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V Venugopal - One of the best experts on this subject based on the ideXlab platform.
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Gibbs free Energy of Formation of calcium rhodite
Thermochimica Acta, 2004Co-Authors: Aparna Banerjee, Ram Prasad, V VenugopalAbstract:Abstract The Gibbs free Energy of Formation of CaRh2O4(s) has been determined using two techniques viz., quadrupole mass spectrometer coupled to a Knudsen cell and solid-state cell incorporating CaF2(s) as the solid electrolyte. In the former method, equilibrium O2(g) pressures were measured over the phase field Rh(s)+Rh2O3(s), in the temperature range 793.7–909.1 K and over the three phase mixture CaRh2O4(s)+Rh(s)+CaO(s) was measured from 862.1 to 1022.7 K. The Gibbs free Energy of Formation of Rh2O3(s) from elements in their standard state can be given by Δ f G°( Rh 2 O 3 (s) ) ( kJ mol −1 ±2.0)=−363.2+0.241T ( K ). The Gibbs free Energy of Formation of CaRh2O4(s) from elements in their standard state can be given by Δ f G°( CaRh 2 O 4 (s) ) ( kJ mol −1 ±2.0)=−1030.5+0.3437T ( K ). In the electrochemical technique, the cell configuration employed was (−) Pt / O 2 ( g ),{ CaO ( s )+ CaF 2 ( s )}// CaF 2 //{ CaRh 2 O 4 ( s )+ Rh 2 O 3 ( s )+ CaF 2 ( s )}, O 2 ( g )/ Pt (+). The emf values were measured in the temperature range 879.7–1000 K can be represented by the following expression: E ( V) (±7.63×10 −4 )=0.3928−2.374×10 −4 T ( K). From the measured emf of the cell and requisite ΔfG° values from the literature, ΔfG°(CaRh2O4(s)) from elements in their standard state has been calculated and can be represented by Δ f G°( CaRh 2 O 4 (s) ) ( kJ mol −1 ±2.0)=−1079+0.390T ( K ) . The uncertainty estimates for ΔfG° include the standard deviation in the emf and uncertainty in the data taken from the literature. The slope and intercept of the above equation gives the entropy and enthalpy of Formation of the compound at the average experimental temperature T av =940 K .
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Gibbs Energy of Formation of UPd3(s)
Journal of Nuclear Materials, 2000Co-Authors: Ram Prasad, Ziley Singh, Smruti Dash, S.c. Parida, V VenugopalAbstract:Abstract Gibbs Energy of Formation of UPd 3 (s) has been determined by measuring the equilibrium CO(g) pressure over {UO 2 (s) + C(s) + UPd 3 (s) + UPd 4 (s)} and is given as Δ f G 0 m ( UPd 3 , s ,T) kJ mol −1 ±4.1=−526.9+0.1259 T (K) , (1175⩽T (K) ⩽1333). Using the required literature data, Δ f H 0 m (UPd 3 , s, 298.15 K) has been calculated as −(502.3 ± 5.1) kJ mol −1 .
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Gibbs Energy of Formation of UPd4(s)
Journal of Alloys and Compounds, 1999Co-Authors: Ram Prasad, Ziley Singh, Smruti Dash, S.c. Parida, V VenugopalAbstract:Abstract Gibbs energies of Formation of UPd 4 (s) have been determined by measuring the equilibrium CO(g) pressures over a UO 2 (s)+C(s)+U 0.15 Pd 0.85 (s)+UPd 4 (s) mixture in the temperature range 1202 to 1306 K and are represented as: Δ f G m o ( UPd 4 , s , T)±4.5 ( kJ mol −1 )=−528.1+0.1223T ( K ) (1202≤T ( K )≤1306).
