A Ghanadzadeh Gilani - Department of Chemistry, Faculty of Science, University of Guilan, Rasht, Iran
S.E Hosseini - Department of Chemistry, Faculty of Science, University of Guilan, Rasht, Iran

Design of mixed solvent of suitable liquid state range and required solvating power byvarying mixture constituents concentration makes them useful in pharmaceutical, biologicaland analytical sciences, and also in technological and laboratory applications [1]. Thedielectric constant is one of the most important properties of the mixed solvents, whichcontrols and enhances its various applications [2, 3].The aim of this study is to provide the precision dielectric constant values of these mixedsolvent and to confirm the nature of H-bonded unlike molecular structures. In addition, wepresent and discuss the results of the concentration and temperature dependence of thepermittivity, excess permittivity, and excess Helmholtz energy of the binary mixture of1,5PD with 2EH at T= 298.2, 308.2 and 318.2 K.