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This article in SSSAJ

  1. Vol. 52 No. 6, p. 1574-1579
    Received: Jan 7, 1988

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Estimation of the Standard Free Energy of Formation of Metal Arsenates, Selenates, and Selenites

  1. M. E. Essington 
  1. Div. of Waste Characterization and Chemistry, Western Research Inst., Univ. of Wyoming Research Corporation, P.O. Box 3395, Laramie, WY 82071



An empirical method developed for estimating the standard free energy of formation (Δf) of solid phases is evaluated for metal arsenates, selenates, and selenites. A free energy function of a solid phase is found to be linearly correlated to a function of the metal oxide Δf and the aqueous metal ion Δf for the compound groups examined. The values estimated by this method are, on average, within ± 10.9, 10.4, and 12.0 kJ mol−1 of the experimental arsenate, selenate, and selenite values, respectively. A method for estimating the Δf of hydrated metal arsenates and selenites is also evaluated. The estimated standard free energy of formation values of hydrated arsenates and selenites, on average, are within ± 23.7 and 10.0 kJ mol−1, respectively, of the observed values. The error involved in estimating metal arsenate, selenate, and selenite Δf values are comparable to those obtained when the estimation technique was applied to other compound types.

Contribution of the Div. of Waste Characterization and Chemistry.

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