Enthalpies of Formation of Alunite and Natroalunite (According to Calorimetric Data)

— A sample of natural alunite of the composition K 0.6 Na 0.4 Al 3 (SO 4 ) 2 (OH) 6 was studied by powder X-ray diffraction, infrared spectroscopy, electron microprobe, and thermal analysis. The enthalpy of formation of the alunite from elements ∆ f H 0 (298.15 K) = −5149 ± 13 kJ/mol was determined...

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Bibliographic Details
Published in:Geochemistry international 2022-06, Vol.60 (6), p.596-602
Main Authors: Ogorodova, L. P., Gritsenko, Yu. D., Vigasina, M. F., Melchakova, L. V., Ksenofontov, D. A.
Format: Article
Language:English
Subjects:
Alunite
Analytical methods
Calorimetry
Earth and Environmental Science
Earth Sciences
Electron microprobe
Electron probes
Enthalpy
Geochemistry
Heat measurement
Infrared analysis
Infrared spectroscopy
Short Communications
Sulphates
Thermal analysis
X ray powder diffraction
X-ray diffraction
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Summary:— A sample of natural alunite of the composition K 0.6 Na 0.4 Al 3 (SO 4 ) 2 (OH) 6 was studied by powder X-ray diffraction, infrared spectroscopy, electron microprobe, and thermal analysis. The enthalpy of formation of the alunite from elements ∆ f H 0 (298.15 K) = −5149 ± 13 kJ/mol was determined by the method of melt solution calorimetry, using a Setaram (France) Calvet microcalorimeter. The calculated enthalpies and Gibbs energies of formation of the end members of the series alunite KAl 3 (SO 4 ) 2 (OH) 6 to natroalunite NaAl 3 (SO 4 ) 2 (OH) 6 are −5164 ± 13 and −4651 ± 13 kJ/mol, respectively, for alunite and − 5127 ± 13 and −4615 ± 13 kJ/mol, respectively, for natroalunite.
ISSN:0016-7029
1556-1968
DOI:10.1134/S0016702922060052