Partial molar enthalpies in “inverted micellar” solutions of water and sodium octanoate in decanol

The relative molar enthalpy of solutions with three constant molar ratios of water to sodium octanoate in the isotropic decanol-rich solution phase, L2, of the system water — sodiumn-octanoate -n-decanol have been determined by means of calorimetry at 2° C. A method of calculating the relative partial enthalpies of the components from these data is described. It is the thermic interaction of the sodium octanoate that dominates the properties throughout the extent of the phase studied. Where the decanol content is highest, the partial enthalpies of the sodium octanoate and the water increase sharply while the partial enthalpy of the decanol remains relatively constant throughout the extent of the phase. This agrees well with the general view that aggregation into “inverted micelles” takes place as a continuous process and that the properties of the aggregates remain constant.