Download Chapter 2- Acids and Bases

Chapter 2
1. From the list below, pick the one species that cannot act as both a Bronsted-Lowry acid
and base.
A) HCO3–
B) H2SO4–
C) H2PO4–
D) OH–
E) HPO42–
Ans: D
2. From the list below, pick the one species that is not a Bronsted-Lowry base.
A) NH3
B) SH–
C) BF3
D) H2O
E) PO43–
Ans: C
3. Which of these is not a true statement?
A) All Bronsted-Lowry bases are also Lewis bases.
B) All Lewis acids contain hydrogen.
C) All Bronsted-Lowry acids contain hydrogen.
D) All Lewis acids are electron deficient.
E) According to the Bronsted-Lowry theory, water is both an acid and a base.
Ans: B
4. From the list below, which is the conjugate base of methanol?
A) CH3O–
B) CH3–
C) CH3OH2+
D) CH4
Ans: A
5. Select the strongest base.
A) OH–
B) SH–
C) NH2–
Ans: E
D) Cl–
E) CH3CH2–
6. Consider the following acid-base reaction. Equilibrium for this reaction lies to the:
OH
A)
B)
C)
D)
Ans:
+
O
H C C
+
H C C H
left.
right.
Equilibrium favors neither forward nor reverse reaction.
It cannot be determined.
B
7. Which of the following choices list the compounds in order of increasing acidity?
A) BrCH2OH < CH3NH2 < CH3OH
D) CH3OH < BrCH2OH < CH3NH2
B) CH3NH2 < CH3OH < BrCH2OH
E) CH3NH2 < BrCH2OH < CH3OH
C) CH3OH < CH3NH2 < BrCH2OH
Ans: B
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8. Rank the acidity of the labeled protons in the following molecule from lowest to highest
acidity.
Hb
Ha
O
O
Hc
O
A) Ha; Hb; Hc
Ha
Ans: D
B) Hb; Hc; Ha
C) Hc; Ha; Hb
D) Hb; Ha; Hc
E) Hc; Hb;
9. Consider the following molecule having three labeled protons, Ha, Hb, and Hc. Rank
these protons in order of increasing acidity.
Ha
C
C
Hc
Hb
A) Ha; Hb; Hc
Ha
Ans: D
B) Hb; Hc; Ha
C) Hc; Ha; Hb
D) Hb; Ha; Hc
E) Hc; Hb;
10. List the following compounds in the order of increasing acidity.
O
A.
B.
A) A, B, C, D
D, B
Ans: B
O
C. CH3OH
OH
B) A, C, B, D
C) B, C, D, A
11. Which is the stronger acid?
A) A
Ans: B
B) B
12. Which is the stronger acid?
A) A
Ans: A
B) B
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D. F
D) D, C, A, B
OH
E) A, C,
13. Compare ethylene and acetylene. Which of the following statements is true?
A)
The C–H bond in ethylene has a higher percent s character, making it a stronger
acid.
B) The C–H bond in ethylene has a lower percent s character, making it a stronger
acid.
C) The C–H bond in acetylene has a higher percent s character, making it a stronger
acid.
D) The C–H bond in acetylene has a lower percent s character, making it a stronger
acid.
E) None of the statements is true.
Ans: C
14. Which of the circled hydrogens is the most acidic?
A) A
Ans: C
B) B
C) C
15. Which compound is the strongest Bronsted-Lowry acid?
A) H2S
B) H2O
C) NH3
Ans: A
16. Which of the following compounds is the strongest Bronsted-Lowry acid?
A) CH3CH2OH
D) ClCH2NH2
E) CH3CH3
B) ClCH2OH
C) CH3OCH2F
Ans: B
17. Identify which of the following species can be (a) Lewis acid(s).
A) CCl3+
B) BF3
C) H2O
D) BF3 and H2O
E) CCl3+, BF3, H2O
Ans: E
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18. Which of the following compounds is the strongest acid?