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Standard molar Gibbs Energy of Formation of UTeO5(s) by the electrochemical method
The Journal of Chemical Thermodynamics, 1999Co-Authors: Ziley Singh, Ram Prasad, Smruti Dash, K. Krishnan, V VenugopalAbstract:Standard molar Gibbs energies of Formation of UTeO5(s) have been determined by measuring the relative oxygen chemical potential over the three phase system {U3O8(s) + TeO2(s) + UTeO5(s)} in the temperature range (821 to 993.5) K using a solid electrolyte galvanic cell having a 0.15 mole fraction calcia-stabilized zirconia (CSZ) as an electrolyte. The cell used was:Pt∣{U3O8(s)+ TeO2(s)+UTeO5(s)}∣∣ CSZ∣∣{Ni(s)+NiO(s)}∣Pt. The observed e.m.f. values are represented by: (E ± 1 · 10−3)/V = 0.7677 − 6.290 · 10−4(T/K). The relative oxygen chemical potential over the three phase system was evaluated from the e.m.f. values and is given as: {Δμ(O2) ± 1.4}/(kJ · mol−1) = −759.8 + 0.4222 (T/K). The standard molar Gibbs energies of Formation of UTeO5(s) are evaluated from the oxygen chemical potential data, and the ΔfGmo(T) of U3O8(s) and TeO2(s) from literature. The resulting standard molar Gibbs energies of Formation of UTeO5(s) are given by: {ΔfGmo(UTeO5,s,T) ± 4.6 }/(kJ·mol−1) = −1642.5 + 0.4784 (T/K). Using the literature values, the ΔfHmo(UTeO5,s,298.15) has been calculated by using the second- and third-law methods. The resulting values are {−(1638.8 ± 9) and −(1601.6 ± 10)} kJ·mol−1, respectively.
Jan Dolfing - One of the best experts on this subject based on the ideXlab platform.
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The Gibbs free Energy of Formation of halogenated benzenes, benzoates and phenols and their potential role as electron acceptors in anaerobic environments
Biodegradation, 2015Co-Authors: Jan Dolfing, Igor NovakAbstract:The sequence of redox reactions in the natural environment generally follows the electron affinity of the electron acceptors present and can be rationalized by the redox potentials of the appropriate half-reactions. Answering the question how halogenated aromatics fit into this sequence requires inFormation on their Gibbs free Energy of Formation values. In 1992 Gibbs free Energy data for various classes of halogenated aromatic compounds were systematically explored for the first time based on Benson’s group contribution method. Since then more accurate quantum chemical calculation methods have become available. Here we use these methods to estimate enthalpy and Gibbs free Energy of Formation values of all chlorinated and brominated phenols. These data and similar state-of-the-art datasets for halogenated benzenes and benzoates were then used to calculate two-electron redox potentials of halogenated aromatics for standard conditions and for pH 7. The results underline the need to take speciation into consideration when evaluating redox potentials at pH 7 and highlight the fact that halogenated aromatics are excellent electron acceptors in aqueous environments.
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Gibbs Free Energy of Formation of Chlordecone and Potential Degradation Products: Implications for Remediation Strategies and Environmental Fate
Environmental Science and Technology, 2012Co-Authors: Jan Dolfing, Igor Novak, Alain Archelas, Hervé MacarieAbstract:Chlordecone (C10Cl10O; CAS number 143-50-0) has been used extensively as an organochlorine insecticide, but is nowadays banned under The Stockholm Convention on Persistent Organic Pollutants (POPs). A search for chlordecone respiring organisms and choosing between reductive versus oxidative remediation tools and strategies to clean up chlordecone polluted environments would benefit from the availability of Gibbs free Energy data of chlordecone and its potential dechlorination products. Presently such data are not available. Polycyclic "cage" molecules of which chlordecone is an example contain considerable strain Energy. It is not a priory clear how this affects thermodynamic properties of the chlorinated members of this unique class of compounds, and to what extent redox potentials for the halogenated congeners are different from those of other aliphatic and aromatic organohalogens. We have performed ab initio quantum chemical calculations to estimate ΔfHmo and ΔfGmo values of chlordecone and selected dechlorination products, and used these data to calculate their Gibbs free Energy and redox potential. With redox potentials in the range of 336 to 413 mV chlordecone has an Eo' value similar to that of other organochlorines. The results indicate that there are no thermodynamic reasons why chlordecone respiring or fermenting organisms should not exist.
