chapter 3

Chapter Three Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1 Difficulty Level: Easy 1. A Brønsted-Lowry acid is defined as a ____ and a Brønsted-Lowry base is defined as a ____. A) proton acceptor, proton donor B) proton donor, proton donor C) proton acceptor, proton acceptor D) proton donor, proton acceptor E) None of these Ans: D Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1 Difficulty Level: Easy 2. Provide a definition of a Brønsted-Lowry acid. Ans: A Brønsted-Lowry acid is a proton donor. Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1 Difficulty Level: Easy 3. Provide a definition of a Brønsted-Lowry base. Ans: A Bronsted-Lowry base is a proton acceptor. Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1 Difficulty Level: Easy 4. For the following reaction, which reactant functions as an acid? O

O

+

+

O

I

A) I B) II C) neither Ans: B

OH

II

Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1

Difficulty Level: Easy 5. For the following reaction, which reactant functions as a base? O

O

+

+

O

I

A) I B) II C) neither Ans: A

OH

II

Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1 Difficulty Level: Easy 6. For the following reaction, which reactant functions as an acid? H2SO4

+

I

O

II

O

+

HSO4

H

A) I B) II C) neither Ans: A Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1 Difficulty Level: Easy 7. For the following reaction, which reactant functions as a base? H2SO4 I

+

O

II

O H

A) I B) II C) neither Ans: B Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1 Difficulty Level: Easy

+

HSO4

8. For the following reaction, which reactant functions as a base? H

Cl

I

+

H OH

II

O

+

Cl

H

A) I B) II C) neither Ans: B Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1 Difficulty Level: Medium 9. A) B) C) D) E)

Which of the following is not a Bronsted-Lowry acid? CH3OH CH3CH3 CH3NH2 CH3SH None of these Ans: B

Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1 Difficulty Level: Medium 10. A) B) C) D) E)

Which of the following is not a Bronsted-Lowry base? CH3OH CH3OCH3 CH3NH2 CH3CH3 None of these Ans: D

Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1 Difficulty Level: Easy 11. A) B) C) D) E)

In a Bronsted-Lowry acid-base reaction the product(s) is (are) a _______. Lewis acid conjugate acid only Lewis acid-base pair conjugate acid-conjugate base pair None of these Ans: D

Topic: Introduction to Brønsted-Lowry Acids and Bases

Section: 3.1 Difficulty Level: Easy 12. In a Brønsted-Lowry acid-base reaction the product(s) is (are) a _______. Ans: conjugate acid-conjugate base pair Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1 Difficulty Level: Easy 13. A) B) C) D) E)

A loss of proton from a Brønsted-Lowry acid results in a ___. Lewis acid conjugate acid conjugate base conjugate acid-base pair None of these Ans: C

Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1 Difficulty Level: Easy 14. A) B) C) D) E)

A gain of proton by a Brønsted-Lowry base results in a ___. Lewis acid conjugate acid conjugate base conjugate acid-base pair None of these Ans: B

Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1 Difficulty Level: Easy 15. A) B) C) D) E)

What is the conjugate base of nitric acid? NO3NO2HNO3 HNO2 None of these Ans: A

Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1 Difficulty Level: Easy

16. A) B) C) D) E)

What is the conjugate base of phosphoric acid? HPO42H2PO4HPO32PO43None of these Ans: B

Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1 Difficulty Level: Easy 17. A) B) C) D) E)

What is the conjugate base of CH3CH2SH? CH3CH2SCH3CH2CH3CH2SH2+ CH3CH2S2None of these Ans: A

Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1 Difficulty Level: Easy 18. Draw the conjugate acid of CH3CH2OH. Ans: CH3CH2OH2

Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1 Difficulty Level: Easy 19. Draw the conjugate acid of CH3OCH3 Ans: CH3OCH3 H

Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1 Difficulty Level: Medium

20. Draw the conjugate acid of the following compound. O

Ans:

OH

Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1 Difficulty Level: Easy 21. Draw the conjugate base of CH3CCH. Ans: H3C

C

C

Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1 Difficulty Level: Easy 22. Draw the conjugate base of CH3CH2NH2. Ans: CH3CH2NH Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1 Difficulty Level: Medium 23. Draw the conjugate base of the following compound. OH

Ans:

O

Topic: Introduction to Brønsted-Lowry Acids and Bases Section: 3.1 Difficulty Level: Medium

24. Draw the conjugate base of the following compound. OH H O O

Ans:

