Describe the preparation, properties and uses of ethanoic acid.
How to lay out the answer. Follow the frame, then write it in your own words.
1 · Open in one line. Ethanoic acid (acetic acid), CH₃COOH, is a carboxylic acid with the -COOH group.
2 · Preparation. Oxidation of ethanol: CH₃CH₂OH + 2[O] → CH₃COOH + H₂O (alkaline KMnO₄ or acidified K₂Cr₂O₇).
3 · Physical properties. Colourless, sour, smells of vinegar; boils at 391 K; freezes at 290 K (glacial acetic acid); mixes with water.
4 · Chemical properties with equations.
2CH₃COOH + 2Na → 2CH₃COONa + H₂↑
2CH₃COOH + Na₂CO₃ → 2CH₃COONa + H₂O + CO₂↑
CH₃COOH + NaOH → CH₃COONa + H₂O
CH₃COOH + C₂H₅OH ⇌ CH₃COOC₂H₅ + H₂O
CH₃COONa + NaOH → CH₄ + Na₂CO₃ (CaO, heat)
5 · Draw the CO₂ test. [Test tube of ethanoic acid with sodium bicarbonate, delivery tube into lime water; labels: CO₂, lime water turns milky]
6 · Uses and real life. Vinegar for pickles; coagulating rubber latex; dyes, perfumes, plastics and medicines.
7 · Close in one line. Ethanoic acid is a weak but very useful organic acid.
Scoring tip: Each balanced equation earns marks, so write the product names under them. Use the words 'brisk effervescence' for the carbonate reaction.
