scholarly journals Experimental determination of the solubility constant of kurnakovite, MgB3O3(OH)5·5H2O

2020 ◽  
Vol 105 (7) ◽  
pp. 977-983 ◽  
Author(s):  
Yongliang Xiong
Keyword(s):  
Thermodynamic Properties ◽  
Equilibrium Constant ◽  
Enthalpy Of Formation ◽  
Structural Formula ◽  
Salt Lakes ◽  
Standard Entropy ◽  
Structural Water ◽  
Experimental Enthalpy ◽  
Long Term Experiment ◽  
Borate Minerals

Abstract In this study, I present experimental results on the equilibrium between boracite [Mg3B7O13C1(cr)] and kurnakovite [chemical formula, Mg2B6O11·15H2O(cr); structural formula, MgB3O3(OH)5·5H2O(cr)] at 22.5 ± 0.5 °C from a long-term experiment up to 1629 days, approaching equilibrium from the direction of supersaturation, Mg3B7O13C1(cr) + H+ + 2B(OH)4− + 18H2O(1) ⇌ 3MgB3O3(OH)5·5H2O(cr) + C1−. Based on solubility measurements, the 10-based logarithm of the equilibrium constant for the above reaction at 25 °C is determined to be 12.83 ± 0.08 (2σ). Based on the equilibrium constant for dissolution of boracite, Mg3B7O13C1(cr) + 15H2O(1) = 3Mg2+ + 7B(OH)4− + C1− + 2H+ at 25 °C measured previously (Xiong et al. 2018) and that for the reaction between boracite and kurnakovite determined here, the equilibrium constant for dissolution of kurnakovite, MgB3O3(OH)5·5H2O(cr) = Mg2+ + 3B(OH)4− + H+ + H2O(1) is derived as −14.11 ± 0.40 (2σ). Using the equilibrium constant for dissolution of kurnakovite obtained in this study and the experimental enthalpy of formation for kurnakovite from the literature, a set of thermodynamic properties for kurnakovite at 25 °C and 1 bar is recommended as follows: ΔHf0 = −4813.24 ± 4.92 kJ/mol, ΔGf0 = −4232.0 ± 2.3 kJ/mol, and S0 = 414.3 ± 0.9 J/(mol·K). Among them, the Gibbs energy of formation is based on the equilibrium constant for kurnakovite determined in this study; the enthalpy of formation is from the literature (Li et al. 1997), and the standard entropy is calculated internally with the Gibbs-Helmholtz equation in this work. The thermodynamic properties of kurnakovite estimated using the group contribution method for borate minerals based on the sums of contributions from the cations, borate polyanions, and structural water to the thermodynamic properties from the literature (Li et al. 2000) are consistent, within their uncertainties, with the values listed above. Since kurnakovite usually forms in salt lakes rich in sulfate, studying the interactions of borate with sulfate is important to modeling kurnakovite in salt lakes. For this purpose, I have re-calibrated our previous model (Xiong et al. 2013) describing the interactions of borate with sulfate based on the new solubility data for borax in Na2SO4 solutions presented here.

Thermodynamic properties of molybdate ion: reaction cycles and experiments

2015 ◽  
Vol 87 (5) ◽  
pp. 461-476 ◽  
Author(s):  
Heinz Gamsjäger ◽  
Masao Morishita
Keyword(s):  
Thermodynamic Properties ◽  
Gibbs Energy ◽  
Metal Ions ◽  
Enthalpy Of Formation ◽  
Alkaline Earth ◽  
Standard Entropy ◽  
Gibbs Energy Of Formation ◽  
Silver Molybdate ◽  
Gibbs Energies ◽  
Energy Of Formation

