The Born equation can be used for estimating the electrostatic component of Gibbs free energy of solvation of an ion. It is an electrostatic model that treats the solvent as a continuous dielectric medium (it is thus one member of a class of methods known as continuum solvation methods).
The equation was derived by Max Born. [1] [2] where:
The energy U stored in an electrostatic field distribution is:Knowing the magnitude of the electric field of an ion in a medium of dielectric constant εr is and the volume element can be expressed as , the energy can be written as: Thus, the energy of solvation of the ion from gas phase (εr = 1) to a medium of dielectric constant εr is: