Name an alcohol and a carboxylic acid having two carbon atoms in their structures. Draw their structures and state how this alcohol can be converted into a carboxylic acid. What happens when these two compounds react in the presence of an acid ? Write chemical equations for the reactions involved in the two cases mentioned above.
Generated by claude-sonnet-4-6 · 2026-06-15 06:50 · grounding rag
Model Answer
Alcohol (2 carbons): Ethanol (C₂H₅OH)
Carboxylic acid (2 carbons): Ethanoic acid (CH₃COOH)
Structures:
$$\text{Ethanol: } \text{CH}_3 - \text{CH}_2 - \text{OH}$$
$$\text{Ethanoic acid: } \text{CH}_3 - \text{COOH}$$
Conversion of ethanol to ethanoic acid:
Ethanol is oxidised using an oxidising agent (like alkaline KMnO₄ or acidified K₂Cr₂O₇) to form ethanoic acid:
$$\text{CH}_3\text{CH}_2\text{OH} \xrightarrow{\text{Oxidising agent}} \text{CH}_3\text{COOH}$$
Reaction between ethanol and ethanoic acid (Esterification):
When ethanol reacts with ethanoic acid in the presence of a concentrated H₂SO₄ catalyst, a sweet-smelling ester (ethyl ethanoate) is formed:
$$\text{CH}_3\text{COOH} + \text{C}_2\text{H}_5\text{OH} \xrightarrow{\text{Conc. H}_2\text{SO}_4} \text{CH}_3\text{COOC}_2\text{H}_5 + \text{H}_2\text{O}$$
The product ethyl ethanoate is used in perfumes and as a flavouring agent.
Source: Chapter 4, Section 4.4.2
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Explanation
- Two reactions are expected: oxidation of ethanol → ethanoic acid, and esterification. Write both equations clearly.
- The oxidising agent is commonly alkaline KMnO₄ or acidified K₂Cr₂O₇ — mention at least one.
- For esterification, note the acid catalyst (conc. H₂SO₄), the sweet-smelling product, and water as by-product.
- Structures should show the –OH group for ethanol and the –COOH group for ethanoic acid; full structural or condensed both acceptable in CBSE.
- Examiners award 1 mark each for: naming/drawing alcohol, naming/drawing acid, oxidation equation, esterification equation, and observation/use of ester.