The ZrCo–H2 system was investigated in this study owing to its importance as a suitable candidate material for storage, supply, and recovery of hydrogen isotopes. Desorption hydrogen pressure-composition isotherms were generated at six different temperatures in the range of 524–624 K. A van’t Hoff plot was constructed using the plateau pressure data of each pressure-composition isotherms and the thermodynamic parameters were calculated for the hydrogen desorption reaction of ZrCo hydride. The enthalpy and entropy change for the desorption of hydrogen were found to be 83.7 ± 3.9 kJ mol?1 H2 and 122 ± 4 J mol?1 H2 K?1, respectively. Hydrogen absorption kinetics of ZrCo–H2 system was studied at four different temperatures in the range of 544–603 K and the activation energy for the absorption of hydrogen by ZrCo was found to be 120 ± 5 kJ mol?1 H2 by fitting kinetic data into suitable kinetic model equation. 相似文献
The immobilisation of lead(II) ions from aqueous solutions on natural coal was investigated to compare calculated and measured adsorption enthalpies. For this purpose, adsorption isotherms were measured at temperatures of 303, 333 and 353 K. Adsorption enthalpy ΔH was evaluated from temperature dependence of the equilibrium constant of adsorption using the van‘t Hoff equation. Thus, the value of ΔH = 27 kJ mol?1 was obtained manifesting endothermic effect of lead(II) immobilisation on the coal. However, based on the flow and immersion calorimetric measurements, the exothermic character of lead(II) adsorption on the studied coal was proven with a value of about ?7 kJ mol?1. 相似文献
Thermochemical data of dibenzofuran, a compound of considerable industrial and environmental significance, obtained from experimental calorimetric and computational techniques are reported in this work. The enthalpy of fusion, (19.4 ± 1.0) kJ mol?1, at the temperature of fusion, (355.52 ± 0.02) K, was determined by differential scanning calorimetry measurements of dibenzofuran. From the standard (p° = 0.1 MPa) molar enthalpies of formation of crystalline dibenzofuran, (?29.2 ± 3.8) kJ mol?1, and of sublimation, (84.5 ± 1.0) kJ mol?1, determined at T = 298.15 K by static bomb combustion calorimetry and by vacuum drop microcalorimetry, respectively, it was possible to calculate the enthalpy of formation of the gaseous compound, (55.0 ± 3.9) kJ mol?1, at the same temperature. The enthalpy of formation in the gaseous phase was also determined from G3(MP2)//B3LYP calculations. The same computational strategy was employed in the calculation of the standard molar enthalpies of formation, at T = 298.15 K, in the gas-phase, of single methylated derivatives of benzofuran and dibenzofuran. 相似文献
Calorimetric measurements of the enthalpy of reaction of WO3(c) with excess OH?(aq) have been made at 85°C. Similar measurements have been made with MoO3(c) at both 85 and 25°C, to permit estimation of ΔH°=?13.4 kcal mol?1 for the reaction WO3(c)+2OH?(aq)=WO2?4(aq)+H2O(liq) at 25°C. Combination of this ΔH° with ΔH°f for WO3(c) leads to ΔH°f=?256.5 kcal mol?1 for WO2?4(aq). We also obtain ΔH°f=?269.5 kcal mol?1 for H2WO4(c). Both of these values are discussed in relation to several earlier investigations. 相似文献
A coordination compound of erbium perchlorate with L-α-glutamic acid, [Er2(Glu)2(H2O)6](ClO4)4·6H2O(s), was synthesized. By chemical analysis, elemental analysis, FTIR, TG/DTG, and comparison with relevant literatures, its chemical composition and structure were established. The mechanism of thermal decomposition of the complex was deduced on the basis of the TG/DTG analysis. Low-temperature heat capacities were measured by a precision automated adiabatic calorimeter from 78 to 318 K. An endothermic peak in the heat capacity curve was observed over the temperature region of 290-318 K, which was ascribed to a solid-to-solid phase transition. The temperature Ttrans, the enthalpy △transHm and the entropy △transSm of the phase transition for the compound were determined to be: (308.73±0.45) K, (10.49±0.05) kJ·mol^-1 and (33.9±0.2) J·K^-1·mol^-1. Polynomial equation of heat capacities as a function of the temperature in the region of 