Summary:
- A physical change is a change to a sample of matter in which some properties of the material change, but the identity of the matter does not.
- Melting ice and grinding wood into sawdust are examples of physical changes.
- When salt is dissolved into water, the salt is said to have entered the aqueous state.
- The salt may be regained by boiling off the water, leaving the salt behind.
- When a piece of wood is ground into saw dust, that change is irreversible since the sawdust could not be reconstituted into the same piece of Wood that it was before.