The Eh-pH diagram (Pourbaix diagram) for N-H2O system was constructed at 623 K based on the revised HKF (H. C. Helgeson, D. H. Kirkham and G. C. Flowers) equation. The fundamental thermodynamic data such as Cp° and ΔG° were derived from the HKF equation directly for ionic species, and from the combination of HKF equation and the Electrostatic Non-Electrostatic Model (H. C. Helgeson) for neutral species. Comparing the Eh-pH diagram at 623 K with that at 298 K, all boundaries between gaseous species were found to slant to the lower E with increasing pH. The stable regions of neutral species, i.e. NH4OH (aq) and HNO3(aq), expanded toward the neutral pH at 623 K, possibly because of the formation of ion pairs.
|Number of pages||3|
|Journal||Nippon Kagaku Kaishi|
|Publication status||Published - 1996|