H O

Topic: Flow of Electron Density: Curved Arrow Notation Section: 3.2 Difficulty Level: Easy 25. Which is the conjugate acid in the following reaction? CH3CH2SH + Na OH A) B) C) D) E)

I I II III IV Both I & IV Ans: D

II

CH3CH2S Na + H2O IV III

Topic: Flow of Electron Density: Curved Arrow Notation Section: 3.2 Difficulty Level: Easy 26. Which is the conjugate base in the following reaction? CH3CH2SH + Na OH I A) B) C) D) E)

I II III IV Both II & III Ans: C

II

CH3CH2S Na + H2O IV III

Topic: Flow of Electron Density: Curved Arrow Notation Section: 3.2 Difficulty Level: Easy

27. Which is the conjugate acid in the following reaction? + CH3CH2 Li

N

A) B) C) D) E)

I

H

H

N H

IV

III

II

+ CH3CH3 + Li

I II III IV Both I & IV Ans: D

Topic: Flow of Electron Density: Curved Arrow Notation Section: 3.2 Difficulty Level: Easy 28. Which is the conjugate base in the following reaction? + CH3CH2 Li

N

A) B) C) D) E)

I

H

H

N H

III

II

+ CH3CH3 + Li IV

I II III IV Both I & III Ans: C

Topic: Flow of Electron Density: Curved Arrow Notation Section: 3.2 Difficulty Level: Medium 29. For the following reaction label the acid, base, conjugate acid and conjugate base. CH3CH2SH + Na OH Ans: CH3CH2SH + Na OH acid

base

CH3CH2S Na + H2O CH3CH2S Na + H2O conjugate base

Topic: Flow of Electron Density: Curved Arrow Notation Section: 3.2 Difficulty Level: Medium

conjugate acid

30. For the following reaction label the acid, base, conjugate acid and conjugate base. + CH3CH2 Li

N

+ CH3CH3 + Li

N H

H

H

Ans:

+ CH3CH2Li

N

+ CH3CH3

N H

+ Li

H

H

base

acid

conjugate acid

conjugate base

Topic: Flow of Electron Density: Curved Arrow Notation Section: 3.2 Difficulty Level: Medium 31. For the following reaction label the acid, base, conjugate acid and conjugate base. + NaOH

Na

+ H2O

Ans: + NaOH

acid

base

Na

conjugate base

+ H2O

conjugate acid

Topic: Flow of Electron Density: Curved Arrow Notation Section: 3.2 Difficulty Level: Easy 32. The tail of the curved arrow must start at ____ electron density and the head must end at ____ electron density. A) low, high B) high, high C) low, low D) high, low Ans: D Topic: Flow of Electron Density: Curved Arrow Notation Section: 3.2 Difficulty Level: Easy 33. Provide a curved arrow mechanism for the following acid-base reaction. H

+ Na OH

S

S Na

+ H2O

Ans: H S

+ Na OH

Topic: Flow of Electron Density: Curved Arrow Notation

S Na

+ H2O

Section: 3.2 Difficulty Level: Easy 34. Provide a curved arrow mechanism for the following acid-base reaction.

+ Na NH2

+ NH3

Na

Ans:

H

+ Na NH2

Na

+ NH3

Topic: Flow of Electron Density: Curved Arrow Notation Section: 3.2 Difficulty Level: Medium 35. Provide a curved arrow mechanism for the following acid-base reaction. H N

H +

NH2

N

H

H +

NH3

H

Ans:

H N

H +

NH2

N

H

H +

NH3

H

Topic: Flow of Electron Density: Curved Arrow Notation Section: 3.2 Difficulty Level: Medium 36. Identify the acid and the base and provide a curved arrow mechanism for the following reaction.

Ans: O H

acid

+ Na OH base

Topic: Flow of Electron Density: Curved Arrow Notation Section: 3.2 Difficulty Level: Medium

O

+ H2O + Na

37. Identify the acid and the base and provide a curved arrow mechanism for the following reaction. O

O

+ NH3

+ NaNH2 Na

Ans:

O

O

+ NH3

+ NaNH2

Acid

Na

Base

H

Topic: Flow of Electron Density: Curved Arrow Notation Section: 3.2 Difficulty Level: Medium 38. Identify the acid and the base and provide a curved arrow mechanism for the following reaction. Na

+ H2O

+ NaOH

Ans:

Topic: Flow of Electron Density: Curved Arrow Notation Section: 3.2 Difficulty Level: Easy 39. The following reaction mechanism contains error. Which of the following statements correctly describes the curved arrows consistent with the reaction? O

O H

+ Na H

O

O Na

+ H2

A) The curved arrow should start at the carbonyl oxygen atom B) The curved arrow should start at the hydride, go to the hydrogen connected to oxygen and a second arrow should start from the O—H covalent bond and go to the oxygen C) The curved arrow should start at the oxygen atom of the OH D) There should be one more arrow Ans: B Topic: Flow of Electron Density: Curved Arrow Notation Section: 3.2 Difficulty Level: Medium

40. For the following reaction mechanism, identify the error, if any and describe the modification necessary by drawing the correct mechanism.

