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从一道习题解答谈水的Λm和Λ∞m

电解质的摩尔电导率Λm是指把含有1mol电解质的溶液置于相距单位距离的电导池的两个平行电极之间时具有的电导.摩尔电导率受溶液的浓度影响,不管是强电解质还是弱电解质,随着溶液浓度的减小,摩尔电导率增大.Λ∞m就是指溶液无限稀释时的摩尔电导率.这里的溶液是用水作溶剂,那对于纯水的Λm和Λ∞m又作何理解呢?下面以一道常见的习题的解答来谈谈笔者的看法,权作引玉之砖.该习题出自南京大学傅献彩等编的<物理化学>(下册)第5版第57页(习题18)[1].     

关于△HΘm和△GΘm的一些问题

本刊在1986年第2期刊登了《对化学反应中△H~0和△G~0单位的探讨》一文。该文对目前在国内外常见的物理化学及普通化学教材中△H~0和△G~0两个物理量单位的不同进行了讨论,并认为沿用[焦耳]比较合理。这一结论是不妥当的。最近本刊陆续收到几篇讨论这一问题的文章,我们现选登高执棣同志的文章,该文从一些基本概念开始推导出该两个物理量的单位应为[焦耳·摩尔~(-1)],较为令人信服。晚些时候又收到有相似看法的东北林业大学林工系史国瑞和山西大学化学系严成华等人的文章,本刊不再一一刊登。本刊编辑部在此向史国瑞、严成华以及其他来稿或指出这一问题的同志表示衷心的谢意。     

SinP+m(n+m=5)结构和稳定性的理论研究

在实验的基础上 ,利用量子化学方法对 Sin P+ m( n+m=5 )的各种可能构型进行几何构型优化 ,预测各团簇的稳定结构 ,从中得出各个团簇稳定构型之间的基本关系 ,当 n>m时 ,团簇的稳定构型与 Si+ n 相似 ,而当 n相似文献   

二元n+m(m≥3)相多体系可能实在网的拓扑结构

本文对作者提出的推导二元n+3相多体系全部可能实在网的方法和结果作进一步归纳,强调了这些网的构型与各稳定级别点的标记或作为标记的相,在化学成分图解上的位置之间确定的对应关系。在此基础上给出了构筑和检查二元n+m(m>3)相多体系可能网的一般原理:任何该类网应是一个或一个以上不同二元n+3相多体系网的合理拚接,其上分别缺失相同m—3相的点数均为n+3。因此,二元n+3相多体系网是二元n+m(m>3)相多体系网的基本构筑单元,作为例子,具体构筑了二元n+4相多体系具有最多稳定点的最大部分封闭网,确认这类网只有一张。     

THE CTYSTAL STRUCTURE OF m—FERROCENYLACETOOHENONE

<正> The title compound C18H16FeO (Mr=304. 17) crystallizes in the mono-clinic system,space group P21/c with cell constants a= 14. 428(3),b=9. 939(8),c = 10. 027(5) A .B=93. 73(1),Z=4,Dc=1.41 gcm-3 and V= 1435. 0A 3.The structure is solved by direct methods and refined by least-squares technique to final R=0. 038 and Rw=0.051 based on 2413 independent reflections with I>3o(I). Result shows that both the Cp rings are approximately parallel with dihedral angle of 1. 2 ,The phenyl ring is somewhat tilted from the Cp ring linked to it with a dihedral angle of 8. 36 . The oxygen and carbon atoms of the aceto group are almost co-planar with the phenyl ring.     

Theoretical Studies of the Electronic Structures and Spectrum Properties of Pt n Ni m (n + m = 7, n, m ≠ 0) Clusters

We studied Pt _n Ni _m (n + m = 7, n, m ≠ 0) clusters within the framework of the density functional theory (B3LYP) at the LANL2DZ level. The calculated results show that the Fermi levels are determined by the number of Pt atoms, which gain electrons from Ni atoms. Meanwhile, multifarious orbital hybridization is found in the frontier molecular orbital, and the more platinum or nickel atoms, the smaller energy gap it has. Moreover, the calculated IR and Raman spectrum indicates the aromatic character, which is vital for transitional metal clusters.     