AbstractStandard molar quantities of molybdate ion entropy, $S_{\rm{m}}^0,$ enthalpy of formation, ${\Delta _{\rm{f}}}H_m^{\rm{o}},$ and Gibbs energy of formation, ${\Delta _{\rm{f}}}G_{\rm{m}}^{\rm{o}},$ are key data for the thermodynamic properties of molybdenum compounds and complexes, which are at present investigated by an OECD NEA review project. The most reliable method to determine ${\Delta _{\rm{f}}}H_{\rm{m}}^{\rm{o}}$ of molybdate ion and alkali molybdates directly consists in measuring calorimetrically the enthalpy of dissolution of crystallized molybdenum trioxide and anhydrous alkali molybdates in corresponding aqueous alkali metal hydroxide solutions. Solubility equilibria of sparingly soluble alkaline earth molybdates and silver molybdate lead to trustworthy data for ${\Delta _{\rm{f}}}G_{\rm{m}}^{\rm{o}}$ of molybdate ion. Thereby the Gibbs energies of the metal molybdates and the corresponding metal ions are combined with the Gibbs energies of dissolution. As reliable values are available for ${\Delta _{\rm{f}}}G_{\rm{m}}^{\rm{o}}$ of the relevant metal ions the problem reduces to select the best values of solubility constants and ${\Delta _{\rm{f}}}G_{\rm{m}}^{\rm{o}}$ of alkaline earth molybdates and silver molybdate. There are two independent possibilities to achieve the latter task. (1) ${\Delta _{\rm{f}}}H_{\rm{m}}^{\rm{o}}$ for alkaline earth molybdates and silver molybdate have been determined by solution calorimetry. Entropy data of molybdenum have been compiled and evaluated recently. CODATA key values are available for $S_{\rm{m}}^{\rm{o}}$ of the other elements involved. Whereas $S_{\rm{m}}^{\rm{o}}({\rm{CaMo}}{{\rm{O}}_4},{\rm{ cr}})$ is well known since decades, low-temperature heat capacity measurements had to be performed recently, but now reliable values for $S_{\rm{m}}^{\rm{o}}$ of Ag2MoO4(cr), BaMoO4(cr) and SrMoO4(cr) are available. (2) ${\Delta _{\rm{f}}}H_{\rm{m}}^{\rm{o}}({\rm{BaMo}}{{\rm{O}}_4},{\rm{ cr}}),$ for example, can be obtained from high temperature equilibria also, but the result is less accurate than that of the first method. Once Gibbs energy of formation, ${\Delta _{\rm{f}}}G_{\rm{m}}^{\rm{o}},$ and enthalpy of formation, ${\Delta _{\rm{f}}}H_{\rm{m}}^{\rm{o}},$ of molybdate ion are known its standard entropy, $S_{\rm{m}}^{\rm{o}},$ can be calculated.

scholarly journals Heat Capacities and Thermodynamic Properties of Hungchaoite and Mcallisterite

Molecules ◽  
2019 ◽  
Vol 24 (24) ◽  
pp. 4470
Author(s):  
Jiangtao Song ◽  
Fei Yuan ◽  
Long Li ◽  
Yafei Guo ◽  
Tianlong Deng
Keyword(s):  
Phase Transition ◽  
Thermodynamic Properties ◽  
Thermodynamic Functions ◽  
Process Design ◽  
Chemical Engineering ◽  
Heat Capacities ◽  
Salt Lakes ◽  
Engineering Process ◽  
Thermal Anomalies ◽  
First Time

The heat capacities on two minerals of hungchaoite (MgB4O7·9H2O, Hu) and mcallisterite (MgB6O10·7.5H2O, Mc) have been measured with a precision calorimeter at temperatures ranging from 306.15 to 355.15 K, experimentally. It was found that there are no phase transition and thermal anomalies, and the molar heat capacities against temperature for the minerals of hungchaoite and mcallisterite were fitted as C p , m , Hu   =   − 27019.23675 + 229.55286 T   −   0.63912 T   2   +   ( 5.95862   ×   10   − 4 )   T   3 and C p , mMc   =   − 9981.88552   +   84.10964 T   −   0.22685 T   2   +   ( 2.0593   ×   10   − 4 )   T   3 , respectively. The molar heat capacities and thermodynamic functions of (HT-H298.15), (ST-S298.15), and (GT-G298.15) at intervals of 1 K for the two minerals were obtained for the first time. These results are significant in order to understand the thermodynamic properties of those minerals existing in nature salt lakes, as well as applying them to the chemical engineering process design.

