邻苯三酚法测定空气中氧气的含量

按照教材中用燃烧红磷除去氧气的方法测定空气中氧气的含量,存在实验现象不明显和实验数据不严谨的问题;采用邻苯三酚法改进空气中氧气含量测定实验,操作更为简单,实验现象更明显,实验数据严谨,宜作为演示实验在教学中推广。     

硫在空气和氧气中燃烧实验的新探究

利用三口烧瓶、打火枪和恒压滴液漏斗等常见的实验仪器设计了一套实验装置,将硫在空气中的燃烧、氧气的制备、硫在氧气中的燃烧以及二氧化硫的吸收处理在一个密闭装置中完成,解决了教材中实验存在的不足。实验改进有利于培养学生的创新能力和环保意识,提高课堂的教学效果。     

蜡烛不完全燃烧实验的改进

指出了初中化学教材中“蜡烛不完全燃烧”实验缺乏直观性的不足,详细介绍了利用铁管和蜡烛演示的实验方法及实验现象。     

以粉笔为载体的几则高中化学实验改进

笔者利用粉笔具有强吸附性和热稳定性的特点,将铝热反应、乙醇催化氧化、铝粉在氧气中燃烧这3个现象不明显、成功率较低的高中化学演示实验进行了有效改进。     

对燃烧条件探究实验的绿色化改进

通过对现行初中化学教材中燃烧条件探究实验的理性分析,以学生已有的生活经验和化学知识为基础,选择学生所熟知的可燃物--纸条和木炭作实验物品,对燃烧条件探究实验进行了绿色化改进。从根本上解决了教材实验的污染问题,将氧气、二氧化碳的实验室制法与性质实验及一氧化碳的可燃性等前后几部分教学内容紧紧地联系在一起,降低了学生的学习难度,培养了学生的创新意识,降低了实验成本,提高了教学的有效性。     

演示钾在空气中燃烧实验的改进

人教版《化学2(必修)》物质结构元素周期律一章里第一节元素周期表中安排了钾在空气中燃烧的实验,并且明确规定此实验由教师演示[1],但是用教材中安排的操作将一干燥的坩埚加热,同时取一小块钾,擦干表面的煤油后,迅速投到热坩埚中,观察现象。作为演示实验,钾在坩埚中燃烧不利于学生观察。     

铁丝在氧气中燃烧的研究

"铁丝在氧气中燃烧"的实验,以小木炭块为铁丝引燃物较好。当铁丝直径为0.20 mm时,最好3根拧在一起燃烧,当铁丝直径小于0.20 mm时,还要增加根数;用直径为0.38 mm的废石棉网铁丝1根、直径为0.23 mm的自行车闸钢丝1根或2根(拧在一起)、直径为0.50 mm的炮线1根为燃烧对象时,效果都好,尤其钢丝燃烧时的火星四射更美观。     

钠在空气中燃烧产生的黑色颗粒究竟为何物

1 问题提出 笔者按照人教版高一教材(2003年版)"钠"一节教学时,按演示实验2-2的实验步骤[1],做了钠在空气中燃烧的实验.但观察到的实验现象不仅仅有淡黄色的固体产生,还有大量的黑色颗粒产生.     

钠在氯气中燃烧实验的改进

指出了现行高中化学教材中钠在氯气中燃烧实验的不足,详细介绍了改进后的实验装置及其实验方法,简化了氯气制备及其实验过程,保障了整个实验在封闭体系内进行,解决了钠在氯气中燃烧实验严重污染环境问题,从而培养了学生的环保意识。     

钠的两个性质实验的创新设计

钠是典型的金属元素,在中学阶段,研究钠的化学性质主要包括2个方面:一是钠与非金属(主要是氧气)的反应,即钠在空气中燃烧;二是钠与水的反应.钠在空气中燃烧的实验多数教材采用的方法是在石棉网上加热,这种方法不仅实验成功率低,而且会损坏石棉网,造成不必要的浪费;人教版普通高中课程标准实验教科书<化学1(必修)>采用的方法是钠在坩埚中燃烧[1],用这种方法实验,学生不容易观察到实验现象,演示效果较差.钠和水的反应,不容易收集到反应时生成的气体,气体产物的检验成为实验的难点,3套新课程标准高中化学教材中都略去了该项实验操作.为了克服以上困难,我们对上述2个实验进行了改进.     

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.     

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。     

Effect of the Method of Modification of Zeolite X on Selectivity of Catalytic Methylation of Toluene

Theoretical and Experimental Chemistry - The effect of the method of modification of catalysts based on zeolite X by cesium and magnesium cations (ion exchange and impregnation) on the selectivity...     

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.     

Synthesis of tetrabenzoporphins of the basis of isoindoline

Chemistry of Heterocyclic Compounds -