Thermodynamic properties of cerium mononitride

Data on the thermodynamic properties of cerium mononitride CeN in the solid state are analyzed. Relations approximating the temperature dependence of the thermodynamic functions of CeN(cr.) in the temperature range of 298.15–2900 K are obtained. Using the relations of thermodynamics known for this temperature range, the thermodynamic functions of cerium mononitride (entropy, Gibbs energy, and enthalpy variation) are calculated. The resulting data is entered into the database of the IVTANTHERMO software package and is used to analyze the thermal stability of CeN(cr.), and to estimate its boiling point at atmospheric pressure.     

Polynomial path for the calculation of liquid state free energies from computer simulations tested on liquid water

The polynomial path is introduced for the calculation of liquid state free energies. The well-characterized SPC, TIP4P, and MCY water models were used to demonstrate its efficiency, as well as its range of applicability in conjunction with Monte Carlo computer simulations using thermodynamic integration based on Gaussian quadratures. The technique employed is compared with the slow-growth method (another variant of thermodynamic integration), the perturbation method, and the use of the grand-canonical ensemble.     

The thermodynamic rules governing polymorphism of beryllium oxide

A thermodynamic analysis of qualitative and quantitative rules governing polymorphism of BeO was performed. Equations for the temperature dependences of its polarization and isobaric heat capacity in the low-temperature neighborhood of the wurtzite polymorph-rutile polymorph transition point were suggested. Equations describing the curvature of the line of this transition and mutual correlation of the temperature dependences of the thermodynamic characteristics of beryllium oxide were obtained.     

New approach to defining thermodynamic surface tension of solids

Using either the chemical potential of the immobile component of a solid dissolved in a fluid phase or the corresponding component of the tensor of chemical potential in solid phase, a new concept of the grand thermodynamic potential of solid-fluid two-phase system is proposed. For a planar interfacial surface, this makes it possible to generalize the notion of thermodynamic surface tension σ introduced by Gibbs that has the meaning of the formation work of a unit surface. This tension is determined as the specific surface excess of the grand thermodynamic potential. This definition of the thermodynamic surface tension does not depend on the position of the dividing surface and is common for fluids and solids. It is shown that, at the arbitrary position of dividing surface, the difference between thermodynamic σ and mechanical @[gamma] surface tensions for solid surface is determined by the nonuniformity of the tensor of chemical potential in a solid, as well as by its anisotropy in the bulk of solid phase.     

Heterolytic and Homolytic N-NO Bond Dissociation Energies of N-Nitroso-benzenesulfonylmethylamines in Acetonitrile

Great interests have been accumulated in recent years in the chemistry and biochemistry of nitric oxide (NO) since the remarkable discoveries of its key roles in a wide range of human physiological processes. To elucidate the mechanistic details of NO migration from its donor to its acceptor, it is necessary to determine the Y-NO bind energy that registers the thermodynamic driving force for NO release and capture. In this paper the heterolytic and homolytic N-NO bond dissociation energies [ i. e., △Hhet(N-NO) and △Hhomo(N-NO)] for ten N-nitroso-p-substituted-benzensulfonyl methylamines in acetonitrile are offered, which were obtained from titration calorimetry and thermodynamic cycles, respectively (Scheme 1).     

明矾的宏观晶体形状

通过简易的热力学模型推测晶体宏观形状及缺陷的成因,借助于本科无机探究实验,培养明矾大晶体并测量其宏观参数,拟合出明矾的热力学参数,以解释明矾的宏观形状、缺陷并预测明矾的完美八面体的可能性与晶体的自范性。     

Obituary : Akira Watanabe (1921–1980)

Since the evaluation of changes in thermodynamic quantities by adsorption and phase transition is essential in the study on the structure and properties of interfacial films, a thermodynamic treatment has been developed on the basis of the interfacial excess quantities defined by Hansen and of the quasithermodynamics. Mean partial molar thermodynamic quantities of constituents at the interface have been introduced in the course of development. It has been shown that the partial supposed that ethyl heptadecanoate has a difficulty in arranging its polar head group so as to produce a regular array of condensed monolayer.The above discussion shows that the thermodynamic approach developed in Chapter II serves as a tool for elucidating the structure and properties of interfacial monolayers.     

