DP Chemistry (last assessment 2024)
Question 20N.3.hl.TZ0.b
| Date | November 2020 | Marks available | [Maximum mark: 1] | Reference code | 20N.3.hl.TZ0.b |
| Level | hl | Paper | 3 | Time zone | TZ0 |
| Command term | Suggest | Question number | b | Adapted from | N/A |
b.
[Maximum mark: 1]
20N.3.hl.TZ0.b
Aspirin is formed by reacting salicylic acid with ethanoic anhydride. The structure of aspirin is given in section 37 of the data booklet.
Aspirin crystals are rinsed with water after recrystallization to remove impurities.
Suggest why cold water is used.
[1]
Markscheme
to avoid dissolving the crystals/aspirin ✔
Accept “to avoid loss of product” OR “aspirin is less soluble in cold water”.
Examiners report
Many were unable to explain why aspirin should be washed with cold water, namely, to avoid dissolving crystals. Surprisingly, the incorrect term "melt" was frequently used instead of "dissolve".
