# Explain why hydrogen chloride (HCl) is a gas at room temperature, whereas sodium chloride (NaCl) is a solid at room temperature. Refer to the types of bonding and structure in each substance in your answer.

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

> Hydrogen chloride and sodium chloride both contain chlorine, but they have very different properties at room temperature.

## Mark scheme (4 marks)

1. HCl contains covalent bonding (a shared pair of electrons between hydrogen and chlorine)
2. HCl exists as simple molecules with only weak intermolecular forces between them
3. NaCl has ionic bonding / is an ionic compound with a giant ionic lattice structure
4. The strong electrostatic forces / ionic bonds in NaCl require much more energy to break than the weak intermolecular forces in HCl, so NaCl is solid and HCl is a gas at room temperature

## 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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