What's the relationship between chemical polarity and vapor pressure？
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.