Thermodynamics Research Center / ThermoML | Thermochimica Acta

ABSTRACT

Densities poundsl of and speeds of sound u in binary mixtures cyclohexane + benzene and + benzaldehyde have been measured over the entire range of composition at atmospheric pressure and at temperatures ranging from (293.15 to 323.15) K using an Anton-Paar DSA 5000. From these data molar isentropic compressibilities S m K , , thermal expansion coefficients NP z excess molar volumes E m V , and excess molar isentropic compressibilities E S m K , at all the temperatures, and excess thermal expansion coefficients E P N and isothermal pressure coefficient of excess molar enthalpy T x E m H P , ( g / g ) at 298.15 K were calculated. E m V for both the mixtures are positive at all temperatures and over entire range of compositions. The values of E S m K , are positive over entire composition for cyclohexane + benzene while E S m K , curve is S-shaped for cyclohexane + benzaldehyde. The values of E P N are negative except for cyclohexane rich region in both the mixtures. The values of all the excess functions are lower for cyclohexane + benzaldehyde as compared to cyclohexane + benzene at all the temperatures and compositions. The Prigogine!V Flory!VPatterson (PFP) theory has been utilized to estimate speeds of sound u, excess molar volumes E m V and values of P E m gV / gT for the investigated binary mixtures.