A new flow instrument for conductance measurements at elevated temperatures and pressures: Measurements on NaCl(aq) to 458 K and 1.4 MPa

摘要

A new flow electrical conductance instrument was constructed and tested on dilute NaCl solutions up to 458 K, and on more concentrated solutions (maximum 0.436 mol center dot kg(-1)) at 373 K. The results of the new instrument agreed with those of previous authors within the estimated experimental errors. The model of Bernard et al. (J. Phys. Chem. 96, 3833-3840 (1992), MSA) was found to represent the high-temperature results without introducing an ion-pairing equilibrium constant. The Fuoss-Hsia conductance equation as given by Fernandez-Prini was found to represent the dilute concentrations with Lambda degrees (NaCI) as the only adjustable parameter. It was found that Lambda degrees (NaCI) could be expressed as a function of solvent viscosity and density by using three parameters found by regression of literature results between 278.15 and 523 K. This equation along with the FHFP theory permits the equivalent conductivity of dilute sodium chloride solutions to be calculated within the accuracy of the existing experimental measurements.