THE ENTROPIES OF IONS IN AQUEOUS SOLUTION: I. DEPENDENCE ON CHARGE AND RADIUS

Publisher Website
Google Scholar
Abstract
Empirical equations recently proposed for the entropies of ions in aqueous solution involve a linear dependence on the first power of the valency z and, in some cases, an inverse dependence on the square of a modified radius. Such relationships have no fundamental validity since the entropies are related arbitrarily to a zero value for the proton. It is shown that the entropy changes for reactions of various ionic types indicate that the entropy must depend on z2, as proposed by Born on the basis of simple electrostatic theory. When the entropies of monatomic ions are related to the absolute scale, in which the proton has a value of −5.5 e.u., they are found to vary linearly with z2/ru, where ru is the univalent radius defined by Pauling. The slope is found to be close to that predicted by the Born equation, and the non-electrostatic part of the entropy is shown to correspond to the movement of the ion in a free volume of 0.73 eu. Å.

This publication has 5 references indexed in Scilit: