A question which confuses me now.
Chemical polarity is one of microscopic properties for certain molecules.
Vapor pressure is a macro thermodynamic properties for certain materials.

But I often read about some violate organics are polar material. So, it has a relatively small vapor pressure and hard to evaporate.

How to connect these two concepts together? If I can access the volatile ability based on the polarity, it will help me to recognize some kind of VOCs which are eager to condense into particle phase.


The vapor pressure of a liquid is the equilibrium pressure of vapor above the liquid at a given temperature. Liquids with higher vapor pressures must have less strong forces holding the molecules together in the liquid phase, thus more of the molecules are able to escape the liquid and be in the vapor phase. This is the connection between inter-molecular forces and vapor pressure.

Polar molecules can attract each other through dipole-dipole and dipole-induced dipole interactions in addition to the induced dipole-induced dipole intermolecular interactions that all molecules experience. Thus, all else (molar mass, for example) equal, a polar molecule will generally have a lower vapor pressure than a non-polar molecule.


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