Deck 2: Acids and Bases: Central to Understanding Organic Chemistry

Question 1

Write a completed equation for the acid-base pair shown below.
HCO₂H + ^-NH₂ →

Answer 1

HCO₂H + ^-NH₂ → HCO₂^- + NH₃

Question 2

2-Propanol is shown below.Draw the structure of its conjugate base.
(CH₃)₂CHOH

Answer 2

Question 3

Give the conjugate acid and the conjugate base for HSO4^-:

Answer 3

conjugate acid: H₂SO₄ conjugate base: SO₄^2-

Question 4

Which of the following ions is the strongest acid?

A)H^-
B)HO^-
C)HSO₄^-
D)H₂O
E)H₃O⁺

Question 5

Which of the following is the strongest acid?

A)HF
B)H₂O
C): NH₃
D)CH₄
E)CH₃OH

Question 6

Which of the following is not a conjugate acid-base pair?

A)(H₂O,HO^-)
B)(H₂O,H₃O⁺)
C)(HSO₄^-,H₂SO₄)
D)(^-OH,O^2-)
E)(NO₃^-,NO₂^-)

Question 7

Consider the set of compounds,NH₃,HF,and H₂O.Rank these compounds in order of increasing acidity and discuss your rationale.

Question 8

Which of the following is the strongest acid?

A)CH₃CH₂OH
B)CH₃OCH₃
C)CH₃-NH-CH₃
D)CH₃-C CH
E)CH₃-CH CH₂

Question 9

If H₂O has a pK_a value of 15.7 and HF has a pK_a value of 3.2,which is a stronger base,HO^- or F^-? Explain.

Question 10

The pKa of CH₃COOH is 4.8 and the pKa of HCOOH is 3.8.Given this information,one knows that

A)CH₃COOH completely ionizes in water.
B)HCOOH is a weaker acid than CH₃COOH.
C)HCOO^- is a weaker base than CH₃COO^-.
D)CH₃COOH reacts with HO^- while HCOOH does not.
E)HCOOH reacts with HO^- while CH₃COOH does not.

Question 11

What is the conjugate acid of CH₃NH₂?

A)CH₃NH₃⁺
B)CH₃NH^-
C)NH₄⁺
D)NH₂^-

Question 12

What is the pH of a 0.1 M solution of HCl? (Note: pK_a for HCl is -6.)

A)6
B)-6
C)1
D)-8
E)-1

Question 13

Which species act as bases in the following reaction?

A)1 and 2
B)3 and 4
C)2 and 4
D)1 and 3
E)2 and 3

Question 14

The conjugate acid of H₂O is

A)H₃O^-.
B)H₃O.
C)H₃O⁺.
D)HO^-.
E)H₂O⁺.

Question 15

What is the conjugate acid of NH₃?

A)(⁺NH₃)
B)(^-NH)
C)(⁺NH₄)
D)(^-NH₂)
E)(⁺NH₂)

Question 16

What is the conjugate base of CH₃NH₂?

A)CH₃NH₃⁺
B)CH₃NH^-
C)NH₄⁺
D)NH₂^-

Question 17

Identify the compound with the highest pK_a.

A)CH₃NH₂
B)CH₃OH
C)CH₃COOH
D)H₂O
E)CH₃NH₃⁺

Question 18

What is the product formed from the following acid-base reaction when ammonia functions as a base? The equilibrium lies far to the reactants.

A)CH₃O^- + ⁺NH₄
B)CH₂OH + ⁺NH₃
C)CH₃OH₂⁺ + ^-NH₂
D)CH₃NH₂ + H₂O
E)CH₄ + NH₂OH

Question 19

Identify the compound with the highest pK_a.

A)CH₃CH₃
B)HCCH
C)CH₂CH₂
D)CH₃OH
E)CH₃NH₂

Question 20

Which of the following is the strongest acid?

A)CH₃OH
B)CH₃OH₂⁺
C)H₂N^-
D)CH₃NH₂
E)CH₃NH₃⁺

Question 21

Identify the most acidic carboxylic acid.

A)ICH₂COOH
B)BrCH₂COOH
C)CH₃COOH
D)FCH₂COOH
E)ClCH₂COOH

Question 22

Predict the direction of equilibrium in the following reaction.Explain your answer.

Question 23

Explain why AlCl₃ is a Lewis acid.

