Thermodynamics of Mixtures Containing Amines. XII. Volumetric and Speed of Sound Data at (293.15, 298.15, and 303.15) K for N-Methylaniline + Hydrocarbon Systems

A vibrating tube densimeter and sound analyzer Anton Paar model DSA-5000 has been used for the measurement of densities, ρ, and speeds of sound, c, of N-methylphenylamine (N-methylaniline) + heptane, or + cyclohexane, or + toluene mixtures at (293.15 to 303.15) K and atmospheric pressure. From these data, we have obtained excess molar volumes, VmE, at the three temperatures and excess functions for c and the isentropic compressibility, KS at 298.15 K. VmE results reveal the existence of structural effects in alkane solutions and of interactions between unlike molecules in systems with toluene. N-Methylaniline + hydrocarbon mixtures have been characterized in terms of the ERAS model. The theory provides a good representation of excess molar enthalpies, HmE, and describes correctly the relative variation of VmE. ERAS calculations show the importance of the physical interactions in the studied systems, which is consistent with the experimental HmE and VmE data.