78-290 K was fitted by the least square method. Standard molar enthalpies of dissolution of the mixture [2ErCl3·6H2O(s)+2L-Glu(s)+6NaClO4·H2O(s)] and the mixture {[Er2(Glu)2(H2O)6](ClO4)4·6H2O(s)+6NaCl(s)} in 100 mL of 2 mol·dm^-3 HClO4 as calorimetric solvent, and {2HClO4(1)} in the solution A' at T=298.15 K were measured to be, △dHm,1=(31.552±0.026) kJ·mol^-1, △dHm,2 = (41.302±0.034) kJ·mol^-1, and △dHm,3 = ( 14.986 ± 0.064) kJ·mol^-1, respectively. In accordance with Hess law, the standard molar enthalpy of formation of the complex was determined as △fHm-=-(7551.0±2.4) kJ·mol^-1 by using an isoperibol solution-reaction calorimeter and designing a thermochemical cycle. 相似文献
The heat capacities of 1-butyl-3-methylimidazolium lactate ionic liquids ([C4mim][Lact]) were measured with a highly accurate automatic adiabatic calorimeter over the temperature range from 79 to 406 K. And the experimental values of molar heat capacities were fitted to a polynomial equation using least square method in the appropriate temperature ranges. The standard molar heat capacity was determined to be 1734.46?±?5.12 J K?1 mol?1 at 298.15 K. The molar enthalpy and molar entropy of the transition were determined to be 15.575?±?0.045 and 64.44?±?0.14 J K?1 mol?1. Other thermodynamic properties, such as (HT???H298.15) and (ST???S298.15), were also calculated. Furthermore, when the temperature reaches 241.87 K, the strongest peaks appeared by analysis of the heat capacity curve. This phenomenon could be explained from the interionic interaction, which is the hydrogen bond between the anions and cations. 相似文献
A noval anilino-pyrimidine fungicide, pyrimethanil butanedioic salt (C28H32N6O4), was synthesized by a chemical reaction of pyrimethanil and butanedioic acid. The low-temperature heat capacities of the compound were measured with an adiabatic calorimeter from 80 to 380 K. The thermodynamic function data relative to 298.15 K were calculated based on the heat capacity fitted curve. The thermal stability of the compound was investigated by TG and DSC. The TG curve shows that pyrimethanil butanedioic salt starts to sublimate at 455.1 K and totally changes into vapor when the temperature reaches 542.5 K with the maximal speed of weight loss at 536.8 K. The melting point, the molar enthalpy (ΔfusHm), and entropy (ΔfusSm) of fusion were determined from its DSC curves. The constant-volume energy of combustion (ΔcUm) of pyrimethanil butanedioic salt was measured by an isoperibol oxygen-bomb combustion calorimeter at T = (298.15 ± 0.001) K. From the Hess thermochemical cycle, the standard molar enthalpy of formation was derived and determined to be ΔfHmo (pyrimethanil butanedioic salt)=?285.4 ± 5.5 kJ mol?1. 相似文献
Novel anilino-pyrimidine fungicides, pyrimethanil maleic salt, and pyrimethanil fumaric salt (C28H30N6O4) were synthesized by a chemical reaction of pyrimethanil with maleic acid/fumaric acid. The low-temperature heat capacities of the two compounds were measured with an adiabatic calorimeter from 80 to 350 K. The heat capacities of pyrimethanil fumaric salt are bigger than that of pyrimethanil maleic salt in the measurement temperature range. The thermodynamic function data relative to 298.15 K were calculated based on the heat capacity-fitted curves. The melting points, the molar enthalpies (ΔfusHm), and entropies (ΔfusSm) of fusion of pyrimethanil maleic salt and pyrimethanil fumaric salt were determined from their DSC curves. The values indicate that pyrimethanil fumaric salt was more thermostable than pyrimethanil maleic salt. The constant-volume energies of combustion (ΔcUmo) of pyrimethanil maleic salt and pyrimethanil fumaric salt were measured using an isoperibol oxygen bomb combustion calorimeter at T = (298.15 ± 0.001) K. From the Hess thermochemical cycle, the standard molar enthalpies of formation of the two compounds were derived and determined to be ΔfHmo (pyrimethanil maleic salt) = ?459.3 ± 4.9 kJ mol?1 and ΔfHmo (pyrimethanil fumaric salt) = ?557.2 ± 4.8 kJ mol?1, respectively. The results suggest that pyrimethanil fumaric salt is more chemically stable than pyrimethanil maleic salt. 相似文献
