The Carboxylic Acid Family Structure

Part of Carboxylic Acids · Section 2 of 15

Deep DiveUnit: Organic ChemistryGCSE

This deep dive covers The Carboxylic Acid Family Structure within Carboxylic Acids for GCSE Chemistry. Revise Carboxylic Acids in Organic Chemistry for GCSE Chemistry with 22 exam-style questions and 15 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 2 of 15 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.

🔬 The Carboxylic Acid Family Structure

General Formula: CₙH₂ₙ₊₁COOH (or CₙH₂ₙO₂)

  • All carboxylic acids contain the -COOH functional group
  • The carboxyl group is always at the end of the carbon chain
  • Example: Ethanoic acid = CH₃COOH = acetic acid (vinegar)

The First Four Carboxylic Acids (Essential to memorise!):

1. Methanoic Acid (HCOOH) — simplest; formic acid; found in ant stings; used in leather tanning
2. Ethanoic Acid (CH₃COOH) — the acid in vinegar (5-8% solution); food preservative
3. Propanoic Acid (C₂H₅COOH) — food preservative, especially in bread; anti-fungal properties
4. Butanoic Acid (C₃H₇COOH) — found in butter; gives rancid butter its smell; used in flavorings
3D ball-and-stick models of methanoic acid (HCOOH) and ethanoic acid (CH₃COOH) showing the -COOH functional group with red oxygen spheres.

Figure 1: The -COOH group contains both a C=O (carbonyl) and an -OH combined. The H in -COOH is the acidic hydrogen that can be donated as H⁺ in solution.

Practice questions for Carboxylic Acids

What is the functional group present in all carboxylic acids?

  • A. -OH
  • B. C=C
  • C. -COOH
  • D. C=O only
1 markfoundation

Explain why carboxylic acids are described as weak acids.

2 marksstandard

Quick recall flashcards

What is the formula of ethanoic acid?
CH₃COOH
What are carboxylic acids?
Organic compounds containing the -COOH carboxyl functional group

22 questions on Carboxylic Acids — practise free

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