高一学生化学学科自我概念与学业成绩的关系

运用化学自我概念问卷,对高一学生化学学科自我概念和化学学业成绩之间的关系进行探讨,结果表明:学生化学学科自我概念达到中等水平,化学学业自信较高,化学学业自我调控较弱;学生化学学科自我概念水平在性别上无显著差异;父母职业背景对学生化学自我概念有较大的影响;学生化学成绩与化学学科自我概念得分之间具有一致性,学生化学成绩对化学学科概念的形成有显著的影响.     

趣味化学实验在初中化学教学中的应用

化学教学离不开实验,趣味性化学小实验,简便易行、安全有趣,实验现象明显,使学生对化学产生强烈的求知欲,从而激发学生的化学学习兴趣.利用化学实验的趣味性,激发学生的化学学习兴趣,使学生有常新常乐的感觉.     

高中生化学价值观的调查研究

以浙江省某中学高一、高二学生为研究对象,调查了344名高中生的化学价值观现状,采用比喻的形式和问卷调查的研究方法进行信息采集,并对不同性别、年级和化学选考倾向的学生进行化学价值观的差异性比较。结果发现,学生选择的食物比喻十分丰富,化学价值观的总体情况较为良好;男女生的化学价值观整体上基本一致;高一学生的化学价值观相较于高二学生更加积极;对于化学选考倾向不同的学生,选考化学的学生具有更加积极的化学价值观,但没有选考化学的学生对化学学科同样也持认可态度。     

化学元素符号的巧妙教学

元素符号是学习化学的重要工具,是化学启蒙教育阶段的基础内容。在教学过程中如果采用死记硬背的方法,不仅加重了学生学业负担,而且严重影响学生学习化学的兴趣。利用巧妙的教学方法,既可以让学生轻松学化学,又能够培养学生的化学情感,对做好化学启蒙教育工作具有重要价值。     

非化学专业选修通识课“化学史话”的教学实践

"化学史话"是针对非化学专业学生开设的选修通识课程。通过介绍一些重要的化学发展过程和化学家的故事,向学生展示化学的发展轨迹,彰显化学在人类文明发展进程中的重要作用,可加深非化学专业学生对化学的理解认识。     

化学化工专业学生绿色化学认识的调查与思考

就化学化工专业学生对绿色化学认识的调查显示：多数学生对绿色化学的属性有较好的理解与认识;不少学生对绿色化学作用的理解与认识不足,甚至是错误的;对绿色化学的12条原则认识不全面。学校与教师应提高对学生进行绿色化学教育重要性的认识,通过开设专门的绿色化学课程,在化学理论课与实验课教学中自觉地渗透绿色化学理念,在实践中培养绿色化学意识。     

学生选择化学专业的动机调查和研究

学习动机不仅影响学生的学习态度 ,也影响学生将来的学习方向。调查研究表明 ,学生在高考时选择化学专业的主要动机因素来自认知需要、自我提高需要和交往需要 ,分析其中最重要的化学学科成绩、化学实验、化学的社会地位和化学教师四项因素 ,探讨运用动机因素的注意点 ,有助于在化学教学中更好地激发学生学习化学的动机和兴趣 ,开展素质教育 ,全面提高化学教育质量。     

例谈“简异”化学实验创设的教学价值

阐述了通过“简异”化学实验的创设,增加化学实验的趣味性,激发学生的好奇心和求知欲;提升化学实验教学的探究性,培养学生的探究能力,实现化学知识的系统建构;引导学生理性质疑书本实验,实现化学实验的创新教育价值。     

发现化学之美 感悟科学魅力

本文指出化学教学的关键,在于引导学生发现化学之美,感悟科学魅力,激发学生的学习兴趣及创造潜能。全文阐述了化学的外在美、揭示了化学的内在美———化学学科思想 (科学之美 )、崇尚化学家的人生之美及化学教师的人格之美。作者认为：化学教师的人格之美源自“以学生发展为本”的教育理念和对学生及化学教育事业的挚爱。本文旨在倡导广大教师更新教育观念,增强自身素质,升华崇高人格,真正实现化学教学中“教师快乐教学,学生享受学习”。     

