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

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.

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.