Densities, excess molar volumes and partial molar volumes of the binary mixtures of acetic acid + alkanol (C1–C4) at 298.15 K

Densities (ρ) of the binary mixtures of acetic acid with methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol and butan-2-ol have been measured at temperature 298.15 K and ambient pressure (815 hPa) as a function of composition using an Anton Paar model DMA 4500 oscillating densimeter. The excess molar volume (V_m^E), partial molar volume (V¯_i) and excess partial molar volumes (V¯_i^E) of the binary mixtures were calculated from the density data. The excess molar volumes were correlated with the Redlich−Kister equation. The excess molar volumes are negative for methanol, ethanol, propan-1-ol, propan-2-ol and butan-1-ol. They are positive for butan-2-ol and an inversion of sign in V_m^E is observed for butan-2-ol around 0.9 mol fraction of acetic acid.

The results obtained in this work were interpreted in terms of intermolecular interaction between like and unlike molecules, difference in size and shape of unlike molecules and the steric hindrance caused by increased methylation.