The difference between physical changes and chemical changes lies in whether the substance’s identity is altered:
Physical Change
- A physical change alters the form, appearance, or state of a substance but does not change its chemical identity.
- No new substance is formed.
- Usually reversible.
- Examples:
- Melting of ice → water (H₂O remains the same).
- Boiling water into steam.
- Breaking glass.
- Dissolving sugar in water.
Chemical Change
- A chemical change results in the formation of one or more new substances with different properties.
- The chemical composition of the original substance changes.
- Usually irreversible.
- Examples:
- Burning of wood → ash, carbon dioxide, water vapor.
- Rusting of iron.
- Digestion of food.
- Sour milk formation.
Key Difference:
- Physical change = change in form/state; no new substance is formed.
- Chemical change = change in composition; new substance(s) are formed.