Modeling chemical equilibrium

Reardon EJ, Beckie RD (1987) Modelling chemical equilibria of acid mine-drainage The FeS04-H2S04-H20 system. Geochim Cosmochim Acta... 

The exp-6 potential has also proved successful in modeling chemical equilibrium at the high pressures and temperatures characteristic of detonation. However, to calibrate the parameters for such models, it is necessary to have experimental data for product molecules and mixtures of molecular species at high temperature and pressure. Static compression and sound-speed measurements provide important data for these models. 

Because of the relative ease of determining the system state by equilibrium calculations relative to experiments or detailed kinetics models, chemical equilibrium analysis has been the traditional approach to CVD process modeling. An extensive literature exists for the Si-Cl-H CVD system (7) and the As-Ga-Cl-H VPE process (I). The analysis of MOCVD systems has been limited by the lack of thermodynamic data. A recent equilibrium analysis of the MOCVD of GaAs (83, 84) is a good source of data for the GaAs system. 

KUT7BER] Kulik, D., Berner, U., Curti, E., Modelling chemical equilibrium partitioning with the GEMS-PSI code, Paul Scherrer Institute, Report, (2004). Cited on pages 284, 331. 

Properties models Chemical equilibrium (time of mass transfer relaxation At = 0) Chemical nonequilibrium (time of mass transfer relaxation At > 0)... 

Molecular level Elementary reactions Molecular modeling Chemical equilibrium... 

A tabulation of the partial pressures of sulfuric acid, water, and sulfur trioxide for sulfuric acid solutions can be found in Reference 80 from data reported in Reference 81. Figure 13 is a plot of total vapor pressure for 0—100% H2SO4 vs temperature. References 81 and 82 present thermodynamic modeling studies for vapor-phase chemical equilibrium and liquid-phase enthalpy concentration behavior for the sulfuric acid—water system. Vapor pressure, enthalpy, and dew poiat data are iacluded. An excellent study of vapor—liquid equilibrium data are available (79). 

Figure 2-1. Chemical equilibrium constants as a function of temperature. (Source M. Modell and R. C. Reid, Thermodynamics and its Applications, Prentice-Hall, Inc., Englewood Cliffs, NJ.)...

Case Type Model Mass Balaaccs Energy Balance Chemical Equilibrium Kircrics/Transpor. 

Meylan S, Odzak N, Behra R, Sigg L (2004) Speciation of copper and zinc in natural freshwater comparison of voltammetric measurements, diffusive gradients in thin Aims (DGT) and chemical equilibrium models. An Chim Acta 510 91... 

Ferreira, P. F. M., Justi, R. (2005). From chemical reaction to chemical equilibrium Learning through modelling. Paper presented at the V Conference of the European Seienee Education Research Association, Barcelona, Spain, 28 August-01 September. 

The specification of the initial state may be partial and lead to incomplete descriptions of various segments of the plant. The modeling facilities of MODEL.LA. contain a complete set of the balance equations, phase and chemical equilibrium, and rate relationships. These relationships are used to propagate the user-supplied specifications and thus complete the description of the initial state throughout the plant. 

This model is similar to the associated species model in that a chemical equilibrium is assumed between existing species, and it is different in that in the latter only a nonassociated ionic species is assumed to be the electrically conducting species. 

The dynamic dissociation model resembles the association (or dissociation) model in that electrically conducting species are assumed to he nonassociated species, and it differs from the association model in that in the dynamic dissociation model the dissociation process itself is the electrically conducting process, while in the association model, the amount of the dissociated species is constant according to the chemical equilibrium. 

Several workers have intended to estimate the chemical compositions of Kuroko ore fluids based on the chemical equilibrium model (Sato, 1973 Kajiwara, 1973 Ichikuni, 1975 Shikazono, 1976 Ohmoto et al., 1983) and computer simulation of the changes in mineralogy and chemical composition of hydrothermal solution during seawater-rock interaction. Although the calculated results (Tables 1.5 and 1.6) are different, they all show that the Kuroko ore fluids have the chemical features (1 )-(4) mentioned above. 

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