Excess Molar Volumes and Excess Isentropic Compressibilities of o-Toluidine plus Tetrahydropyran with Pyridine or Benzene or Toluene Ternary Mixtures at 298.15, 303.15 and 308.15 K

The densities, rho (123), and speeds of sound, u (123), of ternary o-toluidine (OT, 1) + tetrahydropyran (THP, 2) + pyridine (Py) or benzene or toluene (3) mixtures have been measured as a function of composition at 298.15, 303.15 and 308.15 K. Values of the excess molar volumes, and excess isentropic compressibilities, of the studied mixtures have been determined by employing the measured experimental data. The observed thermodynamic properties were fitted with the Redlich-Kister equation to determine adjustable ternary parameters and standard deviations. The and values were also analyzed in terms of Graph theory. It was observed that Graph theory correctly predicts the sign as well as magnitude of and values of the investigated mixtures. Analysis of the data suggests strong interactions and a more close packed arrangement in OT (1) + THP (2) + Py (3) mixtures as compared to those of the OT (1) + THP (2) + benzene (3) or toluene (3) mixtures. This may be due to the presence of a nitrogen atom in Py which results in stronger interactions for the OT:THP molecular entity as compared to those with benzene or toluene.