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1.
孙默  郑晓红 《化学教育》2021,42(23):82-87
以“镁和碳酸氢钠溶液反应”的实验探究过程为例,针对镁和碳酸氢钠溶液反应比镁和水反应速率快这一现象,运用控制变量法和数字化实验,探究了气体产物成分和使速率加快的原因。凸显学生自主生成的实验探究活动在提升学生科学探究与创新意识、证据推理与模型认知等化学核心素养中的重要作用;归纳了解决实验探究问题的一般思维路径;更好地说明化学是一门以实验为基础的科学。  相似文献   

2.
陈懿 《化学教育》2012,33(10):71
在强调开放性实验探究的新课程改革实践过程中,设计开展了“原电池”为主题的课题式课外合作探究实验、“金属与稀硫酸反应”实验的定量化验证及“南京景观水体手持仪器现场监测应用”等一系列课外实验活动,初步建立起了高中化学课外实验活动的校本课程机制,培养了学生化学实验素养和可持续学习研究能力。  相似文献   

3.
戢明 《化学教育》2016,37(3):69-71
利用气体实验微型装置设计了二氧化氮与水反应的一个定量化的微型实验,能够使二氧化氮多次被水吸收转化为硝酸,适宜学生独立实验操作,较好地实现了实验探究活动目标。  相似文献   

4.
根据化学学科核心素养下对化学实验的要求,对人教版教材中“验证牺牲阳极法”实验提出一种改进实验方案。采用被隔成2个区域的废弃饭盒作反应容器,采用镁条作阳极金属,可以实现反应进行与结束的可控化、对照效果的可视化和操作的简便化。该套改进实验装置既适用于演示实验,也适用于学生分组实验对牺牲阳极法的应用效果进行探究,进而掌握科学探究的方法。  相似文献   

5.
朱鹏飞  陈敏  陈凯 《化学教育》2018,39(23):37-42
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。  相似文献   

6.
针对传统甲烷与氯气取代反应实验装置存在环境不友好、实验装置较大、过于分散、反应难以定量化等缺陷,从绿色化学角度出发,对传统甲烷与氯气取代反应装置进行优化设计,实现了该实验过程的绿色化,实验装置的微型化、综合化和反应的可控化、定量化。  相似文献   

7.
概述了"实验-性质-原理"三元整合策略的内涵及在高三化学微专题复习中的实施应用。以"弱电解质的电离与电离平衡"为例,以"区别相同浓度的盐酸、醋酸"实验探究活动为驱动任务,结合盐酸、醋酸与镁反应不同时间段的现象,学生根据反应原理预测可能原因,画图分析c(H+)变化,完成强、弱电解质性质的"宏观-微观-符号"三重表征。引入电离平衡常数的数据分析活动,穿插"原因解释"的答题策略及规范训练、图表阅读、基于控制变量法设计实验方案等学习任务,为高三微专题复习提出教学建议。  相似文献   

8.
卢天宇 《化学教育》2021,42(1):36-41
以倡导“理解与批判、联系与构建、迁移与应用”的深度学习为理念,围绕“分子与原子的概念”比较教材与文献的设计思路,调整认知脉络,着力解决“概念学习过程中实验探究少,宏观现象进入微观分析的相关实验不匹配,忽略证据推理、变化观念与平衡思想核心素养”等不足。设计“3种形态的碘与淀粉的反应、H2O2溶液与品红反应、H2O2溶液的分解反应”3组实验,设置学生画分子模型、画H2O2分子分解的微观过程等活动,提炼“物质种类、分子种类、物质性质之间的关系是什么?你从实验中找到哪些证据支持观点?前2个单元的实验,还有哪些可作为论证的依据?”等问题,引发学生充分论证。“实验、活动、问题、论证”环环相扣,促成教学内容的有效结构化,通过化学概念的深度学习实现化学学科核心素养的发展。  相似文献   

9.
陈晓燕  卢天宇 《化学教育》2021,42(13):41-47
以气压变化在化学实验中的应用为切入点进行复习。以密室逃脱游戏为情境,通过装置气密性的检查归纳气压改变的原因及其导致的现象,构建处理化学实验中气压变化情况的一般模型;通过改进仪器控制反应发生和停止来强化模型;利用模型分析并改进教材中测定空气中O2含量的经典实验;利用模型设计实验证明CO2和NaOH溶液反应的发生。这些学习任务的设计突出了实验探究,促成了模型构建,培养了学生的创新意识,实现了深度教学、发展核心素养的目的。  相似文献   

10.
莫璇 《化学教育》2022,43(1):90-95
针对学生面对化学实验探究问题无从下手的情况,以物质的分离与提纯这一类探究实验为例,通过“教学评一体化”的教学模式引导学生建立解决“物质分离与提纯”探究实验的一般思路方法。  相似文献   

11.
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.  相似文献   

12.
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。  相似文献   

13.

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.

  相似文献   

14.
Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.  相似文献   

15.
In this review, the research of the author in the field of colloidal systems is summarized. The factors influencing colloidal stability are systematized and analyzed. Examples are presented to illustrate the practical utilization of the theory of stability of colloids and thin films.This review was prepared on the basis of the works of the author, which were awarded the State Premium for 1991 in the field of science and technology, chemistry section.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1708–1717, August, 1992.  相似文献   

16.
Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, Mo, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

17.
翟宗玺  刘树深  夏树屏 《化学学报》1990,48(10):946-950
用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。  相似文献   

18.
The enthalpies of solution of several oxosulfides of rare-earth elements and the high-temperature enthalpies of oxosulfides and oxosulfates of lanthanum and yttrium were measured using solution calorimetry and high-temperature microcalorimetry techniques. Standard enthalpies of formation and some thermodynamic properties of oxosulfides and oxosulfates were calculated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2 pp. 294–297, February, 1997.  相似文献   

19.
20.
针对恶臭测试的环境影响问题,提出了解决的实例方案,并对方案的要点及优缺点进行讨论,此方案在实际操作中具有较好的效果。  相似文献   

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