1. Heating/Cooling Curves

2. Melting Point and Hf

3. AP MC (1999)

4. Supercooling
No seed nucleus
Freezes instantly upon disturbance

5. Phase Diagrams
Illustrates relationship between phases of matter and pressure and temperature
Lines represent phase equilibria
Triple point: where all three phases exist in equilibrium
Critical point: T and P for supercritical fluid (density like liquid; viscosity like gas)

6. Phase Diagram: Lines Represent phase equilibria/changes
Normal = 1.0 atm

7. Phase Diagram: Triple Point
When all three states exist in equilibria

8. Phase Diagram: Critical Point
Existence of supercritical fluid

9. Phase Diagram: Density
Typically: solid phase is more dense than liquid phase  S-L line bends right
Atypically: solid phase is less dense than liquid phase  S-L line bends left
When the pressure on an object increases, common sense tells us that the volume of the object will become smaller, giving the substance a higher density. Because ice is less dense than liquid water (due to the open lattice structure of ice), ice and water in equilibrium re- spond to increased pressure (at constant T) by melting ice to form more water be- cause the same mass of water requires less volume.

10. Water
Ice melts with increased pressure

11. Carbon Dioxide

12. AP MC (1994)

13. AP MC (1994)

14. AP MC (1994)

15. AP FR (1995)