Solubility of AgCl in Molten NaCl ‐ AlCl3 and KCl ‐ AlCl3

Autor: David S. Newman, P. J. Tumidajski, M. Blander
Rok vydání: 1994
Předmět:
Zdroj: Journal of The Electrochemical Society. 141:895-900
ISSN: 1945-7111
0013-4651
DOI: 10.1149/1.2054854
Popis: Measurements of AgCl solubility (in mol fraction units) in molten NaCl-AlCl[sub 3] and KCl-AlCl[sub 3] were determined by an electromotive force technique. For the NaCl-AlCl[sub 3] experiments, the temperature was maintained at 448 K and the composition of the solvent varied from X = 0.500 to X = 0.530. There was a compositional dependence of the AgCl solubilities with a minimum near the equimolar solvent composition. The minimum solubility in mol fraction of AgCl was 5.75 [times] 10[sup [minus]3] at X = 0.505. The true solubility produce for AgCl at 448 K was calculated to be 7.35 [times] 10[sup [minus]9]. The magnitude of the solubility product is primarily related to the fact that the standard free energy of information of NaAlCl[sub 4] from NaCl and AlCl[sub 3] is about 67 kJ/mol more negative than the corresponding free energy for AgAlCl[sub 4] (i.e., AgAlCl[sub 4] is unstable). In basic and in somewhat acidic melts, the solubility is related to the formation of the associated ionic species such as AgCl, AgCl[sup [minus]][sub 2], AgCl[sup 2[minus]][sub 3], and AgCl[sup 3[minus]][sub 4]. From the measurements, the formation constant of AgCl at 448 K, K[sub 11], was 1.36 [times] 10[sup 6]. Further, the specific bondmore » free energy for the associated complex AgCl, [Delta]A[sub 11], has been calculated as [minus]47.5 kJ/mol. For the KCl-AlCl[sub 3] experiments, the composition was maintained at the equimolar and the temperature varied in the range 518 to 583 K. The AgCl solubility increases from 4.32 [times] 10[sup [minus]3] at 518 K to 6.85 [times] 10[sup [minus]3] at 583 K. The apparent heat of solution was 17.68 kJ/mol for this temperature range. Such melts are potential electrolytes in batteries under development for automobile propulsion.« less
Databáze: OpenAIRE