Thermophysical Properties of High-Temperature Reacting Mixtures of Carbon and Water in the Range 400–30,000 K and 0.1–10 atm. Part 1: Equilibrium Composition and Thermodynamic Properties

This paper is devoted to the calculation of the chemical equilibrium composition and thermodynamic properties of reacting mixtures of carbon and water at high temperature. Equilibrium particle concentrations and thermodynamic properties including mass density, molar weight, entropy, enthalpy and specific heat at constant pressure, sonic velocity, and heat capacity ratio are determined by the method of Gibbs free energy minimization, using species data from standard thermodynamic tables. The calculations, which assume local thermodynamic equilibrium, are performed in the temperature range from 400 to 30,000 K for pressures of 0.10, 1.0, 3.0, 5.0 and 10.0 atm. The properties of the reacting mixture are affected by the possible occurrence of solid carbon formation at low temperature, and therefore attention is paid to the influence of the carbon phase transition by comparing the results obtained with and without considering solid carbon formation. The results presented here clarify some basic chemical process and are reliable reference data for use in the simulation of plasmas in reacting carbon and water mixtures together with the need of transport coefficients computation.     

Thermodynamic length in a two-dimensional thermodynamic state space

The main goal of this paper is to reach an explicit formulation and possible interpretation of thermodynamic length in a thermodynamic state space with two degrees of freedom. Using the energy and entropy metric in a general form, we get explicit results about thermodynamic length along isotherms, its relation with work and with speed of sound. We also look at the relation between the determinants of the energy and entropy metrics and find that they differ by a factor of T4.     

不同粒度八面体纳米钼酸镉的表面热力学性质

室温条件下,采用反相微乳液法制备了一系列不同粒度的八面体纳米CdMoO4,并对其组成、结构及形貌进行了表征.基于纳米CdMoO4与块体CdMoO4热力学性质的本质差异,结合化学热力学基本理论与热动力学原理,导出了获取纳米CdMoO4表面热力学性质的关系式;在此基础上,利用原位微量热技术成功获得了所制备的不同粒度八面体纳米CdMoO4的表面热力学函数,如比表面Gibbs自由能、比表面焓和比表面熵.本文为获取纳米材料表面热力学函数提供了一种有效而普适的新方法.     

在确定的热力学状态下测量气体导热系数与黏度

气体的导热系数和黏度是重要的热物性参数,其数值大小取决于所处的热力学状态。在目前的导热系数和黏度主要测量方法中,待测工质在测量时需经历非定常的过程或处于具有物性梯度的非平衡态之下,使得待测工质的物性在时间或者空间上不处于一个确定的热力学状态。本文利用圆柱定程干涉法,通过分析气体导热系数和黏度导致的声波能量耗散,结合气体输运理论中对稀疏气体的描述,探索了在确定的热力学状态下同时测量气体导热系数和黏度的方法,并以氩(Ar)为例进行了实验验证。测量结果与已有文献一致性较好,初步证实了方法的可行性。     

Diagramme de phases du systeme binaire LiNO3-NaNO3

Phase diagram of the binary system LiNO₃-NaNO₃ has been obtained by using direct and differential thermal analysis between 323 and 623 K. This system is characterized by an eutectic plateau at 467 K. The eutectic point is at 0.465 mole NaNO₃. A peritectic appears at 550 K. There is no miscibility in the solid state. These findings associated with some other thermodynamic results have been used to calculate the activities of the constituents along the liquids curve and the excess thermodynamic functions at 618 K. The constituents seem not to have a symmetrical influence on the thermodynamic quantities.

     

Thermodynamic interpretation of a single event of separation of the components during the distillation of an ideal solution

The results of a thermodynamic analysis of an elementary process of distillation in which the separation of the components of the solution occurs due to the absence of thermodynamic equilibrium between the phases are summarized and compared with results of studies of a single event of separation of a mixture at the expense of the energy supplied from an external source. A thermodynamic interpretation is proposed for optimum conditions of fine separation of an equimolar binary mixture by single-stage distillation.     

Line of percolation in supercritical water

The percolation transition of the hydrogen-bonded clusters of molecules is investigated in supercritical water by Monte Carlo computer simulations. Simulations have been performed at four thermodynamic state points located above the supercritical extension of the vapor-liquid coexistence curve on the p-T phase diagram and at four state points located below this curve. It is found in a temperature range of a few hundred Kelvin that the extension of the vapor-liquid coexistence curve separates the supercritical thermodynamic states in which the water molecules form infinite hydrogen-bonded clusters from those in which the hydrogen-bonded clusters are isolated oligomers. However, the difference between the size of the hydrogen-bonded clusters at thermodynamic states located at the two sides of the extension of the coexistence curve is found to decrease with increasing temperature, and the present results suggest that this difference is likely to vanish at high enough temperatures.     

