不同类型化学平衡的热力学本质

探讨了定温定容下气相化学平衡、复相化学平衡和纯凝相化学平衡的热力学本质。指出，对于不同类型的反应，建立化学平衡的根本原因其实是不相同的，不能简单地都归因于混合过程对系统Gibbs自由能的影响。     

温度和压力对化学反应方向和化学平衡的调控

根据一般化学反应方程式,给出了理想气体化学反应Gibbs自由能随反应进度变化的关系式。该式由3部分组成,第1部分对应于标准压力和给定温度下,反应物和生成物摩尔生成Gibbs自由能之和随反应进度的变化,是化学反应的温度调控项;第2部分对应于压力对Gibbs自由能的贡献,是压力调控项;第3部分是混合熵的贡献,是决定化学平衡的重要因素。因此,一个化学反应,向什么方向进行,进行到什么程度,可以通过温度和压力的调控来实现。以合成氨和工业合成气为例,讨论了如何利用压力和温度的调控,实现反应方向和平衡的控制。     

G-ξ图的一种错误表示

指出了物理化学教材中有关G-ξ图的一种错误表示,并阐明了错误的原因。     

电化学方法测定纳米材料的热力学函数

以纳米铜为例,首次采用电化学方法获取纳米材料的热力学函数.通过电化学沉积法制备了粒子尺寸约80nm的纳米铜电极,测定纳米铜与块体铜电极的电势差,以块体铜的热力学函数值为参考标准,根据纳米铜与块体铜的热力学关系式,求得纳米铜的标准摩尔生成焓、标准摩尔生成吉布斯自由能、标准摩尔熵分别为5.16kJmol-1、0.216kJmol-1、49.75JK-1mol-1,同时,求得纳米铜可逆电池反应的热效应为-4.95kJmol-1.     

2种标准摩尔反应熵的关系

研究认为以温度和浓度为自变量的摩尔反应熵ΔrSm（c）实质是定容摩尔反应熵,因而不能用偏摩尔量定义,它与相应的定压摩尔反应熵ΔrSm（p）即使在同一状态点数值也不相等。通过严格数学处理得到了c和p2种标准态下摩尔反应熵之间的关系,结果与现有文献不同。文中还推导了其他相关标准态摩尔反应热力学函数间的关系,并通过相互关联和转换印证了本文结论的正确性。     

改进的连接性指数用于链烷烃热力学性质与沸点研究

基于邻接矩阵和原子特征值qi，建立邻接指数^mQ,用^0Qr,^1Q与85种链烷烃的标准生成焓、标准生成自由能、标准熵和沸点关联，相关系数均在0.99以上，属于良好模型，与Randic指数的^mX比较，^mQ具有良好的性质相关性。     

关于理想气体混合熵变的讨论

探讨了关于理想气体混合过程中熵变的教学方法。采用多种方式结合,对于化学热力学理论教学过程中容易混淆概念的区分及记忆给出了一个教学实例。     

不同标态下标准电极电势间关系的热力学解释

利用标准吉布斯自由能变化ΔrGm与标准电极电势和标准反应平衡常数间的联系,分析不同标态下电极标准电极电势间的关系。根据这一思想,以水解离平衡为例,讨论了设计原电池求化学反应平衡常数的一般方法。     

烷烃的热力学性质与结构的关系

在分子图邻接矩阵的基础上提出了一个新的连接性指数mX,mX与烷烃的标准熵、原子化焓、标准生成焓、汽化焓、标准生成吉布斯自由能具有良好的线性关系,相关系数均在0·99以上。结果表明,该模型简单、实用、可靠,而且物理意义明确,对有机物有较高的结构区分能力。对157种烷烃的计算结果表明,热力学性质的计算值和实验值的平均相对误差不超过0·77%。     

Theoretical Studies on the Molecular Structures and Thermodynamic Properties of Polychlorinated Fluoranthenes

