# Explain why water (H₂O) is a liquid at room temperature but methane (CH₄) is a gas at room temperature, even though both are covalent molecules.

> Edexcel GCSE Chemistry (1CH0) — 1.6 Covalent bonding · Explain · 4 marks

> Water has a boiling point of 100 °C, while methane has a boiling point of −161 °C. Both substances are made up of small covalent molecules.

## Mark scheme (4 marks)

1. Both water and methane are small covalent molecules with weak intermolecular forces between the molecules
2. Little energy is needed to overcome the intermolecular forces in methane, so it is a gas at room temperature
3. Water molecules have stronger intermolecular forces than methane molecules
4. More energy is needed to overcome the stronger intermolecular forces in water, so it remains a liquid at room temperature

## Key terms

- [covalent molecules](https://www.gradenine.co.uk/glossary/covalent-molecules)

## Related

- [Revision notes for Edexcel GCSE Chemistry (1CH0)](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-water-h-o-is-a-55e46ef6) · Published by Druglandscape Ltd.