IB Chemistry SL Reactivity 3.3 Electron-Sharing Radical Reactions

Practise recognising radicals, showing one-electron homolytic bond fission and constructing initiation, propagation and termination steps for alkane halogenation.

Syllabus
First assessment 2025
Topic
3.3
Level
SL

Exam points

  • recognise radicals from an unpaired electron and distinguish radical substitution from other mechanisms
  • show UV- or heat-induced homolytic fission with one bonding electron assigned to each radical
  • write and label initiation, propagation and termination equations for alkane halogenation chains

3.3 Electron sharing reactions (Radicals) question 1

[Maximum number: 1]

Antioxidants are a type of food additive.

Antioxidants such as BHT and 3-BHA prevent the unwanted reactions of free radicals. State what a free radical is.

3.3 Electron sharing reactions (Radicals) question 2

[Maximum number: 2]

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 3.3 Electron sharing reactions (Radicals) question 2 — IB Chemistry SL

Question (a)

(a)

Another way to make B is the reaction shown below.

Figure for Question (a) — IB Chemistry SL
[ 2 ]

Question (i)

(i)

State the conditions required for this reaction to occur.

[ 1 ]

Question (ii)

(ii)

Outline why it would give a poor yield of the desired product.

[ 1 ]

3.3 Electron sharing reactions (Radicals) question 3

[Maximum number: 1]

Chlorine undergoes many reactions.

State the type of reaction occurring when ethane reacts with chlorine to produce chloroethane.

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