Question 1

Which of the following best explains why iodide (I⁻) is a better leaving group than fluoride (F⁻) in nucleophilic substitution reactions?

Accepted Answer

Iodide is larger and can better disperse the negative charge, making it more stable after departure.

Question 2

A student is asked to predict the mechanism for the reaction of 1-bromopropane with sodium hydroxide in aqueous solution. Which mechanism is most likely and why?

Accepted Answer

SN2, because the substrate is primary and the nucleophile is strong.

Question 3

Which of the following statements about the SN1 mechanism is correct?

Accepted Answer

The reaction involves a carbocation intermediate and leads to racemization.

Question 4

In a laboratory, a chemist reacts tert-butyl chloride ((CH₃)₃CCl) with water. Which of the following best describes the expected product and mechanism?

Accepted Answer

tert-Butyl alcohol via an SN1 mechanism with racemization.

Question 5

Which of the following is the best description of a Lewis base?

Accepted Answer

A species that donates an electron pair.

Question 6

Rank the following alkyl halides in order of increasing reactivity toward SN2 substitution: methyl bromide, isopropyl bromide, ethyl bromide.

Accepted Answer

Isopropyl bromide \u003c ethyl bromide \u003c methyl bromide

Question 7

Which factor most strongly favors the SN2 mechanism over SN1 for a given substitution reaction?

Accepted Answer

A strong nucleophile and a primary substrate.

Question 8

In the reaction: CH₃CH₂Cl + OH⁻ → CH₃CH₂OH + Cl⁻, which species acts as the nucleophile and which as the electrophile?

Accepted Answer

OH⁻ is the nucleophile; CH₃CH₂Cl is the electrophile.

Question 9

Which of the following best explains why tertiary carbocations are more stable than primary carbocations?

Accepted Answer

Tertiary carbocations have more alkyl groups that donate electron density, stabilizing the positive charge.

Question 10

A reaction between methyl iodide (CH₃I) and cyanide ion (CN⁻) is carried out in acetone. Which mechanism is most likely and what is the major product?

Accepted Answer

SN2; methyl cyanide (CH₃CN) with inversion of configuration.

Question 11

Which of the following statements about leaving groups is correct?

Accepted Answer

A good leaving group is stable after accepting an electron pair.

Question 12

In an acid-base reaction, which direction does electron flow occur?

Accepted Answer

From the base (high electron density) to the acid (low electron density).

Question 13

Which of the following best describes the stereochemical outcome of an SN2 reaction at a chiral center?

Accepted Answer

Inversion of configuration (Walden inversion).

Question 14

A chemist is comparing the reactivity of CH₃Br, CH₃CH₂Br, and (CH₃)₂CHBr in SN2 reactions. Which is expected to react the slowest and why?

Accepted Answer

(CH₃)₂CHBr, because increased substitution hinders nucleophilic attack.

Question 15

Which of the following is a correct statement about the rate law for an SN1 reaction?

Accepted Answer

Rate = k[R-LG]

Question 16

Which of the following scenarios would most likely require a deprotonation step after nucleophilic attack in a substitution reaction?

Accepted Answer

A reaction with a neutral nucleophile such as water.

Question 17

Which of the following best describes the difference between Brønsted-Lowry and Lewis acid-base definitions?

Accepted Answer

Brønsted-Lowry acids donate protons, while Lewis acids accept electron pairs.

Question 18

A reaction is carried out with a tertiary alkyl bromide and methanol as the nucleophile. Which mechanism is most likely and what is the expected stereochemical outcome?

Accepted Answer

SN1; racemization.

Question 19

Which of the following would be the best leaving group for a nucleophilic substitution reaction?

Accepted Answer

Br⁻

Nucleophilic Substitution and Acid-Base Reactions: Mechanisms and Properties

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