Standard Molar Gibbs Energy Research Articles

Thermodynamic study of tin tetraiodide (SnI4) sublimation by effusion techniques

This study presents the first investigation of the sublimation behavior of tin tetraiodide, SnI4, using effusion-based techniques, within a low temperature range (313–340) K. The temperature range covered in the experiments was lower than in previously reported studies based on static methods. Knudsen Effusion Mass Loss (KEML) measurements were performed in the range of (317.1–339.6) K using effusion cells with different orifice sizes. The vapor pressures were measured in the range (0.13–1.13) Pa and were found to be independent of the orifice size. The standard molar enthalpy and Gibbs energy of sublimation at 298.15 K obtained by the Clarke and Glew fit of experimental data are (88.1 ± 0.9) kJ⋅mol−1 and (38.96 ± 0.08) kJ⋅mol−1, respectively. Knudsen Effusion Mass Spectrometry (KEMS) experiments were also performed in the range (313.3–331.7) K, resulting in a sublimation enthalpy value in good agreement with the KEML values and not negligibly higher vapor pressure values. KEMS vapor pressure data were also analyzed by the third-law method. A comparison of our experimental results with the literature data available for both sublimation and evaporation properties of SnI4 is reported. Additionally, ancillary DFT and ab initio calculations were performed to estimate the molecular properties of SnI4(g) and the extent of the gas-phase dissociation to SnI2 and I2.

Thermodynamic insights of ternary compounds of NiO - V2O5 system

We present the first experimental investigation on thermochemical stability of three ternary nickel vanadates, namely, NiV2O6(s), Ni2V2O7(s) and Ni3V2O8(s) in the NiO-V2O5 system. The standard molar entropies of formation of the compounds were determined by low temperature heat capacity measurements from 2 to 300 K using relaxation calorimetry. The standard molar enthalpy of formation and molar heat capacities were determined employing high temperature oxide melt solution calorimetry in conjunction with differential scanning calorimetry. Using the experimentally obtained thermochemical data, the standard molar Gibbs energy of formation of these compounds were derived and the corresponding expressions are given as follows:∆Gf,m°<NiV2O6>±1.4kJmol−1=−1839.4+0.5132(T/K)(T:298.15−1000K)∆Gf,m°<Ni2V2O7>±1.4kJmol−1=−2101.8+0.5971(T/K)(T:298.15−1000K)∆Gf,m°<Ni3V2O8>±3.2kJmol−1=−2360.5+0.6538(T/K)(T:298.15−1000K)

Electrode potentials involving atoms and ions of metals in intermediate oxidation states in aqueous solutions

The electrode potentials of metal atoms (M+/M0 and M2+/M0 couples) were calculated from their standard electrode potentials in water minus the standard molar Gibbs energy of formation of the atoms in the gas phase, ΔfG0(Mgas0), and the Gibbs energy of hydration in solution, ΔhydG°. Electrode potentials are appreciably shifted (by 2.0–2.5 V) toward negative values relative to the potentials of the solid metals. For the univalent metals Cu0, Ag0, and Au0 (d10s1 electronic configuration), the electrode potentials of M+/M0 couples are –2.73, –1.90, and –1.82 V; for Ga0, In0, and Tl0 (d10s2p1 electronic configuration), they are –3.14, –2.45, and –1.99 V, respectively. For bivalent transition metals of period IV with the d5+ns2 configuration, the potentials of M2+/M0 couples are –2.50 V for Mn0, –2.45 V for Fe0, –2.33 V for Co0, –2.34 for Ni0, –1.29 V for Cu0, and –1.34 V for Zn0. For Cd0 and Hg0 (d10s2 configuration), the potentials are –0.87 and + 0.42 V. Estimation of the electrode potentials of bivalent metals in the intermediate and unstable oxidation states (M2+/M+ and M+/M0 couples) revealed their significant difference. In the case of Zn, Cd, and Hg, this difference is particularly noticeable, as large as 2–3 V, because of different configurations of the M+ (d10s1) and M0 (d10s2) electronic shells. Regular trends in variations of the electrode potentials in the periods and groups of the periodic table were revealed. In going from the atomic-molecular to the solid state, the chemical activity of the metals decreases. The metal surface catalyzes the reactions that are thermodynamically unfavorable in the solution volume.

Sublimation of pyridine derivatives: fundamental aspects and application for two-component crystal screening.