A) A
Ans: B
B) B
C) C
19. Which of the following compounds is the strongest acid?
A) CH3OH
B) CH3NH2
C) ClCH2OCH3
D) CH3F
Ans: E
20. Identify which of the following species can be (a) Lewis acid(s).
A) A
Ans: E
B) B
C) C
D) D
E) E
21. Which of the following species is the strongest base?
A) CH3–
B) NH2–
C) Cl–
D) OH–
E) I–
Ans: A
22. Which compound is the strongest base?
A) A
Ans: B
B) B
C) C
23. Which of the following species is the strongest base?
A) NH2–
B) OH–
C) Cl–
D) NH3
E) I–
Ans: A
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E) ClCH2OH
24. Which compound is the strongest base?
A) A
Ans: B
B) B
C) C
25. Which of the following compounds cannot possibly be a Lewis base?
A) A
Ans: C
B) B
C) C
26. Which of the following can be both a Bronsted-Lowry acid and a Bronsted-Lowry base?
A) A
Ans: B
B) B
C) C
27. Which of the following statements is true in comparing CH3–CH3, CH2 CH2,
CH to one another?
HC
A) HC
CH is the weakest acid and has the longest C–H bond distance.
B) HC
CH is the strongest acid and has the shortest C–H bond distance.
C) CH3–CH3 is the strongest acid and has the longest C–H bond distance.
D) CH2 CH2 is the strongest acid and has the shortest C–H bond distance.
E) None of the choices is correct.
Ans: B
28. What is the conjugate acid of CH3CH2NHCH3?
H H
A.
H3C
A) A
Ans: A
CH3
N
H H
B) B
H
H H
B.
H3C
N
H
C) C
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CH2
C.
H3C
N
H
CH3
29. What should go in the box on the right side of the equation?
A) A
Ans: C
B) B
C) C
D) D
E) E
30. Which of the following statements is (are) true?
A) CH3CH2OH can be a Bronsted-Lowry acid.
B) CH3CH2NH2 can be a Bronsted-Lowry base.
C) CH3CH2OH can be a Lewis base.
D) CH3CH2OH can be a Bronsted-Lowry acid, and CH3CH2NH2 can be a
Bronsted-Lowry base.
E) CH3CH2OH can be a Bronsted-Lowry acid, CH3CH2NH2 can be a
Bronsted-Lowry base, and CH3CH2OH can be a Lewis base.
Ans: E
31. Which of the following statements is true?
A) CH3CH3 can be a Lewis base.
B) BBr3 can be a Bronsted-Lowry acid.
C) CH3Cl can be a Lewis base.
D) CH3CH3 can be a Lewis base, and BBr3 can be a Bronsted-Lowry acid.
E) CH3CH3 can be a Lewis base, BBr3 can be a Bronsted-Lowry acid, and CH3Cl can
be a Lewis base.
Ans: C
32. Which of the following statements is true?
A) NH2– can be a Bronsted-Lowry acid.
B) CH3CH3 can be a Bronsted-Lowry base.
C) CH3+ can be a Lewis acid.
D) NH2– can be a Bronsted-Lowry acid, and CH3CH3 can be a Bronsted-Lowry base.
E) CH3CH3 can be a Bronsted-Lowry acid, and CH3+ can be a Lewis acid.
Ans: C
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33. Which of the following statements is true?
A) H2C CH2 can be a Lewis base.
B) NH4+ is both a Bronsted-Lowry acid and a Lewis acid.
C) CH3SCH3 can be a Bronsted-Lowry acid but it cannot be a Bronsted-Lowry base.
D) H2C CH2 can be a Lewis base, and NH4+ is both a Bronsted-Lowry acid and a
Lewis acid.
E) H2C CH2 can be a Lewis base, and CH3SCH3 can be a Bronsted-Lowry acid
but it cannot be a Bronsted-Lowry base.