Electronic structure analysis of small gold clusters Au m (m?��?16) by density functional theory

Small gold clusters Au _m (m????16) were analyzed step by step using the density functional theory at B3LYP level with a Lanl2DZ pseudopotential to understand the rules governing the structures obtained for the most stable clusters. After a characterization by means of the NBO population analysis and spin densities, the particular electronic structure of such species was confronted to their structural parameters and stability. It appears that the most stable structures can be described in an original way through resonance structures resulting from an analysis of Au _m clusters into dimeric Au₂ subunits. These are arranged so as to promote: 1. A good overlap between bonding ?? and anti-bonding ??* areas belonging to different Au₂ units. 2. A cyclic flow of electrons over the whole cluster. This model uses relatively simple chemical concepts in order to justify most of the structures already found in the literature as well as to establish a new approach explaining the structural transition from two- to three-dimensional configurations.     

Photoelectron spectroscopy of silicon and germanium-fluorine binary cluster anions (SinF m − , GenF m − )

Electronic properties of silicon-fluorine and germanium-fluorine cluster anions (Si_nF _m ^? n = 1–9, m = 1–3, Ge_nF _m ^? ; n =1–9, m = 1–3) were investigated by photoelectron spectroscopy using a magnetic-bottle type electron spectrometer. The binary cluster anions were generated by a laser vaporization of a silicon/germanium rod in an He carrier gas mixed with a small amount of SiF₄ or F₂ gas. Comparison between photoelectron spectra of Si_nF^?/Ge_nF^? and Sin /Gen (n = 4–9) gives the insight that the doped F atom can remove one electron from the corresponding Sin _n ^? /Ge _n ^? cluster without any serious rearrangement of Sin/Gen framework, because only the first peak of Si _n ^? /Ge _n ^? , corresponding singly occupied molecular orbital (SOMO), disappears and other successive spectral features are unchanged with the F atom doping     

TOPOLOGICAL CONFIGURATIONS OF POSSIBLE REAL NETS IN BINARY n+m(m≥3) PHASE MULTISYSTEMS

This paper further summarizes the method and results developed to find all possible real nets in binary n+3 phase multisystems, and emphasizes that there is a definite relationship between configurations and symbols of stable and metastable invariant points of nets or positions of phases as symbols on the chemographic bar. On the basis of these, a general principle is developed to construct and check possible neets in binary n+m (m>3) phase multisysterns: this sort of nets must be the reasonable combination of one or more than one distinct binary n+3 phase multisystem subnets, in which the number of points missing respectively same m—3 phases in n+3. Therefore, the binary n-4-3 phase nets are basic construction units of the binary n+m(m>3) phase nets. As an instance, the maximum partially closed net in binary n+4 phase multisystems, which has the most stable invariant points, is constructed, and it is indicated that this sort of net is unique.     

Crystallization of the Lewis-Wahnström ortho-terphenyl model

Crystallization is observed during microsecond long molecular dynamics simulations of bent trimers, a molecular model proposed by Lewis and Wahnstro?m for ortho-terphenyl. In the crystal, the three spheres that make up the rigid molecule sit near sites of a body centered cubic lattice. The trimer bond angle is almost optimal for this structure. The crystal exhibits orientational disorder with the molecules aligned randomly along the three Cartesian axis, i.e., cubatic orientational order. The rotational and translational mobilities exhibit only modest decreases on crystallization, by factors of 10 and 3, respectively. The rotational relaxation does change from Debye-like in the liquid to large angle jumps in the crystal. We consider the origin of the superior glass forming ability of the trimer over the monatomic liquid.     

SOLUBLE POLY-(o, m)-TOLUIDINE

The soluble poly-o-toluidine (POT) and poly-m-toluidine (PMT) have been success-fully prepared under controlled conditions of polymerization and post-treatment, andcharacterized by IR, VPO and elemental analysis. It is found that the soluble and insol-uble polymers obtained with two different methods (Ⅰ and Ⅱ) have the similar conduc-tivity and molecular chain structure. VPO measurement shows that the number averagemolecular weight (Mn) of soluble polymers is about 3000. The mole ratio of benzoidto quinoid is about 3:1 according to ~1H-NMR and elemental analysis. Free-standingfilms of intrinsic POT and PMT have been obtained by casting their CHCl_3, THF orDMF solutions onto a glass surface.     

