Gibbs Energy Of Formation Research Articles

THERMODYNAMIC PROPERTIES OF MELTS OF THE Eu-Ge AND Al-Eu-Ge SYSTEMS

The thermochemical properties of the melts of the Eu–Ge and Al–Eu–Ge systems at 1200–1400 K were determined for the first time by the method of calorimetry. It was established that the minimum value of the enthalpy of mixing of the melts of the Eu–Ge system is -49.1±4.4 for an alloy with xGe = 0.45, ΔH̅∞Eu = -145.7 ± 22.3; ΔH̅∞Ge = −166.8 ± 19.8 kJ/mole at T = 1400 K. The curve of enthalpy of mixing of the studied melts is almost symmetrical, which correlates with the behavior of alloys of this and similar systems in the solid state. The obtained data make it possible to consider the entire spectrum of Ge–Ln systems (lanthanides) and to explain what determines the thermodynamic properties of melts of the Eu–Ge system, in particular, and Ge–Ln, in general. Using the defined thermochemical properties of melts and the known phase diagram of the Eu–Ge system, the Gibbs energy, enthalpy, and entropy of formation of melts, associates in melts, and compounds of the Eu–Ge system were optimized and calculated according to the ideal associated solution (IAS) model. The calculated activities of the components in the melts of this system show large negative deviations from ideal solutions. Using the obtained thermochemical data, the temperatureconcentration dependences of Gibbs energies, enthalpies and entropies of the formation of melts and intermetallics, and the coordinates of the liquidus curve of the state diagram of the Eu–Ge system were also calculated according to the IAS model. The calculated liquidus curve and the one known from experimental data do not fully agree with each other. Comparison of ΔHmin of melts with enthalpies of formation, temperatures of melting Ln5Ge3 compounds, and differences in molar volumes and electronegativities of components of Ge–Ln systems depending on the serial number of Ln showed that they are correlated with each other, and ΔHmin of melts and Ln5Ge3 compounds differ little from each other. In addition, all dependences, with the exception of Δχ, are symbiotic and monotonic, with the exception of compounds and melts of binary Ge–Eu(Yb) systems. It was established that the integral and partial enthalpies of mixing of melts of radial sections with xEu/xGe = 0.85/0.15 and 0.3/0.7 of the Al–Eu–Ge system at 1400 K are exothermic. When aluminum is added to GexEu1-x melts, the thermal effect of its dissolution in the first section initially decreases, and then it increases, and in the second – it increases. This is due to the breaking of strong Eu–Ge bonds and the formation of lower energy bonds between Al and Eu. The thermodynamic properties of melts of the Al–Eu–Ge system were calculated using the “geometric” models and the Redlich-Kister-Mujianu model based on similar data for limiting binary systems. It is shown that those calculated according to the Redlich-Kister-Mujianu model with the ternary contribution L = -220 kJ/mole are in the best agreement with the experimental data. Therefore, the same model was used to calculate other thermodynamic properties of melts of the Al–Eu–Ge system.

Eris - another brick in the wall: Empirical formulas, molar masses, biosynthesis reactions, enthalpy, entropy and Gibbs energy of Omicron EG.5 Eris and EG.5.1 variants of SARS-CoV-2

Since 2019, when it appeared in Wuhan, in the wild type form later labeled Hu-1, SARS-CoV-2 mutated dozens of times and evolved towards increase in infectivity and decrease or maintenance of constant pathogenicity through dozens of variants. The last of them are Omicron EG.5 and EG.5.1. Until 2019, an empirical formula was known only for the poliovirus. Until now empirical formulas and thermodynamic properties were reported for all variants of SARS-CoV-2 and some other viruses. Also, models were developed that describe the biothermodynamic background of SARS-CoV-2 interaction with its human host. With every new mutation in SARS-CoV-2, the question is raised about the further evolution of the virus. This paper reports for the first time empirical formulas and molar masses of Omicron EG.5 and EG.5.1 variants, as well as thermodynamic properties (enthalpy, entropy and Gibbs energy) of formation and biosynthesis. Moreover, the driving force of virus multiplication was analyzed, as well as multiplication rate and pathogenicity of Omicron EG.5 and EG.5.1.

