Solubility of AgCl in molten NaCl-AlCl[sub 3] and KCl-AlCl[sub 3]

Journal Article · Fri Apr 01 00:00:00 EST 1994 · Journal of the Electrochemical Society; (United States)

DOI:https://doi.org/10.1149/1.2054854· OSTI ID:7109927

Tumidajski, P J ^[1]; Blander, M ^[2]; Newman, D S ^[3]

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1. National Research Council of Canada, Ottawa, Ontario (Canada). Materials Lab.
2. Argonne National Lab., IL (United States)
3. Bowling Green State Univ., OH (United States). Dept. of Chemistry

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 bond 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.

• OSTI ID: 7109927
• Journal Information: Journal of the Electrochemical Society; (United States), Vol. 141:4; ISSN 0013-4651
• Country of Publication: United States
• Language: English

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