OCHEM- Ch2

3. Which of the following compounds is both a Brønsted-Lowry acid and base? I. CH3OH II. CH3COCH3 III. H2O IV. (CH3)3N A) I, II B) I, III C) II, IV D) I, IV

B

33. Which of the following compounds has the lowest pKa? A) H2O B) H2S C) NH3 D) CH4

B

36. Which of the following concepts can be used to explain the difference in acidity between ethanol (CH3CH2OH) and 2-fluoroethanol (FCH2CH2OH)? A) Size B) Inductive effect C) Resonance D) Hybridization

B

39. Which of the following statements about Lewis bases is true? A) Lewis bases are electron pair acceptors. B) Lewis bases are electron pair donors. C) Lewis bases are proton donors. D) Lewis bases are proton acceptors.

B

42. What is the correct classification of the following compound? CH3-O-CH3 A) Brønsted-Lowry acid and Lewis acid. C) Brønsted-Lowry base. B) Brønsted-Lowry base and Lewis base. D) Lewis base.

B

43. Identify the Lewis acid in the following reaction. FeBr3 Br2 -------------> -FeBr4 + Br+ I. II. III. IV. A) I B) II C) III D) IV

B

46. What is the role of methylchloride (CH3Cl) in the following reaction? CH3Cl + AlCl3 -----> CH3 + AlCl4- A) Lewis acid C) Brønsted-Lowry acid B) Lewis base D) Brønsted-Lowry base

B

6. Which of the following statements about Brønsted-Lowry acids and bases is true? A) Loss of a proton from a base forms its conjugate acid. B) Loss of a proton from an acid forms its conjugate base. C) Gain of a proton by an acid forms its conjugate base. D) Brønsted-Lowry acid-base reactions always result in the transfer of a proton from a base to an acid.

B

7. Which of the following species is the conjugate base of methanol, CH3OH? A) CH3OH2+ B) CH3O- C) CH3- D) CH4

B

10. Which is the conjugate acid in the following reaction? :CH3- + H2O ---> CH4 + HO- I. II. III. IV. A) I B) II C) III D) IV

C

13. Which is the conjugate BASE in the following reaction? HCl + H2O ---> Cl- + H3O+ I. II. III. IV. A) I B) II C) III D) IV

C

17. Which of the following compounds is the weakest acid? A) HF B) HCl C) HBr D) HI

A

23. Rank the following compounds in order of increasing acidity, putting the least acidic first. I. CH3COOH II. FCH2COOH III. ClCH2COOH IV. BrCH2COOH A) I < IV < III < II C) II < III < IV < I B) I < III < IV < II D) II < IV < III < I

A

26. Rank the following conjugate bases in order of increasing basicity, putting the least basic first. I. NH2- II. HO- III. CH3- A) II < I < III B) II < III < I C) I < II < III D) I < III < II

A

30. What is the direction of equilibrium when acetylene (C2H2) reacts with ethoxide (CH3CH2O-) in an acid-base reaction? H-C==C-H + -OCH2CH3 ? H-C==C:- + HOCH2CH3 A) Left B) Right C) Neither D) Cannot be determined

A

32. Which of the following statements explain why HBr is a stronger acid than HF? A) Br- is more stable than F- because Br- is larger than F-. B) Br- is less stable than F- because Br- is larger than F-. C) Br- is more stable than F- because Br- is less electronegative than F-. D) Br- is less stable than F- because Br- is less electronegative than F-.

A

41. Which of the following species can be both Lewis acid and Lewis base? I. H2O II. CCl4 III. H-C==C-H IV. H3C-C^O-CH3 C^O= Double bonded O above the C A) I, III, IV B) I, II, IV C) II, III, IV D) I, II, III

A

44. Identify the Lewis base in the following reaction. FeBr3 Br2 -------------> -FeBr4 + Br+ I. II. III. IV. A) I B) II C) III D) IV

A

47. What is the electrophilic site in the following compounds? I. CH3Cl II. H3C-O-CH3 III. BF3 A) I = Carbon; II = carbon; III = boron. C) I = Carbon; II = oxygen; III = boron. B) I = Chlorine; II = carbon; III = boron. D) I = Carbon; II = carbon; III = fluorine.

A

5. Which of the following species is not a Brønsted-Lowry base? A) BF3 B) NH3 C) H2O D) PO43-

A

16. Which of the following compounds is the strongest acid? A) CH3OH B) BrCH2OH C) CH3NH2 D) CH3Cl

B

19. Which of the following species is the strongest base? A) HO- B) H2N- C) CH3COO- D) Cl-

B

2. Which of the following statements about a Brønsted-Lowry base is true? A) The net charge may be zero, positive, or negative. B) All Brønsted-Lowry bases contain a lone pair of electrons or a pie bond. C) All Brønsted-Lowry bases contain a proton. D) The net charge may be zero or positive.