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.

Interpretation of experimental findings on the structure of glass in the CaO–MoO3–P2O5 system using a thermodynamic model including oxidation–reduction equilibria

AbstractThis work extends the thermodynamic model of associated solutions used in the past to describe the structure and properties of glasses to the area of complex multicomponent glasses with polyvalent elements, where it has not been applied until now either due to the absence of Gibbs energies of formation of the necessary compounds or due to oxidation–reduction equilibrium in the presence of a gas phase containing oxygen. While the fitting of unknown Gibbs energies based on experimental data has already been applied to some extent in our previous work, the implementation of redox is, to the best of our knowledge, new. Four concentration series were taken from the published data from the glass-forming ternary system CaO–MoO3−P2O5: A) xMoO3−(0.5–0.75x)CaO−(0.5–0.25x)P2O5; B) xMoO3−(0.5–0.875x)CaO−(0.5–0.125x)P2O5; C) xMoO3−(0.5−x)CaO−0.5P2O5; M) xMoO3−(1−x)P2O, for which the distributions of Qn units were also published (Q denotes the PO4 tetrahedral unit with n bridging oxygens) by the 31P MAS NMR method and the Mo[V]/ΣMo fraction by the ESR method [Černošek et al. (J Solid State Chem 303:122522, 2021); Holubová et al., (J Non-Cryst Solids 607:122222, 2023)]. The following compounds were considered in the TD model: P2O5, CaO, Mo[VI]O3, Ca(PO3)2, Ca2P2O7, (Mo[VI]O2)(PO3)2, (Mo[VI]O2)2(P2O7), (Mo[VI]O2)3(PO4)2, (Mo[V]O)2(PO3)2(P2O7), (Mo[V]O)PO4. All except the hypothetical compound (Mo[VI]O2)3(PO4)2 exist, and their structure is known. Binary phosphate compounds with molybdenum lack Gibbs energies of formation. Therefore, one of the series, namely A, was used to determine these energies by nonlinear regression with the help of a genetic algorithm, without/with redox, and then the distribution of Qn units and the fraction of Mo[V]/ΣMo was predicted for the remaining series. It was found that the distribution of Qn units can be described by the TD model with redox only. During the reduction of molybdenum, the distribution of Qn unit’s changes, and thus also the connectivity of the phosphate network, for example, according to the reactions: (MoO2)2(P2O7)—> 2(MoO)PO4 + 1/2O2, in which Q1—> Q0 and 2(MoO2)(PO3)2—> (MoO)2(PO3)2(P2O7) + 1/2O2 in which Q2—> Q1. Despite the fact that the TD model with redox gives excellent agreement in the case of the Qn distribution, the agreement with the ESR measurements of the Mo[V]/ΣMo ratio is not good. The TD model predicts significantly more pentavalent molybdenum in the glass.

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.

Heat capacity and thermodynamic functions of sodium rare earth ternary fluorides

Sodium rare earth ternary fluorides, NaREF4 (RE = rare earth), are intermediate phases for rare earth element extraction and have important technological applications. To better understand their physical properties, energetics, and stability, we measured the heat capacity of three β-structured NaREF4 compounds, NaNdF4, NaYbF4, and NaYF4, from 1.8 to 300 K. Our measurements show an upturn in the low-temperature heat capacity of each sample which we attribute to the splitting of degenerate nuclear magnetic states. We provide calculations of the effective field causing the splitting for each sample. We also report standard entropy, enthalpy, and Gibbs energy increments at selected temperatures from 0 to 300 K. The enthalpy of formation of the three NaREF4 from the elements (ΔΗ°f,el) and the fluorides (ΔΗ°f,fl) were measured previously, enabling us to calculate the Gibbs energies of formation from the elements and fluorides. The Gibbs energy of NaREF4 relative to the elements at 298.15 K was calculated to be −1483.5 kJ∙mol−1, −1502.2 kJ∙mol−1, and −1497.8 kJ∙mol−1 with an estimated standard uncertainty of 1% for NaNdF4, NaYF4, and NaYbF4 respectively. The Gibbs energy of NaREF4 relative to the fluorides at 298.15 K was calculated to be –5.39 kJ∙mol−1, −18.12 kJ∙mol−1, and −19.1 kJ∙mol−1 with an estimated standard uncertainty of 1% for NaNdF4, NaYF4, and NaYbF4 respectively. Each sample’s negative Gibbs energy relative to both the elements and the fluorides indicates stability relative to these compounds. The results confirm that these three NaREF4 compounds are thermodynamically stable relative to the elements and binary fluorides.