DFT-B3LYP/6-311G** method has been used to optimize molecular geometric structures of 527 polychlorinated fluoranthene(PCFRT) congeners and calculate their thermo-dynamic properties in the ideal gas state,such as heat capacity at constant volume(Cv),entropy(S),standard enthalpy of formation(ΔfH) and standard Gibbs free energy of formation(ΔfG).The relations of Cv,S,ΔfH and ΔfG with the number and position of chlorine atoms have also been explored,from which the relative stability of PCFRT congeners was theoretically proposed according to the magnitude of the relative standard Gibbs free energy of formation(Δr,fG).It was found that some of the PCFRT isomers are in a nonplanar configuration and there are intramolecular Cl…Cl weak interactions in some of the isomers.With increasing the number of chlorine atoms,the values of ΔfH and ΔfG of the most stable PCFRT isomers decrease initially and then increase.The values of ΔfH and ΔfG of PCFRT congeners with the same number of chlorine atoms show a strong dependence on the positions of chlorine atoms.The relative thermodynamic stability of PCFRT isomers is determined mainly by intramolecular adjacent Cl…Cl nuclear repulsive interaction between Cl atoms at two different six-membered rings.Most PCFRT congeners are easier to form thermodynamically than their parent compound.     

Chemical Equilibrium, Free Energy, and Entropy of Mixing

In this paper we describe an approach for teaching the relation between chemical equilibrium and free energy that is, according to our experience, very efficient and enlightening. This approach has a strong visual appeal and can be used at different levels, from simple presentation of the results as graphs of free energy versus reaction mixture composition, up to full derivation of formulas to find the equations of the curves.     

Entropy Production along Dominant Pathway of Nonequilibrium Phase Transition in Mesoscopic Chemical System

We consider a bistable mesoscopic chemical reaction system and calculate entropy produc- tion along the dominant pathway during nonequilibrium phase transition. Using probability generating function method and eikonal approximation, we first convert the chemical master equation into the classical Hamilton-Jacobi equation, and then find the dominant pathways between two steady states in the phase space by calculating zero-energy trajectories. We find that entropy productions are related to the actions of the forward and backward dominant pathways. At the coexistence point where the stabilities of the two steady states are equiv alent, both the system entropy change and the medium entropy change are zero; whereas at non-coexistence point both of them are nonzero.     

Chemical Characterization of Kraft Lignin Prepared from Mixed Hardwoods

Chemical characterization of kraft lignin (KL) from mixed hardwoods (Acacia spp. from Vietnam and mixed hardwoods (mainly Quercus spp.) from Korea) was conducted for its future applications. To compare the structural changes that occurred in KL, two milled wood lignins (MWLs) were prepared from the same hardwood samples used in the production of KL. Elemental analysis showed that the MWL from acacia (MWL-aca) and mixed hardwood (MWL-mhw) had almost similar carbon content, methoxyl content, and C₉ formula. KL had high carbon content but low oxygen and methoxyl contents compared to MWLs. The C₉ formula of KL was determined to be C₉H_7.29O_2.26N_0.07S_0.12(OCH₃)_1.24. The M_w of KL and MWLs was about 3000 Da and 12,000–13,000 Da, respectively. The structural features of KL and MWLs were investigated by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectrometry (¹H, ¹³C NMR). The analyses indicated that KL underwent severe structural modifications, such as γ-carbon cleavage, demethylation, and polycondensation reactions during kraft pulping, which resulted in increased aromatic content and decreased aliphatic content. The main linkages in lignin, β-O-4 moieties, were hardly detected in the analysis as these linkages were extensively cleaved by nucleophilic attack of SH^- and OH^- during pulping.     

