# Methanoic acid (HCOOH) is the simplest carboxylic acid. It is found in ant venom and reacts with a range of substances. Describe the chemical properties of methanoic acid that show it is a carboxylic acid, and explain why its reactions with carbonates produce a gas.

> WJEC A-Level Chemistry (Wales) — 3.4 Carbonyls and acids · Describe · 5 marks

> Methanoic acid has the molecular formula HCOOH. It dissolves in water to produce an acidic solution. When methanoic acid is added to sodium carbonate (Na₂CO₃), effervescence is observed.

## Mark scheme (5 marks)

1. Methanoic acid is a weak acid / partially dissociates / does not fully ionise in water
2. Methanoic acid reacts with carbonates / sodium carbonate to produce a salt (sodium methanoate)
3. Carbon dioxide gas is produced / released in the reaction with carbonate
4. Water is also produced in the reaction with carbonate
5. The acid provides hydrogen ions / H⁺ ions which react with the carbonate ions, causing the carbonate to decompose and release CO₂

## Key terms

- [carboxylic acid](https://www.gradenine.co.uk/glossary/carboxylic-acid)
- [carbonate](https://www.gradenine.co.uk/glossary/carbonate)

## Related

- [Revision notes for WJEC A-Level Chemistry (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/methanoic-acid-hcooh-is-the-simplest-0e462eac) · Published by Druglandscape Ltd.