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CAIE A-Level Chemistry AS 15.1 Halogenoalkanes Questions

Practise preparing and classifying halogenoalkanes and choosing substitution or elimination conditions and mechanisms.

Syllabus
2028–2030
Course
Chemistry 9701
Level
AS

Exam points

  • classify the C–X carbon as primary, secondary or tertiary from its carbon attachments
  • choose aqueous OH−, ethanolic CN− or ethanolic NH3 for the required nucleophilic substitution product
  • use hot ethanolic hydroxide for elimination to an alkene and distinguish it from aqueous substitution

Covered syllabus points

15.1.1—Preparation of halogenoalkanes15.1.2—Classify halogenoalkanes into primary,15.1.3—Nucleophilic substitution15.1.4—Elimination reaction with NaOH in ethanol15.1.5—SN1/SN2 substitution mechanisms15.1.6—SN2/SN1 trends in halogenoalkanes15.1.7—Rate of hydrolysis of halogenoalkanes

Question 1

[Maximum number: 1]

1,2-dibromopropane can be made from 1-bromopropane in two steps.
Which row is correct?

step 1

step 2

addition

substitution

elimination

addition

hydrolysis

elimination

substitution

hydrolysis

Question 2

[Maximum number: 1]

Which row shows the correct name and classification of the halogenoalkane shown?

CH3(CH2)2CBr(CH3)CH2CH3\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{2} \mathrm{CBr}\left(\mathrm{CH}_{3}\right) \mathrm{CH}_{2} \mathrm{CH}_{3}

name

classification of halogenoalkane

3-bromo-3-methylhexane

secondary

3-bromo-3-methylhexane

tertiary

3-bromo-4-methylhexane

tertiary

4-bromo-5-methylhexane

secondary

Question 3

[Maximum number: 1]

Compound X is treated with an excess of dilute aqueous potassium hydroxide.

Figure for Question 3 — CAIE A-Level Chemistry AS

What is the structure of the organic product?

A
Figure for Question 3 — CAIE A-Level Chemistry AS — Option A
B
Figure for Question 3 — CAIE A-Level Chemistry AS — Option B
C
Figure for Question 3 — CAIE A-Level Chemistry AS — Option C
Figure for Question 3 — CAIE A-Level Chemistry AS
D

Option D as shown in the official source

Question 4

[Maximum number: 1]

Structural isomerism and stereoisomerism should be considered when answering this question. 2-bromopentane is heated with an excess of ethanolic sodium hydroxide.

How many different hydrocarbons are produced?

A

1

B

2

C

3

D

4

Question 5

[Maximum number: 1]

Q is either a primary or a tertiary halogenoalkane. Q undergoes hydrolysis with aqueous sodium hydroxide.

The first step in the mechanism of this reaction involves two species reacting together.
Which row is correct?

Q

behaviour of hydroxide ion

primary halogenoalkane

electrophile

primary halogenoalkane

nucleophile

tertiary halogenoalkane

electrophile

tertiary halogenoalkane

nucleophile

Question 6

[Maximum number: 1]

Which statement describes what happens when 2-chloro-2-methylpropane is warmed with NaOH(aq) ?

A

This secondary halogenoalkane reacts by a mixture of an SN1\mathrm{S}_{\mathrm{N}} 1 and an SN2\mathrm{S}_{\mathrm{N}} 2 mechanism.

B

This secondary halogenoalkane reacts only by an SN2\mathrm{S}_{\mathrm{N}} 2 mechanism.

C

This tertiary halogenoalkane reacts mostly by an SN1\mathrm{S}_{\mathrm{N}} 1 mechanism.

D

This tertiary halogenoalkane does not react with hydroxide ions under these conditions.

Question 7

[Maximum number: 1]

Which compound reacts most rapidly with aqueous silver nitrate by an SN1\mathrm{S}_{\mathrm{N}} 1 mechanism?

A

1-chloromethylpropane

B

2-chloromethylpropane

C

1-iodomethylpropane

D

2-iodomethylpropane

All question bank results loaded