Interactions between cations and sugars. III. Free energies, enthalpies, and entropies of association of Ca2+, Sr2+, Ba2+, La3+, Gd3+ with D-ribose in water at 25 °C

1987 ◽  
Vol 65 (11) ◽  
pp. 2656-2660 ◽  
Author(s):  
Alfredo Maestre Alvarez ◽  
Nicole Morel-Desrosiers ◽  
Jean-Pierre Morel
Keyword(s):  
Thermodynamic Properties ◽  
Aqueous Solutions ◽  
Equilibrium Constant ◽  
The Other ◽  
Free Energies ◽  
Mean Values ◽  
Enthalpies Of Transfer ◽  
Other Hand ◽  
Solutions Of Electrolytes

The standard enthalpies of transfer of ribose and arabinose from water to aqueous solutions of electrolytes (CaCl2, SrCl2, BaCl2, LaCl3, and GdCl3) have been measured at 25 °C. A method is described to calculate from these data the equilibrium constant and the enthalpy for the association between the cations and the complexing isomers of ribose. Mean values relative to these isomers are given: the constants vary from 2.0 to 4.3 and the enthalpies from −5.9 to −17.9 kJ mol−1 for the different cations studied. The thermodynamic properties of association are not related to the size nor to the charge of the complexed cation in a simple way. On the other hand, the enthalpies of reaction are linearly correlated to the entropies of reaction.

scholarly journals Digitizing “The NBS Tables of Chemical Thermodynamic Properties: Selected Values for Inorganic and C1 and C2 Organic Substances in SI Units”

2020 ◽  
Vol 125 ◽  
Author(s):  
Janiel J. Reed
Keyword(s):  
Heat Capacity ◽  
Thermodynamic Properties ◽  
Gibbs Energy ◽  
Enthalpy Of Formation ◽  
Constant Pressure ◽  
Organic Substances ◽  
Gibbs Energy Of Formation ◽  
Chemical Thermodynamic ◽  
Enthalpy Difference ◽  
Energy Of Formation

The NBS Tables of Chemical Thermodynamic Properties is a collection of thermodynamic properties, published in book form, consisting of 103 tables with 14 330 critically evaluated species. The tables were originally published as a series of NBS Technical Notes As a result of this work, the data is now available in a more accessible spreadsheet format. Enthalpy of formation, ΔfH°, Gibbs energy of formation, ΔfG°, entropy, S°, heat capacity at constant pressure, Cp°, all at 298.15 K, and the enthalpy difference, [H°(298) – H°(0)] are provided where known. Within this collection of data, there are no values given for transuranic elements, Np to Lr (Tables 77–87).

The Size Dependence of Dissolution Thermodynamics of Nanoparticles

NANO ◽  
2016 ◽  
Vol 11 (09) ◽  
pp. 1650100 ◽  
Author(s):  
Zhi-Qiang Wang ◽  
Yong-Qiang Xue ◽  
Zi-Xiang Cui ◽  
Hui-Juan Duan ◽  
Xiao-Yan Xia
Keyword(s):  
Particle Size ◽  
Free Energy ◽  
Thermodynamic Properties ◽  
Equilibrium Constant ◽  
Gibbs Free Energy ◽  
Average Particle ◽  
Dissolution Enthalpy ◽  
Dissolution Entropy ◽  
Dissolution Thermodynamics ◽  
Dissolution Thermodynamic Properties

