JCE Software Chemistry Comes Alive!
Vapor Pressure: Molecular Polarity

Chloromethane and dichloromethane are injected into separate barometers and their vapor pressures are measured. Molecular models of chloromethane and dichloromethane are shown.

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Narrative
Chloromethane and dichloromethane differ in their polarity. Chloromethane depressed the mercury column to 555 millimeters. Whereas when dichloromethane is injected into the barometer, the mercury column is depressed to 351 millimeters.

Dichloromethane has the higher vapor pressure because it is less polar than chloromethane.