Reviews ThermoMLsAn XML-Based Approach for Storage and Exchange of Experimental and Critically Evaluated Thermophysical and Thermochemical Property Data. 1. Experimental Data Michael Frenkel,* Robert D. Chirico, Vladimir V. Diky, and Qian Dong Thermodynamics Research Center (TRC), Physical and Chemical Properties Division, National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305-3328 Svetlana Frenkel and Paul R. Franchois Information Technology Laboratory, National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305-3337 Dale L. Embry ConocoPhillips, 850-16 Street, P.O. Box 1267, Ponca City, Oklahoma 74602-1267 Thomas L. Teague ePlantData, Inc., 9955 South Post Oak Road, Suite 300, Houston, Texas 77096 Kenneth N. Marsh Department of Chemical and Process Engineering, University of Canterbury, Private Bag 4800, Christchurch, New Zealand Randolph C. Wilhoit Texas Experimental Engineering Station, Texas A&M University System, College Station, Texas 77843 ThermoML is an XML-based approach for storage and exchange of experimental and critically evaluated thermophysical and thermochemical property data. The basic principles, scope, and description of all structural elements of ThermoML are discussed. ThermoML covers essentially all experimentally determined thermodynamic and transport property data (more than 120 properties) for pure compounds, multicomponent mixtures, and chemical reactions (including change-of-state and equilibrium). The primary focus at present is molecular compounds. Although the focus of ThermoML is properties determined by direct experimental measurement, ThermoML does cover key derived property data such as azeotropic properties, Henry’s Law constants, virial coefficients (for pure compounds and mixtures), activities and activity coefficients, fugacities and fugacity coefficients, and standard properties derived from high- precision adiabatic heat-capacity calorimetry. The role of ThermoML in global data submission and dissemination is discussed with particular emphasis on the new cooperation in data processing between the Journal of Chemical and Engineering Data and the Thermodynamics Research Center (TRC) at the National Institute of Standards and Technology. The text of several data files illustrating the ThermoML format for pure compounds, mixtures, and chemical reactions, as well as the complete ThermoML schema text, is provided as Supporting Information. Some important issues related to characterization of thermodynamic data are beyond the scope of this paper (uncertainty specification) or are considered in generic terms only (critically evaluated data). These issues will be considered in subsequent papers in this series. Background Efforts to develop a standard for thermophysical and thermochemical property data exchange were initiated in the early 1980s, reflecting a new trend in data collection through design of electronic databases, which became possible due to the rapid development of computer technol- ogy. In the time period 1985 to 1987, the Thermodynamics Research Center (TRC, then with Texas A&M University) developed the first prototype of such a standard called * Corresponding author. Phone: (303)-497-3952. Fax: (303)-497-5044. E-mail: frenkel@boulder.nist.gov. 2 J. Chem. Eng. Data 2003, 48, 2-13 10.1021/je025645o CCC: $25.00 © 2003 American Chemical Society Published on Web 12/17/2002