ACTIVITY-COEFFICIENTS OF WATER AND SULFOLANE FROM THE SOLID + LIQUID-PHASE DIAGRAM

The solid + liquid phase diagram drawn from thermal analysis is presented. It exhibits a eutectic at x2 = 0.303 and T = 262.2 K and precludes the existence of definite compounds between the two components. Mixed crystals are observed in the sulfolane-rich region. The activity coefficients of water, fx, 1, and of sulfolane, fx, 2, are calculated from the initial freezing points of water. Log fx, 1 and log fx, 2 show a steady dependence on volume composition, providing evidence for the supposition that strongly self-associated water and monomer sulfolane scarcely interact with one another, and that the thermodynamic properties of the mixtures should rather be related to steric factors. © 1979.