Experimental study of the density and derived volumetric (excess, apparent, and partial molar volumes) properties of aqueous 1-propanol mixtures at temperatures from 298 K to 582 K and pressures up to 40 MPa

Abstract

Densities of (water+1-propanol) mixtures have been measured over the temperature range from 298K to 582K and at pressures up to 40MPa using the constant-volume piezometer immersed in a precision liquid thermostat. The measurements were made for six compositions of (0.869, 2.465, 2.531, 7.407, 14.377, and 56.348)mol·kg−1 of 1-propanol. The expanded uncertainty of the density, pressure, temperature, and concentration measurements at the 95% confidence level with a coverage factor of k=2 is estimated to be 0.06%, 0.05%, 15mK, and 0.015%, respectively. The derived volumetric properties such as excess (VmE), apparent (VΦ), and partial (V¯2∞) molar volumes were calculated using the measured values of density for the mixture and for pure components (water and 1-propanol). The concentration dependences of the apparent molar volumes were extrapolated to zero concentration to yield the partial molar volumes of 1-propanol at infinite dilution (V¯2∞). The temperature, pressure, and concentration dependence of density and derived properties of the mixture were studied. All experimental and derived properties (excess, apparent, and partial molar volumes) were compared with the reported data by other authors. The small and negative values of excess molar volume for the mixtures were found at all experimental temperatures, pressures, and over the entire concentration range. The excess molar volume minimum is found at concentration about 0.4mole fraction of 1-propanol. The concentration minimum of the derived apparent molar volumes VΦ near the 2.5mol·kg−1 (dilute mixture) was observed.