Experimental Determination of the Standard Gibbs Energy of Formation of Fe3–xVxO4 at 1473 K

In the present study, an approach of determining the standard Gibbs energy of formation of Fe3–xVxO4 was proposed firstly, then the standard Gibbs energies of formation of a variety of Fe3–xVxO4 were determined experimentally, and finally, a calculating model of the standard Gibbs energy of formation of Fe3–xVxO4 was established. The detailed results are as follows: (1) the standard Gibbs energy of formation of Fe3–xVxO4 can be determined successfully by two steps; the first is to measure the chemical potential of Fe in Fe3–xVxO4 under fixed oxygen partial pressure, the second is to derive the chemical potential of V in Fe3–xVxO4 by Gibbs–Duhem relation; (2) the standard Gibbs energies of formation of Fe3–xVxO4 are mainly decided by the Fe/V molar ratio, and almost not influenced by the oxygen partial pressure in the range from 2.39 × 10−12 to 3.83 × 10−11 atm; (3) in this oxygen partial pressure range, the standard Gibbs energies of formation of Fe3–xVxO4 can be calculated satisfactorily by the following model: ΔfGFe3−xVxO4θJ/mol=1−x/2ΔfGFe3O4θ+x/2ΔfGFeV2O4θ+1−x/2RTln1−x/2+x/2RTlnx/2−168627.481−x/2x/2.

Reactivity of [AuF3(SIMes)] - Pathway to Unprecedented Structural Motifs.

We report on a comprehensive reactivity study starting from [AuF3(SIMes)] to synthesize different motifs of monomeric gold(III) fluorides. A plethora of different ligands has been introduced in a mono-substitution yielding trans-[AuF2X(SIMes)] including alkynido, cyanido, azido, and a set of perfluoroalkoxido complexes. The latter were better accomplished via use of perfluorinated carbonyl-bearing molecules, which is unprecedented in gold chemistry. In case of the cyanide and azide, triple substitution gave rise to the corresponding [AuX3(SIMes)] complexes. Comparison of the chemical shift of the carbene carbon atom in the 13C{1H} NMR spectrum, the calculated SIMes affinity and the Au-C bond length in the solid state with related literature-known complexes yields a classification of trans-influences for a variety of ligands attached to the gold center. Therein, the mixed fluorido perfluoroalkoxido complexes have a similar SIMes affinity to AuF3 with a very low Gibbs energy of formation when using the perfluoro carbonyl route.

Thermodynamic properties of benzotriazole derivatives: An experimental and computational study

A thermochemical study of 5-methyl-1H-benzotriazole and 5,6-dimethyl-1H-benzotriazole was carried out experimentally using calorimetric techniques and an effusion method. Parallel to that, a computational methodology was also applied. The massic energies of combustion and the enthalpies of sublimation were determined from static bomb combustion calorimetry and Knudsen mass-loss effusion method and/or high-temperature Calvet microcalorimetry, respectively. From these experimental data, the standard molar enthalpies of formation of the two benzotriazoles in the gaseous phase were derived. Additionally, the gas-phase enthalpies of formation of these benzotriazoles and other two methylated derivatives were calculated using the G3(MP2)//B3LYP level of theory. The data obtained allowed the study of the energetic effects associated with the presence of a methyl group in the benzotriazole structure and their comparison with identical effects in homocyclic molecules, namely benzene and naphthalene. The Gibbs energies of formation of the compounds in the crystalline and gaseous phases were also determined to assess their thermodynamic stability.

