| Abstract
| - A method is proposed for determining the surface tensions of a solid in contact with either a liquid or avapor. Only an equilibrium adsorption isotherm at the solid−vapor interface needs to be added to Gibbsianthermodynamics to obtain the expressions for the solid−vapor and the solid−liquid surface tensions,and, respectively. An equilibrium adsorption isotherm relation is formulated that has the essential property ofnot predicting an infinite amount adsorbed when the pressure is equal to the saturation-vapor pressure. Fivedifferent solid−vapor systems from the literature are examined, and found to be well described by the newisotherm relation. The surface-tension expressions obtained from the isotherm relation are examined bydetermining the surface tension of the solid in the absence of adsorption,, a material property of a solidsurface. The value ofcan be determined by adsorbing different vapors on the same solid, determining theisotherm parameters in each case, and then from the expression fortaking the limit of the pressurevanishing to determine. From previously reported measurements of benzene and of n-hexane adsorbingon graphitized carbon, the same value ofis obtained.
|
