一氧化碳还原氧化铜与氢气还原氧化铜的实验操作为什么不同?

为防止氨气与空气混和受热发生爆炸,在用氢气还原氧化铜的实验操作中,要求先通氢气以排除试管里的空气,再加热氧化铜。还原完毕,先撒去酒精灯,还要继续通入氢气,至试管冷却,以防止还原成的金属铜,遇到空气再被氧化为氧化铜。用一氧化碳还原氧化铜的实验,要求先加热玻璃管里的氧化铜粉末,再通入一氧化碳气体,停止加热后,不再继续通入一氧化碳,这是因为:一氧化碳是极毒的气体,装置和无毒的氢气不同,操作也必然不相同;再者,一氧化碳虽也有易燃,易爆的性质,     

木炭还原氧化铜实验的新认识

正木炭还原氧化铜是义务教育阶段的疑难实验,大家过多地把目光集中在原料的用量比、装置的改进及加热方式的优化上,而忽视了一氧化碳对整个实验的影响~([1-2])。对此实验改进后发现了一个很好的一氧化碳还原氧化铜的实验。1实验过程(1)将1cm×5cm的铜片加热至红热状态,然后自然冷却,铜片表面被氧化成氧化铜。     

使用变温原位X射线衍射技术认识氧化铜在氢气和一氧化碳气氛下的物相变化*

实验与理论相结合是化学专业教与学的原则。通过运用原位X射线衍射技术(in-situ XRD)探究氧化铜在氢气和一氧化碳气氛下的还原,结果发现无论在氢气或一氧化碳气氛下,从300 ℃开始,氧化铜逐渐被还原为氧化亚铜和铜单质,且该3种物相同时存在。直至温度升至450~500 ℃时,所有的氧化铜和氧化亚铜全部变为了铜单质。实验结果表明氧化铜的还原并非是一个由CuO → Cu2O → Cu逐步还原的单一过程,理论上可以得到的纯氧化亚铜物相在实验过程中并未得到,对此结果进行了分析。另外,将大型仪器尤其是原位表征技术推广到本科教学中具有重要意义。     

氧化铈气凝胶担载氧化铜催化剂的TPR研究

 采用程序升温还原研究了氧化铈气凝胶担载氧化铜催化剂的还原行为,并与其对一氧化碳氧化反应的催化活性进行了关联．发现此类催化剂中存在两种类型的氧化铜,即体相氧化铜和分散于载体表面的氧化铜,且后者中的部分氧化铜还原后易被氧化．随着此易被氧化的铜含量的增加,催化剂对一氧化碳氧化反应的催化活性升高,表明此种类型的铜为催化剂的活性组分．     

一氧化碳还原氧化铜实验装置的改进

我认为初中化学课本第120页图3—12“一氧化碳使氧化铜还原成铜”这个实验装置应作如下改进:因为通入的一氧化碳气体不可能全部参加反应,又在冷却还原出来的铜时,还要继续通入一氧化碳气体,而一氧化碳是有毒的气体,所以为了防止一氧化碳的污染,我在演示实验时,将盛有 Ca（OH）2溶液的烧杯改为盛有Ca（OH）2溶液且带有双孔橡皮塞的广口瓶,并把多余的一氧化碳点燃处理掉。     

巧用滤纸做碳还原氧化铜实验

分析了碳还原氧化铜实验难以成功的因素,介绍了各种碳还原氧化铜实验改进的方向及取得的成果。设计出通过滤纸来巧做碳还原氧化铜的创新实验。     

“一氧化碳还原氧化铜”实验的一体化设计

借助物质相互转化的原理,仅在一支试管中设计了一氧化碳还原氧化铜的实验;改进后的实验利用传感器收集实验数据,培养学生严谨的证据意识;从气体制备到尾气的处理,创新实验均体现绿色化学的观念。该实验的一体化设计,药品用量少,操作简单,实验耗时短,现象明显,提高了学生的参与度,提升了实验教学效果。     

氢气还原氧化铜实验的改进

对现行初中化学教材中关于氢气还原氧化铜的实验,按教材氢气还原性实验说明进行,都不易出现光亮的红色这一实验现象。分析其原因与氧化铜粉末跟试管接触不紧密以致氧化铜加热温度不够有关。     

氨气制备和性质的微型组合实验

利用微型气体实验仪设计了氨气的制备和性质的微型组合实验装置,依次探究了氨气的制备、收集、检验和氨气还原氧化铜、氨气的喷泉实验等,观察到了氨气还原氧化铜的实验现象。具有操作简便,现象明显,安全环保等特点。     

氧化铈气凝胶担载氧化铜催化剂上的一氧化碳氧化

 以一氧化碳氧化为探针反应,考察了氧化铈气凝胶担载氧化铜催化剂的催化活性,研究了催化剂中氧化铜的含量、载体及催化剂的焙烧温度对催化剂活性的影响．结果表明,氧化铈气凝胶担载的氧化铜催化剂对一氧化碳氧化反应呈现出高催化活性,适当温度下焙烧载体及催化剂有利于提高催化剂的催化活性;随着催化剂中氧化铜含量的增加,一氧化碳完全转化的温度降低,但当w（CuO）＞12％时,过量的氧化铜以体相形式而不是以高分散形式存在,对催化剂活性的影响很小．     

利用手持技术改进测定乙醇分子结构实验

利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。     

光谱仪测试范围的扩展

由于石化行业的生产需要，其材质的使用具有多样性和广泛性，经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识，根据光谱仪的测试能力及标样的采集，实现了一个或几个元素测量范围的扩展，并对其测量的影响因素进行了研究。     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988.     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin

The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

物质分配系数的测定实验改进

实验教学目的是从解决实际问题出发,以实验技术训练和实验设计思想培养为目标。介绍了将单一的物质分配系数测定实验改进为综合实验,提高了实验效果及实验资源利用率。     

Calculation of enthalpies of hydrogenation of hydrocarbons

Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。