+ Na NH2

H

Na

+ NH3

Ans: There is only one arrow and it is going in the wrong direction. The tail of the curved arrow is placed on the hydrogen atom. The curved arrow represents motion of electrons and not the motion of atoms. The curved arrow must start from the base (high electron density) and should go to the proton on the acid (low electron density)

+ Na NH2

H

Na

+ NH3

Topic: Flow of Electron Density: Curved Arrow Notation Section: 3.2 Difficulty Level: Medium 41. For the following reaction mechanism, identify the error, if any and describe the modification necessary by drawing the correct mechanism. O

O H

Br

+ NaBr

O Na

OH

Ans: The first arrow from the lone pair of oxygen atom is correct, but the second arrow is incorrect. The tail of the arrow is placed on the proton. The second curved arrow must start from the H—Br bond and should go to the bromine atom on the acid. O

O H

Br

O Na

Topic: Flow of Electron Density: Curved Arrow Notation Section: 3.2 Difficulty Level: Hard

+ NaBr OH

42. Predict the products for the following acid-base reaction. O H

Ans:

+ Na OH

Na O

+ H2O

Topic: Flow of Electron Density: Curved Arrow Notation Section: 3.2 Difficulty Level: Hard 43. Predict the products for the following acid-base reaction.

Ans:

O

Na

+ NH3

Topic: Brønsted-Lowry Acid: Quantitative Perspective Section: 3.3 Difficulty Level: Easy

44. What is the Keq for the following reaction? + H3O

O

O

+ H2O

H

II.

I.

H3O

O

Keq=

O

H2O

O

H

Keq=

H3O

O

H

IV.

III. Keq=

H

Keq= H3O

O

A) B) C) D) E)

O

H2O

O

H O

I II III IV Both II & III Ans: C

Topic: Brønsted-Lowry Acid: Quantitative Perspective Section: 3.3 Difficulty Level: Easy 45. Which of the following compounds is most acidic? O

O

O

OH

A) B) C) D) E)

I

II

O

III

I II III IV None of these Ans: B

Topic: Brønsted-Lowry Acid: Quantitative Perspective Section: 3.3 Difficulty Level: Easy

NH2

IV

46. Which of the following compounds is most basic? O

O

O

OH

A) B) C) D) E)

I

NH2

O

II

IV

III

I II III IV None of these Ans: D

Topic: Brønsted-Lowry Acid: Quantitative Perspective Section: 3.3 Difficulty Level: Medium 47. Which of the following compounds is most acidic? OH

OH

NH2 NH2

I

A) B) C) D) E)

II

III

I II III IV All of these Ans: A

Topic: Brønsted-Lowry Acid: Quantitative Perspective Section: 3.3 Difficulty Level: Medium

IV

48. Which of the following compounds is most basic? OH

OH

NH2 NH2

I

A) B) C) D) E)

II

III

IV

I II III IV All of these Ans: C

Topic: Brønsted-Lowry Acid: Quantitative Perspective Section: 3.3 Difficulty Level: Medium 49. Which of the following compounds is most basic? O

I

A) B) C) D) E)

II

III

I II III IV All of these Ans: D

Topic: Brønsted-Lowry Acid: Quantitative Perspective Section: 3.3 Difficulty Level: Hard

IV

50. Tryptophan, an essential amino acid, is important in the synthesis of the neurotransmitter serotonin in the body. It has the following structure. Circle the three most acidic protons in tryptophan. O O H H

N H N H

O

Ans:

O H H

N H N H

Topic: Brønsted-Lowry Acid: Quantitative Perspective Section: 3.3 Difficulty Level: Hard 51. Histidine an amino acid has the following structure. Circle the three most acidic protons in histidine. H

H

H

O

N

C

C

H

CH2

H

O

H

H H

H

O

N

C

C

H

CH2

C C

H

N

N

C

H

Ans: H

H

O

H

C C N

N

H

C

H H

Topic: Brønsted-Lowry Acid: Quantitative Perspective Section: 3.3 Difficulty Level: Medium