高一学生化学学科焦虑调查研究

学习焦虑是普遍存在于学生群体当中的一种负面心理情绪。以化学学科为切入点,选取108名高一学生为研究对象,从化学学习焦虑、化学应用焦虑、化学教师焦虑和化学考试焦虑4个维度深入分析高一学生化学学科焦虑问题。结果表明,高一学生化学学科焦虑整体处于较低水平,其中化学学习焦虑最高,化学考试焦虑最低;6名高焦虑个体中有5名均为男生,化学考试焦虑最严重,应该引起教师关注。     

Investigation of the sorption of water vapor on cation-substituted vermiculite. 2. Thermodynamic description of sorption equilibria

The changes in the thermodynamic functions of the sorbents were calculated for the first time from measurements of the deformations of vermiculite during the sorption of water vapor and adsorption-calorimetric data.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Institute of Colloid Chemistry and the Chemistry of Water, Academy of Sciences of the Ukraine, 252180 Kiev. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1270–1275, June, 1992.     

Thermodynamics of ionization of water over wide ranges of temperature and pressure

We have summarized results of many experimental investigations of the thermodynamics of ionization of H₂O(liq.) from 0–300°C and from 1.0 atm to nearly 8000 atm. Results of these investigations (equilibrium constants, enthalpies of ionization, heat capacities, partial molal volumes, and compressibilities) have been used for a number of thermodynamic calculations. It is particularly noteworthy that it is possible to use thermal data from 0–145°C with an equilibrium constant for 25°C in calculating reasonably accurate equilibrium constants for temperatures as high as 300°C. Similarly, it is possible to use volumetric data that refer to 1.0 atm in calculating useful equilibrium constants that apply for pressures as high as 2000 atm.Much of the work reported here was done while the author was on leave at the University of Lethbridge.     

Thermodynamics of lonization of aqueous lodic acid,an “almost-strong” electrolyte

We have made calorimetric measurements of enthalpies of dilution of aqueous iodic acid and have used these results for evaluation of the standard enthalpy of ionization of HIO₃(aq.). We have also made calorimetric measurements of enthalpies of addition of perchloric acid solution to aqueous solutions of KIO₃, KNO₃, NaIO₃, and NaNO₃ and have used these results to obtain further values for the standard enthalpy of ionization of HIO₃(aq.). On the basis of all these results, we have selected H^o=–660±125 cal-mole^–1 as the best available standard enthalpy of ionization of HIO₃(aq.) at 298.15°K, compared to the previously accepted –2400 cal-mole^–1. Using the best available K=0.157 for ionization, we also obtain G^o=1097 cal-mole^–1 and S^o=–5.9 cal-^oK^–1-mole^–1 for ionization of HIO₃(aq) at 298.15°K.On study leave from Department of Inorganic and Analytical Chemistry, LaTrobe University, Bundoora, Victoria, 3083, Australia, to University of Lethbridge.On study leave from Department of Chemistry, University of Wollongong, Wollongong, N.S.W. 2500, Australia, to University of Lethbridge.     

STUDIES ON THE REACTIVITY PATTERNS OF HETEROCYCLICS IN AQUEOUS DMSO‐INTERACTION BETWEEN POSITIVE END OF SULFOXIDE DIPOLE AND LONE PAIR ON RING NITROGEN IN PYRIDINE DERIVATIVES

Abstract

The signals for the α, β, and γ protons of pyridine exhibit a downfield shift in DMSO-d₆, compared to CCl₄ as solvent, the order being γ > β > α. This is attributed to an interaction between the positive end of the DMSO dipole and the lone pair of electrons on the ring nitrogen. This effect is also reflected in the faster rate of alkaline hydrolysis of ethyl isonicotinate over ethyl nicotinate and ethyl picolinate in aqueous DMSO relative to aqueous ethanol. Similar solvent effects are also observed in the pmr spectrum of pyrazine.     

