Melting Butter (Physical Change):
* Composition remains the same: Butter is still composed of the same molecules (fats) even when it melts. The arrangement of the molecules changes (from solid to liquid), but their chemical makeup stays the same.
* Reversible: You can easily solidify melted butter by cooling it down, returning it to its original state.
* No new substances formed: The melting process doesn't create any new substances. It's simply a change in the physical state of the butter.
Rusting Almirah (Chemical Change):
* New substance formed: Rust (iron oxide) is a completely different substance from the iron in the almirah. This new substance is formed through a chemical reaction.
* Irreversible: Once iron has rusted, you can't easily get the original iron back without significant chemical processing.
* Chemical reaction involved: Rusting occurs due to a chemical reaction between iron, oxygen, and water. This reaction creates a new substance (rust) with different properties.
Key Difference:
The key difference between physical and chemical changes lies in the formation of new substances. In a physical change, only the physical state or appearance changes, not the chemical composition. In a chemical change, a new substance with different properties is formed.
