O Levels Chemistry (5070)•5070/12/O/N/22
Explanation
Acid-carbonate salt formation Steps:
- Recognize propanoic acid as RCOOH (R=CH3CH2), but choices use CH3COOH analogously.
- Recall general reaction: 2RCOOH + CaCO3 → (RCOO)2Ca + CO2 + H2O.
- Balance equation: 2 acids neutralize carbonate, yielding salt, CO2 gas, and water.
- Compare choices to match reactants (CaCO3) and products (salt, CO2, H2O).
Why C is correct:
- Matches acid-carbonate reaction formula, producing calcium propanoate (as (CH3COO)2Ca analog), CO2, and H2O per standard neutralization.
Why the others are wrong:
- A: Wrong salt formula (2CH3COOCa) and unbalanced; implies two separate salts.
- B: Uses CaO (oxide), not CaCO3 (carbonate), so no CO2 produced.
- D: Uses CaO but incorrectly includes CO2, which oxide reactions do not generate.
Final answer: C
Topic: Preparation of salts
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