EXCESS MOLAR VOLUMES OF SOME POLYETHER PLUS WATER-SYSTEMS

Excess molar volumes at 25-degrees, are reported for the system 1,2-di methoxyethane + water and 12-crown-4 + water across their entire respe ctive composition ranges. These data have been compared to others take n from the literature, in an effort to assess the effects of replacing hydroxy by methoxy groups, of switching linear to cyclic polyethers a nd of inserting oxyethylene groups. The data sets were analysed using a segmented composition model in order to obtain a quantitative descri ption of the composition dependence of the excess molar volumes. Exces s partial molar volumes of the organic species at infinite aqueous dil ution were evaluated by means of four segment analyses of the various excess volume data sets. The effectiveness of the group additivity pri nciple is nicely demonstrated.