Critical Evaluation of the Second Dissociation Constants for Aqueous Sulfuric Acid over a Wide Temperature Range

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Abstract

The scope of this article is to study the ability of different equations for K-2 and different sets of Pitzer parameters to model the thermodynamic properties of the H2SO4-H2O system over a wide temperature range. Three Pitzer parameters are found essential in modeling aqueous sulfuric acid, namely, C-phi for H+/SO42- interaction and parameters beta((0)) and beta((1)) for H+/HSO4- interaction. Several thermodynamic models with different K-2-equations consisting of only four Pitzer parameters, the mentioned three parameters extended by beta(0) for H+/SO42- interaction with simple temperature dependency (a + b/T), can describe stoichiometric activity and osmotic coefficients as well as vapor pressure of aqueous sulfuric acid up to a 6 molal solution in the temperature range (0 to 170) degrees C with good to moderate extrapolation capabilities. Increasing the number of parameters above four do not improve the assessment. The predicted values with different K-2-equations are assumed experimentally accurate. One of the four parameters models, Hepler A, can predict the apparent heat of solution in the temperature range (0 to 50) degrees C with reasonable accuracy even though no enthalpy or heat capacity data were included in the assessment.

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Original languageEnglish
Pages (from-to)3009-3032
Number of pages24
JournalJournal of Chemical and Engineering Data
Volume58
Issue number11
Publication statusPublished - Nov 2013
MoE publication typeA1 Journal article-refereed

    Research areas

  • ELECTROMOTIVE-FORCE MEASUREMENTS, SOLVENT ELECTROLYTE SYSTEMS, MODELING PHASE-EQUILIBRIA, THERMODYNAMIC PROPERTIES, OSMOTIC COEFFICIENTS, IONIC-SOLUTIONS, BISULFATE ION, ISOPIESTIC DETERMINATION, ELEVATED-TEMPERATURES, MINERAL SOLUBILITIES

ID: 10500970