52. For the following acid-base reaction, predict which side the equilibrium is favored. + NaOH

O

+ H2O

O

H

A) favor right side B) favor left side C) neither Ans: A Topic: Brønsted-Lowry Acid: Quantitative Perspective Section: 3.3 Difficulty Level: Medium 53. For the following acid-base reaction, predict which side the equilibrium is favored. OH

O

+ H2O

+ H3O

A) favor right side B) favor left side C) neither Ans: B Topic: Brønsted-Lowry Acid: Quantitative Perspective Section: 3.3 Difficulty Level: Hard 54. For the following acid-base reaction, predict which side the equilibrium is favored. O

O

H N

O H

H

A) favor right side B) favor left side C) neither Ans: A Topic: Brønsted-Lowry Acid: Quantitative Perspective Section: 3.3 Difficulty Level: Hard

O N H

H

55. For the following acid-base reaction, predict which side the equilibrium is favored. O

O

Li

+

A) favor right side B) favor left side C) neither Ans: A

+ Li

Topic: Brønsted-Lowry Acid: Qualitative Perspective Section: 3.4 Difficulty Level: Easy 56. A) B) C) D)

Which of the following compounds is most acidic? HF HCl HBr HI Ans: D

Topic: Brønsted-Lowry Acid: Qualitative Perspective Section: 3.4 Difficulty Level: Easy 57. A) B) C) D)

Which of the following compounds is most acidic? CH3OH HCl CH3SH CH3NH2 Ans: B

Topic: Brønsted-Lowry Acid: Qualitative Perspective Section: 3.4 Difficulty Level: Medium 58. Which of the following compounds is more acidic? Explain why. HF and HBr Ans: HBr is more acidic than HF. The Br- ion has larger atomic size than the F- ion, which allows for spreading of charge over a larger volume of space. This results in more stable anion and a weak conjugate base. Topic: Brønsted-Lowry Acid: Qualitative Perspective Section: 3.4 Difficulty Level: Medium

59. Which of the following compounds is more acidic? Explain why. CH3OH and CH3NH2 Ans: CH3OH is more acidic than CH3NH2. The conjugate base CH3O- is more stable than CH3NH-, because oxygen is more electronegative than nitrogen and can stabilize the negative charge better, resulting in weak conjugate base. Topic: Brønsted-Lowry Acid: Qualitative Perspective Section: 3.4 Difficulty Level: Medium 60. Determine which proton is most acidic in the following compound. Explain why. H

S

O

H

II

I

Ans: H(I) is more acidic as the sulfur atom in the conjugate base has larger atomic size than the oxygen, which allows for spreading of charge over a larger volume of space. This results in more stable anion and a weak conjugate base. Topic: Brønsted-Lowry Acid: Qualitative Perspective Section: 3.4 Difficulty Level: Hard 61. Rank the following protons in decreasing order (most to least) of acidity. OH III

N

H

II

I H

A) B) C) D) E)

II>III>I I>II>III III>I>II III>II>I None of these Ans: D

Topic: Brønsted-Lowry Acid: Qualitative Perspective Section: 3.4 Difficulty Level: Easy

62. Which of the following compounds is most acidic? O

O

O

OH

OH

I

A) B) C) D)

II

I II III IV Ans: A

O

IV

III

Topic: Brønsted-Lowry Acid: Qualitative Perspective Section: 3.4 Difficulty Level: Medium 63. Which of the indicated protons is most acidic? H

H

I

A) B) C) D)

H

I II III IV Ans: D

II

III

O

H

IV

Topic: Brønsted-Lowry Acid: Qualitative Perspective Section: 3.4 Difficulty Level: Medium 64. Rank the indicated protons in decreasing order (most to least) of acidity. IH

O

II H III H

A) B) C) D) E)

II>I>III II>III>I I>III>II I>II>III III>II>I Ans: D

Topic: Brønsted-Lowry Acid: Qualitative Perspective Section: 3.4 Difficulty Level: Medium 65. Which compound has the most acidic proton? Explain your choice. O

H

I

II

H

Ans: Compound II. The conjugate base of both compounds is resonance stabilized. For compound II the negative charge ends up on more electronegative oxygen atom in one of the resonance structure whereas in compound I the negative charge is on less electronegative carbon atom in every resonance structure. Topic: Brønsted-Lowry Acid: Qualitative Perspective Section: 3.4 Difficulty Level: Hard 66. Which of the indicated protons is most acidic? Explain your choice. IH