The saturated vapour pressures of five heterocyclic compounds containing the pyridine fragment, namely, three isomers of aminopyridine (2-aminopyridine (2AmPy), 3-aminopyridine (3AmPy), and 4-aminopyridine (4AmPy)); 3-hydroxypyridine (3OHPy) and 2-(1H-imidazol-2-yl)pyridine (ImPy), were measured at appropriate temperature intervals using a transpiration (inert gas flow) method. The standard molar enthalpies, entropies, and Gibbs energies of sublimation for all the studied substances were determined. Among the compounds studied, the largest value of ΔH298sub was observed for ImPy. The influence of substitution and the effects of hydrogen bonds in the crystal lattices on sublimation parameters are discussed herein. The reliable dependences relating ΔG298sub to Tfus and ΔH298sub to ΔG298sub were plotted. A comparative analysis of several calculation schemes for the estimation of sublimation enthalpy and Gibbs free energy was carried out. Thermodynamic parameters obtained in this study were applied for the evaluation of cocrystallisation thermodynamic functions for two-component crystals (virtual screening) on the basis of the studied substituted pyridines.

Molecular recognition of synthetic RNAs by phenothiazinium dyes methylene blue and new methylene blue: Thermodynamic approach

Many biological process and function centers around recognition of double stranded RNA as it impacts numerous pathways associated with maturation of cellular RNA. This work assembles an intricate thermodynamic profiling of the phenothaizinium dyes methylene blue and new methylene blue with three double stranded ribonucleic acids, poly(A).poly(U), poly(C).poly(G) and poly(I).poly(C) with aid of thermal helix melting, isothermal titration calorimetry and differential scanning calorimetry experiments. Isothermal titration calorimetry had put forward that highest binding affinity was observed for poly(A).poly(U)-dye binding while the order varied as poly(A).poly(U) > poly(C).poly(G) > poly(I).poly(C). Strong stability of the polynucleotides against heat strand separation characterises the binding. Non-electrostatic component had larger share in parsing of the standard molar Gibbs energy of the binding. The processes' negative change in heat capacity is evidence of how essential hydrophobic forces are. Release of water molecules which are in random orientation mode occurs from RNA's hydrophobic binding pockets. Negative enthalpy and positive entropic change are the two significant features in this hydrophobic binding scenario. Another vital result of enthalpy-entropy compensation has been identified with the binding processes. The findings bear direct and ubiquitous acknowledgement in revitalizing our interest and broadening our horizon towards successful targeting of small molecules to RNAs.

Phase transitions properties of N,N-dimethyl-4-nitroaniline

The present work reports an experimental study aiming to determine several thermodynamic properties of fusion and sublimation of the chromophore N,N-dimethyl-4-nitroaniline. This compound is commonly used as a reference in studies focused on the non-linear optical (NLO) characteristics of chromophores. Using the Knudsen mass-loss effusion method, the vapor pressures of the crystalline phase of N,N-dimethyl-4-nitroaniline were measured over the temperature range between 341.1 K and 363.5 K. The standard molar enthalpy, entropy, and Gibbs energy of sublimation were calculated from the experimental results, at 298.15 K, and compared with those given in the literature. Differential scanning calorimetry was used to determine the temperature and enthalpy of fusion, as well as the isobaric heat capacities of the crystalline compound under study. Additionally, the enthalpic and entropic contributions to N,N-dimethyl-4-nitroaniline’s volatility were assessed, and it was determined that is greatly conditioned by enthalpic factors.

Estimation of the reduction potential of transition metal atoms in aqueous solutions

The reduction potentials of the M2+/M0 couples of transition metals Mn, Fe, Co, Ni, Cu, and Zn were calculated by subtracting from their standard electrode potentials in liquid water the standard molar Gibbs energy of formation of atoms in the gas phase ΔfG0(Mgas0) and the Gibbs energy of their hydration in solution ΔfG0(Maq0). The potentials are –2.503 V for Mn0, –2.454 V for Fe0, –2.333 V for Co0, –2.335 V for Ni0, –1.291 V for Cu0, and –1.335 V for Zn0. The disproportionation of ions in the intermediate oxidation state M+ with the formation of the M0 atom is thermodynamically favorable in the solution volume only for zinc.

