Recommended values are provided for chemical thermodynamic properties of inorganic substances and for organic substances usually containing only one or two carbon atoms. Where available, values are given for the enthalpy of formation, Gibbs energy of formation, entropy, and heat capacity at 298.15 K (25 degrees C), the enthalpy difference between 298.15 and 0 K and the enthalpy of formation at 0 K. All values are given in SI units and are for a standard state pressure of 100 000 pascal. This volume is a new collective edition of "Selected Values of Chemical Thermodynamic Properties," which was issued serially as National Bureau of Standards Technical Notes 270-1 (1965) to 270-8 (1981). Values are given for properties of gaseous, liquid and crystalline substances, for solutions in water, and for mixed aqueous and organic solutions. Values are not given for alloys or other solid solutions, fused salts or for substances of undefined composition. Compounds of the transuranium elements are not included.

The Web Thermo Tables (WTT) are a collection of critically evaluated thermodynamic property data for pure compounds with a primary focus on organics. These data were generated through dynamic data analysis, as implemented in the NIST ThermoData Engine software package. Also included are some critically evaluated data from the historical TRC Thermodynamic Tables archive. The Professional Edition contains information on over 28,000 compounds. For a subset of the data focused on commonly-used pure compounds please see the Lite Edition (http://www.nist.gov/srd/nistwebsub2.cfm) .

The ThermoData Engine fully implements all major principles of the concept of dynamic data evaluation formulated at NIST?s Thermodynamics Research Center (TRC). Dynamic data evaluation relies on large electronic databases to store the currently known experimental data along with detailed descriptions of relevant metadata and uncertainties. Combining this data with expert software allows the ThermoData Engine to producing data compilations 'to order' which include all major thermophysical properties (such as density, vapor pressure, heat capacity, enthalpies of phase transitions, critical properties, melting and boiling points, etc). As the name of this resource implies, its scope is pure compounds, binary mixtures and reactions. If you are only interested in pure compounds please see NIST ThermoData Engine - Pure Compounds - SRD 103a (https://www.nist.gov/srd/nist-standard-reference-database-103a).