Vapor Pressure: Molecular Polarity
The measurement of pressure exerted by a vapor is demonstrated using barometers. The vapor pressures of chloromethane and dichloromethane are compared.
Dichloromethane has the higher vapor pressure because it is less polar than chloromethane.
(137 )
Keywords
vapor pressure, atmospheric pressure, barometric pressure, barometer, intermolecular forces, polarity, gases and liquids, organic, phase changes, physical properties, polar molecules
Multimedia
_Play
movie (49 seconds, 2.3 MB)
Chloromethane and dichloromethane differ in their polarity. Predict which would have the higher vapor pressure.
When chloromethane is injected, the chloromethane rises to the top and vaporizes. The mercury column is depressed to 556 millimeters. When dichloromethane is injected into the open end of the barometer, the dichloromethane rises to the top and vaporizes. The mercury column is depressed to 350 millimeters.
Dichloromethane has the higher vapor pressure because it is less polar than chloromethane.