Thermodynamics of alternating copolymer of styrene and CO in the 0—600 K region

The temperature dependence of heat capacity and the temperatures and enthalpies of physical transitions of the alternating copolymer of styrene and CO were studied in the 5—600 K region by the adiabatic vacuum and dynamic calorimetric techniques. The heat of combustion of the copolymer was measured at 298.15 K in a calorimeter with a static bomb and an isothermal shield. The thermodynamic parameters of glass transition and fusion were determined. The thermodynamic functions in the 0—550 K region and thermodynamic characteristics of the formation of the copolymer from simple substances at T = 298.15 K and p = 101.325 kPa were calculated. The thermodynamic parameters of alternating copolymerization in the bulk of styrene and CO were calculated in the 0—350 K region at a standard pressure.     

Thermodynamic study of the vapor–liquid equilibrium (VLE) data of the mixture formed by diethylenimide oxide with benzene

The thermodynamic evaluation of the experimental vapor?Cliquid equilibrium (VLE) data obtained at 760?mmHg in a recirculatory still, is presented for the binary system formed by diethylenimide oxide with benzene. The experimental VLE data were checked for thermodynamic consistency and reduced to the binary parameters calculated from three activity coefficients models.     

邻苯二甲酸在异丙醇-水混合溶剂中电离热力学性质的研究

The first thermodynamic dissociation constants of o-phthalic acid were determined at five temperatures from 278.15 to 318.15 K in 10, 14.93 and 20 wt% isopropanol-water solvent mixtures, by precise e. m. f. measurements of hydrogen-silver chlorld electrodes in cells without liquid junction. On the basis of Pitzer's theory, the method of polynomial approximation was used to determine the dissociation constants of H_2P and the results obtained were compared with traditional extrapolation according to the extended Debye-Huckel equation Results obtained from both methods agree within experimental error. The dependence of the first thermodynamic dissociation constant on temperature was given as a function of the thermodynamic temperature T by the empirical equation: pK_1=A_0+A_1/T+A_2/T. The thermodynamic quantities of dissociation in the mixed solvents have been calculated, and the results have been discussed.     

水-乙醇二元体系共沸混合物的热力学研究

用全自动低温绝热量热计测定了水、乙醇以及水和乙醇组成的共沸混合物在不同温区的摩尔热容Cp,m. 建立了共沸混合物Cp,m与温度T的函数关系.结果表明,水和乙醇组成的共沸混合物在98.496 K发生玻璃态转化,在158.939 K 和270.95 K发生固-液相变.获得了其相应的相变焓和相变熵.计算了以298.15 K为基准的该共沸混合物的热力学函数和超额热力学函数.     

邻苯二甲酸在异丙醇-水混合溶剂中电离热力学性质的研究

有机酸在混合溶剂中电离热力学性质的研究,无论在化学还是在生物领域中都有十分重要的意义。长期以来,人们对其进行了大量的研究,但对芳香族酸在混合溶液中的电离热力学性质的研究还只限于单取代苯甲酸在乙醇-水等少数几种混合溶剂中的热力学性质。为此,我们在278.15—318.15K范围内测定了无液接电池:     

ZnO纳米片层结构的原位生长机理及热力学函数

采用绿色水介质体系一步合成了3种不同尺寸的ZnO纳米片层结构。 通过微热量技术获取其原位生长过程的热谱曲线,从动力学和热力学角度分析其生长机理;利用电化学方法测定了不同温度下纳米ZnO与块体ZnO原电池的电势差,结合热力学基本公式求算出ZnO纳米片层结构的热力学函数值,并与生长机理关联讨论。 结果表明,ZnO纳米片层结构的生长经历了先表观吸热后表观放热,放热减慢,最后到达放热平台的热量变化阶段。 标准摩尔熵、标准摩尔生成Gibbs自由能及标准摩尔生成焓均随着尺寸减小而逐渐增大。 本文为纳米材料的原位生长机理与热力学函数的关联研究提供了新的思路和方法。     

Eu3+存在下盐酸头孢替安与牛血清白蛋白相互作用的研究

运用荧光光谱、紫外吸收光谱研究了Eu3+存在下盐酸头孢替安(Cefotiam Hydro-chloride,CH)与牛血清白蛋白(BSA)的相互作用.CH对BSA具有荧光猝灭作用,其猝灭机制为静态猝灭,BSA发射峰蓝移,二者之间的作用力主要为疏水作用和弱的静电作用.Eu3+的存在使得BSA发射峰蓝移程度降低,猝灭常数、结合常数、结合位点数减小,但没有改变CH对BSA的猝灭机制,热力学参数ΔH和ΔS都增大.从热力学参数的变化及Eu3+的竞争作用分析了Eu3+对CH与BSA作用影响的原因.     

