Relationships Between Surface tension, Compressibility, and Molecular Parameter

An expression for the surface tension and isothermal compressibility, derived from scaled particle theory (SPT), are used to predict surface tension of pure substances from compressibility data, and vice versa. A relation between surface tension and compressibility is obtained by multiplying the expressions for surface tension and compressibility. This relationship is dependent only on the liquid density and on the diameter of the molecular compounds. Diameters are calculated readily from either the surface tension or compressibility experimental data. The validity of these expressions is tested for several types of pure substances: saturated hydrocarbons, halogenated hydrocarbons, alcohols, aromatic hydrocarbons and their nitrogen containing derivatives, oxygen containing organic compounds, simple polyatomic compounds and elements. The expressions predict well in most cases. Generally, liquids composed of molecules most closely approximating spherical intermolecular potentials exhibit the best correlation with the surface tension-compressibility relation. Given the good agreement, an approach is suggested for using surface tension data to compute liquid physical properties and thermodynamic values that can be obtained from an equation of state.

کلیدواژه ها:

Molecular diameter ، Scaled Particle Theory ، Surface tension ، Compressibility and Equation of