Temperature Dependence of Partial Molar Volumes of Binary Critical Mixtures Study of the System Isobutyric Acid/Water

Publisher Website
Google Scholar
Abstract
Measurements of the coefficient of thermal expansion of isobutyric acid/water mixtures of critical composition and of the partial molar volumes of the two components in the critical mixtures near the critical temperature Tc show: (a) The temperature dependence of the coefficient of thermal expansion is consistent with a logarithmic singularity. (b) The same is true for the temperature derivatives (∂Vi/∂T)P.xc of the partial molar volumes of the two components of the mixture (isobutyric acid i = 1, water i = 2). (c) The singular parts of (∂V1/∂T)P.xc and (∂V2/∂T)P.xc have opposite signs. Approaching Tc(∂T)P.xc decreases and (∂V1/∂T)P.xc increases. These findings are interpreted by assuming that isobutyric acid/water mixtures of critical composition exhibit hydrophobic effects near Tc.