Acquisition and evaluation of thermodynamic data for bieberite-moorhouseite equilibria at 0.1 MPa

Chou, I‐Ming; Seal, Robert R.

doi:10.2138/am.2005.1695

Cited by 10 publications

(4 citation statements)

References 20 publications

(38 reference statements)

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“…The results of this study and those of Chou et al [6][7][8][9][10] further confirm the conclusion of Hemingway et al [36] that the Gibbs free-energy contribution for each water of crystallization in hydrated sulfate salts, except for the first water, is near -238.0 kJ•mol -1 .…”

Section: Discussionsupporting

confidence: 90%

Acquisition and evaluation of thermodynamic data for mirabilite-thenardite equilibria at 0.1 MPa

Wang

Chou

Zheng

et al. 2017

The Journal of Chemical Thermodynamics

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Mirabilite and thenardite are common minerals found in marine evaporite deposits and also in saline lakes as precipitates. In this study, mirabilite-thenardite equilibria were determined along four humidity-buffer curves at 0.1 MPa and between 285.15 K and 305.15 K. Results for the reaction Na 2 SO 4 •10H 2 O (s) = Na 2 SO 4(s) +10 H 2 O (g) , based on tight reversals along each humidity buffer, can be represented by ln K = 174.032-62815.11/T, where s is solid, g is gas, K is the equilibrium constant and T is temperature in K. Our data are in excellent agreement with several previous vapor-pressure measurements and are consistent with the solubility data reported in the literature. Thermodynamic analysis of these data yields 90.858 kJ•mol-1 for the standard Gibbs free energy of reaction, which is in good agreement with the values of 90.69 kJ•mol-1 and

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Section: Discussionsupporting

confidence: 90%

Acquisition and evaluation of thermodynamic data for mirabilite-thenardite equilibria at 0.1 MPa

Wang

Chou

Zheng

et al. 2017

The Journal of Chemical Thermodynamics

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“…For melanterite-rozenite and chalcanthitebonattite equilibria (Chou et al, 2002), calculated values for DG8 xw, 298 K are À238.34 and À239.90 kJ mol À1 , respectively. The value for morenosite-retgersite equilibria is À237.44 kJ mol À1 (Chou and Seal, 2003a), for bieberite-moorhouseite equilibria is À238.03 kJ mol À1 (Chou and Seal, 2003b), and for epsomite-hexahydrite equilibria is À238.73 kJ mol À1 (Chou and Seal, 2003c). The improved understanding of the free-energy contribution of individual water molecules associated with hydration of efflorescent salts will improve the ability to estimate thermodynamic data for phases in the absence of experimentally determined values.…”

Section: Discussionmentioning

confidence: 99%

“…A better understanding of end-member systems is necessary before solid-solution effects can be addressed. Recent refinements in experimental techniques for investigating dehydration equilibria among the salts have improved our understanding of the FeSO 4 -H 2 O and CuSO 4 -H 2 O systems (Chou et al, 2002), and also the NiSO 4 -H 2 O (Chou and Seal, 2003a), CoSO 4 -H 2 O (Chou and Seal, 2003b) and MgSO 4 -H 2 O (Chou and Seal, 2003c) systems. The present study continues this research into the ZnSO 4 -H 2 O system by investigating the dehydration equilibrium between goslarite [ZnSO 4 d 7H 2 O] and bianchite [ZnSO 4 d 6H 2 O].…”

Section: Introductionmentioning

confidence: 99%

Determination of goslarite–bianchite equilibria by the humidity-buffer technique at 0.1 MPa

