1. CHEM 433 - 10/28/11 VI. 2nd Law of THERMO
• Pressure and Temperature Dependence of the - P dependence
• The “chemical potential”
V. Phase Equilibria (Pure Substances)
• Intro/terms
READ: CHAPTER 4
HW #7: Today via …

4. Attractions or repulsions at each p above?

5. Phase: A form of mater, uniform in chemical composition and physical state.
Phase Transition: The spontaneous conversion of one phase to another (e.g. g —> l)
Transition Temperature (Ttrs): Chemical potentials of 2 phases are equal and the 2 phases are in equilibrium
Phase Diagram: Shows regions of P and T in which phases are stable
Phase boundaries: p and T where 2 phases co-exist (in eq. , ’s are =).
Vapor pressure: pressure of vapor in eq. with liquid (the l-v boundary).
Sublimation vapor pressure: pressure of vapor in eq. with solid
(s-v phase boundary)

6. Boiling: A condition of free vaporization throughout the liquid.
Boiling temperature(Tb): T at which vapor pressure equals external pressure
Normal boiling: boiling T at 1 atm external pressure
Standard boiling point: boiling T at 1 bar external pressure.
Freezing/Melting Temperature (Tf): T at which vapor pressure equals external pressure
Normal/Standard Tf: as above, for 1 atm or 1 bar, respectively.

7. Triple point: Temperature and pressure at which 3 phases coexist (usually s, l, g).
Critical temperature: T when surface between phases disappears (closed system). Density of (l) and (g) become equal!
Critical pressure: vapor pressure at critical temperature.
Supercritical Fluid: The name of the phase above the critical point.

10. CO2

11. H2O

12. He

13. Carbon