Study Notes
Corrosion of metals involves the deterioration of metals due to chemical reactions with their environment. Rusting of iron requires the presence of both water and oxygen to form hydrated iron(III) oxide.
- Rust — the chemical reaction (oxidation) of iron with oxygen in the presence of water. Example: Iron left outside in the rain rusts over time.
- Barrier Methods — techniques used to prevent rust by keeping oxygen and water away from metal surfaces. Example: Painting or coating metal with grease.
- Galvanizing — coating a metal with a more reactive metal to prevent rusting. Example: Coating steel with zinc to protect it from rust.
Exam Tips
Key Definitions to Remember
- Rust: Oxidation of iron in the presence of water and oxygen
- Galvanizing: Coating a metal with a more reactive metal to prevent rust
Common Confusions
- Rusting only applies to iron and steel, not other metals
- Confusing oxidation and reduction processes
Typical Exam Questions
- What conditions are required for iron to rust? Water and oxygen are required.
- How does galvanizing prevent rust? A more reactive metal is oxidized, protecting the less reactive metal.
- What are some barrier methods to prevent rust? Painting, greasing, and coating with plastic.
What Examiners Usually Test
- Understanding of conditions required for rusting
- Knowledge of methods to prevent corrosion
- Application of sacrificial protection concepts