Standard enthalpy of formation of La2CoO4(cr)

The enthalpies of reactions of La₂CoO₄(cr) and CoCl₂(cr) with hydrochloric acid were measured with an isothermal-jacket calorimeter. The results obtained and the available literature data were used to calculate the standard enthalpy of formation of La₂CoO₄(cr) at 298.15 K, Δ_f H ^o = ?2179 ± 7 kJ/mol.     

The standard enthalpy of formation of fullerene chloride C<Subscript>60</Subscript>Cl<Subscript>30</Subscript>

A rotating-bomb calorimeter was used to measure the energy of combustion of crystalline fullerene chloride C₆₀Cl₃₀ · 0.09Cl₂, Δ_c U° = (?24474 ± 135 kJ/mol). The result was used to calculate the standard enthalpy of formation, Δ_f H° (C₆₀Cl₃₀, cr) = 135 ± 135 kJ/mol, and the C-Cl bond energy, 195 ± 5 kJ/mol. The C-X (X = F, F, Cl, and Br) bond energies in fullerene C₆₀ derivatives and other organic compounds are compared.     

Standard enthalpy of formation of LaCoO3(cr)

An isothermal-jacket calorimeter was used to measure the enthalpies of the reactions of LaCoO₃(cr), LaCl₃(cr), and CoCl₂(cr) with a 2m hydrochloric acid solution. Based on these values and the published data, the standard enthalpy of formation of LaCoO₃(cr) at 298.15 K was calculated (Δ_f H ⁰ = ?1232 ± 6 kJ/mol).     

Standard Molar Enthalpies of Formation of Ce(TCA)_3·3H_2O(s) and Ce(TCA)(C_9H_6NO)_2(s)

IntroductionBothrareearthions1and 8 hydroxyquinolineareofantibacterialfunction ,2 andtheircomplexeshavemorepowerfuldisinfection .Theirbinarycomplexeswerereport edasearlyasin 196 3.Atthesametime ,theresearchontheirternarycomplexeshavebecomeveryactiveinrecentyears,andtheyarewidelyappliedinmanyfields .3 6Dong6 reportedthesynthesisandcharacterizationofthecomplexesofrareearthtrichloroaceticacidsaltswith 8 hy droxyquinoline.Itsapplicationinleathermouldyproofshowedthatthecomplexeshavepowerfuldisinfe…     

Thermochemical study of [Sm(C7H5O3)2·(C4H6NO2S)]·2H2O

The product from reaction of samarium chloride hexahydrate with salicylic acid and Thioproline, [Sm(C₇H₅O₃)₂·(C₄H₆NO₂S)]·2H₂O, was synthesized and characterized by IR, elemental analysis, molar conductance, and thermogravimetric analysis. The standard molar enthalpies of solution of [SmCl₃·6H₂O(s)], [2C₇H₆O₃(s)], [C₄H₇NO₂S(s)] and [Sm(C₇H₅O₃)₂·(C₄H₇NO₂S)·H₂O(s)] in a mixed solvent of absolute ethyl alcohol, dimethyl sulfoxide(DMSO) and 3 mol L^?1 HCl were determined by calorimetry to be Δ_s H _m ^Φ [SmCl₃ δ6H₂O (s), 298.15 K]= ?46.68±0.15 kJ mol^?1 Δ_s H _m ^Φ [2C₇H₆O₃ (s), 298.15 K]= 25.19±0.02 kJ mol^?1, Δ_s H _m ^Φ [C₄H₇NO₂S (s), 298.15 K]=16.20±0.17 kJ mol^?1 and Δ_s H _m ^Φ [Sm(C₇H₅O₃)₂·(C₄H₆NO₂S)]·2H₂O (s), 298.15 K]= ?81.24±0.67 kJ mol^?1. The enthalpy change of the reaction (1) $$ SmCl_3 \cdot 6H_2 O(s) + 2C_7 H_6 O_3 (s) + C_4 H_7 NO_2 S(s) = Sm(C_7 H_5 O_3 )_2 \cdot (C_4 H_6 NO_2 S) \cdot 2H_2 O(s) + 3HCl(g) + 4H_2 O(1) $$ was determined to be Δ_s H _m ^Φ =123.45±0.71 kJ mol^?1. From date in the literature, through Hess’ law, the standard molar enthalpy of formation of Sm(C₇H₅O₃)₂(C₄H₆NO₂S)δ2H₂O(s) was estimated to be Δ_s H _m ^Φ [Sm(C₇H₅O₃)₂·(C₄H₆NO₂S)]·2H₂O(s), 298.15 K]= ?2912.03±3.10 kJ mol^?1.     

