Enthalpies of Ion Hydration

A widely accepted estimate of the standard molar enthalpy of hydration of the hydrogen A /f (H ) ion is based on the differences AA 7/°° between the conventional values of cations and anions having the same radii r=r =r. The values of A 7/°°c° (C, r ) andA, 77 ° (A , r ) are plotted against (r, and the differences 

AA are taken for given values of r. When these differences are extrapolation 

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