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gibbs free Energy of Formation of chlordecone and potential degradation products implications for remediation strategies and environmental fate
Environmental Science & Technology, 2012Co-Authors: Jan Dolfing, Igor Novak, Alain Archelas, Hervé MacarieAbstract:Chlordecone (C10Cl10O; CAS number 143-50-0) has been used extensively as an organochlorine insecticide but is nowadays banned under The Stockholm Convention on Persistent Organic Pollutants (POPs). A search for chlordecone-respiring organisms and choosing between reductive versus oxidative remediation tools and strategies to clean up chlordecone-polluted environments would benefit from the availability of Gibbs free Energy data of chlordecone and its potential dechlorination products. Presently such data are not available. Polycyclic “cage” molecules of which chlordecone is an example contain considerable strain Energy. It is not a priori clear how this affects the thermodynamic properties of the chlorinated members of this unique class of compounds and to what extent redox potentials for the halogenated congeners are different from those of other aliphatic and aromatic organohalogens. We performed ab initio quantum chemical calculations to estimate ΔfHm° and ΔfGm° values of chlordecone and selected dechl...
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Estimates of Gibbs free energies of Formation of chlorinated aliphatic compounds
Biodegradation, 1994Co-Authors: Jan Dolfing, Dick B. JanssenAbstract:The Gibbs free Energy of Formation of chlorinated aliphatic compounds was estimated with Mavrovouniotis' group contribution method. The group contribution of chlorine was estimated from the scarce data available on chlorinated aliphatics in the literature, and found to vary somewhat according to the position of chlorine in the molecule. The resulting estimates of the Gibbs free Energy of Formation of chlorinated aliphatic compounds indicate that both reductive dechlorination and aerobic mineralization of these compounds can yield sufficient Energy to sustain microbial growth.
Ziley Singh - One of the best experts on this subject based on the ideXlab platform.
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System Zn–Rh–O: heat capacity and Gibbs free Energy of Formation using differential scanning calorimeter and electrochemical cell
Journal of Solid State Electrochemistry, 2009Co-Authors: Aparna Banerjee, Ziley SinghAbstract:The standard molar Gibbs free Energy of Formation of ZnRh_2O_4(s) has been determined using an oxide solid-state electrochemical cell wherein calcia-stabilized zirconia (CSZ) was used as an electrolyte. The oxide cell can be represented by: $${{\left( - \right){\text{Pt}} - {\text{Rh}}} \mathord{\left/ {\vphantom {{\left( - \right){\text{Pt}} - {\text{Rh}}} {\left\{ {{\text{ZnO}}\left( {\text{s}} \right)} \right.}}} \right. \kern-\nulldelimiterspace} {\left\{ {{\text{ZnO}}\left( {\text{s}} \right)} \right.}} + {\text{ZnRh}}_{\text{2}} {\text{O}}_{\text{4}} \left( {\text{s}} \right) + \left. {{\text{Rh}}\left( {\text{s}} \right)} \right\}//{\text{CSZ//O}}_{\text{2}} {{\left( {p\left( {{\text{O}}_{\text{2}} } \right) = {\text{21}}{\text{.21 kPa}}} \right)} \mathord{\left/ {\vphantom {{\left( {p\left( {{\text{O}}_{\text{2}} } \right) = {\text{21}}{\text{.21 kPa}}} \right)} {{\text{Pt}} - {\text{Rh}}\left( {\text{ + }} \right)}}} \right. \kern-\nulldelimiterspace} {{\text{Pt}} - {\text{Rh}}\left( {\text{ + }} \right)}}$$ . The electromotive force was measured in the temperature range from 943.9 to 1,114.2 K. The standard molar Gibbs Energy of Formation of ZnRh_2O_4(s) from elements in their standard state using the oxide electrochemical cell has been calculated and can be represented by: $$\Delta _{\text{f}} G^{\text{o}} {\text{\{ ZnRh}}_{\text{2}} {\text{O}}_{\text{4}} {\text{(s)\} /kJ mol}}^{ - {\text{1}}} {\text{( $ \pm $ 1}}{\text{.15) = }} - {\text{744}}{\text{.5 + 0}}{\text{.3487 }}T{\text{ (K)}}$$ . Standard molar heat capacity C ^o _p,m( T ) of ZnRh_2O_4(s) was measured using a heat flux-type differential scanning calorimeter in two different temperature ranges, from 127 to 299 and 307 to 845 K. The heat capacity in the higher temperature range was fitted into a polynomial expression and can be represented by: $$\begin{aligned} & C^{\text{o}} _{{\text{p,m}}} {\text{ (ZnRh}}_{\text{2}} {\text{O}}_{\text{4}} {\text{,s,}}T{\text{)}}\;{\text{(J}}\;{\text{K}}^{ - 1} \;{\text{mol}}^{ - 1} {\text{) = 167}}{\text{.685 + 2}}{\text{.446}} \times {\text{10}}^{ - {\text{2}}} T\;{\text{(K)}} - {\text{33}}{\text{.74339}} \times {\text{10}}^{\text{5}} {\text{/}}T^{\text{2}} \;{\text{(K)}} \\ & {\text{ (307}} \leqslant T{\text{ (K)}} \leqslant {\text{845)}} \\ \end{aligned} $$ . The heat capacity of ZnRh_2O_4(s), was used along with the data obtained from the oxide electrochemical cell to calculate the standard enthalpy and entropy of Formation of the compound at 298.15 K.
