Question 1

Which of the following statements best explains why acetate is a weaker base than phenoxide, as depicted in the resonance structures above?

Accepted Answer

Acetate has more resonance contributors, leading to greater delocalization and stabilization of the negative charge.

Question 2

Based on the resonance structures shown, which statement is correct regarding the delocalization of the negative charge in acetate and phenoxide?

Accepted Answer

The negative charge in acetate is delocalized equally between two oxygen atoms, while in phenoxide it is delocalized over the oxygen and the aromatic ring.

Question 3

Why is the resonance stabilization of acetate considered greater than that of phenoxide?

Accepted Answer

Acetate has two major resonance contributors with the negative charge fully on oxygen, while phenoxide has only one major and several minor contributors.

Question 4

Given the resonance structures, which compound would you expect to have a lower pKa (be a stronger acid): acetic acid or phenol?

Accepted Answer

Acetic acid, because its conjugate base (acetate) is more stabilized by resonance.

Question 5

Which of the following best describes the effect of resonance on the basicity of acetate and phenoxide?

Accepted Answer

Resonance decreases the basicity of both acetate and phenoxide by stabilizing their negative charges.

Question 6

If you were to compare the conjugate bases of acetic acid and phenol, which would be more likely to accept a proton (i.e., be a stronger base)?

Accepted Answer

Phenoxide, because it is less stabilized by resonance than acetate.

Question 7

Which of the following is a major contributor to the resonance hybrid of acetate?

Accepted Answer

$$\mathrm{CH_3COO^-}$$ $$\leftrightarrow$$ $$\mathrm{CH_3COO^-}$, with the negative charge delocalized equally between both oxygens.

Question 8

Why are the resonance contributors of phenoxide labeled as 'minor contributors' in the image?

Accepted Answer

Because the negative charge is delocalized onto less electronegative carbon atoms, making these structures less stable.

Question 9

Which of the following best explains why resonance stabilization leads to a lower pKa for acetic acid compared to phenol?

Accepted Answer

Greater resonance stabilization of the conjugate base makes the acid stronger, resulting in a lower pKa.

Question 10

Which of the following statements is true regarding the resonance structures of acetate and phenoxide?

Accepted Answer

Acetate's resonance structures involve only oxygen atoms, while phenoxide's involve both oxygen and carbon atoms.

Acid-Base Chemistry: Structure, Mechanisms, and Reactivity

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