O Levels Chemistry (5070)•5070/11/O/N/19
Explanation
Balanced Chemical Equation for Acid-Carbonate Reaction Steps:
- Identify propanoic acid formula: CH3CH2COOH (three-carbon chain).
- Recall general reaction: 2RCOOH + MCO3 → (RCOO)2M + CO2 + H2O, where M is metal like Ca.
- Form salt: calcium propanoate as (CH3CH2COO)2Ca.
- Balance equation: 2CH3CH2COOH + CaCO3 → (CH3CH2COO)2Ca + CO2 + H2O (atoms match: C12H24O6 left, right; Ca1, O7 both sides).
Why D is correct:
- Matches exact molecular formulas and stoichiometry per acid-carbonate neutralization law, producing specified products.
Why the others are wrong:
- A: Uses ethanoic acid (CH3COOH) instead of propanoic; salt formula incomplete (CH3COOCa lacks subscript 2).
- B: Uses ethanoic acid; unbalanced salt (CH3COOCa) and missing coefficient for salt.
- C: Uses ethanoic acid; same formula errors as A.
Final answer: D
Topic: Preparation of salts
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