Vaporization Pressure

[805812306]

Hi!

Could someone refresh me on what the enthalpy of vaporization pressure is and how it relates to individual elements and molecules? What determines this characteristic and what are the trends associated with it?

Thanks.

[Joanne Sarsam 2F]

Hi! Enthalpy of vaporization is the heat required to vaporize a substance, i.e. convert it from the liquid to gaseous state. Substances with stronger intermolecular forces with have higher enthalpies of vaporization because more energy is required to break those intermolecular forces, convert the state of the matter from liquid to gas (because in the gaseous state fewer of the molecules are connected by intermolecular forces). Thus, to tell which substances would have a higher enthalpy of vaporization, determine the strength of the intermolecular forces they experience. Ionic compounds experience ion-ion forces, the strongest kinds of interactions, so they will have higher enthalpy of vaporization than a covalent compound that only experiences LDF.