Thermodynamic Optimization and Calculation of the LaCl3-CaCl2 System

A thermodynamic evaluation of the binary LaCl3-CaCl2 system was carried out by using CALPHAD method. The Modified Quasihelical Model was defined in order to describe the Gibbs energies of the liquid phases, and the model parameters were optimized from the experimental thermodynamic and phase diagram data. The phase diagram and the enthalpy of mixing of LaCl3-CaCl2 liquid were calculated. For LaCl3-CaCl2, a calculated eutectic point was observed at 924.82 K, 34.8 mol. % LaCl3. The calculated enthalpy of mixing is exothermic, the minimum was found at approximately 30 mol. % LaCl3. The thermodynamic properties and the phase diagram calculated from the optimized parameters agree well with the experimental data.

Phase Stability and Mechanical Properties of Al8Fe4RE via First-Principle Calculations

We report on the phase stability, elastic, electronic, and lattice dynamic properties of 17 Al8Fe4RE (RE = Sc, Y, La–Lu) intermetallic compounds (IMCs) using first-principle calculations. The calculated lattice constants coincided with the experimental results. The calculated enthalpy formation indicated that all the 17 IMCs are stable. The elastic constants and various moduli indicated that Al8Fe4RE can be used as a strengthening phase due to its high Young’s modulus and shear modulus. The 3D surfaces of Young’s modulus for Al8Fe4RE showed anisotropic behavior, and the values of hardness for the IMCs were high (about 14 GPa). The phonon spectra showed that only Al8Fe4Y had a soft mode, which means the other IMCs are all dynamically stable.

Temperature Effects on Thermodynamic Parameters and Solubility of Curcumin O/W Nanodispersions Using Different Thermodynamic Models

Solubility of curcumin at different temperatures is of great importance in subcritical water extraction systems. We newly developed an approach for the solid–liquid equilibrium under subcritical condition to determine the solubility of curcumin. The experimental results were correlated successfully with thermodynamics models such as Van’t Hoff, modified Apelblat equation, Wilson, non-random two-liquid (NRTL) and λh equation and the interaction parameters’ values of curcumin-water were acquired. Good agreement between the experimental and calculated values with λh equation was observed at different temperatures (373.15–433.15 °K) at 1.5 bar. The obtained value of the relative average deviation was 2.29 × 10–5. The molar enthalpy (ΔH0), entropy (ΔS0), Gibbs energy (ΔG0) and their relative fraction of the total process were calculated. The calculated enthalpy with the Van’t Hoff equation (25.32 kJ/mol) agreed well with the differential scanning calorimetry analysis data (26.15 kJ/mol).

A Thermochemical Parameters and Theoretical Study of the Chlorinated Compounds of Thiophene

This contribution sets out to compute thermochemical and geometrical parameters of the complete series of chlorinated isomers of thiophene based on the accurate chemistry model of CBS-QB3. Herein, we compute standard entropies, standard enthalpies of formation, standard Gibbs free energies of formation, and heat capacities. Our calculated enthalpy values agree with available limited experimental values. The DFT-based reactivity descriptors were used to elucidate the site selectivity for the chlorination sequence of thiophene. The relative preference for chlorination was found to be in accord with the thermodynamic stability trends inferred based on the H scale. Calculated Fukui indices predict a chlorination sequence to ensue as follows: 2-chloro → 2,5-dichloro → 2,3,5-trichloro → 2,3,4,5-tetrachlorothiophene.

Enthalpy and Free Energy of Formation of Diamido and Monoamido Phosphoric Acid

Diamidophosphate has been identified as a possible prebiotic compound used in the precursor membranes of the first ‘life’. Compounds such as these will be helpful in developing novel biomimetic approaches in synthetic chemistry. Thermochemical data for this type of compounds are not available. Hess’ law and estimates from calorimetric measurements used by Wakefield in the 1970s for other amido phosphates have been used to estimate the thermochemical values for the diamido and monoamido-phosphoric acid. Enthalpy of formation at 298.15 oC is calculated as – 821.9 kJ/mol and the free energy of formation calculated as -813.5 kJ/mol for the diamidophosphoric acid. The calculated enthalpy of formation of monoamidic phosphoric acid is -1117.1 kJ/mol and its free energy of formation is - -1105 kJ/mol.

Application of spectral graph theory on the enthalpy change of formation of acyclic saturated ketones

The dependence of the enthalpy change of formation of saturated acyclic ketones on molecular structure (the number of carbon atoms, the position of the carbonyl group, and the branching of the molecules) was investigated. For this purpose, a simple computational model, the parameterization of which is based on spectral graph theory, was developed. It was found that the major part of the enthalpy change of formation is determined by molecular size, whereas the fine structure of the enthalpy change of formation is determined by the branching of the molecule and the position of the carbonyl group. The developed model proved itself very useful for such investigations. The model is simple and practical, and the agreement between the experimental and calculated enthalpy changes of formation is very good, with an average relative error of 0.7%.

Evaluation of selected sewage sludge gasification technological parameters

Evaluation of selected sewage sludge gasification technological parameters was shown in this paper. Degree of carbon conducted in combustible substance and syngas efficiency (technological readiness coefficient) in accordance with equations were calculated. Enthalpy of individual compounds formation and energy balance were calculated in accordance with rule of Hess.

Assessing density functionals for the prediction of thermochemistry of Ti–O–Cl species

Titanium dioxide (TiO2) nanoparticles are widely used in contaminant remediation, photocatalysis and solar cell manufacturing. The low-cost production of TiO2 nanoparticles via the combustion of titanium tetrachloride (TiCl4) in oxygen is thus an important industrial process. To accurately model the flame synthesis of TiO2 nanoparticles, reliable thermodynamic data of Ti–O–Cl species are indispensable but often unavailable. We therefore carried out benchmark calculations, using the left-eigenstate completely renormalized singles, doubles and perturbative triples (CR-CC(2,3), aka CR-CCL) method with the cc-pVTZ basis set, to obtain the equilibrium structures and vibrational frequencies of selected Ti–O–Cl species; we then performed single-point CCSD(T)/aug-cc-pVLZ ([Formula: see text]) calculations to extrapolate the CCSD(T)/CBS energies. After analyzing the experimental and calculated enthalpy of selected Ti–O–Cl species, the standard enthalpy of formation of the TiOCl2 molecule is determined to be [Formula: see text]600.5[Formula: see text]kJ/mol at 298[Formula: see text]K. The standard enthalpy of all other Ti–O–Cl species are determined accordingly. Finally, we assessed the accuracy of 42 popular density functionals for the Ti–O–Cl species. Among these assessed functionals, the B98 functional, tightly followed by B97-1 and B3LYP, exhibits the best overall performance in the prediction of the thermochemistry of the Ti–O–Cl species.

First-principles investigation of novel polymorphs of Mg2C

The calculated enthalpy curves as a function of pressure for novel Mg2C polymorphs relative to the cubic phase.