线性聚合物链的m级相互作用近似

导出了线性聚合物链ｍ级相互作用近似统计权重矩阵的递推公式,它满足构象统计的矩阵代数法所要求的连接条件。按作为四元组转动的Ｃ－Ｃ键旋转角的函数计算了正庚烷的构象能。研究了聚乙烯（ＰＥ）链由相隔六键的原子间所施加的四级相互作用对均方末端距和均方回转半径的特征比的影响,结果表明考虑四级相互作用,ＰＥ键的特征比要比三级相互作用近似的小。     

C6FmH6－m (m＝1～6)结构及芳香性的理论研究

运用密度泛函理论方法B3LYP, 选取6-31G(d,p)和6-31G(d)两种基组对C₆F_mH_{6－ m}(m＝1～6)进行了几何优化, 并对优化结构运用B3LYP/6-31G(d,p)方法进行了键能计算, 选用B3LYP-GIAO/6-31＋＋G(d,p)方法进行核无关化学位移(Nucleus-Independent Chemical Shifts, NICS)的计算. 研究表明, 所研究的氟代苯的基态均呈平面几何结构, 6-31G(d,p)基组计算的键长、键角的结果与实验值更加吻合, 其芳香性都较苯的大, 且随取代F数目的增加而增大. 用NBO对分子总NICS及各键对NICS的贡献进行了分解, 结果显示, 氟的p_z孤对电子参与六元环π键的形成是使氟代苯分子芳香性变大的主要原因.     

étude thermodynamique de certains médicaments

Two compounds of sulphamide type:p-amino-benzene sulphonamide (I) and 3,4-dimethylisoxazol 5-sulphanylamide (II) were studied by combustion calorimetry and by differential scanning calorimetry (DSC).The enthalpies in solid state at 298,15 K of combustion, _c H _m ^o (I)=-2788,5±1,6 kJ mol^–1, _c H _m ^o (II)=-5036±3,8 kJ mol^–1 and of formation, _f H _m ^o (I)=-458,3±1,6 kJ mol^–1, _fH _m ^o (II)=-180,1±3,8 kJ mol^–1 were determined.The thermal effects concerning the melting and phase transition of this compounds were also measured.

     

Analysis of peptides and proteins using sub-2 μm fully porous and sub 3-μm shell particles

The objective of this study was to evaluate the potential of sub-2 μm totally porous particles and sub-3 μm shell particles for peptide and protein analysis. Specific analytical strategies must be developed for these biomolecules as their importance in the pharmaceutical industry increases and as their structural complexity involves some issues when classical LC conditions are employed. Attention was paid on comparing these different columns in various LC conditions (different temperatures, gradient times, and mobile phase flow rates). The comparison of the different supports was assessed considering columns characteristics (quality of packing, silanol activity, pore size, totally porous or shell particles). In this article, peptides were first analyzed with both column technologies. Similar results to those achieved with low molecular weight compounds were obtained (peak capacity >100 for t_grad around 3 min and columns dimensions of 2.1 mm id × 50 mm), but specific conditions were required (elevated temperature and the use of a volatile ion-pairing reagent, namely TFA). For peptide analysis following tryptic digestion, the goal was to improve peak capacity and resolution because of the large number of generated peptides. For this purpose, longer columns packed with porous sub-2 μm or shell sub-3 μm particles (i.e., 150 mm) and gradient times (i.e., up to 30 min) were tested. On the other hand, proteins in their intact forms have higher molecular weights (MW > 5000 Da) and a tertiary structure, thus requiring different conditions in terms of stationary phase hydrophobicity (C₄vs. C₁₈) and pore size (300 vs. 120 Å). In addition, there were issues with adsorption onto the LC system and/or the column itself. This study showed that proteins with MWs lower than 40,000 Da required chromatographic conditions close to those employed for peptide analysis. For larger proteins, a C₄ 300 Å stationary phase gave the best results, confirming theoretical predictions.     

Pt_nNi_m（n＋m=7,n,m≠0）团簇结构稳定性与磁学性质

采用密度泛函理论（DFT）中的杂化密度泛函B3LYP方法在LANL2DZ基组水平上对PtnNim团簇的各种可能构型进行了几何结构全优化,得出了它们的基态构型,并对其稳定性和磁学性质进行了计算研究.研究结果表明：PtnNim团簇的基态结构都为立体结构,对称性较低,多重度较高,Pt5Ni2团簇的稳定性最好;从磁性上看,Pt...     

IgA肾病免疫吸附剂的研究（m）

在碱性条件下，用环氧氯丙烷对琼脂糖载体进行活化，并通过戊二醛法引入手臂，偶联羊抗人IgA的抗体，清除IgA肾病病人体内高含量的IgA分子。从而达到治疗病症的目的．通过体外实验发现，新研制的免疫吸附剂最高吸附率可以达到70％左右．