A precision rotating-bomb combustion calorimeter (thermistor of which was constructed in the laboratory) was calibrated using benzoic acid with purity of 99.999 %. The combustion energy of phenanthroline monohydrate (phen·H2O) at 298.15 K was determined to be ΔcUmθ = ?(5,757.45 ± 2.53) kJ mol?1. Then, the standard enthalpy of combustion and the standard enthalpy of formation of phen·H2O were calculated to be ΔcHmθ = ?(5,759.93 ± 2.53) kJ mol?1 and ΔfHmθ = ?(391.34 ± 2.98) kJ mo1?1, respectively. Particularly, the effect of phen·H2O on growth and metabolism of Escherichia coli (E. coli) was also determined by a TAM air isothermal calorimeter at 37 °C. The thermokinetic parameters, including maximum heat output power (Pmax), growth rate constant (κ), generation times (tG), inhibitive rate (I), and half inhibition concentration (CI,50), were obtained. The results showed that phen·H2O possessed the bi-directional biological effect and Hormesis effect, which stimulated the growth of E. coli at lower concentration, but inhibited the growth at higher concentration. The half inhibition concentration CI,50 of phen·H2O was found to be 7.31 mg L?1. 相似文献
The enthalpy change (303 K) for the standard state solid phase complexation reaction is derived using conventional solution calorimetric techniques (ΔH°R=?82.7±2.0 kJ mol?1. Knowlege of ΔH°R is a necessary pre-requisite for the future derivation of the FeS thermochemical bond energy. 相似文献
The results of two independent calorimetric investigations of the pyridine- iodine complex are reported. “Best” values are reported as Km = 128 1/mol and ΔH° = -8.4 kcal mol?1 for the formation of the complex in cyclohexane at 25°C, and Km = 104 and ΔH° = -7.9 kcal mol?1 in carbon tetrachloride. Evidence is presented to support the contention that association constants for weak complexes determined by calorimetric methods can be as reliable as those determined by spectrometric methods, and that values of ΔH° determined by the calorimetric method are much more reliable than those derived from the temperature dependence of equilibrium constants. 相似文献
A novel complex [Ni(H2O)4(TO)2](NO3)2·2H2O (TO = 1,2,4-triazole-5-one) was synthesized and structurally characterized by X-ray crystal diffraction analysis. The decomposition reaction kinetic of the complex was studied using TG-DTG. A multiple heating rate method was utilized to determine the apparent activation energy (Ea) and pre-exponential constant (A) of the former two decomposition stages, and the values are 109.2 kJ mol?1, 1013.80 s?1; 108.0 kJ mol?1, 1023.23 s?1, respectively. The critical temperature of thermal explosion, the entropy of activation (ΔS≠), enthalpy of activation (ΔH≠) and the free energy of activation (ΔG≠) of the initial two decomposition stages of the complex were also calculated. The standard enthalpy of formation of the new complex was determined as being ?1464.55 ± 1.70 kJ mol?1 by a rotating-bomb calorimeter. 相似文献
The complex (C11H18NO)2CuCl4 (s), which may be a potential effective drug, was synthesized. X‐ray crystallography, elemental analysis, and chemical analysis were used to characterize the structure and composition of the complex. Lattice energy and ionic radius of the anion of the complex were derived from the crystal data of the title compound. In addition, a reasonable thermochemical cycle was designed, and standard molar enthalpies of dissolution for reactants and products of the synthesis reaction of the complex were measured by an isoperibol solution‐reaction calorimeter. The enthalpy change of the reaction was calculated to be ΔrH?m=(2.69±0.02) kJ·mol?1 from the data of the above standard molar enthalpies of dissolution. Finally, the standard molar enthalpy of formation of the title compound was determined to be ΔrH?m[(C11 H18NO)2CuCl4, s]= ? (1822.96±6.80) kJ·mol?1 in accordance with Hess law. 相似文献
