Equilibrium computerized chemical

Nordstrom DK, Plummer LN, Wigley TML, Wolery TJ, Ball JW, Jenne EA, Bassett RL, Crerar DA, Florence TM, Fritz B, Hoffman M, Jr G R Holdren, Lafon GM, Mattigod SV, McDuff RE, Morel F, Reddy MM, Sposito G, Thrailkill J. (1979) Chemical Modeling of Aqueous Systems A Comparison of Computerized Chemical Models for Equilibrium Calculations in Aqueous Systems. Am. Chem. Soc. pp 857-892. 

Nordstrom, D. K., Plummer, L. N., and others. A comparison of computerized chemical models for equilibrium calculations in aqueous systems Jenne, E. A., ed., "Chemical Modeling in Aqueous Systems. Speciation, Sorption, Solubility,... 

A Comparison of Computerized Chemical Models for Equilibrium Calculations in Aqueous Systems ... 

Nordstrom D.K., Plummer L.N., Wigley T.M.L., Wolery T.J., Ball J.W., Jenne E.A., Basset R.L., Crerar D.A., Florence T.M., Fritz B., Hoffman M., Holdren G.R., Jr., Lafon G.M., Mattigod S.V., McDuff R.E., Morel R, Reddy M.M., Sposito G. and Thrailkill J. (1979) A comparison of computerized chemical models for equilibrium calculations in aqueous systems in Chemical Modeling in aqueous systems, speciation, sorption, solubility, and kinetics. Jenne, E.A., ed. Series 93, American Chemical Society, pp. 857-892... 

FEL] Felmy, A. R., A Computerized chemical equilibrium program using a... 

Nordstrom DK, Plummer LN, Wigley TML, Wolery TJ et al. (1979) A comparison of computerized chemical models for equilibrium calculations in aqueous systems. In Jenne EA (ed) Chemical modeling of aqueous systems I. Am Chem Soc Symp Ser 93, Washington DC, pp 857-892... 

In order to facilitate calculations and increase the usefulness of the chemical model, the computerized model has been used to obtain simplified correlations suitable for hand calculations. These correlations predict equilibrium SO2 partial pressure and liquor composition as functions of liquor pH and the total dissolved concentrations of magnesium and chloride. 

We have utilized a chemical model in this investigation to interpret the equilibrium behavior of iron in acid mine waters. A successful correlation between calculated and measured Eh values has been found, using WATEQ2, the computerized ion association model. This correlation supports the basic assumption of homogeneous solution equilibrium in these waters and simultaneously corroborates both the validity of the aqueous model and the quantitative interpretation of Eh measurements in these waters. This interpretation makes it possible to calculate the distribution of iron... 

The computerized aqueous chemical model of Truesdell and Jones (, 3), WATEQ, has been greatly revised and expanded to include consideration of ion association and solubility equilibria for several trace metals, Ag, As, Cd, Cu, Mn, Ni, Pb and Zn, solubility equilibria for various metastable and(or) sparingly soluble equilibrium solids, calculation of propagated standard deviation, calculation of redox potential from various couples, polysulfides, and a mass balance section for sulfide solutes. Revisions include expansion and revision of the redox, sulfate, iron, boron, and fluoride solute sections, changes in the possible operations with Fe (II, III, and II + HI), and updating the model s thermodynamic data base using critically evaluated values (81, 50, 58) and new compilations (51, 26 R. M. Siebert and... 

The equilibrium constant K varies somewhat with changes in environmental temperature and pressure, as indicated in Fig. 1-9 for several common environmental reactions. Equilibrium constants are known for a wide variety of reactions and form the basis (when combined with mass balance and electroneutrality equations as described later) for both manual and computerized techniques for determining the equilibrium composition of many complex mixtures of chemicals in surface waters and groundwater (Stumm and Morgan, 1996 Morel and Hering, 1993). 

To calculate the equilibrium chemical composition of a system, equations based on mass conservation, the mass action law, and electroneutrality are sufficient. Note that the electroneutrality equation may not be needed if a system does not contain significant concentrations of ionic reactants or products. Both manual and computerized techniques for determining the equilibrium composition of many complex mixtures of chemicals in water are based on the simultaneous solution of these equations. 

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