Question 1

Which of the following compounds will have the most stabilized conjugate base due to the combined effects of resonance and induction?

Accepted Answer

Trifluoroacetic acid ($$CF_3COOH)$$

Question 2

Which of the following amines is the strongest base in aqueous solution?

Accepted Answer

Methylamine ($$CH_3NH_2)$$

Question 3

Order the acidity of the following compounds in increasing order: acetylene ($$HC \equiv CH$$), ethylene ($$H_2C=CH_2$), ethane (CH_3CH_3$).

Accepted Answer

Ethane \u003c Ethylene \u003c Acetylene

Question 4

Why is trifluoroacetic acid ($$CF_3COOH) $$much stronger than acetic acid ($$CH_3COOH$$)?

Accepted Answer

Because the $$CF_3$$ group withdraws electrons by induction, stabilizing the conjugate base.

Question 5

Which of the following is the correct resonance structure for the phenoxide ion?

Accepted Answer

A structure with the negative charge delocalized onto the ortho and para positions of the benzene ring.

Question 6

Predict the relative acidity of benzoic acid, p-nitrobenzoic acid, and p-methoxybenzoic acid. Which is the most acidic?

Accepted Answer

p-Nitrobenzoic acid is most acidic due to the strong electron-withdrawing effect of the nitro group.

Question 7

How does a para-nitro group on benzoic acid affect its acidity compared to unsubstituted benzoic acid?

Accepted Answer

It increases acidity by withdrawing electrons through both resonance and induction.

Question 8

Which of the following statements best explains why phenol is more acidic than cyclohexanol?

Accepted Answer

Phenol's conjugate base is stabilized by resonance with the aromatic ring.

Question 9

Which of the following is a correct stepwise mechanism for the reaction of benzoic acid with a strong base (e.g., $$NaOH$$)?

Accepted Answer

Deprotonation of the carboxylic acid group to form the benzoate ion.

Question 10

Which of the following best describes the effect of an electron-donating group (EDG) on the acidity of a substituted benzoic acid?

Accepted Answer

EDGs decrease acidity by destabilizing the conjugate base.

Question 11

Which of the following is the correct order of basicity for the following amines in water: aniline, methylamine, ammonia?

Accepted Answer

Methylamine \u003e Ammonia \u003e Aniline

Question 12

Which of the following best explains why acetylene ($$HC \equiv CH) is $$more acidic than ethylene ($$H_2C=CH_2$) and ethane (CH_3CH_3$)?

Accepted Answer

The sp-hybridized carbon in acetylene holds the negative charge more tightly, stabilizing the conjugate base.

Question 13

Which of the following is a possible product when phenol reacts with bromine ($$Br_2) in $$water?

Accepted Answer

2,4,6-tribromophenol

Question 14

Which of the following is the major resonance contributor for the acetate ion ($$CH_3COO^-$$)?

Accepted Answer

A structure with the negative charge delocalized equally between both oxygen atoms.

Question 15

Which of the following statements is true regarding the effect of resonance on acidity?

Accepted Answer

Resonance stabilization of the conjugate base increases acidity.

Question 16

Which of the following is the correct mechanism for the reaction of acetic acid with sodium hydroxide?

Accepted Answer

Deprotonation of acetic acid to form acetate ion and water.

Question 17

Which of the following best explains why p-methoxybenzoic acid is less acidic than benzoic acid?

Accepted Answer

The methoxy group donates electrons by resonance, destabilizing the conjugate base.

Question 18

Which of the following is the correct order of acidity for the following compounds: phenol, methanol, water?

Accepted Answer

Methanol \u003c Water \u003c Phenol

Organic Chemistry II Practice Exam: Acidity, Basicity, Resonance, and Inductive Effects

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