Question 1

Which is the best nucleophile?&#10;A) C-&#10;B) N-&#10;C) O-&#10;D) F-

Accepted Answer

On the periodic chart, basicity increases as you go up the chart in a group or as you go left across a period. Carbon is the furthest left across the 2nd period. It is the strongest base and the most unstable base. This makes it the best nucleophile.

Question 2

The best leaving group produces a _________ base that is a(n) _________ anion.&#10;A) weak, stable&#10;B) strong, stable&#10;C) weak, unstable&#10;D) strong, unstable

Accepted Answer

The more stable the anion produced by the leaving group the more likely the leaving group is to break off the substrate. That makes it a good leaving group. Weak bases are the most stable anions. If an anion is unstable it wants to react and that makes it a strong base.

Question 3

Which is the best leaving group?&#10;A) Br-&#10;B) Cl-&#10;C) F-&#10;D) I-

Accepted Answer

On the periodic chart, basicity increases as you go up the chart in a group or as you go left across a period. Iodine is the lowest in the 17th group and therefore is the weakest base. Recall, weakest base = best leaving group.

Question 4

S_N2 reactions are ________ and have ________ kinetics. A) unimolecular, 2nd order B) unimolecular, 1st order C) bimolecular, 2nd order D) bimolecular, 1st order

Accepted Answer

S_N2 reactions are bimolecular because they involve two species in the rate-determining step: the nucleophile and the substrate. They have second-order kinetics because the rate depends on the concentration of both the nucleophile and the substrate.

Question 5

In an SN2 reaction, if the [nucleophile] doubles, the reaction rate ________. In an SN2 reaction, if the [substrate] doubles, the reaction rate ________.&#10;A) doubles, doubles&#10;B) halves, halves&#10;C) doubles, halves&#10;D) halves, doubles&#10;E) doubles, will not be effected&#10;F) will not be effected, doubles

Accepted Answer

In an SN2 reaction, the reaction rate is affected by both the nucleophile and the substrate. That is what bimolecular means in this case.

Question 6

SN2 reactions proceed with a(n) ________ of configuration.&#10;A) inversion&#10;B) retention&#10;C) racemization

Accepted Answer

SN2 reactions proceed with inversion of configuration because the nucleophile attacks from the opposite side of the leaving group, resulting in a stereochemical inversion.

Question 7

SN1 reactions are ________ and have ________ kinetics.&#10;A) unimolecular, 2nd order&#10;B) unimolecular, 1st order&#10;C) bimolecular, 2nd order&#10;D) bimolecular, 1st order

Accepted Answer

SN1 reactions are unimolecular and follow first-order kinetics because the rate-determining step involves the formation of a carbocation intermediate from a single molecule.

Question 8

In an SN1 reaction, if the [nucleophile] doubles, the reaction rate ________. In an SN1 reaction, if the [substrate] doubles, the reaction rate ________.&#10;A) doubles, doubles&#10;B) halves, halves &#10;C) doubles, halves&#10;D) halves, doubles&#10;E) doubles, will not be effected&#10;F) will not be effected, doubles

Accepted Answer

In an SN1 reaction, the reaction rate is affected by only the substrate. That is what unimolecular means in this case.

Question 9

The SN2 mechanism is characterized by the presence of a(n)________. The SN1 mechanism is characterized by the formation of a(n) _________ called a(n) ________&#10;A) intermediate, transition state, carbocation&#10;B) transition state, intermediate, carbanion&#10;C) intermediate, intermediate, carbanion&#10;D) transition state, intermediate, carbocation e) transition state, transition state, carbocation

Accepted Answer

The SN2 mechanism involves a transition state where the nucleophile attacks the substrate, leading to a concerted reaction. The SN1 mechanism involves the formation of a carbocation intermediate after the leaving group departs.

Question 10

Which mechanism(s) is represented by the following? A) S_N1 B) S_N2 C) E1 D) E2 E) S_N1 solvolysis F) a and c G) b and d H) a, c and e

Accepted Answer

S_N1 solvolysis mechanisms are characterized by the formation of a carbocation and by the removal of a hydrogen to form the final product (3 "energy hills" in the energy diagram).

Question 11

The order for stability of carbocations is __________&#10;A) methyl > tertiary > secondary > primary&#10;B) methyl > primary > secondary > tertiary&#10;C) tertiary > secondary > primary > methyl&#10;D) secondary > tertiary > primary > methyl

Accepted Answer

The answer of The order for stability of carbocations is...

Question 12

Carbocations have __________ geometry&#10;A) tetrahedral&#10;B) octahedral&#10;C) bent&#10;D) linear&#10;E) trigonal pyramidal&#10;F) trigonal planar

Accepted Answer

The answer of Carbocations have __________ geometry&#10;A) tetrahedral&#10;B) octahedral&#10;C) bent&#10;D)...

Question 13

SN1 reactions produce ________ products&#10;A) inverted&#10;B) identical&#10;C) racemic

Accepted Answer

The answer of SN1 reactions produce ________ products&#10;A) inverted&#10;B) identical&#10;C)...

Question 14

In an SN2 reaction, reaction rates are affected by th__________ of the substrate. In an SN1 reaction, reaction rates are determined by the __________ of the carbocation.&#10;A) stability, substrate&#10;B) steric hindrance, stability&#10;C) substrate, concentration&#10;D) stability, steric hindrance

Accepted Answer

The answer of In an SN2 reaction, reaction rates are...

Question 15

SN1 reactions run best in __________ solvents and SN2 reactions run best in _________ solvents.&#10;A) polar protic, polar protic&#10;B) polar protic, polar aprotic&#10;C) polar aprotic, polar aprotic&#10;D) polar aprotic, polar protic

Accepted Answer

The answer of SN1 reactions run best in __________ solvents...

Question 16

Which of the following is a polar protic solvent?&#10; &#10;A) I&#10;B) II&#10;C) III&#10;D) IV&#10;E) I and IV&#10;F) I, II and IV&#10;G) all of the above

Accepted Answer

The answer of Which of the following is a polar...

Question 17

Which mechanism(s) is represented by the following? A) S_N1 B) S_N2 C) E1 D) E2 E) S_N1 solvolysis F) a and c G) b and d H) a, c and e

Accepted Answer

The answer of Which mechanism(s) is represented by the following?&#10;...

Question 18

Which mechanism(s) is represented by the following? A) S_N1 B) S_N2 C) E1 D) E2 E) S_N1 solvolysis F) a and c G) b and d H) a, c and e

Accepted Answer

The answer of Which mechanism(s) is represented by the following?&#10;...

Question 19

__________ increases the likelihood of elimination occurring instead of substitution.&#10;A) Increased pressure&#10;B) Increased temperature&#10;C) Decreased pressure&#10;D) Decreased temperature

Accepted Answer

The answer of __________ increases the likelihood of elimination occurring...

Question 20

SN2 reactions proceed fastest with ________ substrates&#10;A) Primary&#10;B) Secondary&#10;C) Tertiary

Accepted Answer

The answer of SN2 reactions proceed fastest with ________ substrates&#10;A)...

Question 21

Primary substrates always give SN2 reactions with all
Bases except for ________, which will give E2 reactions due to its steric hindrance.

A) Sodium methoxide
B) Sodium ethoxide
C) Potassium hydroxide
D) Potassium methoxide
E) Potassium tert-butoxide

Accepted Answer

The answer of Primary substrates always give SN2 reactions with...

Question 22