Thermochemistry of aqueous solutions of alkylated nucleic acid bases. VIII. Enthalpies of hydration of 6-alkyluracils

Enthalpies of solution in water H _sol ^o and enthalpies of sublimation H _sub ^o were determined for a number of crystalline derivatives of uracil: 1,6-dimethyluracil (m ₂ ^1,6 Ura), 1,3,6-trimethyluracil (m ₃ ^1,3,6 Ura), 6-ethyl-1,3-dimethyluracil (e⁶m ₂ ^1,3 Ura), 6-propyl-1,3-dimethyluracil (pr⁶m ₂ ^1,3 Ura) and 6-butyl-1,3-dimethyluracil (but⁶m ₂ ^1,3 Ura). Standard enthalpies of hydration H _hydr ^o and standard enthalpies of interaction H _int ^o of the solutes with their hydration shells were calculated. The data obtained show that dependence of H _int ^o on the number of-CH₂- groups of n-alkyl chain added upon substitution of diketopyrimidine ring is nonlinear. This finding is discussed in connection with results of X-ray diffraction structure determinations for the crystalline compounds.     

Protonation of leucoemeraldine in the solid state and in solution

The protonation of leucoemeraldine in power form and in N-methylpyrrolidinone (NMP) solution by HCIO₄ and HBF₄ has been studied by x-ray photoelectron spectroscopy (XPS), infrared (IR), and ultraviolet (UV)-visible absorption spectroscopy. In powder form, less than 25% of the amine nitrogens can be protonated in the absence of oxygen. The effects of oxygen on the degree of protonation and the distribution of amine and imine units upon deprotonation of the salt are investigated. The degree of protonation in leuccemeraldine can be increased to about 50% with 3 M HCIO₄, similar to that achievable with emeraldine base in powder form. In NMP solution, leucoemeraldine is easily oxidized by dissolved oxygen. Protonation of both leucoemeraldine and emeraldine base in NMP solutions results in metastable species which gradually undergo deprotonation. The resulting products are affected by the O₂ content of the solutions. © 1993 John Wiley & Sons, Inc.     

Thermochemical study of aliphatic and phenyl-substituted geminal diacetates

The standard enthalpies of combustion _c H ^o of aliphatic diacetates1 and aromatic diacetates2 were measured calorimetrically. The enthalpies of vaporization _vap H ^o or sublimation _sub H ^o of1 and2 were obtained from the temperature function of the vapor pressure measured in a flow system. From _f H ^o(g) of1 and2 new values of group increments for the estimation of standard enthalpies of formation of these classes of compounds were derived. The geminal interaction energy between the geminal acyloxy groups shows no anomeric stabilization.Geminal Substituent Effects, Part 12, for part 11 see Ref. 7.     

钾明矾溶液水解度计算公式

根据盐类水解关系式和水的离子积计算公式,建立了计算盐类水解度和水解产物离解常数的完全方程式。计算值同实验值比较,钾明矾溶液水解度平均偏差为0.6％,离解常数pK_b=11.6±0.1,水的离子积pK_w平均偏差小于0.06,从而改进了苏联的计算公式。     

Relation between characteristic adsorption energy and internal pressure in the theory of volume filling of micropores

An equation for the internal pressure acting on an adsorbate in micropores was obtained on the basis of the assumption that the chemical potential of an adsorbate in micropores is equal to that in an equilibrium gas phase and using the Dubinin-Radushkevich equation. The empirical relation between the characteristic adsorption energy and the half width of pores was expressed in terms of internal pressure and diameter of adsorbate molecules. The two-dimensional pressure was calculated for micropores with plane-parallel walls, where the width of a micropore coincides with the diameter of an adsorbate molecule. The results obtained were compared with the two-dimensional pressure of a monolayer on a free planar surface for an adsorbate and adsorbent of the same nature.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1928–1930, October, 1995.     

计量数比规则与等物质的量规则的比较

指出了计量数比规则存在的缺陷:不利于贯彻有关物质的量及其单位摩尔的SI规定,不能继承当量定律的数据资料,不能表示反应的性质,不能正确表达水硬度、碱度、树脂交换容量及电解定律,缺乏科学的导出过程及计量关系表达式,计算过程繁杂。而等物质的量规则继承和发展了当量定律,使整个滴定分析计算简单规范。