WJEC A Level Chemistry
WJEC A Level Chemistry 4.4 Aldehydes and Ketones Exam Questions
Free WJEC A Level Chemistry exam questions on 4.4 Aldehydes and Ketones, with mark schemes. Covers oxidation, reduction, nucleophilic addition and tests for carbonyl compounds.
4.4 Aldehydes and Ketones exam questions
1 question pack of real past exam questions with its mark scheme. Answer every question without notes, then mark your answers line by line against the mark scheme.
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WJEC A Level Chemistry Flashcards (Anki & Quizlet)
Every answer is written in mark scheme wording, so you learn exactly what examiners give marks for. Use them on Anki or Quizlet, then test yourself with the questions on this page.
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About WJEC A Level Chemistry 4.4 Aldehydes and Ketones
This topic covers carbonyl chemistry.
What you need to know
- Oxidation Aldehydes oxidise to carboxylic acids; ketones do not.
- Reduction NaBH₄ reduces aldehydes to primary alcohols and ketones to secondary alcohols.
- Nucleophilic addition HCN adds to form hydroxynitriles, with a mechanism.
- Tests 2,4-DNPH for carbonyls; Tollens' and Fehling's to distinguish aldehydes.
Common mistakes in 4.4 Aldehydes and Ketones
- Saying ketones give a silver mirror.
- Drawing the nucleophile attacking oxygen.
- Forgetting HCN addition can form a racemic mixture.
Try three 4.4 Aldehydes and Ketones exam-style questions
1. State the observation for an aldehyde with Tollens' reagent. (1 mark)
Show the mark scheme answer
A silver mirror forms.
2. Name the reagent that reduces carbonyls to alcohols. (1 mark)
Show the mark scheme answer
Sodium tetrahydridoborate (NaBH₄).
3. Explain why HCN addition to ethanal gives a racemic mixture. (2 marks)
Show the mark scheme answer
The carbonyl group is planar (1), so the nucleophile attacks equally from either side (1).
4.4 Aldehydes and Ketones FAQs
What does Aldehydes and Ketones cover?
Oxidation, reduction, nucleophilic addition and tests.
Which practical links here?
Identifying carbonyl compounds with 2,4-DNPH and Tollens' reagent.
How is 2,4-DNPH used?
It forms an orange precipitate; its melting point identifies the compound.
Revise this topic with flashcards: WJEC A Level Chemistry Flashcards, with mark scheme answers for Anki and Quizlet.
