Thermodynamic quantities of surface formation of aqueous electrolyte solutions

Thermodynamic quantities of surface formation of aqueous electrolyte solutions

“…As shown in the figure, the difference between Na 2 SO 4 and Cs 2 SO 4 at 25 • C is 0.58 mN m −1 mol kg −1 , while we observed only 0.18 mN m −1 mol kg −1 between LiCl and CsCl [14]. Further, the values for LiNO 3 , NaNO 3 , and KNO 3 at 25 • C are given as 1.14, 1.13, and 1.10 mN m −1 mol kg −1 , respectively [6]. It seems likely that the remarkable dependence of dγ /dm upon cations will prove to be in agreement with the results of the surface potential measurements obtained by Jarvis and Scheiman [7].…”

“…Secondly, there are large spaces between the curves on the figure when we compared with those of nitrate or chloride salts [6,13]. As shown in the figure, the difference between Na 2 SO 4 and Cs 2 SO 4 at 25 • C is 0.58 mN m −1 mol kg −1 , while we observed only 0.18 mN m −1 mol kg −1 between LiCl and CsCl [14].…”

“…At the beginning of the study of the adsorption of surface active molecules at the solution surfaces, the slope of the surface tension against concentration at infinite dilution was used as a quantitative measure of the surface activity of each solute [16,17]. We believe that this idea would presumably apply to the adsorption of ions as well, as noted in our previous report [6]. Further we have shown that the magnitude of Γ H /m helps us more adequately for expressing the surface activity than dγ /dm itself, because it is a kind of partition coefficient of the electrolytes between surface region and bulk solution.…”

“…and the enthalpy change of hydration differ in magnitude and tendency from those of the salts with common cation. Indeed, each of alkali metal nitrates shows nearly the same value of dγ /dm [6]. By means of the surface potential measurement for simple electrolyte solutions, Jarvis and Scheiman also pointed out that the anions primarily determine the sign and the magnitude of the potential [7].…”

Thermodynamic quantities of surface formation of aqueous electrolyte solutions X. Aqueous solution of 2:1 valence-type salts

“…Fortunately, numerical values of this ratio at infinite dilution can be used to evaluate the Previously reported surface tension data used in this figure are taken from the references sodium halides [11,12], sulfates [14], nitrates [17], and ammonium salts [7], respectively. The formation of electrical double layer in the surface region is always accompanied by the decrease in s [18].…”