DP Chemistry (last assessment 2024)

Question 20N.3.hl.TZ0.c

Date	November 2020	Marks available	[Maximum mark: 1]	Reference code	20N.3.hl.TZ0.c
Level	hl	Paper	3	Time zone	TZ0
Command term	Draw	Question number	c	Adapted from	N/A

[Maximum mark: 1]

20N.3.hl.TZ0.c

Aspirin is formed by reacting salicylic acid with ethanoic anhydride. The structure of aspirin is given in section 37 of the data booklet.

The solubility of aspirin is increased by converting it to an ionic form. Draw the structure of the ionic form of aspirin.

[1]

Markscheme

✔

Accept a positive metal ion next to the $C O O^{-}$ such as “ $N a^{-} / K^{+}$ ”.

Accept “ $- O N a / - O K$ ” without showing the charges.

Accept notations such as “ $R C O O^{-}$ ” OR “ $R C O O N a$ ” OR “ $R C O O K$ ” but not “ $R O^{-}$ ” OR “ $R O N a$ ” OR “ $R O K$ ”.

Examiners report

A drawing of the structure of the ionic form of aspirin was required for this question. This question was poorly answered by a significant number of candidates, and lots of basic chemical errors were seen, such as incorrect valencies, writing RCO- instead of RCOO-, showing a cationic structure instead of an anionic structure etc. A couple of candidates also lost the mark by drawing square brackets with a negative charge both inside and outside the bracket.

Syllabus sections

Options

Options » D: Medicinal chemistry » D.2 Aspirin and penicillin

Options » D: Medicinal chemistry

Question 20N.3.hl.TZ0.c

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