| Date | May 2017 | Marks available | 3 | Reference code | 17M.3.hl.TZ1.25 |
| Level | HL | Paper | 3 | Time zone | TZ1 |
| Command term | Discuss | Question number | 25 | Adapted from | N/A |
Question
Solubility plays an important role in the bioavailability of drugs in the body.
Some mild analgesics contain a solid mixture of acidic aspirin and a non-acidic organic chemical of similar polarity to asprin.
Discuss how acid-base properties and the process of solvent extraction can be used to separate aspirin from the mixture.
Markscheme
dissolve compounds in an organic solvent
add NaOH(aq)/OH–(aq) «to the mixture» to convert aspirin to its water soluble salt
separate the two «immiscible» layers
convert salt «in aqueous layer» back to aspirin by reacting with acid/H+
«evaporate solvents and dry»
Accept organic solvents immiscible with water such as hexane, ethyl ethanoate, butyl acetate.
Accept any other base.
Need explanation for mark.
[3 marks]
Examiners report
[N/A]
