Thermodynamic properties of aqueous calcium nitrate {Ca ( NO3)2}to the temperature 373 K including new enthalpy of dilution data

Oakes, Charles S.; Felmy, Andrew R.; Sterner, S. Michael

doi:10.1006/jcht.1999.0565

Cited by 34 publications

(54 citation statements)

References 49 publications

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“…The experimental procedure has been elaborated in previous work [14]. The slope (S) of the electrode response was determined using activity coefficients of Ca(NO 3 ) 2 [20]. The typical value of the slope for the electrode obtained by linear regression analysis of the experimental points was 24.97 mV with a correlation coefficient of 0.99998, which is in reasonable agreement with the theoretical value (RT/F = 25.69 mV at 298.15 K) of the Nernst equation.…”

Section: Measurement Of Cell Potentialmentioning

confidence: 99%

Activity coefficients and conductivities of calcium nitrate in glucose/galactose–water mixtures at 298.15K

Zhuo

Liu²,

Wang

et al. 2007

Fluid Phase Equilibria

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Section: Measurement Of Cell Potentialmentioning

confidence: 99%

Activity coefficients and conductivities of calcium nitrate in glucose/galactose–water mixtures at 298.15K

Zhuo

Liu²,

Wang

et al. 2007

Fluid Phase Equilibria

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“…The database was founded on the original variable-temperature Pitzer parameters 20,21 supplemented by parameter data from several other sources. 13,[22][23][24][25][26][27][28][29][30][31][32] It also includes thermodynamic parameters converted from nonstandard Pitzer equations from the published literature. 14 Temperature-independent parameters based on 25°C data are used for several parameters where temperature dependent data are lacking.…”

Section: B High Temperature Pitzer Modelmentioning

confidence: 99%

Evaporative evolution of a Na–Cl–NO[sub 3]–K–Ca–SO[sub 4]–Mg–Si brine at 95 °C: Experiments and modeling relevant to Yucca Mountain, Nevada

Alai

2005

Geochem. Trans.

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A synthetic Topopah Spring Tuff water representative of one type of pore water at Yucca Mountain, NV was evaporated at 95°C in a series of experiments to determine the geochemical controls for brines that may form on, and possibly impact upon the long-term integrity of waste containers and drip shields at the designated high-level, nuclear-waste repository. Solution chemistry, condensed vapor chemistry, and precipitate mineralogy were used to identify important chemical divides and to validate geochemical calculations of evaporating water chemistry using a high temperature Pitzer thermodynamic database. The water evolved toward a complex "sulfate type" brine that contained about 45 mol % Na, 40 mol % Cl, 9 mol % NO 3 , 5 mol % K, and less than 1 mol % each of SO 4 , Ca, Mg, ͚CO 2 ͑aq͒, F, and Si. All measured ions in the condensed vapor phase were below detection limits. The mineral precipitates identified were halite, anhydrite, bassanite, niter, and nitratine. Trends in the solution composition and identification of CaSO 4 solids suggest that fluorite, carbonate, sulfate, and magnesium-silicate precipitation control the aqueous solution composition of sulfate type waters by removing fluoride, calcium, and magnesium during the early stages of evaporation. In most cases, the high temperature Pitzer database, used by EQ3/6 geochemical code, sufficiently predicts water composition and mineral precipitation during evaporation. Predicted solution compositions are generally within a factor of 2 of the experimental values. The model predicts that sepiolite, bassanite, amorphous silica, calcite, halite, and brucite are the solubility controlling mineral phases.

