Kazuo Nishizawa

Studies on secondary electrocapillary effects: II. The electrocapillary phenomena in thin liquid film

Abstract The electrocapillary curves of thin liquid films of 1 N KCl aq on a mercury surface were obtained by direct measurements on sessile drops of mercury, which showed that the film pressure was dependent on the applied potential. This dependence can be ascribed not only to the change in double layer capacity, but also to the change in film thickness by the applied potential. The curves showed marked depression in interfacial tension of thin film near the electrocapillary maximum; this was the characteristic feature of thin films as compared with that of ordinary electrocapillary curves. This can be explained by the gas adsorption in the absence of double layer in the thin film. The interfacial entropy per square centimeter could be estimated from the slope of the interfacial tension vs temperature relations, while the interfacial entropy per mole could be estimated from the slope of the electrocapillary curve for thin films. It was also possible from these two values to divide the interfacial entropy change into two components, the one due to the formation of ionic double layer and the other mainly due to the orientation of water dipoles.

The adsorption of ethylene glycols and their cyclic compounds at the mercury-aqueous solution interface

ZusammenfassungDie Kapazitäten der differentialen Doppelschicht an der Grenzfläche von Quecksilber und wäßrigen Lösungen von Äthylenglycol und seiner zyklischen Verbindungen wurde gemessen, und die freie Energie der Adsorption berechnet, um die Struktur der adsorbierten Schichten dieser Verbindungen zu untersuchen. Die freie Energie für die zyklischen Verbindungen war höher als diejenige der anderen, mehr als die Hälfte der freien Energie dieser zyklischen Verbindungen ist auf den Bei trag des Benzolringes zurückzuführen. Die Berechnung der adsorbierten Menge zeigte, daß die zyklischen Verbindungen parallel und die anderen geneigt an der Quecksilberoberfläche angeordnet waren. Eine Schlußfolgerung wurde daraus gezogen, daß die Adsorption der zyklischen Verbindungen durch die Wechselwirkung zwischen den intramolekularen π-Elektronen und die Elektronen auf der Quecksilberoberfläche gesteuert wurden. Die freie Energie der Adsorption pro -CH2- und -OH wurde berechnet, und sie betrug -400 bzw.-600 cal/mole.SummaryDifferential double layer capacities were measured at the interface between mercury and aqueous solutions containing ethylene glycols and their cyclic compounds, and free energies of adsorption were calculated in order to study the structure of adsorbed layers of these compounds. Free energies for cyclic compounds were higher than those of others, more than half of the free energies of cyclic compounds were in parallel and others in inclined ring. The calculation of adsorbed amounts showed that cyclic compounds were in parallel, and others in inclined, orientation on the mercury surface. It was concluded that the adsorption of cyclic compounds was governed by the interaction between intra-molecular π-electrons and electrons of mercury surface. Free energies of adsorption per -CH2 and -OH were calculated to be -400 to-600 cal/mole, respectively.