Question 24

H-A is an acid with a pKa of 4.5.Which of the following statements about an aqueous solution of H-A is true?

A)At pH = 4.5,the solution contains much more H-A than.A^-.
B)At pH = 4.5,the solution contains much more A^- than H-A.
C)At pH- 3.5,the solution contains about 90% A^- and 10% H-A.
D)At pH = 6.5,the solution contains about 80% A^{- and 20% H-A}.
E)At pH = 5.5,the solution contains about 90% A^- and 10% H-A.

Question 25

Would you predict trifluoromethanesulfonic acid,CF₃SO₃H,to be a stronger or weaker acid than methanesulfonic acid,CH₃SO₃H? Explain your reasoning.

Question 26

Buffering is used to maintain the pH of human blood in the relatively narrow 7.3 - 7.4 range.What acid/base pair serves to buffer the blood?

A)H₂O / HO^-
B)H₃O⁺ / H₂O
C)H₂CO₃ / HCO₃^-
D)NH₄⁺ / NH₃
E)HCl / Cl^-

Question 27

Propanoic acid,CH₃CH₂COOH,has a pKa =4.9.Draw the structure of the conjugate base of propanoic acid and give the pH above which 90% of the compound will be in this conjugate base form.

Question 28

Structure of Lorazepam,a widely known drug for short-term anxiety is shown below.Is the indicated lone pair localized or delocalized?

Question 29

When a small amount of hexanoic acid [CH₃(CH₂)₄CO₂H,pKa~4.8],is added to a separatory funnel which contains the organic solvent diethyl ether and water with a pH of 2.0,it is found mainly in the ________ phase as ________.

A)ether; CH₃(CH₂)₄CO₂^-
B)water; CH₃(CH₂)₄CO₂^-
C)ether; CH₃(CH₂)₄CO₂H
D)water; CH₃(CH₂)₄CO₂H
E)none of the above

Question 30

HCN has a pKa = 9.1.What form of the compound,HCN or CN^-,will predominate in a solution of pH = 7.0

Question 31

The amino acid glycine (H₃N⁺CH₂CO₂H)has two acidic Hs,one with pKa = 2.34 and the other with pKa=9.60.Draw the structure of the form of glycine that predominates at a pH of 12.

Question 32

When a small amount of hexanoic acid [CH₃(CH₂)₄CO₂H,pK_a~4.8],is added to a separatory funnel which contains the organic solvent diethyl ether and water with a pH of 12.0,it is found mainly in the ________ phase as ________.

A)ether; CH₃(CH₂)₄CO₂^-
B)water; CH₃(CH₂)₄CO₂^-
C)ether; CH₃(CH₂)₄CO₂H
D)water; CH₃(CH₂)₄CO₂H
E)none of the above

Question 33

Draw a resonance contributor and the resonance hybrid for HOCO₂^-.

Question 34

At what pH will 25% of a compound with a pKa of 5.3 be in its basic form?

Question 35

The pKa of CH₃COOH is 4.8.If the pH of an aqueous solution of CH₃COOH and CH₃COO^- is 4.8,then one knows

A)CH₃COOH is completely ionized.
B)[CH₃COOH] > [CH₃COO^-].
C)[CH₃COOH] = [CH₃COO^-].
D)[CH₃COOH] < [CH₃COO^-].
E)CH₃COOH is completely unionized.

Question 36

Which of the following is the strongest acid?

A)I
B)II
C)III
D)IV
E)V

Question 37

Explain why : NF₃ is a weaker base than : NH₃.

Question 38

Which of the following anions,CH₃CHBrCO₂^- or CH₃CHFCO₂^- is the stronger base? Explain your choice.

Question 39

At what pH will the concentration of a compound with a pKa of 5.7 be 100 times greater in its acidic form than in its basic form?

Question 40

What would be the conjugate base in the following acid base reaction?

A)CH₂O
B)CH₃OH
C)CH₃SH₂⁺
D)CH₃S^-
E)H₂O

Question 41

What is the product of the following Lewis acid-base reaction?

Question 42

What would be the conjugate acid in the following acid base reaction?

A)CH₂O
B)CH₃OH
C)CH₃SH₂⁺
D)CH₃S^-
E)H₂O

Question 43

Which of the following species cannot function as a Lewis acid?

A)H⁺
B)TiCl₄
C)AlCl₃
D)NH₄⁺
E)H₂O