O

II H III H

Ans: H-I is most acidic because the conjugate base is resonance stabilized. The negative charge is delocalized over four atoms, one oxygen atom and three carbon atoms. Topic: Brønsted-Lowry Acid: Qualitative Perspective Section: 3.4 Difficulty Level: Easy 67. Which of the following compounds is most acidic? O

O

OH

I

A) B) C) D)

I II III IV Ans: B

O

OH F

II

O

OH I

III

OH Br

IV

Topic: Brønsted-Lowry Acid: Qualitative Perspective Section: 3.4 Difficulty Level: Easy 68. Which of the following compounds is most acidic? O

O

O

O

F OH F

A) B) C) D)

OH

OH

I

Cl

II

I II III IV Ans: A

OH

III

Br

IV

Topic: Brønsted-Lowry Acid: Qualitative Perspective Section: 3.4 Difficulty Level: Easy 69. Which of the following compounds is most acidic? O

F

O

OH

OH F

I

A) B) C) D)

O

Cl

O

OH

II

OH Br

III

IV

I II III IV Ans: B

Topic: Brønsted-Lowry Acid: Qualitative Perspective Section: 3.4 Difficulty Level: Medium 70. Which of the following compounds is most acidic? O

F

OH

I

A) B) C) D)

Cl

I II III IV Ans: D

F

O

O

O

OH

OH

II Cl

III

Cl

OH F

IV

Topic: Brønsted-Lowry Acid: Qualitative Perspective Section: 3.4 Difficulty Level: Hard 71. Rank the following compounds in decreasing order (most to least) of acidity. O

Br

Br

OH

Br

A) B) C) D) E)

OH

OH

II

I

Br

Br III

III>II>IV>I II>IV>III>II IV>III>II>I IV>II>III>I III>IV>II>I Ans: E

Topic: Brønsted-Lowry Acid: Qualitative Perspective Section: 3.4 Difficulty Level: Medium 72. Which of the indicated protons is most acidic? II H

I H

S O H O

A) B) C) D) E)

IV

O H

O

O

O

III

I II III IV All of these Ans: D

Topic: Brønsted-Lowry Acid: Qualitative Perspective Section: 3.4 Difficulty Level: Medium

Br

OH Br

IV

73. Which of the indicated protons is most acidic? Explain why. H

H

CF3

I

N

II H N H

Ans: H-II is more acidic. The conjugate base is stabilized by the inductive effect of the adjacent fluorine atoms, which are closer to position II than position I. Topic: Brønsted-Lowry Acid: Qualitative Perspective Section: 3.4 Difficulty Level: Medium 74. Explain why phenol is more acidic than ethanol. O H H O

ethanol

Phenol

Ans: The conjugate base of phenol is resonance stabilized, resulting in a weaker conjugate base. The conjugate base of ethanol has localized charge. Topic: Brønsted-Lowry Acid: Qualitative Perspective Section: 3.4 Difficulty Level: Medium 75. Which of the following compounds is more acidic? Explain why. O H

N

H

I

II

Ans: Compound I is more acidic. The conjugate base of both compounds is resonance stabilized. The conjugate base of I has negative charge on more electronegative oxygen atom, resulting in a more stable conjugate base. Topic: Brønsted-Lowry Acid: Qualitative Perspective Section: 3.4 Difficulty Level: Hard

76. Aspartic acid, an amino acid, has the following structure. Circle the most acidic proton in aspartic acid. Explain your choice. H

O

O

O H

H N H

O H

Ans:

H O

O

O H

H N H

O H

The conjugate base is stabilized by the inductive effect of the adjacent nitrogen atom. Topic: Position of Equilibrium and Choice of Reagents Section: 3.5 Difficulty Level: Easy 77. For the following acid-base reaction, predict which side the equilibrium is favored. +

O

F3C

OH

OH

+ F3C

O

A) favor right side B) favor left side C) neither Ans: A Topic: Position of Equilibrium and Choice of Reagents Section: 3.5 Difficulty Level: Easy 78. For the following acid-base reaction, predict which side the equilibrium is favored. C

N

N

+

H

C

N

N

+

A) favor right side B) favor left side C) neither Ans: B Topic: Position of Equilibrium and Choice of Reagents Section: 3.5 Difficulty Level: Easy

