Thermodynamic properties of binary mixtures of 2,2,2-trifluoroethanol with water or alkanols at T = 298.15 K

Abstract

Excess molar enthalpies ( H m E ) and excess molar volume ( V m E ) at T = 298.15 K for binary mixtures of {2,2,2-trifluoroethanol (TFE) + water or alcohols (methanol, ethanol, 1-propanol)} were obtained by calorimetry and densimetry. Excess molar enthalpies for the (TFE + water) system showed endothermic mixing, except for the low TFE concentration range ( x 1 < 0.1) in which they showed exothermic one. On the other hand, excess molar volumes for this system were negative over the whole range of concentration. Excess molar enthalpies for all the (TFE + alcohol) systems were exothermic over the whole range of concentration and decrease in absolute value with increase of the carbon number of the alkyl group in the alcohol molecules ( n C). Excess molar volumes were positive over the whole range of concentration and increase with n C. Moreover, we estimated excess partial molar enthalpy ( H m , i E , ∞ ) and volume ( V m , i E , ∞ ) at infinite dilution from the experimental results. These results were discussed qualitatively from the viewpoint of the intermolecular interactions in the pure component liquids and the mixtures.