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Gibbs Energy of Formation of UPd3(s)
Journal of Nuclear Materials, 2000Co-Authors: Ram Prasad, Ziley Singh, Smruti Dash, S.c. Parida, V VenugopalAbstract:Abstract Gibbs Energy of Formation of UPd 3 (s) has been determined by measuring the equilibrium CO(g) pressure over {UO 2 (s) + C(s) + UPd 3 (s) + UPd 4 (s)} and is given as Δ f G 0 m ( UPd 3 , s ,T) kJ mol −1 ±4.1=−526.9+0.1259 T (K) , (1175⩽T (K) ⩽1333). Using the required literature data, Δ f H 0 m (UPd 3 , s, 298.15 K) has been calculated as −(502.3 ± 5.1) kJ mol −1 .
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Gibbs Energy of Formation of UPd4(s)
Journal of Alloys and Compounds, 1999Co-Authors: Ram Prasad, Ziley Singh, Smruti Dash, S.c. Parida, V VenugopalAbstract:Abstract Gibbs energies of Formation of UPd 4 (s) have been determined by measuring the equilibrium CO(g) pressures over a UO 2 (s)+C(s)+U 0.15 Pd 0.85 (s)+UPd 4 (s) mixture in the temperature range 1202 to 1306 K and are represented as: Δ f G m o ( UPd 4 , s , T)±4.5 ( kJ mol −1 )=−528.1+0.1223T ( K ) (1202≤T ( K )≤1306).
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Standard molar Gibbs Energy of Formation of UTeO5(s) by the electrochemical method
The Journal of Chemical Thermodynamics, 1999Co-Authors: Ziley Singh, Ram Prasad, Smruti Dash, K. Krishnan, V VenugopalAbstract:Standard molar Gibbs energies of Formation of UTeO5(s) have been determined by measuring the relative oxygen chemical potential over the three phase system {U3O8(s) + TeO2(s) + UTeO5(s)} in the temperature range (821 to 993.5) K using a solid electrolyte galvanic cell having a 0.15 mole fraction calcia-stabilized zirconia (CSZ) as an electrolyte. The cell used was:Pt∣{U3O8(s)+ TeO2(s)+UTeO5(s)}∣∣ CSZ∣∣{Ni(s)+NiO(s)}∣Pt. The observed e.m.f. values are represented by: (E ± 1 · 10−3)/V = 0.7677 − 6.290 · 10−4(T/K). The relative oxygen chemical potential over the three phase system was evaluated from the e.m.f. values and is given as: {Δμ(O2) ± 1.4}/(kJ · mol−1) = −759.8 + 0.4222 (T/K). The standard molar Gibbs energies of Formation of UTeO5(s) are evaluated from the oxygen chemical potential data, and the ΔfGmo(T) of U3O8(s) and TeO2(s) from literature. The resulting standard molar Gibbs energies of Formation of UTeO5(s) are given by: {ΔfGmo(UTeO5,s,T) ± 4.6 }/(kJ·mol−1) = −1642.5 + 0.4784 (T/K). Using the literature values, the ΔfHmo(UTeO5,s,298.15) has been calculated by using the second- and third-law methods. The resulting values are {−(1638.8 ± 9) and −(1601.6 ± 10)} kJ·mol−1, respectively.
