SOLVENT EFFECTS ON CHEMICAL PROCESSES .3. SURFACE-TENSION OF BINARY AQUEOUS ORGANIC-SOLVENTS

The surface tension of binary solvents is modelled by analogy to solvation effects arising from solvent-solute interactions. Competitive exchange equilibria are postulated between solvent component 1 (water) and solvent component 2 (organic cosolvent) for solute, which in this case is air; the solvation shell is thus the surface phase. A quantitative relationship is given between surface tension and mole fractions x1 and x2, the model parameters being exchange equilibrium constants K1 and K2. The equation is analyzed, it is applied to literature surface tension data, and it is compared with an earlier model from this laboratory. Curve-fits are very good, and the parameters appear to possess physical significance.