CAIE A Level Chemistry 9701 · Carbonyl compounds
A student is given a colourless liquid P. A few drops of P are added to a solution of 2,4-dinitrophenylhydrazine (2,4-DNPH reagent). An orange precipitate forms immediately. Describe how the student can use this result, and the further tests described below, to deduce whether P is an aldehyde or a ketone, and to identify it.
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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