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“…However, the equations of the extended models [10][11][12][13] have not been incorporated in most geochemical modeling codes, and thus there is a continuing need for expanding the parameter databases for the standard Pitzer model.…”

Section: Introductionmentioning

confidence: 99%

“…PitzerÕs ion-interaction model is included in several geochemical modeling codes [7][8][9]. Extended forms of PitzerÕs model with ionic-strength dependent third virial terms [10][11][12][13] have been used to represent thermodynamic data for highly soluble electrolytes, when the standard (three parameter) Pitzer model is not able to represent these data with sufficient accuracy. Rard and Wijesinghe [14] listed studies published up to 2002 that reported parameters for these extended models.…”

Section: Introductionmentioning

confidence: 99%

Conversion and optimization of the parameters from an extended form of the ion-interaction model for Ca(NO3)2(aq) and NaNO3(aq) to those of the standard Pitzer model, and an assessment of the accuracy of the parameter temperature representations

Wijesinghe

Rard

2005

The Journal of Chemical Thermodynamics

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The electrolytes Ca(NO 3 ) 2 (aq) and NaNO 3 (aq) are both extremely soluble but differ in several important respects. Ca(NO 3 ) 2 (aq) has complex behavior at low ionic strengths and forms several thermodynamically stable and metastable solid phases, whereas NaNO 3 (aq) forms only an anhydrous solid phase. The thermodynamic properties of both have previously been modeled using extended Pitzer ion-interaction models that include higher-order virial terms, in addition to those of the standard Pitzer model. The parameters of the original Pitzer model, however, are often needed for thermodynamic modeling calculations. In this paper, we convert the parameters of the extended ion-interaction models for Ca(NO 3 ) 2 (aq) and NaNO 3 (aq) to the standard Pitzer model using an extension of the methodology previously described by Rard and Wijesinghe [J. Chem. Thermodyn. 35 (2003) 439-473]. In this variant, the exponential coefficient a P 1 of PitzerÕs model is also optimized to yield the most accurate overall representation of the osmotic coefficients / over the ionic strength and temperature ranges of interest. The optimal values of a P 1 ¼ 0.87 kg 1=2 Á mol À1=2 for Ca(NO 3 ) 2 (aq) and a P 1 ¼ 1.43 kg 1=2 Á mol À1=2 for NaNO 3 (aq) are smaller than the value a P 1 ¼ 2.00 kg 1=2 Á mol À1=2 normally used for electrolytes of these valence types. In both cases, the accuracy of the osmotic coefficients predicted by the standard Pitzer model was nearly equal to that of the extended Pitzer model up to the solubility limit for T = (298.15 to 423.15) K. This result is consistent with the findings of Rard, Wijesinghe, and Wolery [J. Chem. Eng. Data 49 (2004) 1127-1140] who obtained a substantial improvement in model accuracy for Mg(NO 3 ) 2 (aq) at T = 298.15 K by optimizing a P 1 . The use of a temperature-dependent a P 1 that is optimal at each temperature did not yield a significant improvement in accuracy over using a constant optimal value. We also investigated the impact of choosing different temperature functions to develop temperature correlations for the Pitzer parameters. Higher-order temperature functions were needed for evaluations with solubility limited maximum ionic strength compared to evaluations performed at constant maximum ionic strength over the temperature range, especially for Ca(NO 3 ) 2 (aq) because of its more complex thermodynamic behavior. Accurate temperature correlations are presented for both Ca(NO 3 ) 2 (aq) and NaNO 3 (aq).

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Thermodynamic properties of aqueous calcium nitrate {Ca ( NO3)2}to the temperature 373 K including new enthalpy of dilution data

Cited by 34 publications

References 49 publications

Activity coefficients and conductivities of calcium nitrate in glucose/galactose–water mixtures at 298.15K

Activity coefficients and conductivities of calcium nitrate in glucose/galactose–water mixtures at 298.15K

Evaporative evolution of a Na–Cl–NO[sub 3]–K–Ca–SO[sub 4]–Mg–Si brine at 95 °C: Experiments and modeling relevant to Yucca Mountain, Nevada

Conversion and optimization of the parameters from an extended form of the ion-interaction model for Ca(NO3)2(aq) and NaNO3(aq) to those of the standard Pitzer model, and an assessment of the accuracy of the parameter temperature representations

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