SODALITE: SPECTROSCOPIC AND THERMOCHEMICAL INVESTIGATIONS

Two sodalite samples (sample I is Na8Al6Si6O24Cl2⋅0.4H2O from the Kovdor alkaline ultramafic massif with carbonatites in the Murmansk region, Russia, and sample II is Na8Al6Si6O24Cl2⋅0.2H2O from the Bayan Kol nepheline syenite and miaskite massif in the Republic of Tyva) were studied by thermal and electron-microprobe analyses, powder X-ray diffraction, photoluminescence, and by IR, Raman, and ESR spectroscopy. Solution melt calorimetry was applied to determine the enthalpy of formation from elements for water-bearing sodalite samples: −13536 ± 10 (I) and −13503 ± 19 (II) kJ/mol. The enthalpy of formation of sodalite of the theoretical composition Na8Al6Si6O24Cl2 was evaluated at ΔfH0(298.15 K) = −13446 ± 11 kJ/mol. The data obtained on the enthalpy of formation of sodalite and literature data on its S0(298.15 K) were used to calculate the standard Gibbs energies of formation of anhydrous and of water-bearing sodalite.

Thermodynamic Properties of Coquimbite and Aluminocoquimbite

Coquimbite AlFe3+3[SO4]6(H2O)12⋅6H2O (sample from the Javier Mine, Peru) has been studied by thermal and electron microprobe analysis, X-ray powder diffraction, Raman spectroscopy, and Mössbauer spectroscopy. The enthalpy of formation of the coquimbite from elements ∆fH0(298.15 K) = −11 118 ± 40 kJ/mol was determined by the method of solution calorimetry in melt of lead borate 2PbO∙B2O3 on a Setaram (France) Calvet microcalorimeter. The value of its absolute entropy S0(298.15 K) = 1248.3 ± 3.0 J/(mol K) was estimated, the entropy of formation ∆fS0(298.15 K) = − 5714.0 ±3.0 J/mol K), and the Gibbs energy of formation from elements ∆fG0(298.15 K) = −9411 ± 40 kJ/mol were calculated. The values of the enthalpy and Gibbs energy of formation of aluminocoquimbite Al2Fe3+2[SO4]6(H2O)12⋅6H2O from elements were estimated at −11 540 ± 29 and −9830 ± 29 kJ/mol, respectively.

Thermodynamic properties on the homologous temperature scale from direct upsampling: Understanding electron-vibration coupling and thermal vacancies in bcc refractory metals

We have calculated thermodynamic properties of four bcc refractory elements---V, Ta, Mo, and W---up to the melting point with full density-functional-theory accuracy, using the recently developed direct-upsampling method [J. H. Jung et al., npj Comput. Mater. 9, 3 (2023)]. The direct-upsampling methodology takes full account of explicit anharmonic vibrations and electron-vibration coupling very efficiently using machine-learning potentials. We have thus been able to compute highly converged free-energy surfaces for the PBE exchange-correlation functional, from which accurate temperature dependencies of various thermodynamic properties such as the heat capacity, thermal expansion coefficient, and bulk modulus are accessible. For all four elements, the electronic contribution is large, including a strong coupling with the thermal vibrations. The atomic forces in W are even affected by the temperature-consistent Fermi broadening, which alters the free energy by around 3 meV/atom at the melting point. Trends within group V and group VI refractory elements are observed and explained by qualitative differences in the electronic density of states. We also provide an estimate of the Gibbs energies of vacancy formation and the vacancy contribution to the thermodynamics. Lastly and most importantly, our results are analyzed in terms of the homologous temperature scale relative to theoretically predicted melting points (for the PBE functional). The homologous temperature dependencies show a remarkable agreement with experiments and reveal the predictive power of self-consistently determined ab initio thermodynamic properties.