Modeling aqueous association constants and mineral solubilities at subcritical and supercritical temperatures

The need for sustainable power generation has increased interest in the use of hydrothermal fluids for industrial applications. New high-enthalpy geothermal systems and biowaste-to-fuel processes are two relevant examples that employ supercritical fluids which require an in-depth understanding of complex chemical reactions occurring near the supercritical temperature of water (374 °C). As these processes operate in thermodynamic regimes that are not currently covered by a standard molar Gibbs energy of formation model, only empirical fits for single reaction systems are available which limit the use of multi-component phase equilibria calculations that are standard practice for less extreme environments. Here, we advance a standard molar Gibbs energy of formation model able to operate in these otherwise inaccessible thermodynamic states to include species needed for key mineral solubility systems and ion association reactions. This work extends a model based on molecular statistical thermodynamics (MST) into four new systems (Na3PO4-H2O, LiOH-H2O, KOH-H2O, and BaSO4-H2O) by extending the model to cover 10 new species. For each of these systems, model predictions were consistently within the experimental uncertainties for the new systems covered. A breakdown of MST contributions to the model revealed that electrostatic and hard sphere contributions were key to reproducing density dependencies of standard molar Gibbs energy of formation values around the critical point of water.

A comprehensive investigation on CdO-SnO2 system: Structure, thermal expansion and energetics

An extensive investigation into the thermochemical stability of two ternary oxides, ilmenite-type CdSnO3(s) and orthorhombic Cd2SnO4(s), in the Cd-Sn-O system was reported for the first time using high temperature oxide melt solution calorimetry in conjunction with differential scanning calorimetry and thermal relaxation calorimetry. The values of standard molar enthalpy of formation (∆fH298.15°), standard molar entropy (S298.15°), molar heat capacity and Debye temperature (θD) for ilmenite-type CdSnO3(s) and orthorhombic Cd2SnO4(s) were determined. Using the experimentally obtained thermochemical data, the standard molar Gibbs energy of formation of these compounds were derived and the corresponding expressions are given as follows:∆fGm°<CdSnO3>±1.3kJmol−1=−847.9+0.2781(T/K)(T:298.15−1000K)∆fGm°<Cd2SnO4>±3.6kJmol−1=−1138.1+0.3831(T/K)(T:298.15−1000K)Moreover, high temperature XRD experiments were conducted to evaluate their thermal expansion behaviour as well as for the in-situ identification of phase evolution resulting from decomposition of cadmium stannates.

Phase Transitions Equilibria of Five Dichlorinated Substituted Benzenes.

This work reports an experimental study aiming to determine the thermodynamic properties of five chlorinated compounds with environmental impact. The vapor pressures of the crystalline phases of three isomers of dichlorobenzoic acid (2,4-, 2,5-, and 2,6-) and 2,6-dichlorobenzonitrile were measured at several temperatures using the Knudsen effusion technique. Another technique (a static method based on capacitance diaphragm manometers) allowed the measurement of the vapor pressures of both the crystalline and liquid phases of 2,4-dichlorobenzonitrile between 303.0 and 380.0 K. This latter technique also enabled the measurement of sublimation vapor pressures of 2,6-dichlorobenzonitrile over a larger range interval of temperatures, T = 328.7 and 391.8 K. The standard molar enthalpy, entropy, and Gibbs energy of sublimation (for all the compounds studied) and vaporization (for 2,4-dichlorobenzonitrile) were derived, at reference temperatures, from the experimental vapor pressure results. The temperatures and enthalpies of fusion and the isobaric heat capacities of the five crystalline-substituted benzenes were determined using differential scanning calorimetry. The contributions of the three substituents (-COOH, -CN, and -Cl) to the sublimation thermodynamic properties of the compounds studied were discussed.

Identification of Nano-Metal Oxides That Can Be Synthesized by Precipitation-Calcination Method Reacting Their Chloride Solutions with NaOH Solution and Their Application for Carbon Dioxide Capture from Air-A Thermodynamic Analysis.

