(a) Corrosion:
Corrosion is defined as a process where materials, usually metals, deteriorate as a result
of a chemical reaction with air, moisture, chemicals, etc. For example, iron, in the presence
of moisture, reacts with oxygen to form hydrated iron oxide.
4Fe + 3O2 + nH2O → 2Fe2O3.nH2O
This hydrated iron oxide is rust.
(b) Rancidity: The process of oxidation of fats and oils that can be easily noticed by the
change in taste and smell is known as rancidity.
For example, the taste and smell of butter changes when kept for long. Rancidity can be
avoided by:
1. Storing food in air tight containers
2. Storing food in refrigerators
3. Adding antioxidants
4. Storing food in an environment of nitrogen
