Physical Change:
* Definition: A change in the form or appearance of a substance, but not its chemical composition.
* Key Characteristics:
* No new substances are formed.
* Often reversible.
* Changes in state (solid, liquid, gas) are physical changes.
* Changes in shape or size are physical changes.
* Examples:
* Melting ice (water changing from solid to liquid).
* Boiling water (water changing from liquid to gas).
* Cutting paper.
* Crushing a rock.
Chemical Change:
* Definition: A change in which a new substance is formed with different chemical properties.
* Key Characteristics:
* New substances are formed with different properties.
* Often irreversible.
* Energy is usually released or absorbed (exothermic or endothermic reactions).
* Examples:
* Burning wood (wood reacts with oxygen to produce ash, carbon dioxide, and water).
* Rusting iron (iron reacts with oxygen to form iron oxide).
* Baking a cake (ingredients react to form a new substance).
* Digesting food (chemical breakdown of food molecules).
How to Tell the Difference:
* Formation of new substances: If a new substance is formed, it's a chemical change.
* Reversibility: Physical changes are usually reversible, while chemical changes often are not.
* Energy changes: Chemical changes often involve a significant release or absorption of energy (heat, light, etc.).
Let me know if you'd like more examples or want to discuss specific scenarios!
