Objective Define vapor pressure and analyze vapor pressure

Objective: • Define vapor pressure and analyze vapor pressure curves • Define boiling point, determine boiling points from vapor pressure curves and relate vapor pressure to IM Forces

Open Container Vaporization: In an open container, liquids will vaporize from the surface until all the liquid is gone …

Closed Container Vaporization: In a closed container, liquids still vaporize, but can’t escape … Vapor particles build up inside and start to re-condense … At some point, the rate of evap. = rate of conden.

Closed Container Vaporization: When the rates are equal, the amount of water stays constant … and the amount of water vapor stays constant … The two states of matter are in equilibrium with each other!!!

Closed Container Vaporization: The PH 2 O can be measured at this point and recorded … (assume 25 o. C) This is the VAPOR PRESSURE! The two states of matter are in equilibrium with each other!!!

Closed Container Vaporization: If eqm is achieved and THEN the water is heated … More molecules are forced to vaporize and eqm is reachieved, but with more vapor present

Closed Container Vaporization: Vapor pressure vs. temperature can be graphed to create …

Vapor Pressure Curve What will the equilibrium vapor pressure be over a sample of water at 65 o. C?

Now continue heating … What will happen to this water at 100 o. C?

Boiling Point: temperature when the vapor pressure is equal to atmospheric pressure

What is the boiling point of water at sea level where the pressure is 1 atm?

What is the boiling point of water on Mt. Everest where the pressure is 0. 65 atm?

Molecular view of boiling: The point when ALL particles in the liquid have enough KE to escape the IM Forces and vaporize (does not just happen at the surface) Intermolecular Forces connection: Substances with stronger IM forces will have lower VP’s

Solid State Chemistry Background Knowledge Research • • Work in groups of 2 -3 Research the type of solid that is on your card Due at end of period Lab grade for today