Gibbs Energy and Helmholtz Energy

2021 ◽  
Keyword(s):  
Gibbs Energy ◽  
Helmholtz Energy

scholarly journals Combination of Gibbs and Helmholtz Energy Equations of State in a Multiparameter Mixture Model Using the IAPWS Seawater Model as an Example

2022 ◽  
Vol 43 (3) ◽  
Author(s):  
Benedikt Semrau ◽  
Sebastian Hielscher ◽  
Monika Thol ◽  
Roland Span
Keyword(s):  
Gibbs Energy ◽  
Carbon Capture ◽  
Equations Of State ◽  
Carbon Capture And Storage ◽  
Storage Conditions ◽  
Helmholtz Energy ◽  
Energy Models ◽  
Energy Equations ◽  
Energy Balances ◽  
And Storage

AbstractFor carbon capture and storage (CCS) applications different sets of equations of state are used to describe the whole CCS-chain. While for the transport and pipeline sections highly accurate equations of state (EOS) explicit in the Helmholtz energy are used, properties under typical geological storage conditions are described by more simple, mostly cubic EOS, and brines are described by Gibbs energy models. Combining the transport and storage sections leads to inconsistent calculations. Since the used models are formulated in different independent variables (temperature and density versus temperature and pressure), mass and energy balances are challenging and equilibria in the injection region are difficult to model. To overcome these limitations, a predictive combination of the Gibbs energy-based IAPWS seawater model (IAPWS R13-08, 2008) with Helmholtz energy-based multi-parameter EOS is presented within this work. The Helmholtz energy model used in this work is based on the EOS-CG-2016 of Gernert and Span (J Chem Thermodyn 93:274–293, 10.1016/j.jct.2015.05.015, 2016). The results prove that a consistent combination of the two different models is possible. Furthermore, it is shown, that a more complex brine model needs to be combined with Helmholtz energy EOS for calculations at storage conditions.

Thermodynamic properties of montechellite

2019 ◽  
Vol 64 (12) ◽  
pp. 1274-1280
Author(s):  
L. P. Ogorodova ◽  
Yu. D. Gritsenko ◽  
M. F. Vigasina ◽  
A. Yu. Bychkov ◽  
D. A. Ksenofontov ◽  
...  
Keyword(s):  
High Temperature ◽  
Gibbs Energy ◽  
Solution Calorimetry ◽  
Thermochemical Study ◽  
Gibbs Energy Of Formation ◽  
Calvet Microcalorimeter ◽  
Magnesium Orthosilicate ◽  
Calcium And Magnesium ◽  
The Enthalpy Of Formation ◽  
Energy Of Formation

A thermochemical study of natural calcium and magnesium orthosilicate ─ monticellite (Ca1.00Mg0.95)[SiO4] (Khabarovsk Territory, Russia) was carried out on the Tian-Calvet microcalorimeter. The enthalpy of formation from the elements fHоel(298.15 K) = -2238.4 4.5 kJ / mol was determined by the method of high-temperature melt solution calorimetry. The enthalpy and Gibbs energy of formation of monticellite of the theoretical composition of CaMg[SiO4] are calculated: fH0el(298.15 K) = -2248.4 4.5 kJ/mol and fG0el(298.15 K) = -2130.5 4.5 kJ/mol.

A description of effect of composition of mixed binary solvents on processes in solutions

1988 ◽  
Vol 53 (4) ◽  
pp. 671-685 ◽  
Author(s):  
Oldřich Pytela ◽  
Miroslav Ludwig
Keyword(s):  
Gibbs Energy ◽  
Mixed Solvents ◽  
Theoretical Description ◽  
Energy Change ◽  
Binary Solvents ◽  
Gibbs Energy Change ◽  
Order Model ◽  
Significant Difference

A theoretical description of the effect of changed composition of mixed solvents on processes in solutions has been suggested on the basis of the proportionality between the Gibbs energy change of the process and that of the solvent due to the transition from pure components to the mixture. The additional Gibbs energy has been expressed by means of the so-called classical functions by Margules, van Laar-Wohl, and van Laar-Null. The application to 115 various processes (pK, IR, UV-VIS, NMR, log k, and others) has confirmed that the theoretical presumptions are justified, the most suitable being Margules' 4th order model which shows a statistically significant difference from the models of lower orders.

