高中生对化学核心概念掌握情况的测查分析——以“电解质、离子反应、化学键”概念群为例

电解质、离子反应、化学键组成一个核心概念群,是学生掌握相关知识的重难点。对北京市普通高中370名高二学生的测查显示:(1)概念掌握的程度为:化学键<离子反应<电解质。(2)“电解质的概念”与“导电原理”“离子反应概念”“离子共存”的掌握程度存在显著相关;电离与离子反应概念的掌握程度显著相关;“导电原理”与“离子反应概念”“离子共存”“离子键与共价键综合辨析”的掌握程度显著相关。表明电解质的概念、导电原理的理解与掌握是概念体系中的重要纽带。(3)优秀、中等、学困3类学生在解决容易和较难2类概念的相关问题上差异最大,而中等难度上的差异相对较小。基于此,提出了相应的核心概念教学对策。     

基于DIS实验探究离子反应的生长课堂

在完成离子反应基础知识教学后,增开1节DIS实验探究离子反应的生长课堂,以问题情境引入课堂,通过利用电导率传感器和温度传感器等手持技术和实验数据曲线图分析,以Qu:Est教学策略开启了学生理解离子反应的钥匙,帮助学生利用DIS实验从“离子反应的本质、进行方向、发生机理……”角度认识离子反应.     

化学数字化实验影响学生概念改变的实证研究

选取"离子反应"知识作为研究内容,开展了相关化学数字化实验的教学实践,通过二段式测验工具、SOLO分类法的量化分析,来检测化学数字化实验对学生概念改变的影响。结果显示,化学数字化实验能够在一定程度上促进学生的概念改变。     

发展学生化学学科核心素养的课例研究——以“离子反应”为例

以高中化学“离子反应”概念教学为例,阐述了发展学生化学学科核心素养的课例研究思路和教学活动设计。围绕离子反应概念、离子方程式书写、离子反应发生条件等知识内容,挖掘教学内容与学科核心素养内涵的联系,创设真实且富有价值的问题情境,开设高水平的实验探究活动,注重微观分析过程,将离子反应概念的学习与从微观离子角度分析水溶液中反应的认识思路进行整合,力求发展学生的化学学科核心素养,帮助学生形成对“离子反应”概念的整体认识。     

新旧3版高中化学教材中“离子反应”内容比较研究*

采用流程图结构分析方法对新人教版、新鲁科版、旧人教版3版高中化学教材中“离子反应”内容难度进行测评和比较。研究发现,新教材在核心概念的引入、衔接、组织方式上发生了重要变化。新人教版呈现了层次更加丰富、组织更加合理、意义更加饱满的“离子反应”知识结构体系,新人教版更加注重情境推理与解释表征策略的运用,创设合理情境,在情境中蕴含问题,在问题的解决过程中形成概念;新鲁科版注重宏微符的三重表征,凸显对比和比较的表征策略,为学生展现把握概念内涵与应用的多种路径和多个维度。     

基于微粒作用观的“离子反应”教学研究

1 问题的提出 离子反应是中学化学中重要的核心概念之一;又是高考的重点和难点,考查方式以离子方程式的书写、判断正误和离子共存为主.一直以来,离子反应的教学均采用传统的"宏观→微观"教学法.即先让学生观察实验现象,再由化学反应分析实验现象,最后从电离的角度分析产生这些现象的微观过程.从而引出离子反应的概念和电解质在溶液中反应的实质.这种教学方法更多关注的是对宏观现象的解释,依然延续着宏观思维的方式.     

学生对离子反应概念的认识研究

化学概念是物质及其变化等的抽象或概括,其根本意义在于提供了一种分析问题和解决问题的新方法。学生学习化学概念,不仅是对具体概念的辨析和记忆,更为重要的是要建立起对概念的理解,将化学概念作为认识问题的工具和方法。针对高中化学1“离子反应”概念的学习,从概念的认识、概念的应用2个层面,就学生对于离子反应概念认识中存在的问题进行了探查和分析,提出了相应的教学对策。     

关于总复习时离子反应的规律性小结

中学因没有溶解程度的概念,所以对许多离子反应中的沉淀及沉淀溶解问题不易作出恰当解释,为此我在长期教学中在总复习时采用下列方法引导学生思考,实践中确实收到了良好的效果。     

基于手持技术的“离子反应及其发生条件”教学研究

利用手持技进行实验设计,在离子概念建立环节开展实验探究,利用练习-反馈策略,在离子概念应用环节开展探究,转化学生的迷思概念,完成了课标指出"通过实验事实认识离子反应及其发生条件"的要求。     

让学生深刻体验和感悟离子反应真实发生——电导滴定法在研究酸碱盐反应规律中的应用

借助数字化实验辅助,创设问题情境,利用电导滴定法研究酸、碱、盐间发生复分解型离子反应的规律。基于数字化实验结果,从宏观微观符号曲线四重表征的视角,对实验结果进行了分析和解释,使学生在实证中体验和感悟离子反应真实发生,并进行了教学反思。     

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。     

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.

     

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.     

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。