The reactions that cause transformations in organic compounds in the Earth's crust remain mysterious despite decades of research into how fossil fuel resources form. A major reason for this persistent mysteriousness is the failure of many researchers to realize the intimate involvement of water in those transformations. Our goal was to overcome this staggering ignorance by developing the means to calculate the consequences of reactions involving organic compounds and water. We pursued this research from 1989 through 2006, and this report focuses on progress between 2002 and 2006. There were two major obstacles that we overcame in the course of this research. On the one hand, we developed new theoretical equations that allow researchers to make these calculations. On the other hand, we critiqued available data and provided sound means to make estimates in the absence of experimental data for hundreds of organic compounds dissolved in water. Finally, we merged these two lines of research into an interactive web site that allows users to do the calculations with the equations and data. We call the web site ORCHYD for: "ORganic Compounds HYDration properties database," but it is far more than a database since it allows users to make extremely accurate predictions of data that may never have been measured. Our progress greatly exceeded our anticipations, and has permitted many new research investigations that were previously impossible. Despite the abrupt termination of funding for this project by the Department of Energy, we are maintaining the web site for the international scientific community. Major research results were published in eleven scientific papers, so they are all in the public domain. Benefits to the public include a new, rigorous, quantitative approach to testing ideas about the fate of organic compounds dissolved in water. These tests can be applied to geochemistry or to industrial processes. The increasing use of water as a solvent in Green Chemistry and Sustainable Industrial Practices, means that there is a pressing need for data and calculations of the type we have provided and enabled. Applications include: improved efficiency of industrial processes, improvements in health protections for workers who encounter organic solvents and other organic compounds, predictive tools for cleaning up landfills and other toxic waste, and the potential for a greater understanding of how petroleum forms.

The objective of this research was to combine new experimental measurements on heat capacities, volumes, and association constants of key compounds with theoretical equations of state and with first principles quantum mechanical calculations to generate predictions of thermodynamic data. The resulting thermodynamic data allow quantitative models of geochemical processes at high temperatures and pressures. Research funded by a DOE grant to Prof. Robert Wood at the University of Delaware involved the development of new theoretical equations of state for aqueous solutions of electrolytes and non-electrolytes, methods to estimate thermodynamic data not available from experiments, collection of data on model compounds through experiments and predictions of properties using ab initio quantum mechanics. During the last three and a half years, with support from our DOE grant, 16 papers have been accepted or published, and 3 more are in preparation. Results of this research have been reported in numerous invited and contributed presentations at national and international meetings. For this report, we will briefly comment on the highlights of the last 3 and a half years and give a complete list of papers published, accepted, or submitted during these years.

This project is divided into method experimental measurements, theoretical development, and geochemical applications. We have completed experimental volumetric measurements on aqueous solutions of CO2 H2S, CH4, NH3 and B(OH)3 at 25 to 432°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 Co2. Heat capacity measurements should be completed by the end of the grant period. Simulations of models for methane in water at temperatures to 1000°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 H20-CO2 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°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 CO2(aq) to improve geochemical calculations.