79. For the following acid-base reaction, predict which side the equilibrium is favored. +

+

A) favor right side B) favor left side C) neither Ans: A Topic: Position of Equilibrium and Choice of Reagents Section: 3.5 Difficulty Level: Easy 80. For the following acid-base reaction, predict which side the equilibrium is favored. OH

S

O

+

SH

+

A) favor right side B) favor left side C) neither Ans: B Topic: Position of Equilibrium and Choice of Reagents Section: 3.5 Difficulty Level: Medium 81. For the following acid-base reaction, predict which side the equilibrium is favored. Explain why. OH

S

+

O

SH

+

Ans: Favors the left side. Sulfur is a larger atom and the negative charge is spread over a larger volume of space. This results in more stable anion and a weaker base. Topic: Position of Equilibrium and Choice of Reagents Section: 3.5 Difficulty Level: Medium

82. For the following acid-base reaction, predict which side the equilibrium is favored. Explain why. +

+

Ans: Favors the right side. Both the base and the conjugate base have negative charge on carbon atom. The negative charge on conjugate base is stabilized via resonance, resulting in a more stable base. Topic: Position of Equilibrium and Choice of Reagents Section: 3.5 Difficulty Level: Medium 83. For the following acid-base reaction, predict which side the equilibrium is favored. Explain why. O

+

F3C

OH

OH

+ F3C

O

Ans: Favors the right side. Both the base and the conjugate base have negative charge on oxygen atom. The negative charge on conjugate base is stabilized via inductive effect of the fluorine on the adjacent carbon, resulting in a more stable base. Topic: Position of Equilibrium and Choice of Reagents Section: 3.5 Difficulty Level: Easy 84. Determine if H2O is a suitable reagent to protonate the following compound. O

A) yes B) no Ans: B Topic: Position of Equilibrium and Choice of Reagents Section: 3.5 Difficulty Level: Easy 85. Determine if H2O is a suitable reagent to protonate the following compound. O H

O

S O

A) yes B) no Ans: B

O

Topic: Position of Equilibrium and Choice of Reagents Section: 3.5 Difficulty Level: Medium 86. Determine if H2O is a suitable reagent to protonate the following compound. Explain why. N H

Ans: Yes. The conjugate base of water has negative charge on more electronegative oxygen atom, making it more stable. Topic: Position of Equilibrium and Choice of Reagents Section: 3.5 Difficulty Level: Medium 87. Determine if H2O is a suitable reagent to protonate the following compound. Explain why. O

Ans: No. The base and the conjugate base have localized negative charge on the oxygen atom. This results in similar stability. Topic: Position of Equilibrium and Choice of Reagents Section: 3.5 Difficulty Level: Easy 88. Determine if NaOH is a suitable reagent to deprotonate the following compound. A) Yes B) No Ans: B Topic: Position of Equilibrium and Choice of Reagents Section: 3.5 Difficulty Level: Easy

89. Determine if NaNH2 is a suitable reagent to deprotonate the following compound. O

O

H

A) Yes B) No Ans: A Topic: Position of Equilibrium and Choice of Reagents Section: 3.5 Difficulty Level: Medium 90. Determine if NaOH is a suitable reagent to deprotonate the following compound. Explain why. Ans: No. The base has negative charge on more electronegative oxygen, whereas the conjugate base has negative charge on less electronegative carbon atom. Topic: Position of Equilibrium and Choice of Reagents Section: 3.5 Difficulty Level: Medium 91. Determine if NaNH2 is a suitable reagent to deprotonate the following compound. Explain why. O

O

H

Ans: Yes. The conjugate base is resonance stabilized with delocalization of charge over two oxygen atoms. This is more stable than the amide base, which has a negative charge localized on one nitrogen atom. Topic: Position of Equilibrium and Choice of Reagents Section: 3.5 Difficulty Level: Hard

92. Determine if CH3CH2ONa is a suitable reagent to deprotonate the following compound. Explain why. Draw the complete reaction, including the curved arrow mechanism. N H

Ans: No. +

N

N

O Na

H

Na

+

OH

The base has negative charge on more electronegative oxygen atom, compared to a nitrogen atom in the conjugate base. This results in a more stable base. Topic: Position of Equilibrium and Choice of Reagents Section: 3.5 Difficulty Level: Hard 93. Determine if H2O is a suitable reagent to protonate the following compound. Explain why. Draw the complete reaction, including the curved arrow mechanism. S Na

