Antoine's equation

Mathematical expression of the relation between the vapour pressure and the temperature of pure substances. 

Source:http://en.citizendium.org

Formula

\log _{{10}}\left({\frac {P_{s}}{P^{o}}}\right)=A-{\frac {B}{T+C}} where Ps is the vapor pressure in pascals, A, B and C are constants which depend on subtances and T the absolute temperature in kelvins.