# Explain why dissolving a small amount of sugar in water results in no observable increase in the total volume of the solution compared with the volume of the pure water alone.

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

## Mark scheme (4 marks)

1. Particles (molecules/ions) in a liquid are not arranged in a perfectly close-packed structure and there are spaces/gaps between them.
2. The small sugar molecules/particles can fit into the spaces/gaps between the water molecules.
3. Because the solute occupies pre-existing spaces, no additional volume is created/needed.
4. This behaviour demonstrates that matter is particulate/discontinuous in nature, with significant empty space between particles even in the liquid state.

## Related

- [Revision notes for IB DP Chemistry Higher Level (2023 syllabus)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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