Several metal oxide nanoparticles (NPs) were already obtained by mixing NaOH solution with chloride solution of the corresponding metal to form metal hydroxide or oxide precipitates and wash-dry-calcine the latter. However, the complete list of metal oxide NPs is missing with which this technology works well. The aim of this study was to fill this knowledge gap and to provide a full list of possible metals for which this technology probably works well. Our methodology was chemical thermodynamics, analyzing solubilities of metal chlorides, metal oxides and metal hydroxides in water and also standard molar Gibbs energy changes accompanying the following: (i) the reaction between metal chlorides and NaOH; (ii) the dissociation reaction of metal hydroxides into metal oxide and water vapor and (iii) the reaction between metal oxides and gaseous carbon dioxide to form metal carbonates. The major result of this paper is that the following metal-oxide NPs can be produced by the above technology from the corresponding metal chlorides: Al2O3, BeO, CaO, CdO, CoO, CuO, FeO, Fe2O3, In2O3, La2O3, MgO, MnO, Nd2O3, NiO, Pr2O3, Sb2O3, Sm2O3, SnO, Y2O3 and ZnO. From the analysis of the literature, the following nine nano-oxides have been already obtained experimentally with this technology: CaO, CdO, Co3O4, CuO, Fe2O3, NiO, MgO, SnO2 and ZnO (note: Co3O4 and SnO2 were obtained under oxidizing conditions during calcination in air). Thus, it is predicted here that the following nano-oxides can be potentially synthesized with this technology in the future: Al2O3, BeO, In2O3, La2O3, MnO, Nd2O3, Pr2O3, Sb2O3, Sm2O3 and Y2O3. The secondary result is that among the above 20 nano-oxides, the following five nano-oxides are able to capture carbon dioxide from air at least down to 42 ppm residual CO2-content, i.e., decreasing the current level of 420 ppm of CO2 in the Earth's atmosphere at least tenfold: CaO, MnO, MgO, CdO, CoO. The tertiary result is that by mixing the AuCl3 solution with NaOH solution, Au nano-particles will precipitate without forming Au-oxide NPs. The results are significant for the synthesis of metal nano-oxide particles and for capturing carbon dioxide from air.

A combined experimental and computational thermodynamic study of fluoronitrophenol isomers

Combustion energies of the 5-fluoro-2-nitrophenol, 4-fluoro-2-nitrophenol, 3-fluoro-4-nitrophenol and 2-fluoro-4-nitrophenol isomers were obtained by means of a rotating-bomb combustion calorimeter. From these determinations, standard molar combustion enthalpies and standard molar formation enthalpies, at T = 298.15 K, in the crystalline state, were derived. The Knudsen mass-loss effusion technique was used to determine the standard molar enthalpies, entropies and Gibbs energies of sublimation, at T = 298.15 K, of the studied compounds. The standard molar enthalpies of sublimation of the four isomers were also measured by Calvet microcalorimetry. The gas-phase standard molar enthalpies of formation were derived from the experimental measurements, at T = 298.15 K, for the fluoronitrophenols studied.Additionally, the standard molar enthalpies of formation were estimated by means of computational methodology at the G3(MP2)//B3LYP level. The estimated values are in very good agreement with experimental data, giving us support to estimate the gas-phase enthalpies of formation of the remaining isomers whose values have not been determined experimentally.A simple group additivity scheme was successfully applied for prediction of molar enthalpies of formation.The computational study was also extended to the determination of OH bond dissociation enthalpies for all the isomers.

Taurine in several aqueous binary solvents: Solubility prediction, measurement, modeling, solvent effect, and thermodynamics

The crystallization of taurine in pure water results in a low yield. Introducing anti-solvents during the cooling crystallization process would increase the yield. Therefore, measuring and evaluating the solubility of taurine in different binary aqueous solvents is necessary. In this work, the qualitative trend of the solubility of taurine in the binary solvent systems of 1,2-propanediol-water, acetonitrile–water, and ethylene glycol–water was first predicted using Hansen Solubility Parameters (HSPs), and then experimentally determined using isothermal gravimetric method. The experimentally obtained solubility is correlated with the modified Apelblat model as a linear model, and NRTL, UNIQUAC, Wilson, and λh model as nonlinear models. The solubility of taurine in binary solvents is further analyzed using the KAT-LSER model to investigate the solvent effect on solubility. For all researched systems, the standard molar enthalpy and the standard molar Gibbs energy changes are computed and found to be positive, indicating the dissolution of taurine is an endothermic process.

