Thermodynamics of the System MgCl2–NaCl–H2O to 573 K: New Measurements of Heat of Mixing and Heat of Dilution

Heats of mixing of NaCl(aq) with MgCl2(aq) at 373.15, 423.15, 473.15, 523.15. and 573.15 K for ionic strengths of 0.5 to 3.8 mol • k g - 1 , and heats of dilution of MgCl2(aq) at 523.15 and 573.15 K for ionic strengths of 0.3 to 4.6 mol - k g - 1 , have been measured at 20.5 MPa. These experimental data are combined with published heat of mixing data at 298 and 373 K to provide a comprehensive Pitzer ion-iInteraction treatment for the thermodynamic properties of the NaCl-MgCl2-H2O system to 573 K. The treatment includes a general equation valid to 523 K, incorporating the published equations for NaCl(aq) and MgCl2(aq), and equations for MgCl2(aq) and the mixed system valid at 573 K.