Ans: No. S

S Na

H H

O

H

+ NaOH

Sulfur is a larger atom compared to an oxygen atom and the negative charge is spread over a larger volume of space. Furthermore the sulfur anion is resonance stabilized. These two factors results in more stable anion and a weaker base Topic: Leveling Effect Section: 3.6 Difficulty Level: Easy 94. A) B) C) D)

Which of the following solvents can be used with NaNH2? CH3CH2OH CH3OH H2O Liquid NH3 Ans: D

Topic: Leveling Effect Section: 3.6 Difficulty Level: Easy

95. A) B) C) D) E)

Which of the following solvents can not be used with (CH3)3COK? (CH3CH2)2O (CH3)3COH H2O Liquid NH3 None of these Ans: C

Topic: Leveling Effect Section: 3.6 Difficulty Level: Easy 96. A) B) C) D) E)

Which of the following solvents can be used with (CH3)3CLi? CH3CH2OH CH3OH H2O Liquid NH3 CH3(CH2)4CH3 Ans: E

Topic: Leveling Effect Section: 3.6 Difficulty Level: Easy 97. As a result of the "leveling effect," the strongest acid that can exist in appreciable concentration in aqueous solution is ____. A) H2SO4 B) HCl C) H3O+ D) HNO3 E) All of these Ans: C Topic: Leveling Effect Section: 3.6 Difficulty Level: Medium 98. What is the leveling effect? Ans: It is the deprotonation of a solvent by a base or protonation of solvent by an acid. Topic: Leveling Effect Section: 3.6 Difficulty Level: Medium 99. What is the strongest base that can be used with water as a solvent? Ans: hydroxide

Topic: Counterions Section: 3.8 Difficulty Level: Easy 100. A) B) C) D)

What is a cation? a negatively charged ion a positively charged ion a sodium atom Both B & C Ans: B

Topic: Counterions Section: 3.8 Difficulty Level: Easy 101. A) B) C) D)

What is the counterion in NaOCH2CH3? Na+ NaO— CH3CH2— CH3CH2O— Ans: A

Topic: Counterions Section: 3.8 Difficulty Level: Easy 102. A) B) C) D)

What is the counterion in (CH3)3CLi? CH3+ CH3— C(CH3)3— Li+ Ans: D

Topic: Counterions Section: 3.8 Difficulty Level: Easy 103. What is a counterion in (CH3)3COK? Ans: K+ Topic: Lewis Acids and Bases Section: 3.9 Difficulty Level: Easy

104. A) B) C) D)

A Lewis acid is defined as _____. a proton donor an electron pair donor a hydroxide donor an electron pair acceptor Ans: D

Topic: Lewis Acids and Bases Section: 3.9 Difficulty Level: Easy 105. A) B) C) D)

A Lewis base is defined as _____. a proton donor an electron pair donor a hydroxide donor an electron pair acceptor Ans: B

Topic: Lewis Acids and Bases Section: 3.9 Difficulty Level: Easy 106. A) B) C) D) E)

CH3CH2OCH2CH3, is best classified as a ____. Brønsted-Lowry acid Lewis acid Brønsted-Lowry base Lewis base Both C & D Ans: E

Topic: Lewis Acids and Bases Section: 3.9 Difficulty Level: Easy 107. A) B) C) D) E)

BF3, is best classified as a ____. Brønsted-Lowry acid Lewis acid Brønsted-Lowry base Lewis base Both A & D Ans: B

Topic: Lewis Acids and Bases Section: 3.9 Difficulty Level: Easy

108. The following compound is best classified as a ____. S

A) B) C) D) E)

Brønsted-Lowry acid Lewis acid Brønsted-Lowry base Lewis base Both C & D Ans: E

Topic: Lewis Acids and Bases Section: 3.9 Difficulty Level: Easy 109. The following compound is best classified as a ____.

A) B) C) D) E)

Brønsted-Lowry acid Lewis acid Brønsted-Lowry base Lewis base Both C & D Ans: B

Topic: Lewis Acids and Bases Section: 3.9 Difficulty Level: Medium 110. A) B) C) D) E)

Which of the following compounds is not a Lewis acid? BH3 AlCl3 CH3CH3 CH3CH2+ Both C & D Ans: C

Topic: Lewis Acids and Bases Section: 3.9 Difficulty Level: Medium

111. A) B) C) D) E)

Which of the following compounds is not a Lewis acid? BF3 FeCl3 CH3CH2+ Ph3P none of these Ans: D

Topic: Lewis Acids and Bases Section: 3.9 Difficulty Level: Easy 112. For the following reaction, identify the Lewis acid. Cl