Thermodynamic and structure studies of Gibbs films at soft interfaces

The thermodynamic and X-ray reflectivity studies were applied to the adsorbed films of 1-eicosanol, partially hydrogenated perfluorodecanol, and their mixtures at the hexane/water interface and clearly demonstrated the existence of domains. The thermodynamic and FTIR studies on ethyleneglycol monododecyl ether system and the thermodynamic and total reflection XAFS studies on dodecyltrimethylammonium bromide system at air/water interfaces confirmed that the inhomogeneous structure is rather generally observed in the adsorbed films. The knowledge from the thermodynamic and structure studies has been combined and further utilized in the mesoscopic thermodynamic formulation on the Gibbs films at soft interfaces.     

On the role of solute solvation and excluded-volume interactions in coupled diffusion

Coupled diffusion is observed in multicomponent liquid mixtures in which strong thermodynamic interactions occur. This phenomenon is described by cross terms in the matrix of multicomponent diffusion coefficients. This paper reports a theoretical analysis on the relative role of thermodynamic factors and Onsager cross-coefficients on cross-diffusion coefficients relevant to ternary mixtures containing macromolecules or colloidal particles in the presence of salting-out conditions. A new model based on frictional coefficients between solvated solutes is reported. This model predicts that the Onsager cross-coefficient is negative and contributes significantly to cross-diffusion coefficients even at infinite dilution for solutes with a large difference in size. These predictions are consistent with recent experimental results. The role of preferential solvation and excluded-volume interactions on the thermodynamic factors are also examined. Excluded-volume interactions are introduced through the use of the McMillan-Mayer thermodynamic framework after emphasizing some important aspects of diffusion reference frames and thermodynamic driving forces. Finally, new expressions for cross-diffusion coefficients are proposed.     

Thermodynamic studies on thin liquid films. I. General formulation

From the viewpoint that thermodynamic study is essential to elucidate the structure and properties of thin liquid films, thermodynamic equations based on a new convention and employing pressure as a thermodynamic variable are developed for adsorption at film interfaces of a plane-parallel film. The equations together with quasi-thermodynamic ones correlate the dependence of film tension on concentration, temperature, pressure, and disjoining pressure to film density, entropy and volume changes associated with adsorption, and thermodynamic film thickness, respectively. Based on the formulation adopting pressure as a variable, equations are also derived for the differences in thermodynamic quantity between the film and the bulk interfaces coexisting at equilibrium.This revised version was published online in October 2004.Due to an unfortunate error Figure 1 has been omitted in the first version of the article which was published online first on April 23, 2004.     

On the universal behavior of some thermodynamic properties along the whole liquid-vapor coexistence curve

When thermodynamic properties of a pure substance are transformed to reduced form by using both critical- and triple-point values, the corresponding experimental data along the whole liquid-vapor coexistence curve can be correlated with a very simple analytical expression that interpolates between the behavior near the triple and the critical points. The leading terms of this expression contain only two parameters: the critical exponent and the slope at the triple point. For a given thermodynamic property, the critical exponent has a universal character but the slope at the triple point can vary significantly from one substance to another. However, for certain thermodynamic properties including the difference of coexisting densities, the enthalpy of vaporization, and the surface tension of the saturated liquid, one finds that the slope at the triple point also has a nearly universal value for a wide class of fluids. These thermodynamic properties thus show a corresponding apparently universal behavior along the whole coexistence curve.     

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.     

Physicochemical properties of series of cardanol polyoxyethylene ether carboxylates with different ethoxylation unit at the interface

Series of cardanol polyoxyethylene ether carboxylates were synthesized with biomass cardanol as material to study their physicochemical properties at the interface. The surface tensions of the cardanol nonionic-anionic surfactants were measured at 25?°C and the thermodynamic parameters of adsorption were also calculated. The surface activity and thermodynamic properties of the cardanol nonionic-anionic surfactants were correlated to their chemical structures. With increasing of the number of the ethoxylation unit in the hydrophilic group, a decrease in adsorption efficiency and an increase in surface tension at critical micelle concentration and thermodynamic free energy of adsoption were observed and were attributed to a decrease in adsorption of the cardanol nonionic-anionic surfactants at the interface. Series of the cardanol nonionic-anionic surfactants have good wettability and foaming property. The foaming capacity and the foaming stability of the solution of the cardanol nonionic-anionic surfactants increase by decreasing in the ethoxylation unit and by increasing the double bond of the hydrophobic group. The physicochemical properties of the cardanol nonionic-anionic surfactants at the interface are correlated to the chemical structures of the investigated surfactants, and there is the synergy effect between the nonionic hydrophilic group and the anionic hydrophilic group at the interface.