A new calorimetric technique, which combines a hydrothermal cold-seal pressure vessel and a Calvet-type microcalorimeter, provides direct enthalpy measurements of solutions at temperatures to 1073 K and pressures to 200 MPa. We report initial results for enthalpies measured for NaCl + H2O at temperatures of 985, 536, and 457 K and pressures of 51 and 100 MPa over a molality range of 0 to 6 mol kg-1. The partial molar enthalpies of NaCl, calculated from the results at temperatures above 423 K and pressures of 50 to 100 MPa, appear to be significantly different from those observed along the liquid-vapor saturation curve.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Materials Science(all)
- Physical and Theoretical Chemistry