How to distinguish between methyl formate (HCOOCH3) and ethanoic acid (CH3COOH)?

Step 1: Solve question 4.c.
To distinguish between HCOOCH$_3$ (methyl formate, an ester) and CH$_3$COOH (ethanoic acid, a carboxylic acid).

• Test: Add a small amount of sodium carbonate solution to each compound.
• Observation:
  • CH$_3$COOH (ethanoic acid) will react with sodium carbonate to produce effervescence (fizzing) due to the evolution of carbon dioxide gas. $$\text{2CH}_3\text{COOH} (aq) + \text{Na}_2\text{CO}_3 (aq) \longrightarrow \text{2CH}_3\text{COONa} (aq) + \text{H}_2\text{O} (l) + \text{CO}_2 (g)$$