DP Chemistry (first assessment 2025)

Question 19M.2.HL.TZ2.6d(ii)

Date	May 2019	Marks available	[Maximum mark: 1]	Reference code	19M.2.HL.TZ2.6d(ii)
Level	HL	Paper	2	Time zone	TZ2
Command term	Outline	Question number	d(ii)	Adapted from	N/A

d(ii).

[Maximum mark: 1]

19M.2.HL.TZ2.6d(ii)

(d(ii))

The minor product, C₆H₅–CH₂–CH₂Br, can exist in different conformational forms (isomers).

Outline what this means.

[1]

Markscheme

benzene ring «of the C₆H₅–CH₂» and the bromine «on the CH₂–Br» can take up different relative positions by rotating about the «C–C, σ–»bond [✔]

Note: Accept “different parts of the molecule can rotate relative to each other”.

Accept “rotation around σ–bond”.

Examiners report

If candidates seemed rather confused in the previous question, they seemed more so in this one. Most simply referred to isomers in general, not seeming to be slightly aware of what conformational isomerism is, even if it is in the curriculum.

Syllabus sections

Structure 3. Classification of matter » Structure 3.2—Functional groups: Classification of organic compounds » Structure 3.2.6—Structural isomers are molecules that have the same molecular formula but different connectivities. Recognize isomers, including branched, straight-chain, position and functional group isomers.

Structure 2. Models of bonding and structure » Structure 2.2—The covalent model » Structure 2.2.12—Benzene, C6H6, is an important example of a molecule that has resonance. Discuss the structure of benzene from physical and chemical evidence.

Question 19M.2.HL.TZ2.6d(ii)

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