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IB Chemistry HL 3.3 Electron Sharing Reactions Radicals Questions

Practise IB Chemistry HL 3.3 with HL questions on radicals, single-electron arrows and radical substitution mechanisms.

Syllabus
First assessment 2025
Course
Chemistry HL
Level
HL

Exam points

  • Recognize radical species and explain homolytic fission with single-barbed arrows and initiation conditions.
  • Write propagation and termination equations for alkane–halogen substitution, tracking radical intermediates.

Covered syllabus points

3.3.1—Radicals3.3.2—Homolytic fission3.3.3—Radical substitution

Question 1

[Maximum number: 2]

The Sun's energy is produced by the fusion of hydrogen nuclei.

Nuclear energy produces ionizing radiation which leads to the formation of free radicals.

Explain why free radicals are harmful to living cells.

Question 2

[Maximum number: 1]

Alkenes, such as A (shown below), are important intermediates in the petrochemical industry because they undergo addition reactions to produce a wide variety of products, such as the conversion shown below.

Figure for Question 2 — IB Chemistry HL

Another way to make B is the reaction shown below.

Figure for Question 2 — IB Chemistry HL

State the conditions required for this reaction to occur.

Question 3

[Maximum number: 4]

This question is about carbon and chlorine compounds.

Question (a)

(a)

Ethane, C2H6\mathrm{C}_{2} \mathrm{H}_{6}, reacts with chlorine in sunlight. State the type of this reaction and the name of the mechanism by which it occurs.

Type of reaction:

Mechanism:

[ 1 ]

Question (b)

(b)

Formulate equations for the two propagation steps and one termination step in the formation of chloroethane from ethane.

Two propagation steps:

One termination step:

[ 3 ]
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