Energy Aspects of Thermal Molecular Switching: Molecular Thermal Hysteresis of Helicene Oligomers

Molecular switching is a phenomenon by which a molecule reversibly changes its structure and state in response to external stimuli or energy. Herein, molecular switching is discussed from thermodynamic and kinetic aspects in terms of energy supply with an emphasis on the thermal switching exhibited by helicene oligomers. It includes the inversion of relative thermodynamic stability induced by temperature changes and molecular thermal hysteresis in a closed system. The thermal phenomenon associated with the oligomers involves population/concentration changes between metastable states under nonequilibrium thermodynamic control.     

System with variable energy,volume and number of particles: Evaluation of partition function and thermodynamic quantities

Partition function and thermodynamic parameters of the system open with respect to energy E, volume V and number of particles N, whereas temperature T, chemical potential μ and pressure P were kept constant, were considered by the procedure proposed by Gibbs. The mean values of variable energy, volume and number of particles were obtained by universal expression for such values. The entropy was determined by its general statistical definition. The thermodynamic potential and other thermodynamic quantities were also turned out naturally.     

Simulation of degradation of coal organic matter

Russian Journal of Applied Chemistry - The existing procedures for calculating thermodynamic functions of individual compounds of coal organic matter were analyzed, and possible reactions of its...     

Thermodynamic analysis of ordered and disordered monolayer of argon adsorption on graphite

We presented a detailed thermodynamic analysis of argon adsorption on a graphitized carbon black with a kinetic Monte Carlo scheme. In this study, we particularly paid attention to the formation of a hexagonal two-dimensional molecular layer on a graphite surface and discuss conditions of its stability and thermodynamic properties of the adsorbed phase as a function of loading. It is found that the simulation results are substantially affected by the dimensions of the simulation box when the monolayer forms a hexagonal ordered structure. This is due to the fact that the lattice constant is constrained by the dimensions of the surface. To circumvent this, we presented a thermodynamic technique, which allows for the variation of the box size as a function of loading, to determine the "intrinsic" lattice constant (rather than apparent average value because of the fixed dimensions of the simulation box) and the thermodynamic functions for the adsorbed phase: the Helmholtz free energy, the chemical potential, and the surface tension. The tangential and normal pressures as a function of the distance from the surface are also discussed.     

The Parameters of Intersection Point Equation Between Retention and Carbon Number for Homologues in Supercritical Fluid Chromatography

Supercritical fluid chromatography (SFC) techniques have been developing rapidly, now much attention has been paid to the research for its thermodynamic basis. Based on thermodynamic theory, we have derived the straight linear relationship between the logarithm of capacity factor and carbon number for homologues in SFC. There is a common intersection point among the ln k' vs. n straight lines of homologues at different temperatures. We can determine the intersection point equation of homologues in SFC.     

Al-Fe-P三元系的热力学优化

采用CALPHAD方法对Al-Fe-P三元系进行了热力学评估, 并根据相关的实验数据对边际二元系Al-P进行了热力学再优化, Al-Fe和Fe-P边际二元系的热力学参数取自之前的研究并做了局部调整. 根据相图数据和热力学数据优化了Al-Fe-P三元系的热力学模型参数, 获得了体系中所有相的Gibbs自由能表达式. 所得参数之间自洽且能很好地重现Al-Fe-P体系的大部分实验相图信息. 通过驱动力判据和本文优化所得的模型参数,从热力学上解释了该体系非晶形成能力与组成之间的关系.     

高溶解性盐水体系热力学模型预测能力的比较研究I: 二元体系

用原始Pitzer模型、扩展的Pitzer模型、Pitzer-Simonson-Clegg模型、S-MSA模型和BET模型分别对LiCl-H2O, LiBr-H2O, CaCl2-H2O, Mg(NO3)2-H2O, MnCl2-H2O和Mn(NO3)2-H2O等六种不同体系的热力学性质进行描述, 考察了各种模型的预测能力. 结果表明原始Pitzer模型不能准确描述高浓电解质溶液的性质; 扩展的Pitzer模型虽然能较准确地描述某些体系高浓度的热力学性质, 但预测能力不足; Pitzer-Simonson-Clegg模型对高浓盐水体系热力学性质具有一定的预测能力, 但拟合参数所用的最大浓度与溶解度相差很大时, 外推饱和点的热力学性质则会出现较大偏差; S-MSA模型虽然可以将拟合参数的浓度范围扩大到饱和, 但没有外推能力, 而且需要溶液的密度数据, 这限制了该模型的广泛应用; BET模型对这六种体系均体现出很强的预测能力, 预测结果准确, 且模型参数少, 物理意义明确, 该模型可用于熔盐水化物相变储能材料的设计.     