Chou

Seal

2005

Chemical Geology

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Goslarite-bianchite equilibria were determined along four humidity-buffer curves at 0.1 MPa and between 27 and 36 8C. Results, based on tight reversals along each humidity buffer, can be represented by ln K (F0.005)=19.643À7015.38/T, where K is the equilibrium constant and T is temperature in K. Our data are in excellent agreement with several previous vapor-pressure measurements and are consistent with the solubility data reported in the literature. Thermodynamic analysis of these data yields 9.634 (F0.056) kJ mol À1 for the standard Gibbs free energy of reaction, which is in good agreement with the value of 9.658 kJ mol À1 calculated from the thermodynamic data compiled and evaluated by Wagman et al. [

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“…The shaded field represents the general range of temperature and relative humidity conditions in the eastern United States during the summer. Data sources for curves are: (1) melanterite and rozenite (dotted lines); chalcanthite and bonattite (solid line) (Chou et al, 2002), (2) epsomite, hexahydrite, and kieserite (Chou and Seal, 2003a), (3) morenosite and retgersite (dash-dot line) (Chou and Seal, 2003b), (4) bieberite and moorhouseite (heavy line) (Chou and Seal, 2003c), and (5) goslarite, bianchite, and gunningite (dashed lines) (Chou and Seal, this volume). laboratory, crystallized to copiapite. Blue salts that formed on flotation tailings at the Ely mine are melanterite that incorporates solid solution Cu and Co (Hammarstrom et al, 2001b).…”

Section: Mineralogymentioning

confidence: 99%

Secondary sulfate minerals associated with acid drainage in the eastern US: recycling of metals and acidity in surficial environments

et al. 2005

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Weathering of metal-sulfide minerals produces suites of variably soluble efflorescent sulfate salts at a number of localities in the eastern United States. The salts, which are present on mine wastes, tailings piles, and outcrops, include minerals that incorporate heavy metals in solid solution, primarily the highly soluble members of the melanterite, rozenite, epsomite, halotrichite, and copiapite groups. The minerals were identified by a combination of powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron-microprobe. Base-metal salts are rare at these localities, and Cu, Zn, and Co are commonly sequestered as solid solutions within Fe-and Fe-Al sulfate minerals. Salt dissolution affects the surfacewater chemistry at abandoned mines that exploited the massive sulfide deposits in the Vermont copper belt, the Mineral district of central Virginia, the Copper Basin (Ducktown) mining district of Tennessee, and where sulfide-bearing metamorphic rocks undisturbed by mining are exposed in Great Smoky Mountains National Park in North Carolina and Tennessee.Dissolution experiments on composite salt samples from three minesites and two outcrops of metamorphic rock showed that, in all cases, the pH of the leachates rapidly declined from 6.9 to b3.7, and specific conductance increased gradually over 24 h. Leachates analyzed after 24-h dissolution experiments indicated that all of the salts provided ready sources), and base metals (N1000 mg L À1 for minesites, and 2 mg L À1 for other sites). Geochemical modeling of surface waters, mine-waste leachates, and salt leachates using PHREEQC software predicted saturation in the observed ochre minerals, but significant concentration by evaporation would be needed to reach saturation in most of the sulfate salts. Periodic surface-water monitoring at Vermont minesites indicated peak annual metal loads during spring runoff. At the Virginia site, where no winter-long snowpack develops, metal loads were highest during summer months when salts were dissolved periodically by rainstorms following sustained evaporation during dry spells. areas, persist in protected areas when temperature and relative humidity are appropriate, and contribute to metal loadings and acidity in surface waters upon dissolution, thereby causing short-term perturbations in water quality. Published by Elsevier B.V.

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Acquisition and evaluation of thermodynamic data for bieberite-moorhouseite equilibria at 0.1 MPa

Cited by 10 publications

References 20 publications

Acquisition and evaluation of thermodynamic data for mirabilite-thenardite equilibria at 0.1 MPa

Acquisition and evaluation of thermodynamic data for mirabilite-thenardite equilibria at 0.1 MPa

Determination of goslarite–bianchite equilibria by the humidity-buffer technique at 0.1 MPa

Secondary sulfate minerals associated with acid drainage in the eastern US: recycling of metals and acidity in surficial environments

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