Applying the Gibbs Free Energy Equation

Applying the Gibbs Free Energy Equation

The recognition of the similarity in behaviour of gases and solutions converged in the expression of the Gibb's Free Energy Equation (and the Helmholtz equivalent) the stage was set for an incredibly productive period of applying this new knowledge. The "Gas Constant" had been promoted to be "The Gas and Solutions Constant" (but has retained the original more modest title for official texts).

The United States Geological Soceity (USGS) recognised the potential of establishing the thermodyamic values - particularly the equilibrium constants for water and ground rock systems, and passed the hat around for some researching funding to gather and collate data which would be useful to industry and would provide an information infrastructure asset for the grand plans of improving life. They didn't spend most of the money on fancy offices with corporate meeting hubs - and developing some obscure proprietary patented and commercialised measurement device or to try and rewrite history and generate lots of pHd's to "discover" everything again for themselves (and hold everyone back while they struggled with the more difficult bits that others had already resolved). They just produced data in a consistent tabular form, using a standard test method (the calorimetric bomb) to be used with the established data interpretation method (the Gibbs Free Energy Equation). As a tax payer and shareholder in a sponsoring company I think you could be happy with that.

The tabulated data was (is) published as "Bulletins". USGS Bulletin 1259 "Thermodynamic Properties of Minerals and Related Substances..." was first published in 1968. USBM Bulletin 677 "Thermodynamic Data for Mineral Technology" is similar. I think there is a Bulletin 1452 - maybe an update? I am not sure where the crossover from USGS to USBM is - but it is an obvious connection on use of data - and heralded? the concepts of "GeoChem" and "GeoMet". In the end I guess it is just "Gee - it is all just science".

The tabulated data provides the raw data for incremental enthalpy relative to 298.15 degrees C, in steps of increasing temperature, established at 1 atmosphere pressure. Estimates of errors are provided. The simple procedure shows the enthalpy of phase change in a practical way (as it is implemented in Metsim). The heats of formation from standard conditions, heat capacity, entropy, and "free energy" values derived from the raw data are provided.

This data (or any similar source) can be used in Metsim, or can be used to check component thermodata for particular reactions that you need to check. The pre-amble on "Thermodynamic Data for Mineral Technology" is maybe the best introduction for Metsim Users on the use of thermo data in a practical way.

Cheers, Jim