K. T. Jacob - One of the best experts on this subject based on the ideXlab platform.
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Gibbs Energy of Formation of Eu3O4 and EuO
Journal of Chemical & Engineering Data, 2016Co-Authors: K. T. Jacob, Arneet RajputAbstract:Thermodynamic data for Eu3O4 are not available in standard compilations. However, data for EuO and Eu2O3 are available. Data for Eu2O3 in the compilations are in agreement while those for EuO differ significantly. Two solid–state electrochemical cells incorporating yttria–doped thoria as the electrolyte are used to measure the standard Gibbs Energy of Formation of Eu3O4 and EuO relative to that for Eu2O3 in the temperature range from 1000 to 1300 K. A mixture of Nb and NbO is used as the reference electrode since the oxygen chemical potential associated with the mixture is close to that of the working electrodes EuO + Eu3O4 and Eu3O4 + Eu2O3. The standard Gibbs Energy of Formation of Eu3O4 can be represented by the following equation: ΔfG°(±860)/J·mol–1 = −2267816 + 403.18(T/K) {1090–1300 K}. Below the melting point of Eu, the Gibbs Energy of Formation of Eu3O4 is given by ΔfG°(±860)/J·mol–1 = −2240177 + 377.824(T/K) {1000–1090 K}. Also, the standard Gibbs Energy of Formation of EuO can be represented by ...
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Discussion of enthalpy, entropy and free Energy of Formation of GaN
Journal of Crystal Growth, 2009Co-Authors: K. T. Jacob, G. RajithaAbstract:Presented in this letter is a critical discussion of a recent paper on experimental investigation of the enthalpy, entropy and free Energy of Formation of gallium nitride (GaN) published in this journal [T.J. Peshek, J.C. Angus, K. Kash, J. Cryst. Growth 311 (2008) 185-189]. It is shown that the experimental technique employed detects neither the equilibrium partial pressure of N-2 corresponding to the equilibrium between Ga and GaN at fixed temperatures nor the equilibrium temperature at constant pressure of N-2. The results of Peshek et al. are discussed in the light of other inFormation on the Gibbs Energy of Formation available in the literature. Entropy of GaN is derived from heat-capacity measurements. Based on a critical analysis of all thermodynamic inFormation now available, a set of optimized parameters is identified and a table of thermodynamic data for GaN developed from 298.15 to 1400 K.
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Gibbs Energy of Formation of MnO: Measurement and Assessment
Journal of Phase Equilibria and Diffusion, 2008Co-Authors: K. T. Jacob, A. Kumar, Yoshio WasedaAbstract:Based on the measurements of Alcock and Zador, Grundy et al. estimated an uncertainty of the order of ±5 kJ mol−1 for the standard Gibbs Energy of Formation of MnO in a recent assessment. Since the evaluation of thermodynamic data for the higher oxides Mn3O4, Mn2O3, and MnO2 depends on values for MnO, a redetermination of its Gibbs Energy of Formation was undertaken in the temperature range from 875 to 1300 K using a solid-state electrochemical cell incorporating yttria-doped thoria (YDT) as the solid electrolyte and Fe + Fe1 − δO as the reference electrode. The cell can be presented as $$ {\text{Pt, Mn}} + {\text{MnO}}/{\text{YDT}}/{\text{Fe}} + {\text{Fe}}_{{1 - \updelta }} {\text{O, Pt}} $$
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Gibbs energies of Formation of UMoC 1.7 and UMoC 2
1996Co-Authors: K. Ananthasivan, P. R. Vasudeva Rao, I. Kaliappan, S. Anthonysamy, V. Chandramouli, C.k. Mathews, K. T. JacobAbstract:The chemical potentials of carbon associated with two three-phase fields in the system U---Mo---C were measured by using the methane-hydrogen gas equilibration technique in the temperature range 973 to 1173 K. The technique was validated by measuring the standard Gibbs Energy of Formation of Mo 2 C. From the experimentally measured values of the chemical potential of carbon in the ternary phase fields UC+Mo+UMoC 17 and UC+UMoC 17 +UMoC 2 , and data for UC from the literature, the Gibbs energies of Formation of the two ternary carbides were derived: Δ 1 G 1 ‹UMoC 1Z = -146632 -15.0T(±8200) J mol 1 (973-1173 K) Δ 1 G 2 ‹UMoC 2 =-151 961-13.7T(±8100) Jmol 1 (973-1173K) Experimentally determined values of the Gibbs Energy of Formation of UMoC 17 are reported for the first time.