Dissolution of nanoparticles is involved in the preparation, research and application of nanomaterials, but there is a surprising difference in dissolution thermodynamics between nanoparticles and the corresponding bulk materials. In the paper, the relations of dissolution thermodynamic properties, equilibrium constant of nanoparticles, respectively, and particle size were derived by introducing interface variables and the surface chemical potential. Experimentally, the solubility of nano-barium sulfate with different average particle sizes at different temperatures were determined by the method of electrical conductivity, obtaining the influencing regularities of particle size on the dissolution thermodynamic properties and the equilibrium constant. The regularities are in accordance with the theory. The results show that there are remarkable effects of particle size of nanoparticles on the dissolution thermodynamic properties and the equilibrium constant; with the decreasing of the size of nanoparticles, the dissolution equilibrium constant increases, while the standard dissolution Gibbs free energy, the standard dissolution enthalpy and the standard dissolution entropy decrease; and the logarithm of the dissolution equilibrium constant, the standard dissolution Gibbs free energy, the standard dissolution enthalpy and the standard dissolution entropy are linearly associated with the reciprocal of particle size, respectively. This new theory provides a quantitative description of nanoparticles dissolution behavior, and has important scientific significance for understanding and predicting of thermodynamic regularity of dissolution concerned in the preparation, researches and applications of nanomaterials.

Thermodynamics of deuterium exchange reactions in water-amine and alcohol-amine systems

1981 ◽  
Vol 34 (9) ◽  
pp. 1801
Author(s):  
ZS Kooner ◽  
DV Fenby
Keyword(s):  
Thermodynamic Properties ◽  
Equilibrium Constant ◽  
Deuterium Exchange ◽  
Excess Enthalpies ◽  
Exchange Reactions ◽  
Molar Excess ◽  
Harmonic Frequencies ◽  
Statistical Mechanical

Vapour pressures and molar excess enthalpies at 298.15 K are reported for the systems H2O+(C2H5)2NH and D2O+(C2H5)2NH. They are analysed to give the equilibrium constant and enthalpy of the reaction ����������������� 2(C2H5)2NH(1)+D2O(1)→2(C2H5)2ND(1)+H2O(1) Molar excess enthalpies at 298.15 K of the systems CH3OH+(C2H5)2NH, CH3OD+(C2H5)2NH, C2H5OH+(C2H5)2NH and C2H5OD+(C2H5)2NH are used to obtain enthalpies of the reactions ���������� (C2H5)2NH(1)+ROD(1)→(C2H5)2ND(1)+ROH(1)� (R = CH3, C2H5)Thermodynamic properties of various NH/OD exchange reactions are calculated from statistical mechanical equations by use of harmonic frequencies.

Heat Capacity and Thermodynamic Properties of LaBr3 at 300 – 1100 K

2004 ◽  
Vol 59 (11) ◽  
pp. 825-828
Author(s):  
L. Rycerz ◽  
E. Ingier-Stocka ◽  
B. Ziolek ◽  
S. Gadzuric ◽  
M. Gaune-Escard
Keyword(s):  
Differential Scanning Calorimetry ◽  
Heat Capacity ◽  
Thermodynamic Properties ◽  
Temperature Dependence ◽  
Enthalpy Of Formation ◽  
Thermodynamic Functions ◽  
Molar Enthalpy ◽  
Standard Molar Enthalpy ◽  
Scanning Calorimetry ◽  
Temperature Range

The heat capacity of solid and liquid LaBr3 was measured by Differential Scanning Calorimetry (DSC) in the temperature range 300 - 1100 K. The obtained results were fitted by a polynomial temperature dependence. The enthalpy of fusion of LaBr3 was also measured. By combination of these results with the literature data on the entropy, S0m (LaBr3, s, 298.15 K) and the standard molar enthalpy of formation, ΔformH0m (LaBr3, s, 298.15 K), the thermodynamic functions of lanthanum tribromide were calculated up to 1300 K

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