氯气性质实验的改进

在制取Ｃｌ2 和做Ｃｌ2 性质实验时 ,溢出的Ｃｌ2 对健康有害。我们把Ｃｕ在Ｃｌ2 中的燃烧等实验改在单球干燥管中进行 ,与其相对应的实验装置也微型化了 ,取得了较为满意的效果。1　氯气的制取1.1　实验用品及实验装置 (图 1)18× 180ｍｍ试管、带有橡皮塞的单球干燥管、7号橡皮塞 (孔不打透 )、橡皮塞、铁架台、ＫＭｎＯ4 、浓ＨＣｌ、ＮａＯＨ溶液、脱脂棉、涂有凡士林的纸片。图 1　氯气的制取1.2　操作方法(1)把盛有ＫＭｎＯ4 的试管竖直固定在铁架台上 ,加入浓ＨＣｌ,将带有橡皮塞的单球干燥管插入试管 ,并在干燥管上口放上一团浸有…     

氯气性质实验的改进

在制取Cl2和做Cl2性质实验时,溢出的Cl2对健康有害.我们把Cu在Cl2中的燃烧等实验改在单球干燥管中进行,与其相对应的实验装置也微型化了,取得了较为满意的效果.……     

氯气性质实验的改进

在制取Cl2和做Cl2性质实验时,溢出的Cl2对健康有害.我们把Cu在Cl2中的燃烧等实验改在单球干燥管中进行,与其相对应的实验装置也微型化了,取得了较为满意的效果.     

新课标下的氯气漂白性质的实验改进

为解决氯气漂白性质实验的繁琐和环境污染等问题,对该实验的装置、材料、演示方法进行了探讨,设计了在密闭的装置里进行实验的新方案,取得了良好的实验效果。     

氯气性质实验的装置

在课堂中氯气性质的实验是很困难的,一方面照教科书上的装置做这个实验很费时间,手续也很麻烦;另一方面氯气和燃烧后的 PCl_5、SbCl_5等弥散空气中,使教师和同学都感到很难受,影响身体健康。根据这两方面我在实验装置上作了一些改进,现提供同志们参考,希提出指正。     

用曲管实验氯气性质的经验

用下列的方法实验氯气性质,药品用量少,无须在通风橱中做。 (1)氯气与锑粉的反应     

氯气与水反应实验改进

现行高级中学化学课本（必修、第一册通过实验〔1一6〕介绍氯水光照分解,验证氯气可与水反应,生成盐酸和次氯酸;次氯酸光照可分解生成盐酸和氧气。     

氯气与氢气反应实验改进

H2和Cl2在点燃和光照的条件下均可以发生反应生成HCl,但Cl2有毒,并有强烈的刺激性,再加上H2和Cl2的混合气体在点燃条件下会发生爆炸,如果2者的用量及比例控制不好,有一定的危险性,并且会造成教室环境污染,影响师生身体健康,鉴于此,我对该实验进行了改进,取得了不错的效果.     

氯气的制取与性质实验绿色化设计

针对氯气有毒及其与金属反应易于泄露等实验不足,设计了氯气制取、氯气与金属反应和氯水成分探究的全封闭实验。其中,氯气与金属的反应采用原位电加热的方式,加热速度快,金属在氯气中的燃烧现象明显,且能快速识别产物,有效地消除了因加热带来的氯气泄露问题;氯水成分的探究是通过青霉素瓶在封闭条件下进行的。整个实验仪器常规,装置简单,药品用量少,操作容易,现象明显,安全无污染,非常适合课堂演示。     

氯气的制备及性质一体化实验改进设计*

目前在化学教材中涉及氯气制备、性质的实验存在一些不足,如反应物用量大、反应时间长、反应分开进行及对环境污染大等。因此,在传统实验与现有改进实验的基础上,将氯气制备、漂白性、酸性、氧化性等多性质检验与尾气处理综合进行一体化改进设计,不仅操作简单、有效减少试剂用量,且对环境污染小,体现绿色化学思想。     

Improving the solubility of berberine

A possible solution for improving the water solubility of berberine by the formation of multicomponent pharmaceutical salts provides the background for this commentary.     

Improving the fabrication of all-polythiophene supercapacitors

The influence of the preparation method in the properties of poly(3,4-ethylenedioxythiophene) (PEDOT) electrodes used to manufacture organic energy storage devices, as for example supercapacitors, have been examined by considering a reduction of both monomer and supporting electrolyte concentrations during the anodic polymerization reaction. Thus, the excellent electrochemical properties of PEDOT films prepared using quiescent solutions have been preserved by applying controlled agitation to the polymerization process, even though the concentration of monomer and supporting electrolyte were reduced 5 and 2 times, respectively. For example, the charge stored for reversible exchange in a redox process, the electrochemical stability and the current productivity of films achieved using quiescent solutions have been preserved using a dynamic reaction medium in which the concentrations of monomer and supporting electrolyte are several times lower. The excellent properties of PEDOT electrodes prepared using optimized dynamic conditions have also been proved by constructing a symmetric supercapacitor. This energy storage device, which has been used as power source for a LED bulb, is rechargeable and exhibits higher charge-discharge capacities than supercapacitors prepared with electrodes derived from quiescent solutions. In addition of bring an efficacious procedure for preparing cost-effective PEDOT films with excellent properties, the proposed dynamic conditions reduce the environmental hazards of depleted reaction media.     