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Gibbs energies of Formation of UMoC1.7 and UMoC2
Journal of Alloys and Compounds, 1996Co-Authors: K. Ananthasivan, P. R. Vasudeva Rao, I. Kaliappan, S. Anthonysamy, V. Chandramouli, C.k. Mathews, K. T. JacobAbstract:Abstract The chemical potentials of carbon associated with two three-phase fields in the system UMoC were measured by using the methane-hydrogen gas equilibration technique in the temperature range 973 to 1173 K. The technique was validated by measuring the standard Gibbs Energy of Formation of Mo2C. From the experimentally measured values of the chemical potential of carbon in the ternary phase fields UC+Mo+UMoC17 and UC+UMoC17+UMoC2, and data for UC from the literature, the Gibbs energies of Formation of the two ternary carbides were derived: Δ 1 G 1 〈 UMoC 1Z = − 146 632 − 15.0T(±8200) J mol 1 (973 − 1173 K ) Δ 1 G 2 〈 UMoC 2 = − 151 961 − 13.7T(±8100) J mol 1 (973 − 1173 K ) Experimentally determined values of the Gibbs Energy of Formation of UMoC17 are reported for the first time.
Ram Prasad - One of the best experts on this subject based on the ideXlab platform.
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Gibbs free Energy of Formation of the ternary oxide Nd3RuO7
Journal of Alloys and Compounds, 2006Co-Authors: Aparna Banerjee, Ram Prasad, V.n. VaidyaAbstract:Abstract The Gibbs free Energy of Formation of Nd 3 RuO 7 (s) has been determined using solid-state electrochemical cell employing oxide ion conducting electrolyte. The electromotive force (e.m.f.) of the following solid-state electrochemical cell has been measured, in the temperature range from 929.3 to 1228.6 K. Cell: (−)Pt/{Nd 3 RuO 7 (s) + Nd 2 O 3 (s) + Ru(s)}//CSZ//O 2 ( p (O 2 ) = 21.21 kPa)/Pt(+) The Gibbs free Energy of Formation of Nd 3 RuO 7 (s) from elements in their standard state, calculated by the least squares regression analysis of the data obtained in the present study, can be given by: {Δ f G °(Nd 3 RuO 7 , s)/(kJ mol −1 ) ± 1.6} = −3074.3 + 0.6097( T /K); (929.3 ≤ T /K ≤ 1228.6). The uncertainty estimate for Δ f G °( T ) includes the standard deviation in e.m.f. and the uncertainty in the data taken from the literature. The intercept and the slope of the above equation correspond to the enthalpy of Formation and entropy, respectively, at the average experimental temperature of T av. = 1079 K.
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Gibbs free Energy of Formation of calcium rhodite
Thermochimica Acta, 2004Co-Authors: Aparna Banerjee, Ram Prasad, V VenugopalAbstract:Abstract The Gibbs free Energy of Formation of CaRh2O4(s) has been determined using two techniques viz., quadrupole mass spectrometer coupled to a Knudsen cell and solid-state cell incorporating CaF2(s) as the solid electrolyte. In the former method, equilibrium O2(g) pressures were measured over the phase field Rh(s)+Rh2O3(s), in the temperature range 793.7–909.1 K and over the three phase mixture CaRh2O4(s)+Rh(s)+CaO(s) was measured from 862.1 to 1022.7 K. The Gibbs free Energy of Formation of Rh2O3(s) from elements in their standard state can be given by Δ f G°( Rh 2 O 3 (s) ) ( kJ mol −1 ±2.0)=−363.2+0.241T ( K ). The Gibbs free Energy of Formation of CaRh2O4(s) from elements in their standard state can be given by Δ f G°( CaRh 2 O 4 (s) ) ( kJ mol −1 ±2.0)=−1030.5+0.3437T ( K ). In the electrochemical technique, the cell configuration employed was (−) Pt / O 2 ( g ),{ CaO ( s )+ CaF 2 ( s )}// CaF 2 //{ CaRh 2 O 4 ( s )+ Rh 2 O 3 ( s )+ CaF 2 ( s )}, O 2 ( g )/ Pt (+). The emf values were measured in the temperature range 879.7–1000 K can be represented by the following expression: E ( V) (±7.63×10 −4 )=0.3928−2.374×10 −4 T ( K). From the measured emf of the cell and requisite ΔfG° values from the literature, ΔfG°(CaRh2O4(s)) from elements in their standard state has been calculated and can be represented by Δ f G°( CaRh 2 O 4 (s) ) ( kJ mol −1 ±2.0)=−1079+0.390T ( K ) . The uncertainty estimates for ΔfG° include the standard deviation in the emf and uncertainty in the data taken from the literature. The slope and intercept of the above equation gives the entropy and enthalpy of Formation of the compound at the average experimental temperature T av =940 K .
