Calcite , thermodynamic properties

Gillet P, McMillan P, Schott J, Badro J, Grzechnik A (1996) Thermodynamic properties and isotopic fractionation of calcite from vibrational spectroscopy of 0-substituted calcite. Geochim Cosmochim... 

Lattice defects may influence the rates of mineral dissolution in two ways (1) by changing the bulk thermodynamic properties and (2) by creating sites of accelerated dissolution on the solid surface. Strain and core energies associated with dislocations contribute insignificantly to the total energy of minerals. For instance, even with the extremely high dislocations density of 1011 cm"2, the free energy of calcite is increased by only 80 J mol", which corresponds to a 25°C activity of 1.04. The same features are observed for quartz and silicate minerals. 

Catti, M., Pavese, A., and Price, G.D. (1993) Thermodynamic properties of CaCOs calcite and aragonite a quasi-harmonic calculation, Phys. Chem. Minerals 19,472-479. 

Table 6.1 Thermodynamic properties of calcite and aragonite, from Appendix B.

Chapters 15 and 16 especially demonstrate the broad range of application of thermodynamics to chemical processes. In the discussions of the Haber cycle, synthesis of diamond, solubility of calcite, and the thermodynamics of metabolism, techniques are used to solve a specific problem for a particular substance. On the other hand, in the discussion of macrocyclic complexes, the description and interpretation involves the comparison of the properties of a number of complexes. This global approach is particularly helpful in the description of the energetics of ternary oxides in Chapter 15 and the stabilities of proteins and DNA in Chapter 16, where useful conclusions are obtained only after the comparison of a large amount of experimental data. 

Tribble J. S., Arvidson R. S., Lane M., Ill, and Mackenzie F. T. (1995) Crystal chemistry, and thermodynamic and kinetic properties of calcite, dolomite, apatite, and biogenic silica applications to petrologic problems. Sedim. Geol. 95, 11-37. 

For example, you cannot apply thermodynamics to the ocean as a whole. Calcite is supersaturated at the surface, but undersaturated at 5 km depth (Chapter 16). Thermodynamics cannot be applied to a system which is both supersaturated and undersaturated. You can apply thermodynamics to volumes close to equilibrium at the surface or at depth, not both together, so we say we apply thermodynamics to areas of local equilibrium. It is obviously important to apply thermodynamics appropriately, and generally we do this, but the point is that local equilibrium is not part of thermodynamics, it is a concept we need, a property that real systems must have, in order to apply thermodynamics. 

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