| Popis: |
The isocoulombic approach is valid in estimating instability constants of many metal chloride complexes up to 300°C. These have been grouped into two classes: those whose central metal ions are classified as hard, and those that are soft. This difference gives rise to characteristic shapes of the variation of the instability constants on temperature plots. Trends in the calculated equilibrium constants and enthalpies and entropies of reactions are consistent with changes in the thermodynamic and electrostatic properties of the solvent with temperature rise. Limitations of the method include questionable low temperature thermodynamic data, lack of additional model equilibria, and lack of proof of the general validity of the method above 300°C. Results have been applied to Cu speciation and Cu sulfide solubilities in hydrothermal solutions. |