几种过渡金属混配配合物的构型和量子化学研究

对几种五配位的过渡金属配合物晶体结构构型进行了详细讨论,通过扭曲角的计算证明它们均为正三角双锥(TBP)和正向四方锥(TP)的过渡构型。运用AM1量子化学计算方法,对混配体的一些物理化学参数,特别是配位N原子轨道对前线轨道的贡献进行了研究。结果表明,配位N原子轨道对前线轨道的贡献不大,而且也不影响配位构型的变化。计算还表明大多数以三(2-苯并咪唑亚甲基)胺为配体的过渡金属配合物均具有扭曲的三角双锥构型,而铜配合物的构型随协同配体的不同,在正三角双锥和正向四方锥之间的变化范围很大,这是由于铜离子较强的John-Teller效应造成的。     

混合导电型陶瓷透氧膜材料的化学稳定性

考察了Sr-Co -Fe -O系列和Bi-Sr-Fe -O系列混合导电型无机透氧膜材料在氧分压小于 1.0 13Pa的气氛中 ,在 850℃和 950℃高温下加热 2 4～ 10 0h前后结构的变化。发现Bi -Sr -Fe-O系列透氧膜材料具有良好的化学稳定型 ,可以用于还原气氛下的催化反应。     

Fidelity and Mutual Entropy in Mixed States for Fermi-resonance Coupling Vibrations of CS2

states of Fermi-resonance coupling vibrations in molecule CS₂. It is demonstrated that those fidelities are dominant-positively correlated with each other, one of which by Wang et al. (Phys. Lett. A 373, 58 (2008)) is the most striking in dominant anti-correlation with quantum mutual entropy. That is useful for molecular quantum computing and quantum information.     

Conditions for Mixed Mode Oscillations and Deterministic Chaos in Nonlinear Chemical Systems

An approach has been proposed for finding the conditions for the existence of mixed-mode oscillations and deterministic chaos in a kinetic scheme after reduction to a simple system of equations. Analysis of the position and stability of the steady states of this system suggested simple conditions for the existence of mixed-mode oscillations and deterministic chaos. The boundaries for monostability, bistability, and oscillations were also found. The results obtained were completely confirmed by numerical modelling.     

锌镀层表面混合稀土转化膜的研究

利用浸液法在匀底层上获得混合稀土转化膜，研究了处理溶液的浓度，ｐＨ，温度，促进剂Ｈ２Ｏ２的含量及处理时间等因素对膜层耐蚀性的影响，从而是确定了适宜的工艺条件。用俄歇电子能谱对膜层的组成，厚度进行了测定。     

From Chemical Processes to Electrochemical Processes: The Key to Minimal Entropy Production

Exothermic chemical reactions exploited in the chemical industry today represent opportunities for the development of fuel cell like devices that can perform these reactions electrochemically. Thereby, the excessive generation of waste heat is avoided and electric power is produced. Moreover, the reactions that exhibit a positive entropy change (S > 0) when performed electrochemically may enable the direct conversion of heat into power to compensate for S. The rapid development of fuel cell technology appears to be an ideal precursor for such new developments. On the other hand, interest form the chemical industry for the development of fuel cell technology can boost the market penetration of conventional fuel cells. In some cases, conventional fuel cell types like the MCFC and the SOFC may be used without change, in other cases maybe only the anode or cathode catalyst materials have to be modified or replaced. New, dedicated electrochemical reactors may be developed. Because of the different reactions, reactants, and products, a new research area for the design of new electrocatalyst lies ahead.     

10-十一烯酸衍生物混合体系的表面化学

自表面张力测定对１０－十一烯酸胆碱衍生物（三甲基－［２－（１０－十一烯酰氧乙基）］碘化铵）与１０－十一烯酸钠混合体系的表面吸附和胶团形成作了研究；对该体系中的囊泡形成进行了电镜观察。结果表明，疏水链端基为不饱和烯基的正、负离子表面活性剂混合体系和有饱和疏水链的混合体系一样，也有很高的表面活性，易于表面吸附和形成胶团，并且容易在水及乙醇－水溶液中形成相当稳定的囊泡。这些结果的原因可归之于正、负表面活