Study on the volatility of four benzaldehydes

This work reports the experimental determination of relevant thermodynamic properties of four benzaldehydes. The vapor pressures of both crystalline and liquid phases (including supercooled liquid) of syringaldehyde, 3,4,5-trimethoxybenzaldehyde, 4-(dimethylamino)benzaldehyde and of the liquid phase of veratraldehyde were determined using a static method based on capacitance diaphragm manometers. Additionally, the sublimation vapor pressures of the four compounds were also determined at different temperatures, using the Knudsen mass-loss effusion method. The experimental results allowed accurate determination of the standard molar enthalpies, entropies and Gibbs energies of sublimation and of vaporization for the benzaldehydes studied, at reference temperatures, allowing phase diagram representations of the (p,T) results, in the neighborhood of the triple point of the four compounds. Their temperatures and molar enthalpies of fusion were determined using differential scanning calorimetry and were compared with the ones obtained indirectly through vapor pressure measurements. Using high-precision drop calorimetry, the standard isobaric molar heat capacities of the four crystalline benzaldehydes were determined at 298.15 K. The enthalpy of the intermolecular hydrogen bond OH…O in the crystalline phase of syringaldehyde was estimated.

Biophysical and molecular modeling evidences for the binding of sulfa molecules with hemoglobin

The molecular mechanism of the heme protein, hemoglobin (Hb) interaction with sulfa molecule, sulfadiazine (SDZ) has been investigated through spectroscopic, neutron scattering and molecular modeling techniques. Absorption and emission spectroscopic studies showed that SDZ molecules were bound to Hb protein, non-cooperatively. The binding affinityof SDZ-Hb complex at standard experimental condition was evaluated to be around (4.2 ± 0.07) ×104, M−1with 1:1 stoichiometry. Drug induced structural perturbation of the 3 D protein moiety was confirmed through circular dichroism (CD), synchronous fluorescence and small angle neutron scattering methods. From the temperature dependent spectrofluorometric studies, the negative standard molar Gibbs energy change suggested the spontaneity of the reaction. The negative enthalpy and positive entropy change(s) indicated towards the involvement of both electrostatic and hydrophobic forces during the association process. Salt dependent fluorescence study revealed major contributions from non-poly-electrolytic forces. Molecular modeling studies determined the probable binding sites, types of interaction involved and the conformational alteration of the compactness of the Hb structure upon interaction with SDZ molecule. Overall, the study provides detailed insights into the binding mechanism of SDZ antibiotics to Hb protein. Communicated by Ramaswamy H. Sarma

Sublimation Study of Six 5-Substituted-1,10-Phenanthrolines by Knudsen Effusion Mass Loss and Solution Calorimetry.

The vapor pressures of six solid 5-X-1,10-phenanthrolines (where X = Cl, CH3, CN, OCH3, NH2, NO2) were determined in suitable temperature ranges by Knudsen Effusion Mass Loss (KEML). From the temperature dependencies of vapor pressure, the molar sublimation enthalpies, ΔcrgHm0(⟨T⟩), were calculated at the corresponding average ⟨T⟩ of the explored temperature ranges. Since to the best of our knowledge no thermochemical data seem to be available in the literature regarding these compounds, the ΔcrgHm0(⟨T⟩) values obtained by KEML experiments were adjusted to 298.15 K using a well known empirical procedure reported in the literature. The standard (p0 = 0.1 MPa) molar sublimation enthalpies, ΔcrgHm0(298.15 K), were compared with those determined using a recently proposed solution calorimetry approach, which was validated using a remarkable amount of thermochemical data of molecular compounds. For this purpose, solution enthalpies at infinite dilution of the studied 5-chloro and 5-methylphenantrolines in benzene were measured at 298.15 K. Good agreement was found between the values derived by the two different approaches, and final mean values of ΔcrgHm0(298.15 K) were recommended. Finally, the standard molar entropies and Gibbs energies of sublimation were also derived at T = 298.15 K. The volatilities of the six compounds were found to vary over a range of three orders of magnitude in the explored temperature range. The large difference in volatility was analyzed in the light of enthalpies and entropies of sublimation. The latter was tentatively put in relation to the rotational contribution of the substituent group on the phenanthroline unit.

Thermodynamic Stability of Fenclorim and Clopyralid.

