A Levels Chemistry (9701)•9701/12/O/N/20
Explanation
Acid-base reaction of carboxylic acid with sodium carbonate
Steps:
- Compound Z contains a carboxylic acid group, which is acidic.
- Sodium carbonate (Na2CO3) acts as a base, reacting with the acid to form the sodium carboxylate salt and carbonic acid.
- Carbonic acid decomposes to CO2 gas and water at room temperature.
- Excess Na2CO3 ensures complete conversion to the salt in good yield.
Why A is correct:
- A depicts the sodium carboxylate salt, formed via the neutralization reaction: RCOOH + Na2CO3 → RCOONa + CO2 + H2O.
Why the others are wrong:
- B shows a decarboxylated product, requiring heat, not room temperature conditions.
- C represents an ester, which would not form under these aqueous basic conditions at room temperature.
- D indicates no reaction, but carboxylic acids readily react with carbonate bases.
Final answer: A
Topic: Carboxylic acids and derivatives
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