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CAIE A-Level Chemistry 17.1.5 Aldehyde and Ketone Tests

Practise distinguishing aldehydes from ketones using Tollens’, Fehling’s and oxidation evidence.

Syllabus
2028–2030
Course
Chemistry 9701
Level
AS

Exam points

  • identify an aldehyde from a silver mirror with Tollens’ reagent or brick-red precipitate with Fehling’s
  • identify a ketone when 2,4-DNPH is positive but Tollens’ and Fehling’s tests remain negative
  • use reduction product and oxidation behaviour as supporting evidence when several functional groups are possible

17.1.5—The nature (aldehyde or ketone) of an unknown question 1

[Maximum number: 1]

4(CH3)3CCHO4\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCHO} is used in the synthesis of some antibiotics.

X, Y and Z are all isomers of (CH3)3CCHO\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCHO}.

A summary of some of the reactions and properties of X, Y and Z is shown in the table.

Table for Question 17.1.5—The nature (aldehyde or ketone) of an unknown question 1 — CAIE A-Level Chemistry AS

Identify the functional group present in Y that causes the recorded observation with Fehling's solution.

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