1. Kinetic Molecular Theory of Solids and Liquids gases liquids solids volume/shape container density low compressibility high motion free definite volume shape of container highslightslide definite volume definite shape highnone vibrate liquids and solids condensed phases Intermolecular forces Intramolecular forces chemical bonds much stronger physical propertieschemical properties

2. Changes of State solid melting liquid freezing gas sublimation deposition vaporizationcondensation endothermic exothermic  H fus  H vap

3. Phase changes Liquid-Vapor Equilibrium liquid gas evaporation gas liquidcondensation depends on T depends on [vapor]

4. ln P T1 P T2 =  H R 1 T2T2 - 1 T1T1  H = heat of vaporizaton vapor pressure = 1 atmboiling point

5. vaporization within the liquid vapor pressure in bubble = external pressure bubble 1 atm Phase changes Boiling Point liquidgas T b = normal boiling point 1 atm raise P raise boiling point lower Pboiling point 374 o C 218 atm critical T critical P fluid lower

6. Condensation gasliquid decrease Tincrease P decrease K.E. decrease distance critical T (T c ) gas phase can not be liquified highest T at which a liquid can exist above T c fluids critical P (P c ) minimum P which will liquify gas at T c IMF independent of T finite strength Phase changes CO 2 critical T = 31 o C critical P = 73 atm at > 73 atmsupercritical fluiddecaffeinate coffee

7. Liquid-Solid Equilibrium Phase changes liquidsolid freezing fusion (melting) solids -molecules vibrate around average positions liquids - molecules move past each other T f = normal freezing point 1 atm raise P raise VlVl VsVs > < = V water V ice > < = raise Plower freezing point water freezing point larger V smaller V

8. heat (J) = Heating Curve C  T ( o C) T f - Ti (J/ o C) x C ice = 37.6 J/mol o C = 37.6 x ( ) o C 0 -(-20) 1 mole of H 2 O = 752 J heat (J) =  H fus = 6.01 kJ/mol = 6010 J gas heat (J) =  T ( o C) C(J/ o C) x C water = 75.3 J/mol o C = 75.3 x ( ) o C 100 -(0)= 7530 J heat (J) =  H vap = 40.67 kJ/mol = 40670 J. solidliquid heat (J) = C steam = 33.1 J/mol o C =.102 x( ) o C120-100= 662 J  T ( o C) (J/ o C) x C 0 -20 20 60 100 heat

9. P T 1 atm 273 K373 K solidliquidgas = normal melting and boiling points = “triple point” of water (0.0098 o C, 0.006 atm) Phase Diagram = critical point of water (647 K, 218 atm)

10. gas solid liquid 0.006 0.01 100 1.0 218 374 5.1 -56.6-78.5 1.0 73 31.1 H2OH2OCO 2 liquid solid gas T P T P Phase Diagram ABC T time A B C 0.00 D D