# Explain why a gas can be compressed much more easily than a liquid, using ideas about particles and the forces between them.

> IB DP Chemistry Standard Level (2023 syllabus) — S1.1 Introduction to the particulate nature of matter · Explain · 4 marks

## Mark scheme (4 marks)

1. In a gas, particles are far apart / have large distances between them (whereas in a liquid particles are close together).
2. Intermolecular / interparticle forces in a gas are negligible / very weak (compared to those in a liquid).
3. Compression reduces the volume / distance between particles; in a gas the large spaces allow the particles to be pushed closer together.
4. In a liquid, particles are already close together / touching, so the strong intermolecular forces resist further reduction in volume, making compression very difficult.

## Key terms

- [gas](https://www.gradenine.co.uk/glossary/gas)
- [liquid](https://www.gradenine.co.uk/glossary/liquid)

## Related

- [Revision notes for IB DP Chemistry Standard Level (2023 syllabus)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-a-gas-can-be-df5078af) · Published by Druglandscape Ltd.