Improving the Cetane Number of Diesel Fuels

Effect of paraffins C_{1 0}-C_{1 3}, C_{1 4}-C_{1 7}, C_{1 8}-C_{2 3}, tert-butyl hydroperoxide, cumyl hydroperoxide, and isopropyl nitrate as cetane number improvers for summer- and winter-grade diesel fuels, added in amount of 0.4-5 wt %, is studied.     

Improving the quality of potentiometric pH measurements

Like all experimentally determined physical and chemical properties, pH measurements are affected by the limited precision and accuracy of the measurement procedures. Fundamental studies of pH standards, based on measurement of the potential of an electrochemical cell without transference, known as the Harned cell, containing a platinum–hydrogen electrode and a silver–silver chloride reference electrode, indicate that vapour condensation phenomena on potentiometric cell walls not immersed in the thermostatic bath are a major source of error in assessment of pH values. In this work a study was conducted on phthalate buffer, 0.05 mol kg⁻¹ KHPhth, and results are reported for the effect of this phenomenon on the assignment of pH values and on their corresponding uncertainties. Identification and quantification of this effect constitute an original contribution to improvement of the primary method of pH measurement and, therefore, more rigorous pH (PS) values.     

提高探究学习活动的实效性

探究学习活动实质上是让学生在做中学,不是辅助教师"灌输知识"的手段.新课程实施要努力提高探究学习活动的自主性、探究性和实效性.教师要尊重学生学习的主体地位,关注学生在学习上可能出现的问题,注意挖掘学习课题中蕴涵的科学方法、思维训练等教育因素,注意创设能引发学生发现问题、找到探究实验设计思路的真实情景,注意探究学习活动和其他教学环节的整合.     

Improving the quality of environmental trace analysis

Summary After general remarks on the quality of analyses, the principal sources of error are pointed out (method of determination, pretreatment of the sample, human factor). Then, the possibilities for the quality control of analyses are discussed (control within the laboratory, interlaboratory control, use of reference methods and reference materials).

---

Verbesserung der Qualität von Spurenanalysen von Umweltmaterial

Zusammenfassung Nach allgemeinen Bemerkungen zur Qualität von Analysen werden die hauptsächlichen Fehlerquellen (Bestimmungsmethode, Verfahren der Vorbehandlung der Probe, menschliche Faktoren) aufgezeigt und anschließend die Möglichkeiten zur Qualitätskontrolle diskutiert (Kontrollen innerhalb des Laboratoriums, Ringversuche, Verwendung von Referenzverfahren und Referenzmaterialien).

---

---

Dedicated to Prof. Dr. W. Fresenius on the occasion of his 70th birthday     

An Improving Method For the Preparation of Ethynylferrocene

Ethynylferrocene was prepared in satisfactory yield by reaction of formylferrocene with triphenylphosphine and carbon tetrachloride followed by dehydrohalogenation in presence of n-butyllithum. The reaction condition is mild and the reaction time is much shorter. The method is convenient and economical.     

Improving the length-fractionation of DNA during capillary electrophoresis

The present study develops a path-lengthening strategy for capillary electrophoresis of short double-stranded DNA molecules, in an aqueous solution of neutral polymer (hydroxypropylmethylcellulose). Tests of the dependence of fractionations on pulse times reveal the operation of at least one mechanism in addition to increase in effective path length. Electrophoresis is performed in the following two-stage cycles (cyclic electrophoresis): The first analysis-stage of each cycle is a constant field (forward) capillary electrophoresis. This analysis-stage reveals the length distribution of the shortest DNA molecules not previously analyzed. The second, enhancement-stage of each cycle is zero-integrated field electrophoresis (ZIFE). The enhancement-stage improves the DNA length-fractionation for the next DNA molecules to be analyzed. A slight reverse migration occurs in the enhancement-stage. Increase in both peak separation and peak sharpness contribute to improvement in the length-fractionation of DNA molecules.     

Improving the catabolic functions of desiccation-tolerant soil bacteria

Bacterial strains were selected from a desiccated polluted soil for their drought tolerance and their ability to grow on diesel oil in view of incorporating them in a bioaugmentation product. These products are useful in case of recal citrant xenobiotic pollution, where there is no intrinsic biodegradation activity in the soil. These strains grow on the easily degradable components of diesel oil. In troduction of new catabolic genes into these desiccation-tolerant bacteria in order to improve their catabolic functions was considered. Plasmid-borne catabolic genes coding for enzymes in volved in the degradation of more recalcitrant compounds (Isopropylbenzene, trichloroethene, 3-chloroben zoate, 4-chlorobiphenyl, biphenyl) were successfully introduced in some of the desiccation-tolerant strains by means of natural conjugation. Strains exhibiting good tolerance to desiccation and able to grow on the new carbon sources were obtained. The frequencies of integration of the plasmids ranged from 2×10⁻⁸ to 9.2 10⁻² transconjugants/acceptor. Drought-tolerance is indeed important for bioaugmentation because of its in trinsic ecological significance and because a bioaugmentation starter has to be conditioned in a desic cated form to ensure good shelf-life. The conservation of the properties during storage was evaluated by accelerated storage tests.