1. 9.4 Change of phase

2. distinguish between the processes of melting, boiling and evaporation.

3. Melting Change of Phase from solid to liquid
Heat goes into the solid as it melts.
There is no change in temperature during the Phase change.
What happens to the internal energy?
What happens to the Average kinetic energy of the particles?
What happens to the Average potential energy of the particles?

4. Boiling Change of Phase from liquid to gas
Heat goes into the solid as it melts.
There is no change in temperature during the Phase change.
What happens to the internal energy?
What happens to the Average kinetic energy of the particles?
What happens to the Average potential energy of the particles?

5. Evaporation Change of Phase from liquid to gas
The temperature of the liquid goes down .
What happens to the internal energy?
Where does that energy come from?
What happens to the Average kinetic energy of the particles left behind?

6. Differences between Boiling and Evaporation
Takes place at the boiling point
Takes place at temperatures (above about freezing) below the boiling point
Takes place throughout the liquid
Only occurs at surface
Takes energy in (endothermic) to occur
Evaporation lets only the molecules with the highest kinetic energy out, leaving the rest of the water net lower kinetic energy, so evaporation is exothermic.

7. Useful link