Ans: D
34. Rank the following species from weakest to strongest base.
A) OH– < Cl– < NH2–
D) Cl– < OH– < NH2–
–
–
–
B) Cl < NH2 < OH
E) NH2– < Cl– < OH–
C) NH2– < OH– < Cl–
Ans: D
35. Which is the electrophilic site in the following compounds?
A)
B)
C)
Ans:
A: chlorine; B: carbon; C: boron
A: carbon; B: carbon; C: boron
A: carbon; B: oxygen; C: boron
B
D)
E)
A: carbon; B: carbon; C: hydrogen
A: carbon; B: oxygen; C: hydrogen
36. What is the nucleophilic site in each of the following molecules?
A)
B)
C)
D)
E)
Ans:
A: hydrogen; B: nitrogen; C: π electrons in bond
A: oxygen; B: nitrogen; C: carbon
A: oxygen; B: nitrogen; C: π electrons in bond
A: oxygen; B: carbon; C: π electrons in bond
A: carbon; B: nitrogen; C: hydrogen
C
37. Estimate the pKa of the indicated hydrogen to the nearest multiple of 5.
CH3
H3C
N
A) 15
Ans: E
H
B) 20
C) 25
D) 30
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E) 35
38. Estimate the pKa of the indicated hydrogen to the nearest multiple of 5.
O
A) 10
Ans: B
H
B) 15
C) 20
D) 25
E) 30
39. Estimate the pKa of the methyl hydrogen to the nearest multiple of 5.
A) 10
Ans: D
B) 20
C) 30
D) 40
E) 50
40. What is the pKa for a compound with Ka = 10–14?
A) −14
B) 1.4
C) 14
D) −1.4
Ans: C
41. What is the pKa for a compound with Ka = 102?
A) 200
B) –2
C) 2
D) 10−2
E) log2
Ans: B
42. What is the Ka for a compound with pKa = 25?
A) –25
B) 1025
C) 10–25
D) 0.25
Ans: C
43. What is the Ka for a compound with pKa = –3?
A) 103
B) 10–3
C) 3–2
D) −0.3
Ans: A
44. Which pKa indicates the weakest acid?
A) pKa = −3
B) pKa = 5
C) pKa = 24
Ans: C
E) log25
E) log(−3)
D) pKa = −0.03
45. Does equilibrium lie to the right or left in the following reaction?
A)
B)
C)
D)
Ans:
Right
Left
It cannot be determined.
The forward and reverse reactions are equally favored.
A
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E) pKa = 18
46. What is the product of this reaction?
A) A
Ans: B
B) B
C) C
47. Does the equilibrium of this reaction lie to the left or right?
A)
B)
C)
D)
Ans:
Left
Right
It cannot be determined.
The forward and reverse reactions are equally favored.
A
48. Does the equilibrium of this reaction lie to the left or right?
OH
A)
B)
C)
D)
Ans:
+
BF3
O
H
BF3
Left
Right
It cannot be determined.
The forward and reverse reactions are equally favored.
B
49. Which species is the strongest base?
A) NH3
B) NH2–
C) OH–
Ans: D
D) H–
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Challenge Questions
50. Amino acids exist in different charged forms depending on the pH of the solution.
Leucine has two acidic protons with pKa values of 2.33 and 9.74 and its neutral form
exists at pH = 6.04. Identify the form of leucine likely to exist at pH = 11.20.
O
O
O
O
A
(neutral form
of leucine)
A) A
Ans: B
B) B
D
C
B
C) C
H3N H
H3N H
H2N H
OH
O
O
H3N H
H3N H
O
OH
O
D) D
51. Carboxylic acids are usually converted to their acid chlorides or other similar
derivatives before reaction with nucleophiles. In the following reaction, what product
would form if NH3 was added directly to the starting carboxylic acid?
O
O
SOCl2
OH
OH
NH
B
B) B
O
O
OH
OH
A
A) A
Ans: D
NH2
Cl
OH
HO NH2
O
NH3
C
C) C
D
D) D
52. Rank the labeled protons in the following compound in order of increasing acidity.
Ha
OH
Hb
H
CN
H
A) Ha < Hb < Hc
Ans: C
Hc
B) Hc < Hb < Ha
C) Hb < Ha < Hc
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D) Hc < Ha < Hb
53. In peptide synthesis, DCC is used to initiate the reaction between two amino acids.
What is the structure of the conjugate base that is formed when DCC reacts with
protected glycine?
A) A
Ans: A
B) B
C) C
54. Identify which of the following species below is the strongest base.
O
O
O
O
O
N
H
A
A) A
Ans: C
B
B) B
C
C) C
D) D
D
E) E
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E