THERMODYNAMICS AND STATISTICAL MECHANICS OF DILUTE BINARY MIXTURES.

The asymptotic laws which govern the behavior of solute and solvent fugacity coefficients in a dilute binary mixture are rephrased in fluctuation-explicit form. Solute-solvent fluctuation covariances are shown to be equivalent, in the infinite dilution limit, to the concept of a cluster, which acquires mechanistic significance in the case of binary mixtures of non-volatile solutes in supercritical fluids. Infinite dilution solute partial molar volume measurements in binary mixtures are shown to be equivalent to cluster size determinations. Experimental evidence for a multivalued relationship between cluster size and compressibility is presented and interpreted in the light of fluctuation theory.