CAIE A Level Chemistry 9701 · Carbonyl compounds
A colourless liquid is suspected to be a carbonyl compound. A student adds a few drops of 2,4-dinitrophenylhydrazine (2,4-DNPH) reagent to a sample of the liquid. Describe what the student would observe if the liquid is a carbonyl compound, and explain why 2,4-DNPH can be used to detect carbonyl compounds.
5 marks, so the mark scheme is looking for about 5 separate creditworthy points. Making the same point twice in different words earns it once.
Describe means: Say what happens or what something is like, in order and with detail. You are not being asked why. If there is data, quote it: name the trend, then give figures with units at the points where it changes.
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