Glossary of Terms used in ThermoData Engine (TDE):

Alternative Equations (Navigation Tree item): For most properties, alternative equations can be fit to property values generated from the Default Representations. For example, a data evaluation may yield the 2,5-form of the Wagner equation as the Default Representation; however, the user may specifically need Antoine equation parameters for a particular application. The Alternative Equations section allows this option. Plots of differences between the Default and Alternative Equations can be seen within the Alternative Equations section of the Navigation Tree.

Carrier: This term is used in Solvent for Extraction within the Product Design menu on the main screen. This the solvent that originally contains the solute to be extracted.

Cryoscopic Constant: A quantity that can be derived from the study of melting temperature as a function of impurity level. It is the enthalpy of fusion divided by the gas constant times the square of the melting temperature. (i.e., Hfus/RTm2).

Data Set (column in a Data Table): These are results of an experimental determination of a property from a particular source (i.e., article or reference). It is possible to have more than one data set from a single source for a given compound and property, if, for example, different methods or different samples were used.

Default Representations (Navigation Tree item): Default Representations are critically evaluated property representations generated dynamically by the ThermoData Engine (TDE) software. As part of the evaluation process, the program chooses amongst models of different complexity based upon data-quality and range considerations. The Default Representation is the model chosen by the software for a particular data scenario. The program user can select an Alternative Equation for secondary fitting, if desired.

Evaluated Data (Navigation Tree item): These are results of the dynamic data evaluation (a critical evaluation) generated by the ThermoData Engine (TDE) program. NOTE: These should not be confused with Predicted Data, which are generated with a particular estimation method, such as group-contribution or corresponding states.

Experimental Data (Navigation Tree item): Experimental data are defined as those obtained as the result of a particular experiment on a particular sample by a particular investigator. The feature that distinguishes experimental data from predicted and critically evaluated data is use of a chemical sample.

Invalid Data (column entry in a Data Table): This term is assigned by the program to data that are invalid by definition. For example, values involving negative temperatures or pressures. Origins of these problems include typographical errors in the bundled database of experimental values, typographical errors in the original data report, misidentified compounds in either the database or original report, errors in units, and others.

Large Deviation (column entry in a Data Table): This term is assigned by the program to data that show a relatively large deviation from the fitting equation or weighted average value. Rejection involves multiple considerations including deviations from predicted data, deviations from fitted equations or weighted averages, and relative local data quality. Local data quality is the data quality near the data point under consideration. Complete descriptions of the methods used for data rejection will be published separately.

Navigation Tree: The leftmost program frame that includes expandable nodes entitled Compound, Experimental and Predicted Data, Default Representations, etc.

Navigation Tree End Node: The final (end) expansion item for an entry in the Navigation Tree.

Out of Range (column entry in a Data Table): This term is assigned by the program to data that are invalid by definition. The meaning is similar to that for Invalid Data, except that for Out-of-Range data the lack of validity is with the variable(s) rather than with the property. (For example, vapor pressures for T > Tc, or densities for the liquid phase for p < psat are 'out of range.')

Predicted Data: Property values generated with a particular estimation method. These values are used to check the validity of experimental data and to aid in the extrapolation or interpolation of experimental values. NOTE: These values should not be confused with Evaluated Data, which are the critically evaluated results generated by the ThermoData Engine software.

Reaction Participant: This term applies to any reactant or product in a chemical reaction.

Reject (column in a Data Table): This column is used to indicate data that were rejected by the ThermoData Engine software during the critical evaluation process or by the program user prior to evaluation. Entries in this column are Invalid Data, Out of Range, Large Deviation, and By User.

Selectivity (property of a solvent: See Selective Solvent for Solute Mixture) and Solvent for Extraction). For Selective Solvent for Solute Mixture: Selectivity = solubility of solute/ solubility of the contaminant. For Solvent for Extraction: Selectivity = solubility of solute in the carrier/ solubility of the solute in the extracting solvent.

Smooth Data (column in a Data Table): At times, experimental data are reported in original sources in the form of equations only or as tables generated from fitted equations. Such values are not primary experimental data and are indicated as 'smooth' in TDE. There are two types of such experimental data; values calculated at NIST with equations provided by authors (indicated with a "C"), and smoothed values provided in tabular form by the authors (indicated with the letter "S"). Common examples are vapor pressures for which only a fitted equation is reported (designated "C") and thermodynamic functions (heat capacity, enthalpy. and entropy) derived from low-temperature adiabatic heat capacity studies for pure compounds (designated "S").

Source (column in a Data Table): A 'source' is a data source, such as a journal article, thesis, report, prediction, or evaluation. Data sources are displayed in various formats.

Uncertainty: Uncertainties listed in all tables and output files of the ThermoData Engine software represent estimates of the Combined Expanded Uncertainty (with 95% Level of Confidence) for the property value. Click the Uncertainty link for references with complete details.

User Data: These data are supplied by the user of the program. Procedures for Addition of User Data are provided.