On Temperature Dependence of Excess Gibbs Energy

1999 ◽  
Vol 64 (7) ◽  
pp. 1093-1099 ◽  
Author(s):  
Ivona Malijevská ◽  
Anatol Malijevský
Keyword(s):  
Heat Capacity ◽  
Gibbs Energy ◽  
Temperature Dependence ◽  
Excess Gibbs Energy ◽  
Excess Enthalpy ◽  
Excess Heat Capacity ◽  
Wilson Equation ◽  
Excess Heat ◽  
Energy Excess ◽  
Wilson And Nrtl Equations

Temperature dependence of GE is discussed for three widely used equations linear and nonlinear in parameters. It is shown that the Wilson equation predicts always positive excess heat capacity regardless of values of its parameters. Several temperature modifications of the Redlich-Kister, Wilson and NRTL equations are discussed with respect to the sign of the excess Gibbs energy, excess enthalpy and excess heat capacity.

Activities of Components in the Ca2MgSi2O7-CaSiO3Molten System

1996 ◽  
Vol 61 (6) ◽  
pp. 837-843
Author(s):  
Ladislav Kosa ◽  
Ivan Nerád ◽  
Katarína Adamkovičová ◽  
Jozef Strečko ◽  
Ivo Proks
Keyword(s):  
Gibbs Energy ◽  
Molar Mass ◽  
Excess Entropy ◽  
Enthalpy Of Mixing ◽  
Real Particle ◽  
Entropy Of Mixing ◽  
Energy Of Mixing ◽  
Gibbs Energy Of Mixing

Activities of the components, the Gibbs energy of mixing, and the excess entropy of mixing have been calculated for the Ca2MgSi2O7-CaSiO3 system. The mole fractions of the components were calculated assuming that in the point of the formal component Ca2MgSi2O7, the molar mass of the quasi-real particle in the melt corresponds to its formula molar mass, whereas in the point of the formal component CaSiO3 the molar mass of the quasi-real particle in the melt is 8.5 times higher than as corresponds to its formula. The fact that the enthalpy of mixing is zero whereas the excess entropy of mixing is non-zero suggests that Ca2MgSi2O7-CaSiO3 melts behave as athermal solutions.

A Comparative Study of Adsorption of Aliphatic Amines at a Gold Electrode

2005 ◽  
Vol 70 (12) ◽  
pp. 2027-2037 ◽  
Author(s):  
Teresa Łuczak
Keyword(s):  
Gibbs Energy ◽  
Comparative Study ◽  
Gold Electrode ◽  
Surface Coverage ◽  
Standard Gibbs Energy ◽  
Gold Surface ◽  
Experimental Dependence ◽  
Aliphatic Amines ◽  
Solvent Interactions ◽  
Amine Concentration

Adsorption of aliphatic amines (C1-C4) at the gold electrode was studied by tensammetry. It has been established that the experimental dependence between the gold surface coverage (Θ) and the bulk amine concentration (cA) fits satisfactorily both by the Frumkin and Flory-Huggins isotherms. The standard Gibbs energy of adsorption, ∆G°ad at Emax for Θ < 0.8 has been found to increase in the order methylamine < ethylamine < propylamine < butylamine. This is rationalised in terms of surface-adsorbate, adsorbate-adsorbate and adsorbate-solvent interactions.

Determination of the Nucleophilicity of Tricarbonyliron Coordinated Cyclohepta-1,3,5-triene

1999 ◽  
Vol 64 (11) ◽  
pp. 1770-1779 ◽  
Author(s):  
Herbert Mayr ◽  
Karl-Heinz Müller
Keyword(s):  
Gibbs Energy ◽  
Ambient Temperature ◽  
Rate Constants ◽  
Second Order ◽  
Order Rate ◽  
Electrophilic Additions ◽  
Kinetics Of

The kinetics of the electrophilic additions of four diarylcarbenium ions (4a-4d) to tricarbonyl(η4-cyclohepta-1,3,5-triene)iron (1) have been studied photometrically. The second-order rate constants match the linear Gibbs energy relationship log k20 °C = s(E + N) and yield the nucleophilicity parameter N(1) = 3.69. It is concluded that electrophiles with E ≥ -9 will react with complex 1 at ambient temperature.

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