A Levels Chemistry (9701)•9701/11/M/J/18
Explanation
Incorrect product from CO2 reaction with carboxylate salt
Steps:
- Identify standard reactions: hydrolysis for A and D, acid-metal for B, acidification for C.
- Check A: Potassium propanoate hydrolyzes to propanoic acid and KOH, formulas match.
- Check B: Propanoic acid reduces Mg to form magnesium propanoate and H2, formulas correct despite missing coefficient.
- Check C: CO2 + H2O forms H2CO3, which protonates carboxylate to give RCOOH and HCO3-, not CO3^2-.
- Check D: Calcium propanoate hydrolyzes to 2 propanoic acids and Ca(OH)2, formulas match.
Why C is correct:
- Reaction of sodium carboxylate with CO2 produces NaHCO3 (bicarbonate) per acid-base equilibrium, not Na2CO3 (carbonate), violating product stoichiometry from carbonic acid dissociation.
Why the others are wrong:
- A: Shows accurate hydrolysis products for alkali metal carboxylate.
- B: Lists correct salt and gas products from carboxylic acid-metal reaction.
- D: Displays proper hydrolysis products for alkaline earth carboxylate salt.
Final answer: C
Topic: Carboxylic acids and derivatives
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