OCR A Level Chemistry B (Salters)
OCR A Level Chemistry B What’s in a Medicine? (WM) Exam Questions
Free OCR A Level Chemistry B exam questions for What’s in a Medicine? (WM), with a mark scheme for every pack. Covers alcohols, phenols, carboxylic acids, esters, oxidation, esterification, infrared spectroscopy, mass spectrometry, chromatography and organic practical techniques such as aspirin synthesis.
What’s in a Medicine? (WM) exam questions
1 question pack of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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A-Level Chemistry Flashcards for 2027 Onwards
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About OCR A Level Chemistry B What’s in a Medicine? (WM)
What’s in a Medicine? is a Year 1 storyline of OCR A Level Chemistry B (Salters) built around aspirin and other medicines. It covers the functional groups found in drug molecules, especially alcohols, phenols and carboxylic acids, and their reactions including oxidation and esterification. You also learn analytical techniques such as infrared spectroscopy, mass spectrometry and thin-layer chromatography, and practical skills for preparing and purifying an organic solid, for example by recrystallisation and checking melting point. Examiners like tests to distinguish functional groups, identifying compounds from IR and mass spectra, and describing preparation and purification steps.
What you need to know
- Alcohols Primary, secondary and tertiary alcohols; oxidation with acidified dichromate (orange to green) to aldehydes, carboxylic acids or ketones; dehydration to alkenes; esterification with carboxylic acids or anhydrides.
- Phenols Phenols are weak acids: they react with sodium hydroxide but not sodium carbonate. Neutral iron(III) chloride gives a purple colour with phenols.
- Carboxylic acids and esters Carboxylic acids react with carbonates giving CO2; they form esters with alcohols using a concentrated sulfuric acid catalyst. Aspirin is made by esterifying the phenol group in salicylic acid.
- Infrared spectroscopy Bonds absorb IR at characteristic wavenumbers: broad O to H in alcohols around 3200 to 3600 cm-1, very broad O to H in acids, and C=O around 1700 cm-1.
- Mass spectrometry The molecular ion gives Mr; fragmentation peaks give structural clues; high resolution mass spectra can distinguish molecules with the same nominal Mr.
- Practical techniques Heating under reflux, distillation, recrystallisation from minimum hot solvent, filtration under reduced pressure, melting point to check purity and TLC with Rf values.
Common mistakes in What’s in a Medicine? (WM)
- Saying tertiary alcohols are oxidised to ketones. They are not oxidised by acidified dichromate.
- Testing phenol with sodium carbonate and expecting fizzing. Phenol is too weak an acid.
- Identifying an alcohol from any peak near 3000 cm-1. Look for the broad O to H band and remember C to H absorbs near 2900 cm-1.
- Describing recrystallisation with too much solvent. Use the minimum volume of hot solvent so the product crystallises on cooling.
- Measuring Rf from the bottom of the plate rather than from the baseline.
Try three What’s in a Medicine? (WM) exam-style questions
1. Describe chemical tests to distinguish between ethanol, phenol and ethanoic acid. (3 marks)
Show the mark scheme answer
Add sodium carbonate solution: ethanoic acid fizzes (CO2); add neutral iron(III) chloride solution: phenol gives a purple colour; ethanol gives no change with either.
2. In a TLC experiment, a spot travels 2.4 cm and the solvent front travels 6.0 cm. Calculate the Rf value and explain how TLC shows a product is pure. (2 marks)
Show the mark scheme answer
Rf = 2.4 / 6.0 = 0.40; a pure product gives a single spot (with the same Rf as a reference sample).
3. Outline how impure aspirin can be purified by recrystallisation. (3 marks)
Show the mark scheme answer
Dissolve in the minimum volume of hot solvent; filter hot to remove insoluble impurities, then cool to crystallise; filter under reduced pressure, wash with a little cold solvent and dry.
What’s in a Medicine? (WM) FAQs
What does OCR A Level Chemistry B What’s in a Medicine? (WM) cover?
It covers alcohols, phenols, carboxylic acids and esters, oxidation and esterification, infrared spectroscopy, mass spectrometry, chromatography and organic preparation and purification techniques.
Which papers is What’s in a Medicine? examined in?
In the Salters A Level, content from any storyline can be assessed in all three papers: Fundamentals of chemistry, Scientific literacy in chemistry and Practical skills in chemistry.
What practical skills does WM involve?
You should be able to describe and evaluate reflux, distillation, recrystallisation, filtration under reduced pressure, melting point determination and TLC, especially in the context of making aspirin.