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Gibbs Energy of Formation of UPd3(s)
Journal of Nuclear Materials, 2000Co-Authors: Ram Prasad, Ziley Singh, Smruti Dash, S.c. Parida, V VenugopalAbstract:Abstract Gibbs Energy of Formation of UPd 3 (s) has been determined by measuring the equilibrium CO(g) pressure over {UO 2 (s) + C(s) + UPd 3 (s) + UPd 4 (s)} and is given as Δ f G 0 m ( UPd 3 , s ,T) kJ mol −1 ±4.1=−526.9+0.1259 T (K) , (1175⩽T (K) ⩽1333). Using the required literature data, Δ f H 0 m (UPd 3 , s, 298.15 K) has been calculated as −(502.3 ± 5.1) kJ mol −1 .
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Gibbs Energy of Formation of UPd4(s)
Journal of Alloys and Compounds, 1999Co-Authors: Ram Prasad, Ziley Singh, Smruti Dash, S.c. Parida, V VenugopalAbstract:Abstract Gibbs energies of Formation of UPd 4 (s) have been determined by measuring the equilibrium CO(g) pressures over a UO 2 (s)+C(s)+U 0.15 Pd 0.85 (s)+UPd 4 (s) mixture in the temperature range 1202 to 1306 K and are represented as: Δ f G m o ( UPd 4 , s , T)±4.5 ( kJ mol −1 )=−528.1+0.1223T ( K ) (1202≤T ( K )≤1306).
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Standard molar Gibbs Energy of Formation of UTeO5(s) by the electrochemical method
The Journal of Chemical Thermodynamics, 1999Co-Authors: Ziley Singh, Ram Prasad, Smruti Dash, K. Krishnan, V VenugopalAbstract:Standard molar Gibbs energies of Formation of UTeO5(s) have been determined by measuring the relative oxygen chemical potential over the three phase system {U3O8(s) + TeO2(s) + UTeO5(s)} in the temperature range (821 to 993.5) K using a solid electrolyte galvanic cell having a 0.15 mole fraction calcia-stabilized zirconia (CSZ) as an electrolyte. The cell used was:Pt∣{U3O8(s)+ TeO2(s)+UTeO5(s)}∣∣ CSZ∣∣{Ni(s)+NiO(s)}∣Pt. The observed e.m.f. values are represented by: (E ± 1 · 10−3)/V = 0.7677 − 6.290 · 10−4(T/K). The relative oxygen chemical potential over the three phase system was evaluated from the e.m.f. values and is given as: {Δμ(O2) ± 1.4}/(kJ · mol−1) = −759.8 + 0.4222 (T/K). The standard molar Gibbs energies of Formation of UTeO5(s) are evaluated from the oxygen chemical potential data, and the ΔfGmo(T) of U3O8(s) and TeO2(s) from literature. The resulting standard molar Gibbs energies of Formation of UTeO5(s) are given by: {ΔfGmo(UTeO5,s,T) ± 4.6 }/(kJ·mol−1) = −1642.5 + 0.4784 (T/K). Using the literature values, the ΔfHmo(UTeO5,s,298.15) has been calculated by using the second- and third-law methods. The resulting values are {−(1638.8 ± 9) and −(1601.6 ± 10)} kJ·mol−1, respectively.