Experimental Enthalpy of Formation of Isonitrile from Collision-Induced Dissociation Threshold Energy Measurements

2000 ◽  
Vol 104 (23) ◽  
pp. 5612-5616 ◽  
Author(s):  
Paul G. Wenthold
Keyword(s):  
Enthalpy Of Formation ◽  
Threshold Energy ◽  
Collision Induced Dissociation ◽  
Experimental Enthalpy ◽  
Dissociation Threshold

Enthalpy formation of fluorene: Is a challenging problem for theory or experiment?

2021 ◽  
Author(s):  
Olga V. Dorofeeva ◽  
Anna Druzhinina
Keyword(s):  
Enthalpy Of Formation ◽  
Challenging Problem ◽  
Mp2 Method ◽  
Experimental Enthalpy

The large discrepancy between the experimental enthalpy of formation of fluorene and theoretical value calculated by G3(MP2) method was revealed more than ten years ago. Three years later, a new...

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.

Thermodynamics of EuCl3: Experimental Enthalpy of Fusion and Heat Capacity and Estimation of Thermodynamic Functions up to 1300 K

2002 ◽  
Vol 57 (5) ◽  
pp. 215-220 ◽  
Author(s):  
L. Rycerz ◽  
M. Gaune-Escard
Keyword(s):  
Differential Scanning Calorimetry ◽  
Heat Capacity ◽  
Temperature Dependence ◽  
Melting Temperature ◽  
Enthalpy Of Formation ◽  
Thermodynamic Functions ◽  
Molar Enthalpy ◽  
Standard Molar Enthalpy ◽  
Scanning Calorimetry ◽  
Experimental Enthalpy

The heat capacity of solid EuCl3 was measured by differential scanning calorimetry from 300 K up to the melting temperature, and beyond. These results were compared with literature data and fitted by a polynomial temperature dependence. The enthalpy of EuCl3 fusion was measured. Furthermore, by combination of these results with literature data on the entropy at 298.15 Sm0 (EuCl3, s, 298.15 K) and the standard molar enthalpy of formation of ∆form H0m (EuCl3, s, 298.15 K), the thermodynamic functions have been calculated up to 1300 K.

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