Osmotic and Activity Coefficients of the {xZnCl2 + (1 - x)ZnSO4}(aq) System at 298.15 K
Isopiestic vapor pressure measurements were made for (xZnCl{sub 2} + (1 - x)ZnSO{sub 4})(aq) solutions with ZnCl{sub 2} molality fractions of x = (0, 0.3062, 0.5730, 0.7969, and 1) at the temperature 298.15 K, using KCl(aq) as the reference standard. These measurements cover the water activity range 0.901-0.919 {le} a{sub w} {le} 0.978. The experimental osmotic coefficients were used to evaluate the parameters of an extended ion-interaction (Pitzer) model for these mixed electrolyte solutions. A similar analysis was made of the available activity data for ZnCl{sub 2}(aq) at 298.15 K, while assuming the presence of equilibrium amounts of ZnCl{sup +}(aq) ion-pairs, to derive the ion-interaction parameters for the hypothetical pure binary electrolytes (Zn{sup 2+}, 2Cl{sup -}) and (ZnCl{sup +},Cl{sup -}). These parameters are required for the analysis of the mixture results. Although significant concentrations of higher-order zinc chloride complexes may also be present in these solutions, it was possible to represent the osmotic coefficients accurately by explicitly including only the predominant complex ZnCl{sup +}(aq) and the completely dissociated ions. The ionic activity coefficients and osmotic coefficients were calculated over the investigated molality range using the evaluated extended Pitzer model parameters.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 907831
- Report Number(s):
- UCRL-JRNL-222931; JSLCAG; TRN: US200721%%406
- Journal Information:
- Journal of Solution Chemistry, Vol. 36, Issue 4; ISSN 0095-9782
- Country of Publication:
- United States
- Language:
- English
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