Roles of water for chemical reactions in high-temperature water

Prediction of the thermodynamic properties of aqueous metal complexes to 1000°C and 5 kb

EQ3NR is an aqueous solution speciation-solubility modeling code. It is part of the EQ3/6 software package for geochemical modeling. It computes the thermodynamic state of an aqueous solution by determining the distribution of chemical species, including simple ions, ion pairs, and complexes, using standard state thermodynamic data and various equations which describe the thermodynamic activity coefficients of these species. The input to the code describes the aqueous solution in terms of analytical data, including total (analytical) concentrations of dissolved components and such other parameters as the pH, pHCl, Eh, pe, and oxygen fugacity. The input may also include a desired electrical balancing adjustment and various constraints which impose equilibrium with special pure minerals, solid solution end-member components (of specified mole fractions), and gases (of specified fugacities). The code evaluates the degree of disequilibrium in terms of the saturation index (SI = 1og Q/K) and the thermodynamic affinity (A = {minus}2.303 RT log Q/K) for various reactions, such as mineral dissolution or oxidation-reduction in the aqueous solution itself. Individual values of Eh, pe, oxygen fugacity, and Ah (redox affinity) are computed for aqueous redox couples. Equilibrium fugacities are computed for gas species. The code is highly flexible in dealing with various parameters as either model inputs or outputs. The user can specify modification or substitution of equilibrium constants at run time by using options on the input file.

/pdf/eq3nr-a-computer-program-for-geochemical-aqueous-speciation-56jwf7h92t.pdf

EQ3NR, a computer program for geochemical aqueous speciation-solubility calculations: Theoretical manual, user`s guide, and related documentation (Version 7.0); Part 3

https://fluids.unileoben.ac.at/Publications_files/Bakker2003a.pdf

Package FLUIDS 1. Computer programs for analysis of fluid inclusion data and for modelling bulk fluid properties

The solubility of quartz in H2O in the lower crust and upper mantle

Electrochemical and electrical conductance cells have been widely used at ORNL over the years to quantitatively determine equilibrium constants and their salt effects to 300°C (EMF) and 800°C (conductance) at the saturation pressure of water (EMF) and to 4000 bars (conductance). The most precise results to 300°C for a large number of weak acids and bases show very similar thermodynamic behavior, which will be discussed. Results for the ionization constants of water, NH3(aq), HCl(aq), and NaCl(aq), which extend well into the supercritical region, have been fitted in terms of a model with dependence on density and temperature. The entropy change is found to be the driving force for ion-association reactions and this tendency increases (as it must) with increasing temperature at a given pressure. Also, the variation of all thermodynamic properties is greatly reduced at high fixed densities. Considerable variation occurs at low densities. From this analysis, the dependence of the reaction thermodynamics on the P-V-T properties of the solvent is shown, and the implication of large changes in hydration for solutes in the vicinity of the critical temperature will be discussed. Finally, the change in the molar compressibility coefficient for all reactions in water is shown to be the same and dependent only on the compressibility of the solvent.

Thermodynamics of aqueous association and ionization reactions at high temperatures and pressures

The enthalpy of dilution of HCl(aq) to 648 K and 40 MPa thermodynamic properties

The enthalpy of dilution of aqueous sodium chloride to 673 K using a new heat-flow and liquid-flow microcalorimeter. Excess thermodynamic properties and their pressure coefficients

H.F. Holmes

Papers

Thermodynamics of aqueous association and ionization reactions at high temperatures and pressures

The enthalpy of dilution of HCl(aq) to 648 K and 40 MPa thermodynamic properties

The enthalpy of dilution of aqueous sodium chloride to 673 K using a new heat-flow and liquid-flow microcalorimeter. Excess thermodynamic properties and their pressure coefficients

Isopiestic studies of aqueous solutions at elevated temperatures I. KCl, CaCl2, and MgCl2

CaCl2(aq) at elevated temperatures. Enthalpies of dilution, isopiestic molalities, and thermodynamic properties