Methanoic acid is a carboxylic acid found naturally in ant venom. Describe what is observed and identify the products formed when methanoic acid reacts with magnesium ribbon.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Methanoic acid, HCOOH, is the simplest carboxylic acid. It is a weak acid that undergoes typical acid reactions with metals.
Model answer (4 marks)
Effervescence is observed as bubbles of gas form.
The magnesium ribbon dissolves, becoming smaller.
Hydrogen gas is released.
A salt, magnesium methanoate (Mg(HCOO)₂), is formed.
The magnesium ribbon dissolves, becoming smaller.
Hydrogen gas is released.
A salt, magnesium methanoate (Mg(HCOO)₂), is formed.
Examiner tips
- Use the word "effervescence" to show observation. Mention the magnesium ribbon dissolving. State that H₂ gas is produced. Identify the salt as magnesium methanoate.
Common mistakes
- Writing "fizzing" instead of "effervescence". Forgetting to mention the magnesium dissolving. Calling the salt simply "magnesium salt" without specifying methanoate.
Mark scheme (4 marks)
- Effervescence / bubbles / fizzing observed
- Magnesium dissolves / disappears / ribbon gets smaller
- Hydrogen gas is produced
- A salt / magnesium methanoate is formed
Key terms in this question
carboxylic acid · methanoic acid
Related
- All Cambridge International IGCSE Chemistry (0620) revision notes →
- How to answer a "Describe" question →
- Decode the mark scheme abbreviations →
More Carboxylic acids questions
- Propanoic acid is a carboxylic acid used as a food preservative. Explain why pro…
- Ethanol can be oxidised to produce ethanoic acid. State the name of the function…
- Ethanoic acid reacts with ethanol in the presence of an acid catalyst to form a …
- Ethanoic acid is a carboxylic acid found in vinegar. Describe the reaction of et…