Individual Ionic Surface Tension Increments in Aqueous Solutions

Surface tension increments by aqueous electrolytes, kE = [?(cE) ? ?(W)]/cE, can be split into the ionic values, ki (kE = Σ?iki), on an arbitrary but plausible manner, notwithstanding the effects of counterions on the behavior of specific ions. Values for 41 ions, mono- and polyatomic and uni- and multivalent, are presented in conjunction with some other ionic properties. The surface potential increments of electrolytes, ??? = ??E (at cE = 1 M) ? ??W, depend linearly on the kE values for four anion series with common cations and on the differences between cation and anion ki values. The ki (normalized to unit charge number) are correlated linearly with the ionic radii ri, the excess ionic molar refractivity over that of water, RDi ? RDW, the ionic softness parameters (modified by adding +0.5 to anion and ?0.5 to cation values), σ±0.5, and to the geometrical factor of water structure making/breaking, ?HBG. No correlation takes place with the ionic polarization corrected for that of water, αi* = αi ? αW(ri/rW)3, nor with the molar Gibbs energy or enthalpy of hydration. The latter fact implies that ion dehydration does not play a major role in the sorption/desorption of ions at the surface. The correlations that were found are discussed in a qualitative manner and compared with theoretical arguments in the literature. Surface tension increments by aqueous electrolytes, kE = [?(cE) ? ?(W)]/cE, can be split into the ionic values, ki (kE = Σ?iki), on an arbitrary but plausible manner, notwithstanding the effects of counterions on the behavior of specific ions. Values for 41 ions, mono- and polyatomic and uni- and multivalent, are presented in conjunction with some other ionic properties. The surface potential increments of electrolytes, ??? = ??E (at cE = 1 M) ? ??W, depend linearly on the kE values for four anion series with common cations and on the differences between cation and anion ki values. The ki (normalized to unit charge number) are correlated linearly with the ionic radii ri, the excess ionic molar refractivity over that of water, RDi ? RDW, the ionic softness parameters (modified by adding +0.5 to anion and ?0.5 to cation values), σ±0.5, and to the geometrical factor of water structure making/breaking, ?HBG. No correlation takes place with the ionic polarization corrected for that of water, αi* = αi ? αW(ri/rW)3, nor with the molar Gibbs energy or enthalpy of hydration. The latter fact implies that ion dehydration does not play a major role in the sorption/desorption of ions at the surface. The correlations that were found are discussed in a qualitative manner and compared with theoretical arguments in the literature.