Development of an experimental data base and theories for prediction of thermodynamic properties of aqueous electrolytes and nonelectrolytes of geochemical significance at supercritical temperatures and pressures. Annual performance report

• Main Authors: Wood, R. H., Hnedkovsky, L., Lin, Ching Lung, Shock, E. L.
• Other Authors: United States. Department of Energy.
• Format: Report
• Language: English
• Published: Delaware Univ., Newark, DE (United States). Dept. of Chemistry and Biochemistry 1992
• Subjects: Progress Report; Solubility; Volume; Bubbles; Thermodynamic Properties; Chemical And Physicochemical Properties; 580000; 58 Geosciences; Methane; Carbonic Acid; Geosciences; Hydrogen Sulfides; Rock-Fluid Interactions 400201; Free Energy; Boric Acid; Aqueous Solutions; Ammonia; High Pressure; Hydrothermal Systems; Temperature Range 0400-1000 K; Carbon Dioxide; 37 Inorganic; Organic; Physical And Analytical Chemistry; Density; Geochemistry; Very High Pressure; Carbonic acid
• Online Access: https://doi.org/10.2172/10182216; https://digital.library.unt.edu/ark:/67531/metadc1400347/

This project is divided into method experimental measurements, theoretical development, and geochemical applications. We have completed experimental volumetric measurements on aqueous solutions of CO{sub 2} H{sub 2}S, CH{sub 4}, NH{sub 3} and B(OH){sub 3} at 25 to 432{degree}C and 280 and 350 bar. A vibrating tube densitometer that allows density measurements near bubble point and also measures the bubble pressure was developed and used to measure densities and bubble pressures of aqueous Co{sub 2}. Heat capacity measurements should be completed by the end of the grant period. Simulations of models for methane in water at temperatures to 1000{degrees}C are in progress. In order to facilitate these free energy calculations the possible errors associated with the calculations have been explored in two papers (Wood, 1991; Wood et al., 1991) and methods of controlling and estimating these errors have been developed. Applications of the new data to geochemical processes is now possible. Efforts have focussed on extracting equilibrium constants for carbonic acid dissociation at supercritical condition from published experiments on mineral equilibria in H{sub 2}0-CO{sub 2} fluids (Boehlke and Shock, 1990; and in prep.). As a result, estimates of pKa for carbonic acid are now available at temperatures from 300 to 750{degrees}C and pressures from 1 to 7 kilobars. They will be combined with {bar V}{sup {degree}} and {bar C}p{sup {degree}} data for CO{sup 2}(aq) to improve geochemical calculations.