The first full-scale software implementation of the dynamic data evaluation concept {ThermoData Engine (TDE)} is described for thermophysical property data. This concept requires the development of large electronic databases capable of storing essentially all experimental data known to date with detailed descriptions of relevant metadata and uncertainties. The combination of these electronic databases with expert-system software, designed to automatically generate recommended data based on available experimental data, leads to the ability to produce critically evaluated data dynamically or 'to order'. Six major design tasks are described with emphasis on the software architecture for automated critical evaluation including dynamic selection and application of prediction methods and enforcement of thermodynamic consistency. The direction of future enhancements is discussed.

The development, scope, and functionality of the Web-based ionic liquids database, ILThermo, are described. The database is available free to the public and aims to provide users worldwide with up to date information from publications of experimental thermophysical properties for ionic liquids, including numerical property values, measurement methods, sample purities, purification methods, and uncertainties. The database can be searched in terms of the ions constituting the ionic liquids, the ionic liquids themselves, and their properties and through literature citation information

This article describes a 10-year cooperative effort between the U.S. National Institute of Standards and Technology (NIST) and five major journals in the field of thermophysical and thermochemical properties to improve the quality of published reports of experimental data. The journals are Journal of Chemical and Engineering Data, The Journal of Chemical Thermodynamics, Fluid Phase Equilibria, Thermochimica Acta, and International Journal of Thermophysics. The history of this unique cooperation is outlined, together with an overview of software tools and procedures that have been developed and implemented to aid authors, editors, and reviewers at all stages of the publication process, including experiment

ThermoML is an XML-based approach for storage and exchange of experimental and critically evaluated thermophysical and thermochemical property data. Extensions to the ThermoML schema for the expression of uncertainties are described. Basic principles, scope, and description of all new structural elements are discussed. Representation of upper and lower limits for property values is also addressed. 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). Properties of polymers and radicals and some properties of ionic systems are not represented at present. The present role of ThermoML in global data submission and dissemination is discussed with particular emphasis on cooperation between major journals in the field and the Thermodynamics Research Center (TRC) at the National Institute of Standards and Technology. The text of several data files illustrating the expression of uncertainties in ThermoML format for pure compounds, mixtures, and chemical reactions are provided as Supporting Information, as well as the complete updated ThermoML schema text.

A quality assessment algorithm for vapor-liquid equilibrium (VLE) data has been developed. The proposed algorithm combines four widely used tests of VLE consistency based on the requirements of the Gibbs-Duhem equation, with a check of consistency between the VLE binary data and the pure compound vapor pressures. A VLE data-quality criterion is proposed based on the developed algorithm, and it has been implemented in a software application in support of dynamic data evaluation. VLE predictions (NRTL and UNIFAC) were deployed to detect possible anomalies in the data sets. The proposed algorithm can be applied to VLE data sets with at least three state variables reported (pressure, temperature, plus liquid and/ or vapor composition) and is applicable to all nonreacting chemical systems at subcritical conditions. Application of the developed algorithms to identification of erroneous published VLE data sets is demonstrated.

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This article is a product of IUPAC Project 2002-005-1-100 (Thermodynamics of ionic liquids, ionic liquid mixtures, and the development of standardized systems). Experimental results of thermodynamic, transport, and phase equilibrium studies made on a reference sample of the ionic liquid 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]amide are summarized, compared, and critically evaluated to provide recommended values with uncertainties for the properties measured. Properties measured included thermal properties (triple-point temperature, glass-transition temperature, enthalpy of fusion, heat capacities of condensed states), volumetric properties, speeds of sound, viscosities, electrolytic conductivities, relative permittivities, as well as properties for mixtures, such as gas solubilities (solubility pressures), solute activity coefficients at infinite dilution, and liquid-liquid equilibrium temperatures. Recommended values with uncertainties are provided for the properties studied experimentally. The effect of the presence of water on the property values is discussed.

ThermoData Engine (TDE) is the first full-scale software implementation of the dynamic data evaluation concept, as reported recently in this journal. The present paper describes the first application of this concept to the evaluation of thermophysical properties for binary chemical systems. Five activity-coefficient models have been implemented for representation of phase-equilibrium data (vapor-liquid, liquid-liquid, and solid-liquid equilibrium): NRTL, UNIQUAC, Van Laar, Margules/Redlich-Kister, and Wilson. Implementation of these models in TDE is fully described. Properties modeled individually are densities, surface tensions, critical temperatures, critical pressures, excess enthalpies, and the transport properties-viscosity and thermal conductivity. Extensions to the class structure of the program are described with emphasis on special features allowing close linkage between mixture and pure-component properties required for implementation of the models. Details of gas-phase models used in conjunction with the activity-coefficient models are shown. Initial implementation of the dynamic data evaluation concept for reactions is demonstrated with evaluation of enthalpies of formation for compounds containing carbon, hydrogen, oxygen, and nitrogen. Directions for future enhancements are outlined.