Prediction of the speed of sound in the ethanol+n-heptane system: New application of the Extended Real Associated Solution model

The ERAS (Extended Real Associated Solution) Model developed by Heintz [A. Heintz, Ber. Bunsenges. Phys. Chem., 89 (1985) 172] for describing thermodynamic excess properties of alcohol+alkane mixtures, was modified, in order to take into account the effect of pressure (p≠0), and applied for calculating the compressibility and the speed of sound in ethanol+n-heptane mixtures at T=298.15 K and p=0.1 MPa. The calculated compressibility and ultrasonic speed values are in good qualitative agreement with the experimental ones. Even the quantitative consistence seems to be rather satisfactory (the differences between the calculated and experimental speed values do not exceed 0.5% in the whole concentration range).