Enthalpy of formation of triphenylphosphine sulfide

The first measurements of the enthalpies of combustion, sublimation, and fusion of an organo-phosphorus sulfide, triphenylphosphine sulfide, are reported: _c H _m ^o (C₁₈H₁₅PS, cr)=–(10752.58 ±2.90), _sub H _m ^o (C₁₈H₁₅PS, 403 K)=(136.80±6.09), and _fus H _m ^o (C₁₈H₁₅PS, T_m=435.92 K) =(30.53±0.21) kJ·mol^–1. Correction of the phase change enthalpies toT=298.15K and p^o =0.1 MPa results in the standard phase change enthalpy values of _sub H _m ^o (298.15 K)=(142.8 ±6.8) and _fus H _m ^o (298.15 K)=(19.28±0.21) kj·mol^–1. Accordingly, the enthalpies of formation of solid, liquid, and gaseous triphenylphosphine sulfide are derived: _f H _m ^o (C₁₈H₁₅PS, cr) =(63.20±2.56), _fH _m ^o (C₁₈H₁₅PS, l)=(82.48±2.57), and _fH _m ^o (C₁₈H₁₅PS, g)=(206.0±7.3) kJ·mol^–1. From these ancillary data, the P=S double-bond enthalpy is 394 kJ-mol^–1 and in good agreement with earlier reaction calorimetry results. These phosphorus sulfide values are compared with those for the arsenic sulfides. Plausibility arguments are given for our results.     

用Benson基团加和法预测气相色谱保留值

应用Ｂａｎｓｏｎ基团加和法，对氯代苯，脂肪醇两类化合物分子结构与气相色谱保留值间的关系进行了研究。对部分化合物的保留值做了预测，结果表明这两类化合敢相色谱保留值具有基团加和性，预测值与实验值吻合很好。     

Partial molal volumes and compressibilities of carbohydrates in water

The partial molal volumes and isentropic partial molal compressibilities of sugars, sugar alcohols, uronic acids, and some di- and trisaccharides in water have been measured at 25°C. The results suggest that the hydration of carbohydrates depends on the detailed stereochemistry of the solute and the way the solute molecule fits in the water structure. It seemed impossible at this stage to establish any additivity rules for the various functional groups or otherwise systematize the results.     

Additivity rule for electron--molecule total cross section calculations at 50--5000eV: a new geometrical approach

Taking into consideration the changes of the geometric shielding effect in a molecule as the energy of incident electrons varies, this paper presents an empirical fraction, which depends on the energy of incident electrons, the target＇s molecular dimension and the atomic and electronic numbers in the molecule. Using this empirical fraction, it proposes a new formulation of the additivity rule. Employing the new additivity rule, it calculates the total cross sections of electron scattering by C2H4, C6H6, C6H14 and C8H18 over the energy range from 50 to 5000eV. In order to exclude the calculation deviations caused by solving the radial Schrodinger equation of electron scattering by atoms, here the atomic cross sections are derived from the experimental total cross section results of simple molecules （H2, O2, CO） via the inversion algorithm. The quantitative total cross sections are compared with those obtained by experiments and other theories, and good agreement is obtained over a wide energy range, even at energy of several tens of eV.     

Magic Mountain and Devil's Staircase swapping problems

Two open questions concerning additivity problems in theoretical chemistry have been posed in this article. Each question involves swapping of the square root function (in the formula for the zero-point energy of a linear oscillator) with a highly irregular function. Global contextualization of molecular problems and function swapping are indispensable strategies in tackling additivity problems in theoretical chemistry.     

K-拟可加模糊数值积分的伪自连续及结构特征

在K-拟可加模糊测度空间上,针对给出的K-拟可加模糊数值积分,将这种积分整体看成可测空间上取值于模糊数值的集函数,进而研究这种K-拟可加模糊积分的伪上(下)自连续、伪一致上(下)自连续和伪双零渐近可加性等结构特征.     

中、高能电子被SO2分子散射的微分截面、动量转移截面及弹性积分截面

在考虑分子内成键原子间的电子云重叠效应的基础上, 提出了一种能够准确计算“中、高能电子-分子”散射的微分截面、动量转移截面及弹性积分截面的修正势方法. 利用可加性规则、使用Hartree-Fock波函数并采用被这一方法修正过的复光学势, 在100—1000eV内对电子被SO₂分子散射的微分截面、动量转移截面及弹性积分截面进行了计算, 并将计算结果与实验及其他理论结果进行比较. 结果表明, 利用这一修正过的复光学势及可加性规则获得的微分截面比利用未修正的复光学势及可加性规则得到的结果准 关键词： 可加性规则 微分截面 动量转移截面 电子散射     

Response surface and group additivity methodology for estimation of thermodynamic properties of organosilanes

Group additivity methods simplify the determination of thermodynamic properties of a wide range of chemically related species involved in detailed reaction schemes. In this paper, we expand Benson's group additivity method to organosilanes. Based on quantum‐chemical calculations, the thermodynamic data of 22 stable silicon‐organic species are calculated, presented in the form of NASA polynomials, and compared to the available experimental data. Based on this theoretical database, a complete set of 24 Si‐ and C‐atom‐centered, single‐bonded and nonradical group additivity values for enthalpy of formation, standard entropy, and heat capacity at temperatures from 200 to 4000 K is derived through unweighted multivariate linear regression.     

Thermocapillary Vortices Induced by a Light Beam near a Bubble Surface in a Hele-Shaw Cell

This paper studies thermocapillary vortices induced by local heating of a bubble surface in a Hele-Shaw cell by a light beam. It is found that the vortex rotation frequency and its depth depend on the distance from the light-beam projection onto the layer to the bubble boundary. The surface velocity of the thermocapillary flow is calculated using the balance of the near-surface and return flows of the thermocapillary vortex and the equality of capillary and dynamic pressures. It is shown that a decrease in the surface velocity and the vortex rotation frequency with increase in the distance from the light beam to the bubble surface is due to a decrease in the temperature gradient between the illuminated and cold poles of the bubble.__________Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 5, pp. 93–99, September–October, 2005.     

MOLECULAR VOLUMES OF SALTS. WITH TRIANGULAR RADICALS

The present paper discusses some characteristics of the molecular volumes of carbonates, nitrates and borates. It confirms that the molecular volume of H_2O in the hydrates of this kind of salts approximates to a constant. When the coordination numbers of cations in mixed salts are identical with those in the single salts, the additivity of the molecular volume is quite accurate. Over 100 sets of data demonstrate that a general additivity is true, the average relative error being ±2.31%. The concept of the topological molecular volume is proposed based, on the additivity. For salts with the same radical and equally charged cations, the molecular volume varies linearly with the cation radius. The volume effects of CO_3~(2-) NO_3~- and BO_3~(3-) in packing can be obtained by extrapolation. They are equal to a large sphere whose volume is the sum of those of three O~(2-). This paper also discusses the possibility of compiling a table of ionic volumes.