Review of Thermodynamic Properties of the Cr-N System

Existing thermodynamic data for the Cr-N system were analyzed. High-temperature heat contents measured by Sato were reevaluated, and the heat capacity of Cr₂N was determined to be 15.05+6.58×10⁻³ T (°K) and that of CrN 11.10+ 1.58×10³ T . Using these heat capacities and an estimated ΔS°_{298, f} of 20×1 cal/°K-g atom N for the formation of the nitrides, second- and third-law calculations for all available vapor-pressure data were made. The two calculations agreed very well for the data of Mills. The heats of formation of Cr₂N and CrN are -31.8×1.0 and -28.4×1.5 kcal/mol, respectively. A partial phase diagram of the Cr-N system is presented.     

二甲基亚砜水溶液的热力学性质

采用静态法测定了二甲基亚砜的饱和蒸汽压和温度之间的关系,用ＲＯＳＥ平衡釜测定了二甲基亚砜与水组成的二元体系的汽液平衡数据。经过数据处理,求出了Ｗｉｌｓｏｎ方程中的能量作用参数和,以及ＶａｎＬｅａｒ方程中的端值常数和。结果表明在低压情况下,该体系用ＶａｎＬａａｒ方程得到的计算值与实验数据符合较好。     

水-丙酸二元体系汽液平衡的热力学性质

用新型泵式沸点仪测定了在101.325kPa下水-丙酸二元系在不同液相组成时的沸点,用过量自由焓函数Q,采用间接法由Tpx推算了水-丙酸二元系的汽相平衡组成y。汽相的非理想性用截至第二项的维里系数的状态方程求出汽相混合物中组分逸度系数。二元体系活度系数的关联分别用Wilson模型、NRTL模型、Margules模型和vanLaar模型进行关联,用最小二乘法求出了它们的液相活度系数模型参数。用所得的液相活度系数来计算三个二元体系的过量吉布斯自由焓函数GE/RT。计算的泡点温度与实验测得的沸点温度吻合良好,由面积积分法检验这些模型参数计算的二元体系相平衡数据,得到很好的热力学一致性。     

Vaporization and Thermodynamic Properties of the NbO2–TiO2 System

Glass Physics and Chemistry - The vaporization and thermodynamic properties of the NbO2–TiO2 system are studied by high-temperature differential mass spectrometry. The samples are evaporated...     

Thermodynamic Properties of Lipases

The Gibbs free energy difference (ΔG) between the native and denatured enzymes for Pseudomonas, Penicillium simplicissimum and Geotrichum candida lipases was estimated from the activity temperature profile data. The (ΔG) estimates of 5.7, 8.0 and 19.5 kJI mol respectively were obtained for these lipases. These values were compared to those reported for other lipases and discusses the implication of these values with respect to their thermodynamic stability.     

乙醚-甲醇-正丁醇多元系汽液平衡的热力学性质

用新型泵式沸点仪测定了在101.325 kPa下乙醚-甲醇、乙醚-正丁醇、甲醇-正丁醇3个二元系以及乙醚-甲醇-正丁醇三元系在不同液相组成时的沸点,并用间接法Tpx推算了3个二元系的汽相平衡组成y.3个二元体系活度系数分别用Wilson模型、NRTL模型、Margules模型和van Laar模型进行关联,用最小二乘法...     

LNG热物性计算

天然气在其液化或液态状态下输送过程中,其物性参数随着温度和压力的变化而不断改变,因此液化天然气物性计算中不能按理想状态处理。根据实际工程需要,使用LKP方程及其关联式对密度、焓和熵值进行计算;通过对比态原理和Lohrenz等关联式计算了比热容和粘度。计算结果和实验数据对比,表明其计算精度满足工程实际需求。     

Thermodynamic Properties of Manganese Oxides

Transposed temperature drop calorimetry and hightemperature drop solution calorimetry in molten 2PbO·B₂O₃ at 977 K were used to study the energetics of some manganese oxides, namely pyrolusite (MnO₂), bixbyite (Mn₂O₃), hausmannite (Mn₃O₄), and manganosite (MnO). The enthalpies of oxidation at 298 K in the manganeseoxygen system, which were determined by appropriate thermodynamic cycles, were (in kJ/mol of oxygen): –441.4 ± 5.8 for the reaction 6MnO + O₂→ 2Mn₃O₄, –201.8 ± 8.7 for the reaction 4Mn₃O₄+ O₂→ 6Mn₂O₃, and –162.1 + 7.2 for the reaction 2Mn₂O₃+ O₂→ 4MnO₂. These values agreed very well with previous data that were obtained using equilibrium measurements that were reported in the literature. Thus, direct calorimetric measurements were well suited to obtain reliable enthalpy of formation data for oxides that contain manganese in the 2+, 3+, and 4+ states. Using these new values of enthalpies and reliable standard entropies, the phase-stability diagram of the manganeseoxygen system was constructed.     

Thermodynamic Properties of Sulfobetaine-Type Surfactants

Sulfobetaine-type surfactants containing a hydroxy group were synthesized by the reaction of long chain monoalkyl dimethyl tertiary amine with 3-chloro-2-hydroxypropanesulfonic acid sodium salt. The structures were characterized by ¹H NMR and ESI-MS. Their critical micelle concentrations (CMC) in aqueous solution were determined by the plate method in the temperature rang from 298.15 to 328.15 K. The thermodynamic parameters of micellization ( $\Delta G_{\text{mic}}^{\theta}$ , $\Delta H_{\text{mic}}^{\theta}$ and $\Delta S_{\text{mic}}^{\theta}$ ) and surface adsorption ( $\Delta G_{\text{ad}}^{\theta}$ , $\Delta H_{\text{ad}}^{\theta}$ and $\Delta S_{\text{ad}}^{\theta}$ ) were calculated from CMC data. The results showed that the micellization and surface adsorption of these surfactants in aqueous solution was a spontaneous and entropy-driven process. The micellization and surface adsorption became easier when the alkyl chain length increased from 12 carbon atoms to 14. The enthalpy–entropy compensation of micellization and adsorption was investigated. The compensation temperature were found to be (311 ± 2) K for both micellization and adsorption. The $\Delta H_{\text{mic}}^{*}$ and $\Delta H_{\text{ad}}^{*}$ decreased, but the $\Delta S_{\text{mic}}^{*}$ and $\Delta S_{\text{ad}}^{*}$ increased with increasing the hydrophobic chain length from 12 to 14.     

