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ION–SOLVENT INTERACTIONS 135
one finds
Furthermore, for three degrees of free rotations is calculated with the same
general approach to be 43.85 Adding these components together, one
obtains a calculated entropy for the structure-broken part of model C, that is,
Thus, the total entropy for model C is
The values of of models A and C as well as their comparisons with experi-
mental values are shown in Table 2.20 and in Figs. 2.43 and 2.44. It is necessary to
reject model 1C because X-ray determinations of the CN indicate not 4, but numbers
that vary from 6 to 8 as a function of the ion. The experimental results on solvation
numbers have similar inference; a sharp distinction between the solvation numbers of
Fig. 2.43. Entropy of hydration against recip-
rocal of ionic radius for monovalent cations (1
Å = 100 pm; 1 cal = 4.184 J). (Reprinted from
J. O’M. Bockris and P. P. S. Saluja, J. Phys.
Chem. 76: 2298, 1972.)