The present work reports an experimental thermodynamic study of two nitrogen heterocyclic organic compounds, fenclorim and clopyralid, that have been used as herbicides. The sublimation vapor pressures of fenclorim (4,6-dichloro-2-phenylpyrimidine) and of clopyralid (3,6-dichloro-2-pyridinecarboxylic acid) were measured, at different temperatures, using a Knudsen mass-loss effusion technique. The vapor pressures of both crystalline and liquid (including supercooled liquid) phases of fenclorim were also determined using a static method based on capacitance diaphragm manometers. The experimental results enabled accurate determination of the standard molar enthalpies, entropies and Gibbs energies of sublimation for both compounds and of vaporization for fenclorim, allowing a phase diagram representation of the (p,T) results, in the neighborhood of the triple point of this compound. The temperatures and molar enthalpies of fusion of the two compounds studied were determined using differential scanning calorimetry. The standard isobaric molar heat capacities of the two crystalline compounds were determined at 298.15 K, using drop calorimetry. The gas phase thermodynamic properties of the two compounds were estimated through ab initio calculations, at the G3(MP2)//B3LYP level, and their thermodynamic stability was evaluated in the gaseous and crystalline phases, considering the calculated values of the standard Gibbs energies of formation, at 298.15 K. All these data, together with other physical and chemical properties, will be useful to predict the mobility and environmental distribution of these two compounds.

Experimental and Theoretical Investigation on the Thermochemistry of 3-Methyl-2-benzoxazolinone and 6-Nitro-2-benzoxazolinone.

The determination of the reliable thermodynamic properties of 2-benzoxazolinone derivatives is the main goal of this work. Some correlations are established between the energetic properties determined and the structural characteristics of the title compounds, and the reactivity of this class of compounds is also evaluated. Static-bomb combustion calorimetry and high-temperature Calvet microcalorimetry were used to determine, respectively, the standard molar enthalpies of formation in the solid state and the standard molar enthalpies of sublimation, both at T = 298.15 K. Using the results obtained for each compound, the respective gas-phase standard molar enthalpy of formation was derived. High-level quantum chemical calculations were performed to estimate the same property and the results evidence good accordance. Moreover, the gas-phase relative thermodynamic stability of 2-benzoxazolinone derivatives was also evaluated using the respective gas-phase standard molar Gibbs energy of formation. In addition, the relationship between the energetic and structural characteristics of the benzoxazolinones is presented, evidencing the enthalpic increments associated with the presence of a methyl and a nitro groups in the molecule, and this effect is compared with similar ones in other structurally related compounds.

Calorimetric investigations on lithium based ceramics

Lithium based ceramics namely lithium titanate, lithium zirconate, and lithium aluminate are proposed materials for tritium breeding in a D-T based fusion reactor. Thermodynamic stability of these materials is important for their use under extreme conditions. In this paper, the thermodynamic stability analysis of lithium titanate, lithium zirconate, and lithium aluminate ceramics is reported. The standard molar enthalpy of formation Li2TiO3(s), Li2ZrO3(s), and LiAlO2(s) compounds have been determined for the first time employing an isoperibol room temperature solution calorimeter. The standard molar enthalpy of formation of Li2TiO3(s), Li2ZrO3(s), and LiAlO2(s) at 298.15 K are found to be – (1632.4 ± 9.7), – (1776.7 ± 6.7), and – (1188.2 ± 5.2) kJ·mol−1, respectively. The isobaric heat capacity of these compounds has been measured over the temperature range 300 K to 770 K employing Differential Scanning Calorimeter (DSC). Using the above experimental results the standard molar Gibbs energy of formation and other thermodynamic functions for these compounds have been derived and compared with the literature values.

Thermodynamic properties over two phase region of Gd–Al system: Knudsen effusion mass spectrometric study

Vaporisation behaviour of <GdAl2(cr)+GdAl(cr)> two phase region of Gd-Al system was investigated by employing Knudsen Effusion Mass Spectrometry (KEMS) in the temperature range 1158–1323 K. Al(g) was the neutral species observed in the equilibrium vapour and partial pressure-Temperature (p-T) relation over this two phase region was deduced as log (pAl/Pa) = (−20282 ± 260)/T + (13.06 ± 0.21). The standard enthalpy change, at 298.15 K, of the reaction (GdAl2(cr) = GdAl(cr) + Al(g)) was evaluated by second law method. ΔfHm,GdAlcr,298.15Ko was deduced to be − 83.8 ± 11.8 kJ mol−1. The expression for standard molar Gibbs energy of formation of GdAl(s) derived is given as, ΔfGm,GdAlcr,To = (−101.7 ± 6.6) + (0.00667 ± 0.00560)T kJ mol−1. These data are being reported for the first time.