PVTx and Isochoric Heat Capacity Measurements for Aqueous Methanol Solutions
M M. Aliev, Joe W. Magee, I M. Abdulagatov
Isochoric heat capacity and PVTx properties of an aqueous methanol solution (050 mass fraction or 0.36 mol fraction of methanol) were measured in the liquid phase with a twin-cell adiabatic calometer. Temperatures ranged from 333 K to 422 K, and pressures ranged to 20 Mpa. The calorimetric-cell (70 cm3 capacity) was surrounded by adiabatic thermal shielding (high vacuum) and a steel-sheathed electric heater wound tightly on its surface. The sample pressures were measured by means of a quartz crystal transducer. The relative uncertainty of CV was estimated to be 2%, by combining the various sources of experimental uncertainty using a root-sum-of-squares formula. The uncertainty of the density measurements is about 0.1%. The measured desities were used to calculate excess molar columes that were sompared with values calculated with a reliable model by Simonson et al. Good agreement within +0.008 cm3 x mol-1 (or + 0.03% of the density) was found between measured values of excess molar volume and those calculated from model by Simonson et al. Values of saturated temperatures and densities were determined by extrapolating experimental P-T data to the saturation curve.