DP Chemistry (last assessment 2024)

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Question 22N.2.hl.TZ0.6a

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Date November 2022 Marks available [Maximum mark: 2] Reference code 22N.2.hl.TZ0.6a
Level hl Paper 2 Time zone TZ0
Command term Sketch Question number a Adapted from N/A
a.
[Maximum mark: 2]
22N.2.hl.TZ0.6a

2-Bromobutane can react with cyanide, CN−, in a nucleophilic substitution reaction.

(a)

This reaction could proceed through either SN1 or SN2 mechanisms depending on the reaction conditions. Sketch a graph of the rate versus nucleophile concentration, [CN−], for each of the mechanisms.

[2]

Markscheme

SN1 mechanism:

✔

 

SN2 mechanism:

✔

Examiners report

The average mark was <50% which probably arose from many candidates having difficulty in translating their rate equation knowledge of SN1 and SN2 reactions into a graphical context.

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