2008年全国各地高考卷非选择题部分中化学计算题考查内容的特色分析

2008年高考化学计算试题特色各异,难度较大,从不同侧面反映了中学化学科目中对计算能力要求的重点考查,较好体现了学科高层次的能力要求与素养.     

利用数轴法求解热力学问题

利用数轴法求解化学热力学中化学反应的吉布斯自由能变、焓变、熵变的问题, 把ΔH、T1ΔS、T2ΔS的数值或相对位置直接标在数轴上, 根据相对大小判断它们的正负号和反应的自发性。该方法既直观, 又方便、快捷, 更容易被学生理解和掌握运用。     

Andrographolide: Solving Chemical Instability and Poor Solubility by Means of Cocrystals

The bioactive agent andrographolide was screened with pharmaceutically acceptable coformers to discover a novel solid form that will solve the chemical instability and poor solubility problems of this herbal medicine. Liquid‐assisted grinding of andrographolide with GRAS (generally regarded as safe) coformers in a fixed stoichiometry resulted in cocrystals with vanillin (1:1), vanillic acid (1:1), salicylic acid (1:1), resorcinol (1:1), and guaiacol (1:1). All the crystalline products were characterized by thermal, spectroscopic, and diffraction methods. Interestingly, even though the cocrystals are isostructural, their physicochemical properties are quite different. The andrographolide–salicylic acid cocrystal completely inhibited the chemical transformation of andrographolide to its inactive sulfate metabolite, and moreover, the cocrystal exhibited a dissolution rate that was three times faster and a drug release that was two times higher than pure andrographolide.     

用数轴法快速书写质子守恒表达式

介绍了用数轴法书写质子守恒表达式的基本操作,分别对单一溶液、混合溶液进行了研究,阐述了化学教学中数形结合的重要性。     

借助数轴透析金属与盐溶液的反应进程

借助数轴透析“一种金属与溶液中多种盐反应”和“多种金属与溶液中一种盐反应”中溶质与滤渣的组成,直观地将反应进程和结果展现其中,建立思维模型,化难为易,有利于学生掌握与应用。     

Asymmetric Catalytic Epoxydation by Means of Cyclodextrins

Asymmetric synthesis occurs in the epoxidation of trans-chalcone with sodium hypochlorite and cyclodextrins, with enantiomeric excess up to 11%.     

单光子LIF方法研究亚硝基苯266 nm光解动力学

用266 nm激光解离亚硝基苯（C6H5NO) 产生光解碎片NO,并利用单光子激光诱导荧光(LIF)技术（X2Πν″=0→A2Σ+ν′=0）测得初生态光解产物NO的振转光谱。根据计算所得的模拟光谱对光解碎片NO（X,ν″＝0)的转动量子数J″进行了归属,得到量子数最大到J″＝50.5的各转动能级的相对布居,这表明光解碎片NO具有较高的转动激发。提出了C6H5NO在266 nm下可能的光解机理。     

Industrial-Scale Process Control by Means of Electrostatics Probes

We performed a series of measurements by means of the triple probe technique during plasma deposition of polymer films on large volume plastic containers. Based on the measured data, the process stability and process homogeneity were determined. The process stability was better than 5% and process reproducibility was about 6%. An inhomogeneity of the plasma density correlated to the barrier efficiency of the film deposited at different positions on the container. An increase in the power losses were found after changes in the electrical configuration of the deposition set-up. The quotient of electron density n_e and product of molar mass of the working gas M and its flow F is proposed as invariant instead the Yasuda's parameter W/MF for characterization of large-scale industrial plasma polymerization process.     

Unzipping Nucleoside Channels by Means of Alcohol Disassembly

Gold nanoparticles capped with simple adenosine derivatives can form colloidal aggregates in nonpolar solvents. Theoretical calculations indicate the formation of organic channels by the supramolecular assembly of the nanoparticles by means of hydrogen bonds between the adenine moieties. The aggregates were only negligibly sensitive to nPrOH, iPrOH, and tBuOH, whereas some showed a similar response to MeOH and EtOH, and others showed high selectivity toward MeOH. DNA nucleoside derivatives (1‐(2‐deoxy‐β‐D ‐ribofuranosyl)‐5‐methyluracil and 2′,3′‐O‐isopropylideneadenosine) as well as thymine and other aromatic compounds such as pyrene derivatives (pyrene, 1‐chloropyrene, 1‐hydroxypyrene, (1‐pyrenyl)methanol, and 2‐hydroxynapthalene) did not induce disassembly of the nanoparticle aggregates. Data suggest that the nucleoside channels allow access to alcohols according to their size, and an efficient interaction between the alcohol and the adenine units destabilizes the hydrogen bonds, which eventually leads to nanoparticle disassembly.     

Modeling Liquid Antimony by Means of Molecular Dynamics

Russian Journal of Physical Chemistry A - The potential of the embedded-atom model (EAM) for liquid antimony is calculated, and the molecular dynamics models are constructed for antimony at...     

Determination of Critical Micelle Concentration by Electrochemical Means

Abstract

Overview of electrochemical methods for critical micelle concentration (cmc) determination is given. The principles and examples of cmc determination by conductometry, potentiometry, tensammetry, polarography, voltammetry, electrophoresis, and isotachophoresis are reviewed and discussed.