ThermoMLAn XML-Based Approach for Storage and Exchange of Experimental and Critically Evaluated Thermophysical and Thermochemical Property Data. 2. Uncertainties

Abstract

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.

XML-Based IUPAC Standard for Experimental, Predicted, and Critically Evaluated Thermodynamic Property Data Storage and Capture (ThermoML) (IUPAC Recommendations 2006)

“…In the second article [14] in the series [2,14,15] describing the development of ThermoML, application of the recommendations of the Guide to particular aspects of experimental thermodynamic property data were discussed, and additions to the ThermoML schema for representation of uncertainties were described. In the present paper, the basic principles are reviewed briefly, but the reader is referred to the earlier papers [14,[25][26][27] for comprehensive discussions of the internationally accepted quantities and terms for describing uncertainty, including standard uncertainty, combined standard uncertainty, coverage factor, expanded uncertainty, combined expanded uncertainty, and level of confidence.…”

“…In the present paper, the basic principles are reviewed briefly, but the reader is referred to the earlier papers [14,[25][26][27] for comprehensive discussions of the internationally accepted quantities and terms for describing uncertainty, including standard uncertainty, combined standard uncertainty, coverage factor, expanded uncertainty, combined expanded uncertainty, and level of confidence. Table 2 shows the general mathematical relationships between the quantities used for the expression of uncertainty, which are used explicitly in ThermoML.…”

“…Definitions for repeatability [14,29], curve deviation [14], and device specification [14] were given previously, and are the only representations of precision included in ThermoML. It must be recognized clearly by the user of this information that these are components in an array of information that can be used in estimating the uncertainty of measurement.…”

“…Mathematical definitions were given previously [14]. A discussion of the application of these formulae to particular experimental conditions is beyond the scope of this paper.…”

“…Much of the material given below was published previously in a series of three articles describing the original formulation of ThermoML for representation of experimental data [2], extensions to the schema for representation of uncertainties [14], and further extensions for representation of predicted data, critically evaluated data, and fitting equations [15]. Every effort was made to ensure that information represented with the formats described in these earlier articles would remain valid within the new IUPAC standard version of ThermoML.…”