Methanoic acid is the simplest carboxylic acid and is found naturally in ant venom. Describe the reactions of methanoic acid with sodium carbonate and with ethanol, including the name of each organic product formed.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Methanoic acid has the molecular formula HCOOH. It is a carboxylic acid that can take part in several chemical reactions typical of this functional group.
Model answer (5 marks)
Methanoic acid reacts with sodium carbonate according to:
HCOOH + Na₂CO₃ → 2 Na⁺ + HCOO⁻ + CO₂↑ + H₂O
Effervescence (bubbles of CO₂) is observed. The products are sodium methanoate (Na⁺ + HCOO⁻) and water.
In the presence of an acid catalyst (concentrated H₂SO₄) methanoic acid reacts with ethanol:
HCOOH + CH₃CH₂OH → CH₃COOCH₂CH₃ + H₂O
The organic product is ethyl methanoate (an ester).
HCOOH + Na₂CO₃ → 2 Na⁺ + HCOO⁻ + CO₂↑ + H₂O
Effervescence (bubbles of CO₂) is observed. The products are sodium methanoate (Na⁺ + HCOO⁻) and water.
In the presence of an acid catalyst (concentrated H₂SO₄) methanoic acid reacts with ethanol:
HCOOH + CH₃CH₂OH → CH₃COOCH₂CH₃ + H₂O
The organic product is ethyl methanoate (an ester).
Examiner tips
- Use the correct balanced equations, include CO₂ effervescence and water for the carbonate reaction; mention the ester for the ethanol reaction.
- Show the acid catalyst in the esterification step; name the ester explicitly.
- Use UK spelling (e.g., ‘ethanol’).
Common mistakes
- Writing the carbonate reaction without CO₂ effervescence or water; confusing the salt name; omitting the acid catalyst in the esterification; misnaming the ester (e.g., ‘methyl methanoate’).
Mark scheme (5 marks)
- Methanoic acid reacts with sodium carbonate to produce carbon dioxide (effervescence / bubbles / fizzing observed)
- A salt (sodium methanoate) is also produced in the reaction with sodium carbonate
- Water is also produced in the reaction with sodium carbonate
- Methanoic acid reacts with ethanol in the presence of an acid catalyst (concentrated sulfuric acid) to form an ester
- The ester formed is ethyl methanoate
Key terms in this question
carboxylic acid · sodium carbonate · ethanol
Related
- All Eduqas A-Level Chemistry revision notes →
- How to answer a "Describe" question →
- Decode the mark scheme abbreviations →
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