The treatment of the bacterial arthritis of the joints is still a great challenge for orthopedic surgeons and rheumatologists. Aerobic Gram-negative bacteria are involved only in 20–25 % of cases. The inadequate therapy can cause cartilage destruction and can result in severe osteoarthritis of the affected joint. The aim of this study was to demonstrate and follow the destruction of the joints’ hyaline cartilage by calorimetric method. We induced experimental septic arthritis in knee joints of seven New Zealand rabbits by a single inoculation of Escherichiacoli ATCC 25922 culture (0.5 mL cc. 108 ± 5 % c.f.u.). The duration of this experiment was 7 days from the first to the last injection. After euthanizing the first subject, all other animals were given an overdose of anesthetics and samples were isolated from the cartilage of the femurs by surgical intervention for calorimetric measurements. The DSC scans clearly demonstrated the development of infective structural destruction in the cartilage from the first to the tenth day of incubation. In case of healthy control the melting temperatures (Tm) were: 57 and 63.1 °C and the total calorimetric enthalpy change (ΔH) was 0.37 J g?1. After the third day, the enthalpy increased extremely (3.67 J g?1), the two transition temperatures shifted toward lower temperature: 47.7 and 62.3 °C. At the fifth day, the effect of infection is culminated with Tm = 62.2 °C and a further elevation in ΔH (3.75 J g?1). These results can indicate a dramatic change of the structure of rabbit cartilage between the third and fifth days. Therefore, the time elapsed seems to be critical and possesses clinical relevance, since by the sixth day, ΔH decreased to 2.6 J g?1 with a practically unchanged melting temperature. Between the sixth and tenth days, significantly increased melting temperatures (64.9 °C) were observed with decreased (3.38 J g?1) calorimetric enthalpy. In conclusion, calorimetric measurements have been proven to be a reliable method in the measurement of cartilage destruction, caused by Gram-negative septic arthritis. 相似文献
For the first time, the energy of combustion ΔcU of crystalline triphenylantimony bis(acetophenoneoximate) Ph3Sb(ONCPhMe)2 has been measured at T = 298.15 K using the isothermal combustion calorimeter with a stationary bomb. The standard molar enthalpy of combustion ΔcHº, the standard molar enthalpy ΔfHº, and free Gibbs energy ΔfGº of formation of the above oximate have been calculated. 相似文献
The enthalpies of dissolution of N-guanylurea dinitramide (GUDN) in dimethyl sulfoxide (DMSO) and N-methyl-2-pyrrolidone (NMP) were measured using an RD496-2000 Calvet microcalorimeter at 298.15 K under atmospheric pressure, respectively. Empirical formulae for the calculation of the enthalpy of dissolution (ΔdissH), relative partial molar enthalpy (ΔdissHpartial), and relative apparent molar enthalpy (ΔdissHapparent) were obtained from the experimental data of the dissolution processes of GUDN in DMSO and NMP. Furthermore, the corresponding kinetic equations describing the two dissolution processes were dα/dt = 10?3.39(1 ? α)0.70 for the dissolution of GUDN in DMSO, and dα/dt = 10?4.06(1 ? α)1.11 for the dissolution of GUDN in NMP. 相似文献
In this work, the interaction of memantine with human serum albumin (HSA) immobilized on porous silica particles was studied using a biochromatographic approach. The determination of the enthalpy change at different pH values suggested that the protonated group in the memantine–HSA complex exhibits a heat protonation with a magnitude around 65 kJ mol?1. This value agrees with the protonation of a guanidinium group, and confirmed that an arginine group may become protonated in the memantine–HSA complex formation. The thermodynamic data showed that memantine–HSA binding, for low temperature (<293 K), is dominated by a positive entropy change. This result suggests that dehydration at the binding interface and charge–charge interactions contribute to the memantine–HSA complex formation. Above 293 K, the thermodynamic data ΔH and ΔS became negative due to van der Waals interactions and hydrogen bonding which are engaged at the complex interface. The temperature dependence of the free energy of binding is weak because of the enthalpy–entropy compensation caused by a large heat capacity change, ΔCp = ? 3.79 kJ mol?1 K?1 at pH = 7. These results were used to determine the potential binding site of this drug on HSA. 相似文献