CHAPTER 17 LIQUIDS

17-1 melting and Freezing
For a pure substance, freezing and melting occur at the same temperature
When the temp of a solid is raised, the particles increase in velocity
until they slip over one another and the solid 	melts

17-2 Vapor equilibrium
The average kinetic energy of the particles in a gas is constant for all
substances at a given temperature
Molecules in solids and liquids can escape from the surface to form a
vapor if they gain enough kinetic energy to overcome
	The attractive forces of neighboring molecules (surface tension)
A gas and a vapor are BASICALLY the same thing.
Molecules escape and return to the solid or liquid surface continuously
and at the same rate in dynamic equilibrium

17-3 Le Chatelier's principle(LC)(my symbol not used in book , etc.)
LC principle applies to any equilibrium system.  It is introduced
	Here in relation to a liquid-solid equilibrium system.  It will
	Also be introduced in chap 23 in chemical equilibrium
Vapor pressure is directly related to temperature
LC principle: a system at equilibrium will adjust to relieve 
	Outside stress
Stress: increased pressure ice (greater volume)->water (less volume)
Stress: increased temp ice (melting)->water uses energy
Low vapor pressures are the result of strong intermolecular
 	forces.  High vapor pressure is the result of weak 
	Intermolecular forces.

17-4 Melting Point
Melting point-temp at which the vapor pressure of the solid
	And the vapor pressure of the liquid is the same
	Solid turns to liquid

17-5 Sublimation
Sublimation-solid goes directly to gas/no liquid phase

17-7 Boiling Point
bp-temp at which the vapor pressure is equal to the standard
	Atmospheric pressure (101.325kpa)/bp is a function of
	pressure/point at which a liquid turn to a gas
At ordinary temp, volatile substances have high vapor press
	And nonvolatile substances have low vapor pressure
Evaporation-is the process whereby molecules escape from the
	Surface of a liquid or solid
Boiling-molecules escape from within the liquid (bubbles)

17-8 Liquefaction of Gases
Liquefaction-condensation of substances that are normally gases
Critical temperature (Tc)-temp above which no amount of pressure
	Will liquefy a gas
Critical pressure (Pc)-minimum pressure needed to liquefy a gas 
	At Tc
Tc indicates the relative strength of attractive forces between
	Particles

17-9 Phase Diagrams
Phase diagrams graphically represent changes in state at varying
	Temperature and pressure
Triple point is the temperature and pressure at which all 3
phases of a substance are in equilibrium
SUPER IMPORTANT-BE ABLE TO DRAW AND EXPLAIN A PHASE DIAGRAM

17-10 Energy and Change of State
Hf (HEAT OF FUSION) is the energy required to melt one gram of
a substance at its
	m.p.
Hv(HEAT OF VAPORIZATION) is the energy required to vaporize one
gram of a substance at its b.p.
c = specific heat (chap 3)
m = mass in grams
Q (HEAT)=cm deltaT (unit is in joules)
Q=Hfm
Q=Hvm
 Be able to show 3 equations above on phase diagram
SEE THE 'SUPER IMPORTANT STATEMENT ABOVE'!!!!!!!!!!!!!!!!!!!!!

17-11 Hydrogen bonding
When hydrogen is bonded to a highly electronegative element, the
	Behavior of the substance may differ from predicted behavior
Hydrogen bonds have energies in the range of 8-36 kJ/mol

17-12 Hydrogen bonding in water
Ice is less dense than liquid water, which is most dense at 3.98C
	The expansion of water as it freezes into ice occurs because
	Hydrogen bonding pulls the molecules into open crystalline
	Structure that occupies more space than a liquid
	
WATER IS THE ONLY THING I CAN THINK OF THAT GETS LARGER IN VOLUME
WHEN IT GOES FROM LIQUID TO SOLID- THE REST OF THE MATTER IN THE
UNIVERSE GETS SMALLER DURING THIS PHASE CHANGE!!


17-13 Surface tension and capillary rise
Surface tension is due to unbalanced forces on surface particles
Capillary rise (capillary action)-rise of a liquid in a tube of
	small diameter
Adhesion-attraction between unlike atoms
Cohesion-attraction between like atoms