Standard enthalpies of formation of bis(β-diketonate)cobalt(II) complexes: The mean (CoO) bond-dissociation enthalpies

The standard enthalpies of formation, at 298 K, of the 1-phenyl-1,3-butanedione (HBZAC) and 1,1,1-trifluoro-2,4-pentanedione (HTFAC) crystalline complexes of cobalt(II) were determined by precise solution—reaction calorimetry: ΔH⁰_f{Co(BZAC)₂,cr} = −632±6.0 kJ mol⁻¹ ΔH⁰_f{Co(TFAC)₂,cr} = −2140±10 kJ mol⁻¹. The average molar bond-dissociation enthalpies, <D>(CoO) were derived.     

Standard enthalpy of the formation of Ba[AuF6]2(cr.)

The enthalpies of the interaction of Ba[AuF₆]₂(cr.) with water and an aqueous potassium hydroxide solution have been measured in a calorimeter with an isothermal shell at 298.15 K. The standard enthalpy of the formation of the studied compound Δ_f H° Ba[AuF₆]₂(cr.) = −2341 ± 10 kJ/mol has been found by two independent methods based on these results and literature data.     

Thermochemistry of Solvated Crystals of C60> and C70> with o-Xylene

Differential scanning calorimetry (DSC) was used to study the binary systems of C₆₀-o-xylene and C₇₀-o-xylene and the ternary system C₆₀-C₇₀-o-xylene. Fullerene C₆₀ formed solvated crystals C₆₀·2C₈H₁₀ with incongruent melting point 320 K and with enthalpy of decomposition 31±3 kJ (mol of C₆₀)^-1. Two solvated crystals of C₇₀ with incongruent melting points 283 and 369 K, and with decomposition enthalpies 18.5±2.2 and 23.0±1.5 kJ (mol of C₇₀)^-1, were formed from o-xylene solutions. Three ternary compositions with C₆₀/C₇₀ mole ratios of 3:1, 1:1 and 1:3 were scanned by DSC. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermochemical properties of the Fe-analogue of cryolite, Na3FeF6

Relative enthalpies for low-and high-temperature modifications of Na₃FeF₆ and for the Na₃FeF₆ melt have been measured by drop calorimetry in the temperature range 723–1318 K. Enthalpy of modification transition at 920 K, δ_trans H(Na₃FeF₆, 920 K) = (19 ± 3) kJ mol⁻¹ and enthalpy of fusion at the temperature of fusion 1255 K, δ_fusH(Na₃FeF₆, 1255 K) = (89 ± 3) kJ mol⁻¹ have been determined from the experimental data. Following heat capacities were obtained for the crystalline phases and for the melt, respectively: C _p(Na₃FeF₆, cr, α) = (294 ± 14) J (mol K)⁻¹, for 723 = T/K ≤ 920, C _p(Na₃FeF₆, cr, β) = (300 ± 11) J (mol K)⁻¹ for 920 ≤ T/K = 1233 and C _p(Na₃FeF₆, melt) = (275 ± 22) J (mol K)⁻¹ for 1258 ≤ T/K ≤ 1318. The obtained enthalpies indicate that melting of Na3FeF6 proceeds through a continuous series of temperature dependent equilibrium states, likely associated with the production of a solid solution.      

The thermodynamic properties of S-lactic acid

The enthalpies of combustion and formation of S-lactic acid at 298.15 K, Δ_c H _m^o(cr.) = −1337.9 ± 0.8 and Δ_f H _m^o(cr.) = −700.1 ± 0.9 kJ/mol, were determined by calorimetry. The temperature dependence of acid vapor pressure was studied by the transpiration method, and the enthalpy of its vaporization was obtained, Δ_vap H ^o(298.15 K) = 69.1 ± 1.0 kJ/mol. The temperature and enthalpy of fusion, T _m (330.4 K) and Δ_m H ^o(298.15 K) = 14.7 ± 0.2 kJ/mol, were determined by differential scanning calorimetry. The enthalpy of formation of the acid in the gas phase was obtained. Ab initio methods were used to perform a conformational analysis of the acid, calculate fundamental vibration frequencies, moments of inertia, and total and relative energies of the stablest conformers. Thermodynamic properties were calculated in the ideal gas state over the temperature range 0–1500 K. A thermodynamic analysis of mutual transformation processes (the formation of SS- and RS(meso)-lactides from S-lactic acid and the racemization of these lactides) and the formation of poly-(RS)-lactide from S-lactic acid and SS- and RS(meso)-lactides was performed.     

