Q: What is the rate law for an SN1 reaction involving a tertiary alkyl bromide and water as the nucleophile?

$$ \text{Rate} = k[\text{R-Br}] $$

Question 1

Which of the following statements best explains why tertiary alkyl halides react much faster than primary alkyl halides in SN1 reactions?

Accepted Answer

Tertiary alkyl halides form more stable carbocations due to greater alkyl group electron donation.

Question 2

What is the rate law for an SN1 reaction involving a tertiary alkyl bromide and water as the nucleophile?

Accepted Answer

$$ 	ext{Rate} = k[	ext{R-Br}] $$

Question 3

Which of the following best describes the stereochemical outcome of an SN1 reaction starting from an enantiomerically pure chiral alkyl halide?

Accepted Answer

A racemic mixture due to planar carbocation intermediate.

Question 4

Why does the SN1 reaction often result in incomplete racemization rather than a perfectly racemic mixture?

Accepted Answer

Ion pairs partially shield one face of the carbocation, favoring one configuration.

Question 5

Which of the following solvents would most increase the rate of an SN1 reaction?

Accepted Answer

Water

Question 6

Which of the following is the best leaving group for an SN1 reaction?

Accepted Answer

$$ 	ext{H}_2	ext{O} $$

Question 7

A tertiary alcohol reacts with HBr to form a tertiary alkyl bromide. What is the first mechanistic step in this reaction?

Accepted Answer

Protonation of the alcohol oxygen by HBr.

Question 8

Which of the following carbocations is most stabilized by resonance?

Accepted Answer

Benzylic carbocation

Question 9

According to Zaitsev’s rule, which alkene is favored in an elimination reaction?

Accepted Answer

The alkene with the most alkyl substituents.

Question 10

Which of the following statements about the E2 elimination mechanism is correct?

Accepted Answer

The C–H and C–X bonds break simultaneously in a single step.

Question 11

Which of the following best explains why polar solvents increase the rate of SN1 reactions?

Accepted Answer

They stabilize the carbocation intermediate by solvation.

Question 12

Which of the following is the correct order of carbocation stability?

Accepted Answer

Methyl \u003c Primary \u003c Allylic ≈ Benzylic \u003c Secondary \u003c Tertiary

Question 13

In the SN1 reaction of (R)-6-chloro-2,6-dimethyloctane in ethanol, the product mixture is 60% S and 40% R. What does this indicate about the mechanism?

Accepted Answer

The reaction involves ion pairs that partially shield one face of the carbocation.

Question 14

Which of the following statements about the nucleophile in SN1 reactions is correct?

Accepted Answer

The nucleophile does not affect the rate of the reaction.

Question 15

Which of the following best describes the E1cB elimination mechanism?

Accepted Answer

C–H bond breaks first, forming a carbanion intermediate.

Question 16

Which of the following is the correct order of leaving group reactivity for SN1 reactions?

Accepted Answer

$$ 	ext{HO}^- \u003c 	ext{Cl}^- \u003c 	ext{Br}^- \u003c 	ext{I}^- \u003c 	ext{H}_2	ext{O} $$

Question 17

A student mixes 2-bromobutane with sodium ethoxide in ethanol. The major product is 2-butene. Which rule explains this outcome?

Accepted Answer

Zaitsev's rule

Question 18

Which of the following best describes the rate-determining step in an SN1 reaction?

Accepted Answer

Loss of the leaving group to form a carbocation.

Question 19

Which of the following statements about the effect of solvent on SN1 reaction rates is correct?

Accepted Answer

Polar solvents stabilize the carbocation intermediate, increasing the reaction rate.

Nucleophilic Substitution and Elimination Reactions of Alkyl Halides (SN1, E1, E2, E1cB)

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