|Title||An outline of reaction equilibrium|
|Source||Geological Survey of Canada, Current Research (Online) 2006-H2, 2006, 12 pages; 1 CD-ROM, https://doi.org/10.4095/222698 (Open Access)|
|Publisher||Natural Resources Canada|
|Media||on-line; CD-ROM; digital|
|Related||This publication is related to Froese, E; (2013). An outline
of phase equilibrium, Geological Survey of Canada, Open File 7057|
|Subjects||geochemistry; equilibrium; phase equilibria; chemical analysis; chemical processes; thermodynamics; energy; temperature; pressure-temperature conditions|
|Released||2006 09 01|
|Abstract||The consideration of the mole numbers of chemical species as variables characterizing a macroscopic state makes it possible to define the affinity of a chemical reaction in terms of thermodynamic
concepts. This approach leads to the basic relationship of reaction equilibrium in a closed system with one chemical reaction:|
where G is the total Gibbs energy, (epsilon) is the extent of reaction,Gi is the
partial molar Gibbs energy of a species, and (nu)i is the stoichiometric coefficient. The partial derivative <> is commonly designated as the Gibbs energy change of reaction and given the symbol (Delta)G. At arbitrary values of
(epsilon), (epsilon) can be regarded as a constraint keeping the system in a metastable equilibrium. Upon release of this constraint, a negative value of (Delta)G indicates a tendency of the reaction to proceed from reactants to products.
Relationships required to evaluate (Delta)G at a given pressure, temperature, and composition of solid and gaseous species are discussed.