Question 1

Which of the following statements about free radicals is TRUE?

Accepted Answer

Free radicals are stabilized by adjacent electron-donating groups and destabilized by adjacent electron-withdrawing groups.

Question 2

Which of the following is a chain propagation step in the free radical bromination of methane?

Accepted Answer

$$\mathrm{CH_4$ + Br^\cdot \rightarrow CH_3$^\cdot + HBr}$$

Question 3

Which of these free radicals is the most stable?

Accepted Answer

The allylic radical (radical adjacent to a double bond)

Question 4

What is the formal charge on the oxygen atom in the hydroxyl radical ($$\cdotOH$$)?

Accepted Answer

$$0$$

Question 5

In the free-radical chlorination of 1-chlorobutane, which product is formed in the highest relative proportion?

Accepted Answer

1,3-dichlorobutane

Question 6

Which of the following best describes the initiation step in the free radical halogenation of alkanes?

Accepted Answer

Homolytic cleavage of a halogen molecule by heat or light to generate two halogen radicals.

Question 7

Which of the following statements about bond dissociation energy (BDE) and radical stability is correct?

Accepted Answer

Lower BDE values indicate more stable radicals are formed upon bond cleavage.

Question 8

Which of the following best explains why tertiary radicals are more stable than secondary or primary radicals?

Accepted Answer

Tertiary radicals are stabilized by hyperconjugation and inductive effects from adjacent alkyl groups.

Question 9

Which of the following is the correct curved arrow notation for the homolytic cleavage of $$\mathrm{Cl-Cl} to $$form two chlorine radicals?

Accepted Answer

A single-headed arrow from the bond to each Cl atom.

Question 10

Which of the following pairs of hydrogens, when removed by a bromine radical, will result in the same free radical?

Accepted Answer

The two hydrogens in option B (on the same carbon adjacent to the double bond)

Question 11

Which of the following statements about the selectivity of free-radical bromination versus chlorination is correct?

Accepted Answer

Bromination is more selective for the most stable radical, while chlorination is less selective.

Question 12

In the free-radical chlorination of 1-chlorobutane, if the least reactive C-H bond has a reactivity of 1, and the relative yields are 0.16, 0.48, 1.0, and 0.40, which C-H bond is the most reactive?

Accepted Answer

The C-H bond leading to 1,3-dichlorobutane

Question 13

Which of the following best describes the effect of resonance on free radical stability?

Accepted Answer

Resonance delocalizes the unpaired electron, increasing radical stability.

Question 14

Which of the following is NOT a true statement about free radical reactions?

Accepted Answer

Free radical reactions are always initiated by acids.

Question 15

Which of the following best explains why free radicals on oxygen and nitrogen atoms are more stable than those on carbon atoms?

Accepted Answer

Oxygen and nitrogen can stabilize the unpaired electron through lone pair interactions and electronegativity.

Free Radical Chemistry Study Guide

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