1. Heating & Cooling Curves Do Now: Name the phase change S  L L  G G  L L  S S  G G  S Melting (fusion) Boiling (vaporization) condensation Freezing (solidification) sublimation deposition

2. All Phase changes accompanied by energy changes Phase changes are physical changes: –sometimes energy is absorbed (endothermic) –sometimes energy is released (exothermic) Energy change for given phase change can be measured/calculated (we’re going to learn how to do this tomorrow)

3. As you go from S  L  G, you are increasing the distance between molecules, so you are increasing their PE !PE We can see these energy changes by looking at a heat/cooling curve – next slide PE Solid Liquid Gas Endothermic Exothermic Sublimation Vaporization Melting (fusion) Deposition Condensation Freezing (solidification)

4. TURN TO PACKET page 11, take notes here:

5. Time Temperature I II IIIIVV Solid Solid & Liquid Liquid Liquid & Gas Gas K.E.  K.E.↔ P.E.↔ P.E.  Melt pt. Boil pt. ● ●

6. During Phase changes More than one phase is present –Melting : solid and liquid –Boiling: liquid and gas (lets check out a tiger animation) temperature is constant:  T=0 –There is no change in temp!!!!! ***NOTE: if 2 phases are present, temp is constant

7. Melting & Boiling Points Plateaus = Phase changes = PE changes –always given as temp (˚C, K) WHY IS IT CALLED A POINT?

8. QUICK QUESTION: What happens to temperature as heat is added at boiling point? Nothing, temp doesn't’t change until only 1 phase is present!

9. What do you think a cooling curve would look like?