Wednesday, January 12, 2011
11.2
Volatility- The tendency of a liquid to vaporize
- As temperature increases volatility increases
Why? Energy causes molecules to move and break off, at higher temperatures number of molecules
with sufficient kinetic energy increases to overcome intermolecular forces.
In a closed container a liquid can evaporate but it won’t disperse
- The gas molecules can condense back into the liquid
Dynamic equilibrium- the molecules entering plus leaving liquid phase at equal rates.
P reaches a maximum = vapor pressure
Decreasing inter molecules forces= increasing vapor pressure
Boiling – occurs when the vapor pressure = atmosphere pressure
Normal boiling point = when atmospheric pressure at 1 atm
- Vaporization occurs throughout the liquid
- Bubbles of pure vapor form + rise to the surface
Clausius-clapeyron eqn
As intermolecule forces increase
Boiling point – increases, takes a higher temp
Viscosity – increases- becomes more difficult to flow
Surface tension- increases, harder to spread out, more “droP” like
Vapore pressure - decrease, harder to vaporize
(Delta)H vap- increase, harder to vaproize
11.3
Phase changes- due to changes in forces among the molecule- not within the molecule, molecules
remain intact im forces
Vaporization – liquid to a gas, molecules have enough KE to leave liquid Endothermic process
