Review of the Apparent Molar Heat Capacities of NaCl(Aq), HCl(Aq), and NaOH(Aq) and their Representation using the Pitzer Model at Temperatures from (298.15 to 493.15) K

Manya, J. J. (Universidad de Zaragoza) ; Antal, M. J.

Resumen: In this study, a new estimation of the standard state partial molar heat capacity (Cp0) of three binary systems [NaCl(aq), HCl(aq), and NaOH(aq)] for temperatures ranging from (298.15 to 493.15) K is performed. From experimental data (available in the literature to date) corresponding to the apparent molar heat capacities of the above-mentioned electrolytes, a procedure based on the assumption of Pitzer’s ion interaction model was applied to calculate these important Cp0 values at a given temperature. Results obtained for each electrolyte (or ion) were correlated as functions of temperature by commonly used polynomial equations. Use of the hydrogen ion convention enabled estimates of the temperature-dependent values of Cp0 of the individual ions Na+(aq), Cl−(aq), and OH−(aq). When used to calculate the temperature-dependent values of the Gibbs free energy of formation of OH−(aq), the formula for Cp0(T) of OH−(aq) given herein provides good agreement with values derived from independent measurements of the ion constant of water at elevated temperatures. In the specific case of NaCl, a considerable disagreement was observed between the estimations performed using Archer’s model (Archer, D. G. J. Phys. Chem. Ref. Data1992, 793−829) and some experimental data published years later. This fact can be explained, among other factors, by the dependence of the model parameters on the experimental uncertainty and systematic errors, which can be incurred during calorimetric experiments. For this reason, continuous revisions and updating of the proposed correlations are required when new experimental data become available.

Idioma: Inglés

Año: 2009

Publicado en: JOURNAL OF CHEMICAL AND ENGINEERING DATA 54, 8 (2009), 2158-2169
ISSN: 0021-9568

Factor impacto JCR: 1.695 (2009)

Categ. JCR: ENGINEERING, CHEMICAL rank: 40 / 125 = 0.32 (2009) - Q2 - T1
Categ. JCR: CHEMISTRY, MULTIDISCIPLINARY rank: 53 / 139 = 0.381 (2009) - Q2 - T2

Tipo y forma: Article (PostPrint)

Área (Departamento): Área Ingeniería Química (Dpto. Ing.Quím.Tecnol.Med.Amb.)