Ion-Solvent Interactions According to the Born Model

The Born model [11] provides a means of estimating the Gibbs energy of solvation for an ion in an infinitely dilute solution. It is based on a continuum description of the solvent as a uniform dielectric with a relative permittivity of The work of transferring the ion from vacuum to the dielectric medium is estimated on the basis of the following three-step process (a) the ion is reversibly discharged in vacuum (b) the discharged ion, which is assumed to be a sphere of radius, r, is 

The total work associated with the above three-step process for solvation can be written 

Assuming that Wb, the work associated with introducing the uncharged sphere into the dielectric liquid, is zero, then 

Having obtained the Gibbs energy of solvation, one may now determine the other thermodynamic parameters. The entropy is obtained from the temperature derivative of A Ci  

The Gibbs energy and entropy may now be combined to obtain an expression for the enthalpy of solvation  

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