AQA A-Level Chemistry Paper 3, June 2022: Question 26

1 mark · Easy difficulty · Multiple Choice

Identify which given organic formula represents an amide.

Practise this question

Question

Multiple-choice question 26 asks: 'Which compound is an amide?' followed by four options: A: CH3CH2CH2CN, B: CH3CONHCH2CH3, C: CH3COOCH2CH3, D: CH3NHCH2CH2CH3. Each option has a selection bubble to the right.
Question text

26 Which compound is an amide?

[1 mark]

A CH3CH2CH2CN

B CH3CONHCH2CH3

C CH3COOCH2CH3

D CH3NHCH2CH2CH3

Mark scheme

Show the mark scheme Mark scheme table row for question 26 shows the correct answer is B (AO1) with 1 mark, corresponding to CH3CONHCH2CH3.

26 B (AO1) 1 CH3CONHCH2CH3

How to answer it

Identifying Organic Functional Groups: Amides

📋 What this question tests

This question assesses fundamental recall and structural recognition (AO1) from organic chemistry:

  • Recognising condensed structural formulas of common functional groups.
  • Distinguishing between amides ( -CONH- ), amines ( -NH- ), esters ( -COO- ), and nitriles ( -CN ).
Question 26

Which compound is an amide?

Multiple Choice Question (1 Mark)

✅ Correct Answer

B: CH₃CONHCH₂CH₃

Mark Scheme: Award 1 mark for option B (AO1).

The condensed formula contains the group -CONH- , which represents a carbonyl group bonded directly to a nitrogen atom ( -C(=O)-NH- ). This is a secondary (N-substituted) amide, named N-ethylethanamide.

💡 Key Knowledge: Deconstructing the Options

  • A: CH₃CH₂CH₂CN
    Functional group: -C≡N .
    Class: Nitrile (butan-1-nitrile).
  • B: CH₃CONHCH₂CH₃
    Functional group: -C(=O)NH- .
    Class: Amide (N-ethylethanamide).
  • C: CH₃COOCH₂CH₃
    Functional group: -C(=O)O- .
    Class: Ester (ethyl ethanoate).
  • D: CH₃NHCH₂CH₂CH₃
    Functional group: -NH- (no adjacent C=O).
    Class: Secondary Amine (N-methylpropylamine).

❌ Common Errors & Misconceptions

  • Confusing Amides with Amines: Students frequently confuse option B with option D. Remember:
    • Amine: Nitrogen bonded strictly to alkyl carbons or hydrogens (e.g. R-NH-R' ).
    • Amide: Nitrogen bonded directly to a carbonyl carbon ( R-CO-NH-R' ).
  • Misreading Condensed Formulas: Glancing quickly at the formulas can cause students to overlook the CO in CH₃CONH... , mistaking it for a simple alkyl chain or amine.

🧠 Exam Technique: 5-Second Scan

  • Scan for the carbonyl: For an amide, you need both a carbonyl ( C=O ) and a nitrogen ( N ) bonded together. Look specifically for the CONH sequence.
  • Elimination method:
    • See CN at the end? Immediately eliminate (nitrile).
    • See COO with no N? Immediately eliminate (ester).
    • See NH but no CO ? Eliminate (amine).

Topics

Organic Chemistry · 3.3.1 Introduction to Organic Chemistry · 3.3.9 Carboxylic Acids and Derivatives

Question and mark scheme from the AQA A-Level Chemistry examination, Paper 3, June 2022. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.