An example of a chemical change is the rusting of iron.
When iron is exposed to oxygen and moisture, it reacts to form a new substance called iron oxide (rust).
- This is a permanent and irreversible change.
- A new substance with different properties is formed.
- Energy may be absorbed or released during the process.
Reaction:
Iron (Fe) + Oxygen (O₂) + Water (H₂O) → Hydrated Iron Oxide (Rust)
Other examples of chemical changes include:
- Burning of paper or wood
- Cooking of food
- Baking a cake
- Souring of milk
- Digestion of food in our body
Unlike a physical change, a chemical change alters the chemical composition of the substance.