B

22. Rank the following compounds in order of increasing acidity, putting the least acidic first. I. CH3COOH II.ClCH2COOH III. CH3CH2OH IV. ClCH2CH2OH A) III < I < IV < II C) II < I < IV < III B) III < IV < I < II D) III < I < II < IV

B

25. Rank the following compounds in order of decreasing acidity, putting the most acidic first. I. CH3OCH3 II. CH3CHO III. CH3CH2OH IV. CH3COOH A) IV > II > III > I C) III > IV > II > I B) IV > III > II > I D) III > IV > I > II

B

29. What is the direction of equilibrium when acetylene (C2H2) reacts with H2N- in an acid-base reaction? H-C==C-H + :NH2 ? H-C==C:- + :NH3 A) Left B) Right C) Neither D) Cannot be determined

B

27. Rank the following conjugate bases in order of decreasing basicity, putting the most basic first. I. H2C=CH- II. HC==C- III. CH3- == is a Triple bond A) II > I > III B) I > II > III C) III > I > II D) III > II > I

C

28. Which of the following is the strongest base? A) CH3COCH3 B) CH3COOH C) NH3 D) H2O

C

34. Which of the following concepts can be used to explain the difference in acidity between acetic acid (CH3COOH) and ethanol (CH3CH2OH)? A) Hybridization B) Electronegativity C) Resonance D) Size

C

4. Which of the following species cannot act as both a Brønsted-Lowry acid and base? A) HCO3- B) HSO4- C) HO- D) H2PO4-

C

8. Which of the following species is the conjugate base of the hydronium ion, H3O+? A) H3O B) H2O- C) H2O D) HO-

C

1. Which of the following statements is a correct definition for a Brønsted-Lowry acid? A) Proton acceptor C) Electron pair acceptor B) Electron pair donor D) Proton donor

D

11. Which is the conjugate base in the following reaction? :CH3- + H2O ---> CH4 + HO- I. II. III. IV. A) I B) II C) III D) IV

D

12. Which is the conjugate acid in the following reaction? HCl + H2O ---> Cl- + H3O+ I. II. III. IV. A) I B) II C) III D) IV

D

14. Which of the following statements about acid strength is true? A) The stronger the acid, the further the equilibrium lies to the left. B) The stronger the acid, the smaller the Ka. C) The stronger the acid, the larger the pKa. D) The stronger the acid, the smaller the pKa.

D

15. Which of the following compounds is the strongest acid? CH4 CH3CH3 H2C=CH2 HC==CH I. II. III. IV. IV= Triple bond A) I B) II C) III D) IV

D

18. Which of the following compounds is the weakest acid? A) H2S B) PH3 C) HCl D) SiH4

D

20. Which of the following ranks the compounds in order of increasing basicity, putting the least basic first? A) CH3NH2 < CH3OH < CH4 C) CH4 < CH3NH2 < CH3OH B) CH3OH < CH3NH2 < CH4 D) CH4 < CH3OH < CH3NH2

D

24. Rank the following compounds in order of decreasing acidity, putting the most acidic first. I. CH4 II. NH3 III. HF IV. H2O A) IV > II > III > I C) I > II > IV > III B) III > II > IV > I D) III > IV > II > I

D

31. Which of the following statements explain why H2O is a stronger acid than CH4? A) H2O can form hydrogen bonds while CH4 cannot. B) H2O forms a less stable conjugate base, HO-. C) CH4 forms a more stable conjugate base, CH3-. D) H2O forms a more stable conjugate base, HO-.

D

35. Which of the following concepts can be used to explain the difference in acidity between acetylene (C2H2) and ethylene (C2H4)? A) Size B) Resonance C) Inductive effect D) Hybridization

D

37. Rank the following compounds in order of decreasing acidity, putting the most acidic first. I. CH3CH2OH II. CH3CH2NH2 III. ClCH2CH2OH A) I > II > III B) III > II > I C) II > III > I D) III > I > II

D

38. Which of the following statements about Lewis acids is true? A) Lewis acids are proton donors. B) Lewis acids are proton acceptors. C) Lewis acids are electron pair donors. D) Lewis acids are electron pair acceptors.

D

40. Which of the following is a Lewis acid but not a Brønsted-Lowry acid? A) CH3OH B) H2O C) CH3COOH D) BF3

D

45. Which of the following compounds is not a Lewis acid? A) AlCl3 B) HCl C) H2O D) CBr4

D

48. What is the nucleophilic site in the following compounds? I. H3C-O-CH3 II. H2C=CH2 III. CH3NH2 A) I = Hydrogen; II = electrons in bond; III = nitrogen. B) I = Oxygen; II = carbon; III = nitrogen. C) I = Hydrogen; II = carbon; III = carbon. D) I = Oxygen; II = electrons in bond; III = nitrogen.

D

9. Which of the following species is the conjugate acid of ammonia, NH3? A) H4N B) H3N+ C) H2N- D) H4N+

D