1. Warm-up:
Draw a Line Graph using the following data: Average Temperatures

2. Warm-up: sample graph

3. HEAT and HEAT TECHNOLOGY
Chapter 10

4. Review of Unit-1 Concepts:
Phase Changes / Changes of State
Creating and Analyzing Graphs

5. Changes of state
Change of a substance from one physical form to another
Energy is gained or released (added or removed)
There are Temperature “Points” where this happens
Endothermic: energy is gained as a substance changes state
Exothermic: energy is removed as a substance changes state (it “exits”)

6. Changes of state “Points”
Melting Pt = solid  liquid solid  liquid = Freezing Pt . Boiling Pt (or Evaporation Pt) = liquid  gas liquid  gas = Condensation.. .. Sublimation Pt = solid  gas solid  gas = De-Sublimation Pt
Exothermic (energy is being removed /“exits”)

7. Remember: there are Differences between BOILING and EVAPORATION
EVAPORATION: happens at the surface of a liquid only even if it is not boiling
BOILING: occurs throughout the entire liquid
Remember: there are Differences between BOILING and EVAPORATION

8. Graph “flat” parts show a change is taking place
(or could use “Energy”)

9. Changes of state - SUMMARY
Endothermic (energy is gained)
Exothermic (energy is removed /“exits”)
Do not confuse “Freezing Point” with “coldness”
Temperature stays steady at its “Point” / does not change (it pauses) until its State has changed

10. Sample Graph: Changes of State for Water
(or, if Energy is constant, can use “Time” for x-axis)

11. Exit Ticket: a substance is being continuously cooled…1 2 3 4 5 6 7
(Hours)