Cl

+

Fe Cl

Cl

Cl

I

A) B) C) D)

Cl

Cl

Cl

II

I II III Both I & III Ans: A

Fe

Cl

Cl

III

Topic: Lewis Acids and Bases Section: 3.9 Difficulty Level: Easy 113. For the following reaction, identify the Lewis acid. H H H

B

H

H

I

+

N

NH2 H

B

II H

A) B) C) D)

I II III Both I & III Ans: A

Topic: Lewis Acids and Bases Section: 3.9 Difficulty Level: Medium

H

III

114. For the following reaction, identify the Lewis acid.

A) B) C) D) E)

I II III IV None of these Ans: A

Topic: Lewis Acids and Bases Section: 3.9 Difficulty Level: Medium 115. For the following reaction, identify the Lewis acid. O N

+ O

N

II

I

A) B) C) D)

O

O

III

I II III None of these Ans: B

Topic: Lewis Acids and Bases Section: 3.9 Difficulty Level: Easy 116. For the following reaction, identify the Lewis base. H H H

B

I

H

+

H

N

NH2

II

H

B H

A) B) C) D)

I II III None of these Ans: B

Topic: Lewis Acids and Bases

H

III

Section: 3.9 Difficulty Level: Easy 117. For the following reaction, identify the Lewis base. Cl

Cl

+

Fe Cl

Cl

Cl

I

A) B) C) D)

Cl

Cl

Cl

II

I II III None of these Ans: B

Fe

Cl

Cl

III

Topic: Lewis Acids and Bases Section: 3.9 Difficulty Level: Medium 118. For the following reaction, identify the Lewis acid and the Lewis base. + AlCl3

AlCl3

Cl

Cl

Ans: + AlCl3

AlCl3

Cl

Cl

Lewis acid

Lewis base

Topic: Lewis Acids and Bases Section: 3.9 Difficulty Level: Medium 119. For the following reaction, identify the Lewis acid and the Lewis base. H

H N

+

NH2

Ans:

H

H N

+

Lewis acid

NH2

Lewis base

Topic: Lewis Acids and Bases Section: 3.9 Difficulty Level: Hard 120. For the following reaction, identify the Lewis acid and the Lewis base and draw the curved arrow mechanism. Cl

Cl

+

Fe Cl

Cl

Cl

Cl

Fe

Cl

Ans:

Cl

Cl

Cl Cl

Cl

+

Fe Cl

Cl

Cl

Cl

Fe

Cl

Cl

Cl

Cl

Lewis acid

Lewis base

Topic: Lewis Acids and Bases Section: 3.9 Difficulty Level: Hard 121. For the following reaction, identify the Lewis acid and the Lewis base and draw the curved arrow mechanism. H

H N

+

NH2

Ans:

H

H N

+

Lewis acid

NH2

Lewis base

Topic: Lewis Acids and Bases Section: 3.9 Difficulty Level: Hard 122. Predict the product(s) for the following reaction and draw the curved arrow mechanism. S

+ BF3

Ans:

BF3 S

+ BF3

Topic: Lewis Acids and Bases

S

Section: 3.9 Difficulty Level: Hard 123. Predict the product(s) for the following reaction and draw the curved arrow mechanism. O

+ AlCl3

Ans:

O

O

O

AlCl3

AlCl3

+ AlCl3

Topic: Integrated Problems Section: 3.1-3.5 Difficulty Level: Hard 124. For the following reaction identify the acid and the base and predict the products. Draw the curved arrow mechanism for the formation of products and predict the direction of the equilibrium. H N

+ Na CN

H

H

H

Ans:

N

N

+ Na CN

H

H

+ HCN + Na

H

H

Base

Acid

Topic: Integrated Problems Section: 3.1-3.5 Difficulty Level: Hard 125. For the following reaction identify the acid and the base and predict the products. Draw the curved arrow mechanism for the formation of products and predict the direction of the equilibrium. O

O

+

O H

Ans:

O

O

O

+

O H

Base

Acid

O

+

O

Topic: Integrated Problems Section: 3.1-3.5 Difficulty Level: Hard 126. For the following reaction identify the acid and the base and predict the products. Draw the curved arrow mechanism for the formation of products and predict the direction of the equilibrium. O

H

H N

N

O

Ans:

N

+

H H

H

O

H

H N

N

O

N

+

H

Base

Acid

O H H

N O

H

H

+ H

N H

N

H