Rapid Estimation of Thermodynamic Parameters and Vapor Pressures of Volatile Materials at Nanoscale

Non‐isothermal measurements of thermodynamic parameters and vapor pressures of low‐volatile materials are favored when time is a crucial factor to be considered, such as in the case of detection of hazardous materials. In this article, we demonstrate that optical absorbance spectroscopy can be used non‐isothermally to estimate the thermodynamic properties and vapor pressures of volatile materials with good accuracy. This is the first method to determine such parameters in nanoscale in just minutes. Trinitrotoluene (TNT) is chosen because of its low melting temperature, which makes it impossible to determine its thermodynamic parameter by other rising‐temperature techniques, such as thermogravimetric analysis (TGA). The well‐characterized vapor pressure of benzoic acid is used to calibrate the spectrometer in order to determine the vapor pressure of low‐volatile TNT. The estimated thermodynamic properties of both benzoic acid and TNT are in excellent agreement with the literature. The estimated vapor pressure of TNT is one order of magnitude larger than that determined isothermally using the same method. However, the values are still within the range reported in the literature. The data indicate the high potential for use of rising‐temperature absorbance spectroscopy in determining vapor pressures of materials at nanometer scale in minutes instead of hours or days.     

Relative Boltzmann entropy, evolution equations for fluctuations of thermodynamic intensive variables, and a statistical mechanical representation of the zeroth law of thermodynamics

Generalized thermodynamics or extended irreversible thermodynamics presumes the existence of thermodynamic intensive variables (e.g., temperature, pressure, chemical potentials, generalized potentials) even if the system is removed from equilibrium. It is necessary to properly understand the nature of such intensive variables and, in particular, of their fluctuations, that is, their deviations from those defined in the extended irreversible thermodynamic sense. The meaning of temperature is examined by means of a kinetic theory of macroscopic irreversible processes to assess the validity of the generalized (or extended) thermodynamic method applied to nonequilibrium phenomena. The Boltzmann equation is used for the purpose. Since the relative Boltzmann entropy has been known to be intimately related to the evolution of the aforementioned fluctuations in the intensive thermodynamic variables, we derive the evolution equations for such fluctuations of intensive variables to lay the foundation for investigating the physical implications and evolution of the relative Boltzmann entropy, so that the range of validity of the thermodynamic theory of irreversible processes can be elucidated. Within the framework of this work, we examine a special case of the evolution equations for the aforementioned fluctuations of intensive variables, which also facilitate investigation of the molecular theory meaning of the zeroth law of thermodynamics. We derive an evolution equation describing the relaxation of temperature fluctuations from its local value and present a formula for the temperature relaxation time.     

Thermochemistry of alkyl derivatives of urea

A thermodynamic study was carried out on urea and 12 of its alkyl derivatives by the methods of combustion calorimetry, vapor formation, and differential scanning calorimetry. The numerical data obtained permitted determination of the enthalpy of formation of the above substances under standard conditions and in the gas phase. An additive scheme was proposed for calculating the thermodynamic properties of alkyl substituted urea.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 750–755, April, 1990.     

含氯化钠电解质水溶液体系热力学性质研究进展

总结了近几十年来含氯化钠电解质水溶液体系热力学性质的研究成果及其在盐湖、地下卤水、油田水和海盐制备等领域的应用,并对含钠水盐体系在不同温度下的热力学性质进行了总结,对于推动含钠水盐体系电解质溶液理论的发展和促进富盐湖卤水、地下卤水及海水的开发利用具有重要的意义。     

The partial solubility parameters: An equation-of-state approach

The division of the well-known solubility parameter into its dispersion, polar, and hydrogen-bonding components has significantly upgraded its capacity and usefulness in the screening and selection of the appropriate solvents in Industry and in Laboratory. This work presents a new statistical thermodynamic approach for the estimation of these partial components over a broad range of temperature and pressure. Key to this approach is the development of explicit expressions for the contribution of dispersion, dipolar, and hydrogen-bonding interactions to the potential energy of the fluid. The approach is applicable to ordinary solvents, to supercritical fluids, as well as to high polymers. Information on various thermodynamic properties of fluids is used in order to estimate the three solubility parameter components. Extensive tables with the key parameters are presented. On the other hand, available information on these separate components is exploited in order to extract information for the thermodynamic behaviour of the fluids over an extended range of external conditions.