Nd(NO_3)_3-HNO_3-H_2O体系的过量吉布斯自由能和Nd(NO_3)_3-HNO_3-H_2O-HDEHP-AMSCO体系水相中各组分活度系数的计算

我们简化了混合电解质溶液过量吉布斯自由能的Pitzer公式。用此简化公式并结合我们以往的工作计算了Nd(NO_3)_3-HNO_3-H_2O体系的过量吉布斯自由能和Nd(NO_3)_3-HNO_3-H_2O-HDEHP-AMSCO体系水相中各组分的活度系数,计算值与实验值均很接近。此工作为镧系金属萃取分离进行热力学分析提供了方便。     

环己烷-乙醇体系活度系数的测定

作者通过测定环己烷 乙醇体系气液平衡实验数据,用热力学公式计算出活度系数作为实验值。然后采用超额吉布斯函数与活度系数之间的关联式,即Willson方程作数学模型,用最小二乘法对实验数据进行回归,求出关联式中的常数,从而获取整个浓度范围内的活度系数,得到的活度系数用Gibbs Duhem公式进行热力学一致性校正,说明所用模型正确,数据可靠。同时计算出超额吉布斯函数,从而可以用能量来表示实际溶液与理想溶液之间存在的偏差。     

用稳定化合物的熔化自由能从含稀土二元相图提取活度

本文用正规溶液模型，导出了用二元系稳定化合物的熔化自由能提取组元活度的公式，用Ｒｉｃｈａｒｄｓｏｎ假设进行了推广，并预报了Ｆｅ－Ｙ、Ｆｅ－Ｌａ二元系组元的活度。     

计算高聚物增塑体系混合自由能新方法

高聚物增塑体系混合自由能与浓度关系 ΔGm=f(ω1) ,不仅反映了增塑体系热力学稳定性好坏 ,而且可以预测溶液各组分间的作用能力 [1,2 ] .通过实验可直接得到增塑体系混合自由能的相关数据 ,其中包括偏蒸气压值测量法、渗透压法、反相气相色谱法及小角 X射线散射法等[3～ 8] .这些方法可以测量增塑体系挥发性组分的偏摩尔化学位值 ,利用下面公式计算Δμ1/RT =ln(p1/p1,S)式中 p1,p1,S是某温度下增塑体系增塑剂的偏蒸气压值和纯增塑剂的饱和蒸气压 .1　现有的高聚物混合体系自由能 ηGm计算方法对于低分子溶液体系各组分的偏摩尔化学位Δ…     

通用化学平衡计算和载流床反应器模拟程序的初步研究

Ⅰ.通用化学平衡计算 与热化学数据库相联结,采用进度调整方法编制了多相多元体系的化学平衡计算程序。 本文在选取独立组元的算法上提出了改进,可以减少运算量。另外还扩展了程序的功能,使本程序在以下三种输入条件下都能计算,包括:(1)给定原子矩阵,各组元的标准吉布斯生成自由能及初始摩尔数;(2)给定一组独立化学反应的计量系数矩阵,平衡常数和各组元的初始摩尔数;(3)给定原子矩阵,各组元的标准吉布斯生成自由能和体系的元素组成。     

稀土Invar合金热力学性质研究

制备了稀土Invar（因瓦）合金YFe_(12-x)V_x（x＝1.6，2.0；2.4，2.8，3.2）和SmFe_(12－x_V_x（x=2.4, 2.8）采用电动势法以CaF_2单晶作为固体电解质，测定了钇和钐在相应合金中的活度．计算了偏摩尔自由能等热力学性质．测定温度对两类合金分别为920－1020 K和900－1000 K．     

热力学过剩函数与相图计算

一、引言热力学过剩函数的定义可以写成Y~E=Y~R-Y~I(1)式中Y~R和Y~I分别为实际溶液和同一组成假想为理想溶液的某热力学性质,可以是Gibbs自由能G、熵S、焓H和体积V等.这个定义也适用于溶液中各组元的偏摩尔热力学性质,容易证明,溶液中组元i的偏摩尔过剩函数与活度系数γ_i之间的关系如下,     

