What is a Physical Change?
A physical change alters the appearance or form of a substance but doesn't change its chemical composition. This means the molecules themselves stay the same, just arranged differently.
Examples of Physical Changes:
* Melting Ice: Ice (solid water) melts into liquid water. The chemical formula (H₂O) remains the same; it's just a change in state.
* Boiling Water: Liquid water turns into water vapor (steam). Again, the chemical composition is unchanged.
* Cutting Paper: You change the shape of the paper, but it's still paper (cellulose).
* Freezing Juice: Liquid juice turns into solid juice. The ingredients and their chemical makeup remain the same.
* Crushing a Can: The can changes shape, but it's still made of aluminum.
* Dissolving Sugar in Water: The sugar disappears into the water, but it's still sugar (sucrose) dissolved in water. You could get the sugar back by evaporating the water.
* Mixing Sand and Salt: The sand and salt mix, but they retain their individual chemical properties.
Key Point: Physical changes are usually reversible. You can often get the original substance back by reversing the change (like freezing water back into ice).
