ACTIVITIES AND THERMODYNAMIC EXCESS PROPERTIES OF AQUEOUS 2,5-DIMETHYLPYRIDINE MIXTURES NEAR THE CRITICAL DEMIXING POINT - COMPARISON WITH 2,6-DIMETHYLPYRIDINE WATER MIXTURES

Activities of 2,5-dimethylpyridine in aqueous solution have been measu red at eleven temperatures, two below and nine above the lower critica l temperature of the mixture, by the dynamic method of Randall and Web er. Gibbs free energy, enthalpy and entropy are derived to obtain exce ss quantities and all the results are discussed in connection with the liquid-liquid phase separation, the critical situation and the associ ation properties of the molecules. A comparison is also made with the aqueous 2,6-dimethylpyridine system. A new version of the phase diagra m is proposed.