TmCl3-ACl（A=Na，K，Rb，Cs）体系相图的热力学优化计算

综合实验相图信息和热力学数据运用CALPHAD技术优化和计算了TmCl3-ACl体系的相图。液相的吉布斯全摩尔自由能采用新改进的用于短程有序体系的以近似似化学模型进行描述。借助计算机辅助分析，一系列的热力学函数被优化得到。计算的相图和热力学参数是热力学自恰一致的。     

偏摩尔量加和公式可能的两处新应用

本文探讨了偏摩尔量加和公式的两处新的应用。其中之一应用于摩尔反应吉布斯自由能与化学势关系式的推解,另一应用于离子活度关系式的推解。在这两个关系式的推解过程中若采用偏摩尔量的加和公式,不仅可以使两个关系式的物理概念更加明晰,推导更加合理化,也可以使这两个关系式的适用环境更易被人接受和理解。     

三元系中两相区边界上活度之间的关系以及该关系与结线方位的依从性

本文研究了三元系中两相区边界上某组元的活度与三个组元的活度积φ之间的关系, 并导出了表示上述关系的重要公式, 该公式是一个将各种类型的三元系两相区的公式都概括进去的普遍式. 同时本文还详细地分析了结线的方位对活度之间关系的影响. 又应用了θ函数克服沿两相区边界上积分中的困难. 此外还完善了Krivsky和schuhmann规则。     

雷公藤内酯甲的制备和晶体结构

从雷公藤(TripterygiumwilfordiiHook.F.)根心部分的乙醇提取液中,采用硅胶柱色谱法和TLC方法得到纯的雷公藤内酯甲(WilforlideA).用IR,¹HNMR和元素分析表征,并测定其单晶结构.化合物分子式为C₃₀H₄₆O₃,M_r=454.70,晶体属正交晶系,P2₁2₁2₁空间群,晶胞参数:a=0.732(4)nm,b=1.283(7)nm,c=2.693(6)nm,V=2.5327nm₃,Z=4,D_c=1.192g·cm^-3,μ(MoKα)=0.695cm^-1,F(000)=1107,R=0.039,R_W=0.044,分子为五环三萜γ-内酯.分子中C22-C23为烯键,C11连有羟基,C33_O3为羰基,整个分子呈起伏状,不在同一平面内.从AM1计算结果可以看出,仲羟基中的O1及γ-内酯中的O3原子净电荷大,致使分子极性较大,易在O1和O3部位发生亲核反应和氧化还原反应,显示分子的反应活性     

Operational method for slope estimations

The operational method yields an abundance of new slope estimating formulae that apply to equidistant, curvilinear data. The performances of two of these new formulae are compared to the standard formula for center-point slope estimations on three data points. It is demonstrated that the standard formula is only a special case developed from the more general operational approach. New slope formulae at the terminal values of three curvilinear data are derived. Formulae applicable to more than three data points can also be obtained.     

Numerical analysis of complex dielectric mixture formulae

As a continuation of our earlier work (Ref. [9]) the complex (frequency dependent) dielectric behaviour of some mixture formulae are studied numerically. These include matrix-inclusion type formulae (as the Wagner-Sillars or the Bruggeman-Boyle equations), mean-field statistical mixture formulae (as the Böttcher-Hsu equation) and symmetrical integral formulae (as the Looyenga equation). The frequency dependent dielectric properties are first calculated for a model system at various particle shapes, field orientations and volume fractions. After this, the validity of these equations is checked on typical sets of experimental data. For low loss powders, the Böttcher and Looyenga equations are suggested; for emulsions, suspensions and filled polymers, the matrix-inclusion type formulae give acceptable results in most cases, while for metal-insulator composites mean-field statistical mixture formulae have to be used, as they are capable of describing the percolation phenomenon.     