Enthalpy of the formation of natural hydrous aluminum hydroxosulfate (aluminite)

A thermochemical study of natural aluminum hydroxosulfate Al₂[(OH)₄SO₄] · 7H₂O, aluminite (Nakhodka deposit, West Chukotka, Russia) is performed on a Tian-Calvet “Setaram” high-temperature heat-conducting microcalorimeter (France). The enthalpy of aluminite formation from simple compounds is obtained via the melt calorimetry of dissolution, Δ_f H ^○(298.15 K) = ?4986 ± 21 kJ/mol.     

Thermodynamic parameters of vaporization of EuBr2

The vaporization process of europium dibromide was studied using high-temperature mass spectrometry. It was ascertained that saturated vapor in temperature range of 1049–1261 K was represented mainly by EuBr₂ molecules; the fraction of dimer molecules Eu₂Br₄ was less than 1%. Heat capacities of solid and liquid europium dibromide, as well as the melting enthalpy were measured by means of differential scanning calorimetry in temperature range 300–1100 K; using these data thermodynamic functions for EuBr₂ in condensed state were calculated. For all experimental data, including the literature data, thermodynamic characteristics of the vaporization of europium dibromide were determined using a unified set of thermodynamic functions according to the methods of the second and third laws of thermodynamics. The value of Δ_s H ^o(298.15 K) = 354 ± 5 kJ/mol was recommended for the reaction of sublimation of EuBr₂(cr.) = EuBr₂.     

The enthalpies of formation of bis-(benzene)molybdenum and of bis-(toluene)tungsten

Microcalorimetric measurements at 520–523 K of the heats of thermal decomposition and of iodination of bis-(benzene)molybdenum and of bis-(toluene)tungsten have led to the values (kJ mol^?): ΔH^o_f[Mo(η-C₆H₆)₂, c] = (235.3 ± 8) and ΔH^o_f[W(η⁶-C₇H₈)₂, c] = (242.2 ± 8) for the standard enthalpies of formation at 25°C. The corresponding ΔH^o_f(g) values, using available and estimated enthalpies of sublimation, are (329.9 ± 11) and 352.2 ± 11) respectively, from which the metalligand mean bond-dissociation enthalpies, $\text{D}$(Mo—benzene) = (247.0 ± 6) and $\text{D}$(W—toluene) = (304.0 ± 6) kJ mol^?1, are derived.     

The platinumcarbon bond strength in Pt(PPh3)2(CH3)I

The enthalpies of reaction 1–3 have been determined

as ΔH(1) = ?176.6 ± 5.4, ΔH(2) = ?107.8 ± 6.0, and ΔH(3) = ?78.9 ± 2.0 kJ mol^?1. The bond dissociation energy difference D₁(PtCH₃) ? D₁(PtI) = +6 ± 5 kJ mol^?1 is calculated, which indicates that the two bonds have very similar strengths.     

Standard enthalpy of formation of (NO2)2[NiF6](cr)

The enthalpies of interactions of (NO₂)₂[NiF₆](cr) with water and aqueous KOH, enthalpies of solution of KF(cr) in dilute aqueous solutions of KNO₃ and KOH, and enthalpy of mixing of solutions of NiF₂, HNO₃, and HF were measured at 298.15 K using isothermic-shell calorimeters. Based on the obtained data and values in the literature, the standard enthalpy of formation of the compound under study was determined by two independent methods: Δ_f H°(NO₂)₂[NiF₆](cr) = −1099 ± 9 kJ/mol.     

Complex equilibria in unsaturated vapor over AlBr<Subscript>3</Subscript>

Unsaturated AlBr 3 vapor pressure was measured over the temperature and pressure ranges 560–845 K and 54–145 torr by the static method using a quartz diaphragm pressure gauge with increased sensitivity (the confidence interval of pressure, including thermal drift of zero pressure gauge point, was 0.3 torr, and that of temperature, 0.3 K). Two equilibrium models were considered, one including AlBr₃ and Al₂Br₆ and the other, AlBr₃, Al₂Br₆, and Al₃Br₉. The molecular constants of all vapor constituents were determined using density functional theory at the B3LYP/6-31G(d,p) level. The thermodynamic functions of all bromides were calculated in the rigid rotator-harmonic oscillator approximation. The enthalpies of independent equilibria for each model were determined by minimizing the residual sum of the squares of pressure discrepancies. According to the first model, 0.5Al₂Br₆ = AlBr₃, ΔH ^o(298.15) = 13629.1 ± 9 cal/mol. According to the second model, 0.5Al₂Br₆ = AlBr₃, ΔH ^o(298.15) = 13638.8 ± 8 cal/mol, and 1.5Al₂Br₆ = Al₃Br₉, ΔH ^o(298.15) = ?8528 ± 800 cal/mol. The second model, for which the variance of pressure differs insignificantly from the experimental variance of pressure, should be given preference.     

