This topic summary covers Knowledge Organiser: Carboxylic Acids 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 15 of 15 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Knowledge Organiser: Carboxylic Acids
Key Terms
- Functional group — -COOH (carboxyl)
- Weak acid — partially dissociates
- General formula — CₙH₂ₙ₊₁COOH
- Formation — oxidise alcohols
First Four Acids
- Methanoic acid — HCOOH (ants)
- Ethanoic acid — CH₃COOH (vinegar)
- Propanoic acid — C₂H₅COOH
- Butanoic acid — C₃H₇COOH (butter)
Key Reactions
- + Metal → salt + H₂
- + Carbonate → salt + H₂O + CO₂ (test!)
- + Alkali → salt + H₂O
- + Alcohol → ester + H₂O (reversible)
Exam Checklist
- Weak acid = partial dissociation, ⇌ symbol
- Carbonate test: fizzing → CO₂ → milky limewater
- Ester formation uses ⇌ (reversible)
- Naming: -anoic acid suffix
Key Equations
- CH₃COOH ⇌ CH₃COO⁻ + H⁺ (ethanoic acid dissociation — weak/partial)
- 2CH₃COOH + Na₂CO₃ → 2CH₃COONa + H₂O + CO₂
- CH₃COOH + C₂H₅OH ⇌ CH₃COOC₂H₅ + H₂O (esterification)
Common Mistakes
- Saying carboxylic acids are strong acids: They are WEAK acids — they only partially dissociate in water; use ⇌ not → in the dissociation equation
- Forgetting esterification is reversible: Carboxylic acid + alcohol ⇌ ester + water — the ⇌ symbol must be used; writing → loses marks
- Confusing the -COOH and -OH functional groups: Carboxylic acids have -COOH; alcohols have -OH — they are different functional groups with different properties
- Saying no gas is produced with carbonates: Carboxylic acids DO react with carbonates to produce CO₂ (fizzing) — this is the test for carboxylic acids vs alcohols
Practice questions for Carboxylic Acids
What is the functional group present in all carboxylic acids?
Explain why carboxylic acids are described as weak acids.
Quick recall flashcards
What are carboxylic acids?
Organic compounds containing the -COOH carboxyl functional group
What is the formula of ethanoic acid?
CH₃COOH