1. CHANGES IN MATTER
BASED ON THIS IMAGE WHAT DO YOU THINK THE DEFINITION OF CONDENSATION,
EVAPORATION, MELTING, SOLIDIFICATION, SUBLIMATION, DEPOSITION IS?
2. If we melt an ice cube can it be frozen
again?
Yes, this is called reversing changes in physical matter
We can also reverse changes in physical matter by:
• A bottle of frozen water thawed to a liquid state again
• Water vapour that has condensed on a cold window
evaporates into a vaporous state again
• water from a puddle that has evaporated will fall to the
ground as rain
3. Chemical changes are irreversible
• when the chrome on a bicycle rusts, it can never go
back to being chrome
• when an egg is boiled it can never go back to being
a raw egg
4. What happens when water freezes?
• when water freezes it releases heat
What happens when an when an ice cube melts?
• it absorbs heat
This means that changes of state involve the release of
heat or the absorption of heat