High temperature thermo-chemical properties evolution of NaF-NiF2 system

In Molten Salt Reactor (MSR), Ni based alloys are more suitable for handling of the molten fluoride salts because of formation of corrosive resistive NiF2 layer over the structural material components. A ternary mixture of LiF-NaF-KF (FLiNaK) can be used as coolant salt for transfer of heat from the reactor core. NiF2 layer of the Ni-based alloys shows reactivity towards NaF at reactor operating temperature. NaNiF3(s) is the single complex ternary compound in the NaF-NiF2 system. The compound has been synthesized and characterized. The thermodynamic stability of NaNiF3(s) has been experimentally measured in terms of Gibbs energy of formation using Galvanic cell technique and its measured ΔfG°m(T) was obtained as.ΔfG°m(T) [NaNiF3(s)]/kJ mol−1 = (−1242.9 ± 2.3) + (0.2312 ± 0.0039) × (T/K).The heat capcity and high temperature enthalpy increment was also experimentally measured using DSC and high temperature calorimetric technique, respectively and the values were obtained as.Cp,m(J·mol−1·K−1) = 117.74 + 0.0498 × T −1.07351 × 106/T2(303 ≤ T/K ≤ 828).(HT-H298)(J·mol−1) = −40270.6 + 120.4 × T + 0.0234 × T2+717669.7/T.Effect of oxygen impurity over the stability of the compound has been investigated by calculating the chemical potential diagram of Na-Ni-F-O system. The binary phase diagram of NaF-NiF2 system and the ternary phase diagram of Na-Ni-F2 system has been calculated based on Gibbs energy minimization technique using the experimental thermodynamic data.

Thermodynamics of the Sodium-Iron-Phosphate-Water System Under Hydrothermal Conditions II: The Solubility and Gibbs Energy of Formation of Maricite (NaFeIIPO4) from 220 to 300 °C

Thermodynamics of the Sodium-Iron-Phosphate-Water System Under Hydrothermal Conditions II: The Solubility and Gibbs Energy of Formation of Maricite (NaFeIIPO4) from 220 to 300 °C

Direct synthesis of CH3OH from CO2 hydrogenation over Ni5Ga3/SiO2 catalysts

Ni5Ga3/SiO2 catalysts were synthesized by co-precipitation method. The catalytic components of Ni5Ga3/SiO2 were gallium species, which was confirmed by X–ray photoelectron spectroscopy (XPS) measurements. Notably, the fine structures of the metal atoms in Ni5Ga3/SiO2 were obtained using X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy. The optimal catalytic performances of Ni5Ga3/SiO2 (CO2 conversion = 100.0 %, CH3OH selectivity = 84.7 %, CH3OH yield = 84.7 %) were obtained at 250 °C. At 250 °C, the low activation energies and Gibbs energies of formation for CH3OH (Ea = 42.604 kJ mol−1, hG523E= 3.26 kJ mol−1) revealed that their spontaneities were significantly enhanced by catalysts. Cost assessment of a 10-TPD (ton per day) waste gas utility process for a petrochemical refinery plant shown that the overall income was USD$88,932/d with a payback of 1.86 years. This work provides a serial route to produce high-value-added chemicals in large scale from industrial emitted CO2 and syngas utility.

Measurements and modelling of FeCO3 solubility in water relevant to corrosion and CO2 mineralization

FeCO3 is present as a CO2 corrosion product in many industrial processes and takes part in the natural CO2 mineralization process. This work presents the solid-liquid equilibrium of the system FeCO3-H2O at 5-120 °C. The FeCO3 solubility showed little temperature dependence. However, temperature affected kinetics as the rate constants for FeCO3 dissolution increased with temperature. The activation energy of FeCO3 dissolution in water was determined to 1.55 kJ mol-1. Gibbs energy of formation was found to be -653.27 kJ mol-1 and the enthalpy of formation for FeCO3 was -710.01 kJ mol-1 using the Extended UNIQUAC model. Extended UNIQUAC could predict the experimental solubility data of FeCO3 in water within an average absolute relative deviation of 0.08. The data obtained in this study creates the basis of reducing the consequences of CO2 corrosion and increasing knowledge of the CO2 mineralization process.