水-乙酸二元体系汽液平衡的热力学性质分析

用新型泵式沸点仪测定了在101.325kPa下水-乙酸二元系在不同液相组成时的沸点,用过量自由能函数Q,采用间接法由Tpx推算了水-乙酸二元系的汽相平衡组成y。汽相的非理想性用截至第二项的维里系数的状态方程求出汽相混合物中组分逸度系数。二元体系活度系数的关联分别用Wilson模型、NRTL模型、Margules模型和vanLaar模型进行关联,用最小二乘法求出了它们的液相活度系数模型参数。所得的液相活度系数来计算三个二元体系的过量吉布斯自由能函数GE/RT。计算的泡点温度与实验的所测得的沸点温度吻合良好,由面积积分法检验这些模型参数计算的二元体系相平衡数据得到很好的热力学一致性。     

Estimation of Thermodynamic Properties of Polysaccharides

Polysaccharides are the most important components of herbal biomass with a high application potential. Their thermochemical characteristics, however, have been little studied. In the present paper, an effective thermodynamic analysis was carried out with the aim of setting a method for reasonably estimating the thermochemical properties of polysaccharides such as cellulose. The properties of formation and heat capacities were estimated by general thermodynamic methods like group contribution methods as well as methods followed from synthetic polymer studies. The results were compared with those obtained by empirical correlations derived from the data for short chain carbohydrates, the only literature data available for validation. The properties were determined depending on the degree of polymerization and temperature.     

Thermodynamic Properties of Non-Oxide Composite Refractories

For initiative application of non-oxides in refractories, it is essential to study thermodynamic properties of non-oxides. The stability and stable order of non-ox- ides under oxidized atmosphere are analyzed firstly and then a new process, “converse reaction sintering”, is proposed. The results of study on oxidation mechanism of silicon and aluminum nitrides indicate that the gaseous suboxides can be produced observably when the oxygen partial pressure is lower than “conversion oxygen partial pressure”. The suboxides can be deposited near the surface of composite to become a compact layer. This causes the material possessing a performance of “self-impedient oxidation”. Metal Si and Al are the better additives for increasing the density and width of compact layer and increasing the ability of anti-oxidation and anti-corrosion. The study on Si3 N4-Al2O3, Si3N4-MgO, Si3 N4-SiC systems is also enumerated as examples in the paper. The experimental results show that the converse reaction sintering is able to make high performance composites and metal Si and Al not only can promote the sintering but also increase the density and width of compact layer.     

己内酰胺类离子液体的热力学性质(英文)

A series of caprolactam ionic liquids(ILs) containing incorporated halide anions were synthesized.Their physical properties,such as melting points,heats of fusion and heat capacities,were measured by differential scanning calorimeter(DSC).The results indicate that these ionic liquids exhibit proper melting points,high value of heats of fusion,and satisfying heat capacities which are suitable for thermal energy storage applications.     

Thermodynamic Properties of Caprolactam Ionic Liquids

A series of caprolactam ionic liquids (ILs) containing incorporated halide anions were synthesized. Their physical properties, such as melting points, heats of fusion and heat capacities, were measured by differential scanning calorimeter (DSC). The results indicate that these ionic liquids exhibit proper melting points, high value of heats of fusion, and satisfying heat capacities which are suitable for thermal energy storage applications.     

The Thermodynamic Properties of Silicon Oxynitride

A critical assessment of thermal and equilibrium data for silicon oxynitride (Si₂N₂O) is presented. Selected values for the heat of formation of Si₂N₂O from the elements and the absolute entropy of Si₂N₂O at 298.15 K are ΔH⁰_f,298=−947.7 ± 5.4 kJ/mol and S⁰₂₉₈= 45.35 ± 0.4 J/mol·K, respectively. A table of thermodynamic functions for Si₂N₂Ofrom 298 to 2500 K, which has been calculated from the analysis of the literature data, is also presented.     

Thermodynamic Assessment of the System CoO-MnO

The thermodynamic properties of pure CoO and CoO-MnO solutions have been analyzed in terms of thermodynamic models applying various experimental data. Expressions for the Gibbs energy of the individual phases have been obtained and the phase diagram is calculated. It reveals a homogeneous solid solution at temperatures above room temperature but a miscibility gap at very low temperatures.     

Thermodynamic Evaluation of the Bi-Cu-O System

A thermodynamic evaluation of the ternary Bi-Cu-O system has been made and a set of parameters consistently describing the system at 1 bar total pressure has been determined. The ternary system contains a liquid phase which is continuous at high temperature and separates into a metal liquid and an oxide liquid at low temperature and the ternary compound Bi₂CuO₄ in addition to the binary compounds. Concentration/temperature diagrams are given for the Bi₂O₃-CuO _x system at oxygen partial pressures of 1, 0.21 and 10⁻⁵ bar, as well as a potential diagram. Selected isothermal sections at 1100 and 1473 K are also presented. Available experimental data are rather limited and often show a relatively large scatter, but nevertheless make it possible to determine a sufficient set of thermodynamic parameters.