Apparent molar volumes and apparent molar heat capacities of aqueous ethane-1,2-diol, propane-1,2-diol, and propane-1,3-diol at temperatures from 278.15 K to 393.15 K and at the pressure 0.35 MPa

Abstract

Apparent molar heat capacities Cp, φand apparent molar volumesVφ were determined for aqueous solutions of ethane-1,2-diol, propane-1,2-diol, and propane-1,3-diol at temperatures T from 278.15 K to 393.15 K and at the pressure 0.35 MPa. The molalities m investigated ranged from 1.0 mol · kg −1to about 0.02 mol · kg −1. We used a vibrating tube densimeter (DMA 512P, Anton PAAR, Austria) to determine the densities and volumetric properties. Heat capacities were obtained using a twin fixed-cell, power-compensation, differential-output, temperature-scanning calorimeter (NanoDSC 6100, Calorimetry Sciences Corporation, American Fork, UT, U.S.A.). The results were fit by regression to equations that describe the surfaces ( Vφ, T, m) and (Cp, φ , T, m). Infinite dilution partial molar volumesV2o and heat capacities Cp,2owere obtained over the range of temperatures by extrapolation of these surfaces to m= 0 mol · kg−1 .