Ch. 12 - Liquids

1
III. Changes of State(p. 372 - 382)

• Ch. 12 - Liquids Solids

2
A. Phase Changes
3
A. Phase Changes

• Evaporation
• molecules at the surface gain enough energy to
  overcome IMF
• Volatility
• measure of evaporation rate
• depends on temp IMF

4
A. Phase Changes
Boltzmann Distribution
p. 477
5
A. Phase Changes

• Equilibrium
• trapped molecules reach a balance between
  evaporation condensation

6
A. Phase Changes
p.478

• Vapor Pressure
• pressure of vapor above a liquid at equilibrium

v.p.

• depends on temp IMF
• directly related to volatility

temp
7
A. Phase Changes

• Boiling Point
• temp at which v.p. of liquid equals external
  pressure

• depends on Patm IMF
• Normal B.P. - b.p. at 1 atm

8
A. Phase Changes

• Melting Point
• equal to freezing point

• Which has a higher m.p.?
• polar or nonpolar?
• covalent or ionic?

polar
ionic
9
A. Phase Changes

• Sublimation
• solid ? gas
• v.p. of solid equals external pressure

• EX dry ice, mothballs, solid air fresheners