
O
- CH2CH3
CH3CH2
..
O
.. CH CH
2
3
- BF
3
O
+ CH2CH3
CH3CH2
c) :BF3
d)
CH3CH2
BF3
CH3CH2
O
CH2CH3
CH3CH2
..
O
.. CH CH
2
3
BF3
O
+ CH2CH3
+ BF
3
CH3CH2
O
- CH2CH3
Fill in the Blank
1. The weaker the acid, the ________________ the conjugate base. (Sec. 2.5)
2. The higher concentration (reactants or products) at equilibrium will lie on the side of the ___________ acid.
(Sec. 2.5)
3. Complete the following reaction. (Sec. 2.3)
O
O
CH3COH +
H2O
CH3CO-
+
4. Complete the following reaction. (Sec. 2.3)
O
NH4Cl + CH3CONa
NH3 +
5. Complete the following reaction. (Sec. 2.3)
+
H2O
NH3 + H3O+ + Cl-
20
Chapter 2 Acids and Bases
6. Complete the following reaction. (Sec. 2.3)
O
O
CH3CONa + NaHCO3
CH3COH +
7. Complete the following reaction scheme with the appropriate equilibrium arrow (indicating the higher
concentrations at equilibrium). (Sec. 2.5)
O
O
CH3CONa + HCN
CH3COH + NaCN
8. Complete the following reaction scheme with the appropriate equilibrium arrow (indicating the higher
concentrations at equilibrium). (Sec. 2.5)
NaH2PO4 + NaHCO3
Na2PO4 + H2CO3
9. Identify the acid, base, conjugate acid, conjugate base in the following reaction. (Sec. 2.3)
NaCN + NaHSO4
HCN +
Na2SO4
10. Identify the acid, base, conjugate acid, conjugate base in the following reaction. (Sec. 2.3)
NH4Cl + NaHCO3
NH3
+ H2CO3 + NaCl
True-False
1. Brønsted-Lowry acids accept protons when reacting. (Sec. 2.3)
2. Lewis bases donate electrons when reacting. (Sec. 2.7)
3. The stronger acid has the larger (more positive) pK a. (Sec. 2.4)
4. Strong acids have weak conjugate bases. (Sec. 2.4)
5. The equilibrium will lie to the right in the following reaction. (Sec. 2.5)
NH4Cl +
H2O
NH3
+ H3O+
+
6. The equilibrium will lie to the right in the following reaction. (Sec. 2.5)
HCN +
NaH2PO4
H3PO4 + NaCN
21
Cl-
Chapter 2 Acids and Bases
7. Water acts as a base in the following reaction. (Sec. 2.3)
NH3 + H2O
NH4OH
8. Ammonia acts as a Brønsted-Lowry base in the following reaction. (Sec. 2.3)
NH4Cl
+ NaHCO3
NH3 + H2CO3
+
NaCl
9. The strongest acid in the following list is sodium bicarbonate. (Sec. 2.4)
NH4Cl
NaHCO3
H2O
CH3CH2OH
10. The weakest acid in the following list is acetic acid. (Sec. 2.6)
O
CH3COH
O
ClCH2COH
O
O
FCH2COH
22
FCH2CH2COH
Chapter 2 Acids and Bases
Answers
Multiple Choice
1. d
2. a
3. b
4. d
5. d
6. c
7. b
8. a
9. d
10. d
11. b
12. a
13. c
14. b
15. d
16. a
17. c
18. b
19. b
20. d
21. b
22. b
23. c
24. b
25. b
Fill in the Blank
1. stronger
2. weaker
3. H3O+
4. CH3COOH + NaCl
5. NH4Cl
6. Na2CO3
7. equilibrium arrow pointed to the left
8. equilibrium arrow pointed to the left
9. base, acid, c.acid, c. base
10. acid, base, c. base, c. acid
True-False
1. F
2. T
3. F
4. T
5. F
6. F
7. F
8. T
9. F
10. T
23