# Describe how the conditions needed for rusting can be demonstrated experimentally, and state what the results would show.

> Cambridge International IGCSE Chemistry (0620) — 9.5 Corrosion of metals · Describe · 4 marks

> Rusting is a chemical process that requires specific conditions to occur. A student sets up three test tubes, each containing an iron nail, to investigate which conditions cause rusting.

## Mark scheme (4 marks)

1. One test tube contains a nail in water (with air/oxygen present) — this nail rusts
2. One test tube contains a nail in boiled/distilled water sealed with oil (no air/oxygen) — this nail does not rust
3. One test tube contains a nail in a dry tube with a drying agent (e.g. calcium chloride/silica gel) — no water present — this nail does not rust
4. Conclusion: both water (moisture) and air (oxygen) are required for rusting to occur

## Key terms

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

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