Volumes of MgCl2(aq) at temperatures from 298 K to 623 K and pressures up to 30 MPa

Obsil, M., Majer, V., Hefter, G. and Hynek, V. (1997) Volumes of MgCl2(aq) at temperatures from 298 K to 623 K and pressures up to 30 MPa. Journal of Chemical Thermodynamics, 29 (5). pp. 575-593.

Abstract

Vibrating tube densimetry was used to investigate volumetric properties of MgCl2(aq) at target molalities between 0.005 mol·kg−1and 3 mol·kg−1, at temperatures from 298 K to 623 K and pressures up to 30 MPa. The new data are correlated at constantTandpas a function of molality by the Pitzer equation in order to obtain partial molar volumes at infinite dilution. Volumes for MgCl2(aq) as a function of temperature and pressure are compared with those for other basic types of strong electrolytes. Data on association constants, volumes of ion-pairing, and activity coefficients, derived from information available in the literature, were used to calculate the degree of association in MgCl2(aq) as a function of molality and temperature. A modified form of the Pitzer equation was used to obtain a semiquantitative estimate of the partial molar volumes at infinite dilution for the ionized salt.