An isopiestic study of aqueous solutions of the alkali metal hydrogensulfates at elevated temperatures

✍ Scribed by H.F. Holmes; R.E. Mesmer

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 439 KB
• Volume: 28
• Category: Article
• ISSN: 0021-9614
• DOI: 10.1006/jcht.1996.0007

✦ Synopsis

Isopiestic molalities of LiHSO4(aq), KHSO4(aq), and CsHSO4(aq) have been measured over the temperature range 383.46 K to 498.19 K with NaCl(aq) serving as the reference electrolyte for the calculation of excess thermodynamic quantities. Molalities of the reference electrolyte ranged from about 0.5 mol•kg -1 to greater than 6 mol•kg -1 . The ion-interaction model of Pitzer gave an excellent description of the experimental results when the solutions were treated as mixed-electrolyte systems resulting from partial ionization of HSO - 4 (aq). A simple polynomial model for the temperature dependence of the ion-interaction parameters is sufficient to reproduce the experimental results. When calculated as stoichiometric activity coefficients for 1-2 charge types, the resulting quantities are quite small, especially when compared with activity coefficients based on the assumption of a 1-1 charge type. The activity coefficients are consistent with limited dissociation of the hydrogensulfate anion which decreases with increasing temperature.