Entropy-energy decomposition from nonequilibrium work trajectories

We derive expressions for the equilibrium entropy and energy changes in the context of the Jarzynski equality relating nonequilibrium work to equilibrium free energy. The derivation is based on a stochastic path integral technique that reweights paths at different temperatures. Stochastic dynamics generated by either a Langevin equation or a Metropolis Monte Carlo scheme are treated. The approach enables the entropy-energy decomposition from trajectories evolving at a single-temperature and does not require simulations or measurements at two or more temperatures. Both finite difference and analytical formulae are derived. Testing is performed on a prototypical model system and the method is compared with existing thermodynamic integration and thermodynamic perturbation approaches for entropy-energy decomposition. The new formulae are also put in the context of more general, dynamics-independent expressions that derive from either a fluctuation theorem or the Feynman-Kac theorem.     

A new method for calculating activity coefficients of mixed electrolytes

In present work, a new method is developed from which activity coefficients for both electrolytes in admixture can be obtained simultaneously from the fitting of experimental activity coefficients of one of the electrolyte. The calculated results for the system HCl+KCl at 25°C are reported and discussed.     

High order accurate,one-sided finite-difference approximations to concentration gradients at the boundaries,for the simulation of electrochemical reaction-diffusion problems in one-dimensional space geometry

Accurate calculation of concentration gradients at the boundaries is crucial in electrochemical kinetic simulations, owing to the frequent occurrence of gradient-dependent boundary conditions, and the importance of the gradient-dependent electric current. By using the information about higher spatial derivatives of the concentrations, contained in the time-dependent, kinetic reaction-diffusion partial differential equation(s) in one-dimensional space geometry, under appropriate assumptions it is possible to increase the accuracy orders of the conventional, one-sided n-point finite-difference formulae for the concentration gradients at the boundaries, without increasing n. In this way a new class of high order accurate gradient approximations is derived, and tested in simulations of potential-step chronoamperometric and current-step chronopotentiometric transients for the Reinert-Berg system. The new formulae possess advantages over the conventional gradient approximations. For example, they allow one to obtain a third order accuracy by using two space points only, or fourth order accuracy by using three points, and yet they yield smaller errors than the conventional four-point, or five-point formulae, respectively. Needing fewer points, for approximating the gradients with a given accuracy, simplifies also the solution of the linear algebraic equations arising from the application of implicit time integration schemes.     

All mixing coefficients and consistency test calculations for binary mixed electrolytes

Two new methods are reported from which the mixing activity coefficients of both electrolytes in a binary mixture can be computed simultaneously from fitting the activity coefficients of one of the electrolytes only and without using the derivatives of the parameters. Furthermore, variations caused by changing the fractional ionic strengths at fixed total ionic strength entails no assumptions about the ionic strength dependence of the mixing coefficients. The methods are shown to be superior to other methods. The results for the system HCl+KCl at 25°C are discussed.     

A point-charge representation of frost-model wave functions

A point-charge representation of Frost-model wave functions is derived from a symmetry-adapted perturbation theoretic expansion. The new point-charge model is simpler than those suggested previously yet gives good estimates of first-order molecular properties. The treatment can easily be extended to deal with second-order properties and, when this is done, formulae similar to those of the Drude theory are obtained. Using these formulae, theoretical expressions for the refractive indices of methane, ethane and water are computed and are in reasonable accord with experiment for the two hydrocarbons but less satisfactory for water.     

Simple methods for dead-time and pile-up corrections in analytical gamma-ray spectrometry

In the paper the mathematical methods for dead-time and pile-up corrections are discussed. The dead-time correction formulae for a system of two short-lived isotopes and constant component (background) are reported which mathematical problem has not been solved so far. The new electronic circuit for simultaneous measurements of clock- and live- (or dead-) times is described. It is shown that using this circuit one can correct the counting loss for both effects simultaneously. Finally, the advantages and disadvantages of mathematical methods for dead-time and pile-up corrections are discussed based on the authors' several-year laboratory practice.     

Activity coefficients of electrolytes in binary mixtures calculated using total molal quantities

Activity coefficients in binary mixed electrolytes are expressed in terms of the parameters from total molal quantities. Two versions of the calculations are presented and compared with the methods of Pitzer and Scatchard. For each method interrelations among the various parameters are examined. The system being tested is HCl+CoCl₂+H₂O at 25°C, for which new experimental data at low ionic strengths are included.