Vapor molecules in equilibrium with a liquid in a closed system exert a pressure proportional to the concentration of molecules in the vaporphase.

The pressure exerted by a vapor in equilibrium with its corresponding liquid at a given temperature is called the EQUILIBRIUM VAPOR PRESSURE of the liquid.

The equilibrium vapor pressure increases with temperature

increasing the temperature of a liquid increases the average kinetic energy of the liquid's molecules

Because all liquids have characteristic forces of attraction between their particles, every liquid has a specific equilibrium vapor pressure at a given temperature

VOLATILE LIQUIDS are liquids that evaporate readily and have weak forces of attraction between particles

NONVOLATILE LIQUIDS have strong forces of attraction between their particles

BOILING is the conversion of liquid to vapor on the surface as well as within the liquid

BOILING POINT of a liquid is the temperature at which the equilibrium vapor pressure equals the atmospheric pressure

The lower atmospheric pressure is the lower boiling point is

At the boiling point all the energy absorbed is used to evaporate the liquid and temperature remains constant as long as atmospheric pressure does not change

Normal atmospheric pressure is boiling point of water

Energy must be added continuously to keep a liquid boiling. and the temperature will remain constant despite constant addition of energy

MOLAR ENTHALPY OF VAPORIZATION is the amount of energy as heat needed to vaporize one mole of liquid at the liquids boiling point at constant pressure

the stronger the attrction between particles the more energy needed to overcome it

liquid to solid is FREEZING

FREEZING POINT is the temperature at which the solid and liquid are at equilibrium at 1 atm pressure.. at freezing point particles of the liquid and solid have the same kinetic energy

melting is the reverse of freezing and occurrs at constant temperature

at equilibrium melting and freezing proceed at equal rates
at normal atmospheric pressure the temperature of a system containing ice and liquid water will remain at 0 degrees C as long as both ice and water are present (and you keep stirring)

at sufficiently low temperature and pressure liquid cannot exist so the substaance exits equilibrium as vapor instead of liquid

SUBLIMATION is the change of state from a solid directly to a gas

DEPOSITION is a change of state directly from a gas to a solid