Thermodynamic Properties of Sm3Cl7 Chloride in the Standard State at 298.15 K

The EMF in the 473–728 K range of temperatures is measured for solid-phase galvanic cells (‒) Sm|SmCl2||BaCl2||SmCl3|Sm3Cl7 (+), (–) Sm|SmCl2||BaCl2||Sm3Cl7|SmCl2 (+), (–) SmCl2|Sm3Cl7|| BaCl2||SmCl3|Sm3Cl7 (+), and (–) Mg|MgCl2||BaCl2||SmCl3|Sm3Cl7 (+). Experimental data are processed according to the second law of thermodynamics using literature values of thermodynamic characteristics of the components of the EMF-forming reaction: Sm, Mg, SmCl2, SmCl3, and MgCl2. Values of the standard Gibbs energy of formation, the standard enthalpy of formation, and the standard entropy of chloride Sm3Cl7 at a temperature of 298.15 K are obtained by averaging data on four galvanic cells.

Thermodynamic Studies on Sr5Nb4O15

The SrO–Nb2O5 system, especially Sr5Nb4O15 compound is of interest for their use as an electroceramics. In this work, Sr5Nb4O15 compound was synthesized by solid-state reaction and characterised by XRD. Thermodynamic properties like heat capacity, enthalpy of formation and Gibbs energy of formation of Sr5Nb4O15 have been measured. The standard molar enthalpy of formation of Sr5Nb4O15(s) was determined using an oxide melt solution high temperature calorimeter. Based on these experimental data, a self-consistent thermodynamic function of this compound was also generated. This thermodynamic data is essential for the optimization of synthesis conditions for materials and for the evaluation of their stability under appropriate technological operating conditions.

Gibbs Energy of Formation of U2Mo and U2Ti Determined by EMF Measurements in LiCl-KCl-UCl3 Melt

Gibbs energy of formation of U2Mo and U2Ti intermetallic phases in U-Mo and U-Ti binary systems, respectively was determined employing electromotive force measurements in LiCl-KCl-UCl3 melt. U-Mo and U-Ti alloys corresponding to two-phase field U2Mo+Mo and U2Ti+Ti were prepared by vacuum arc-melting and characterized by X-ray diffraction. Single phase U2Mo and U2Ti intermetallics were also prepared and characterized to support the indexing of Bragg peaks in two-phase alloys. Temperature dependence of ΔfGU2Mo∘ and ΔfGU2Ti∘ were, respectively expressed asΔfGU2Mo∘(kJ/mol-atom)=(−144.9±1.5)+(63±3)×10−3T(K)ΔfGU2Ti∘(kJ/mol-atom)=(−116.2±1.7)+(60±3)×10−3T(K)Since there were no other experimental data available that could be used to compare present correlations, results by DFT calculations from earlier works were compared and discussed. LiCl-KCl-UCl3 melt was analyzed after completion of electromotive force runs by cyclic voltammetry and no identifiable redox features due to Mo or Ti species in melt were observed. This suggested that both alloys remained stable in the melt even after 100 h duration of electromotive force runs and there was no chemical leaching of Mo or Ti from the alloy.

Mineralogical characteristics of sulfuric acid formation during bacterial oxidation of flotation concentrate

The article presents the results of a study on the formation of sulfuric acid in the process of bacterial oxidation of sulfide ore flotation concentrate. The results are estimated from the point of view of the thermodynamics of the course of some bacterial oxidation reactions, calculating the standard enthalpies of formation - (ΔН0298), entropy (ΔS0298) and Gibbs energy of formation (ΔG0298) of some reactions and substances at 298 K. Conclusions about the formation of sulfuric acid based on X-ray phase and electron scanning microscope results of changes in mineralogical and elemental composition in the processes of bacterial oxidation of flotation concentrate are substantiated.