Thermochemistry of inorganic sulfur compounds III. The standard molar enthalpy of formation at 298.15 K of US1.992 (β-uranium disulfide) by fluorine bomb calorimetry

A thoroughly analyzed specimen of β-uranium disulfide of composition US_1.992±0.002 has been studied by fluorine-bomb calorimetry. The standard molar energy of combustion: Δ_cU_m^o(US_1.992, cr, β, 298.15 K) = ?(4092.5±7.5) kJ·mol^?1 has been determined on the basis of the reaction: US_1.992(cr, β) + 8.976F₂(g) = UF₆(cr) + 1.992F₆(g). The standard molar enthalpy of formation: Δ_fH_m^o(US_1.992, cr, β, 298.15 K) = ?(519.7±8.0) kJ·mol^?1 was derived, and from that result Δ_fH_m^o(US₂, cr, 298.15 K) = ?(521±8) kJ·mol^?1 is estimated.     

Enthalpy of formation of wulfenite (natural lead molybdate)

A thermochemical study of wulfenite, i.e., natural lead molybdate PbMoO₄ (Kyzyl-Espe field deposit, Central Kazakhstan), is performed on a Setaram high-temperature heat-flux Tian-Calvet microcalorimeter (France). Enthalpies of the formation of wulfenite from oxides Δ_f H _ox ^o (298.15 K) = ?88.5 ± 4.3 kJ/mol and simple substances Δ_f H°(298.15 K) = ?1051.2 ± 4.3 kJ/mol were determined by means of melt calorimetry. The Δ_f G°(298.15 K) of wulfenite corresponding to ?949.1 ± 4.3 kJ/mol was calculated using data obtained earlier for S°(298.15 K) = 161.5 ± 0.27 J/(K mol).     

Isopiestic Determination of the Osmotic and Activity Coefficients of Li2SO4(aq) at T=298.15 and 323.15 K, and Representation with an Extended Ion-Interaction (Pitzer) Model

Isopiestic vapor-pressure measurements were made for Li₂SO₄(aq) from 0.1069 to 2.8190 mol?kg^?1 at 298.15 K, and from 0.1148 to 2.7969 mol?kg^?1 at 323.15 K, with NaCl(aq) as the reference standard. Published thermodynamic data for this system were reviewed, recalculated for consistency, and critically assessed. The present results and the more reliable published results were used to evaluate the parameters of an extended version of Pitzer’s ion-interaction model with an ionic-strength dependent third-virial coefficient, as well as those of the standard Pitzer model, for the osmotic and activity coefficients at both temperatures. Published enthalpies of dilution at 298.15 K were also analyzed to yield the parameters of the ion-interaction models for the relative apparent molar enthalpies of dilution. The resulting models at 298.15 K are valid to the saturated solution molality of the thermodynamically stable phase Li₂SO₄?H₂O(cr). Solubilities of Li₂SO₄?H₂O(cr) at 298.15 K were assessed and the selected value of m(sat.)=3.13±0.04 mol?kg^?1 was used to evaluate the thermodynamic solubility product K _s(Li₂SO₄?H₂O, cr, 298.15 K) = (2.62±0.19) and a CODATA-compatible standard molar Gibbs energy of formation Δ_f G _m ^o (Li₂SO₄?H₂O, cr, 298.15 K) = ?(1564.6±0.5) kJ?mol^?1.     

Low-Temperature Heat Capacities of Terbium Molybdate Phosphates M 2 I Tb(MoO4)(PO4) (MI = Na or K)

The heat capacities of Na₂Tb(MoO₄)(PO₄) and K₂Tb(MoO₄)(PO₄) were measured by adiabatic calorimetry at low temperatures (6.34–333.74 and 7.20–341.17 K, respectively). Smoothed thermal-capacities values were used to calculate the entropy, enthalpy increments, and reduced Gibbs energy. The respective values at 298.15 K are as follows: for Na₂Tb(MoO₄)(PO₄), C _p ⁰ (298.15 K) = 240.1 ± 0.2 J/(K mol), ⁰ (298.15 K) = 307.4 ± 0.4 J/(K mol), H ⁰(298.15 K) ? H ⁰(0) = 44.95 ± 0.03 kJ/mol, and Φ⁰(298.15 K) = 156.6 ± 0.5 J/(K mol); and for K₂Tb(MoO₄)(PO₄): C _p ⁰ (298.15 K) = 245.1 ± 0.1 J/(K mol), S ⁰(298.15 K) = 322.9 ± 0.1 J/(K mol), H ⁰(298.15 K) ? H ⁰(0) = 46.58 ± 0.02 kJ/mol, and Φ⁰(298.15 K) = 166.6 ± 0.2 J/(K mol). The noncooperative magnetic component of the heat capacity was estimated.