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ION–SOLVENT INTERACTIONS 189
Hence, the compression in the first layer of water molecules around an ion
would be about (1.71/18) or 10% of the average volume of water in the bulk.
2.22.4. Volume Change and Where It Occurs In Electrostriction
Calculation shows that most of the electrostrictional volume change due to the
electrical pressure exerted by an ion in the surrounding solvent arises in the first shell of
solvent around it. The calculated volume changes for typical fields are shown in Table
2.28.
Fig. 2.76. (a) Deformation of the adsorbed ions
due to the electric field at the metal–solution inter-
phase. (b) Schematic representation of the bisul-
fate ion and its equivalent spherical structure
before and after its deformation at the interphase.
(Reprinted from J. O’M. Bockris, Maria Gamboa-AI-
deco, and M. Szklarczyk, J. Electroanalyt. Chem.
339: 335, 1992.)
