溶液中有机酸碱的广义氧化还原电极电势及应用

 根据广义氧化还原理论，给出溶液中部分有机酸碱的电极电势。利用这些电势，定量地比较酸碱的氧化性和还原性的强弱；定量地判断反应的方向和计算反应的平衡常数。有机化学反应得到进一步系统化。     

土壤化学中的广义氧化还原反应

 土壤化学中的酸碱反应、沉淀溶解反应、配位反应和氧化还原反应都属于广义氧化还原反应。土壤化学反应中的某些性质可用广义氧化还原理论给出新的解释。     

电子交换反应机理初探

氧化还原反应是无机化学重要基础理论之一,它在农医科学中也具有很重要的实际意义。氧化还原反应的实质简单地讲就是电子交换。许多氧化还原反应都是简单的电子转移反应。与无机反应有关的金属离子的电子交换反应主要有以下四类:     

无机氧化还原反应方程式的配平方法

在高中化学知识学习中,由于学科特性,知识较为抽象和复杂,学习难度较高,作为一名高中生,对于化学知识的学习也是感到十分的吃力。无机氧化还原反应是其中重要的知识点,同时也是学习难点,由于无机氧化还原反应类型多样,所以如何正确书写无机氧化还原反应方程式,确定原子个数难度较大。无机氧化还原反应方程式书写中,如何快速、准确进行配平,是本人和绝大多数学生的学习难点所在。本文就无机氧化还原反应方程式的配平方法进行分析,客观阐述如何解题。     

土壤化学中的Eh-pH图尚待商榷

 土壤化学中的Eh-pH图对研究土壤中的营养元素具有很重要的作用,然而过去绘出的有关Lewis酸碱反应(即非氧化还原反应)部分的图像是不正确的。根据广义氧化还原理论,本文给出了经修正后的Eh-pH图。     

深刻理解平衡常数K的含义

平衡常数是描述化学平衡的一个物理量,它能更好地反映事物的本质,能解决自然中的一些实际问题,因此,它是化学中的一个重要数值。为了更好地掌握平衡常数的主要含义,需从下述八个方面理解。1 可逆反应与平衡在化学反应中,平衡是对可逆反应而言,对非可逆反应则无平衡可言。但在自然界中,除放射性蜕变外,几乎所有反应都是可逆的。如:     

土壤养分位与广义氧化还原电极电势

 根据广义氧化还原理论,给出了土壤溶液中NH₄⁺,P,Ca等养料成份的广义氧化还原电极电势。与养分位比较,用广义氧化还原电极电势来量度土壤养分有效度具有较多的优越性。     

小麦新鲜根系铁氰化钾还原酶与氢、钾跨膜运输的关系

为研究麦根质膜氧化还原反应与钾离子吸收的关系,比较不同基因型小麦吸钾差异,以水培和短期生物吸收试验方法,检测到小麦根系铁氰化钾还原酶的存在,而且不同品种铁氰化钾还原酶还原活性不同。反应液中由于根系内外质子和钾离子的迁移,加与不加铁氰化钾,不同品种根系都引起了溶液pH的改变,但外部电子受体Fe(CN)63-的存在即铁氰化钾还原酶底物的存在加强了溶液pH改变(更多为降低)的程度。铁氰化钾还原也明显影响了根系钾离子的吸收或外排动态,但不同品种影响不同。小麦根细胞膜氧化还原系统明显影响质子和钾离子的跨膜运输,不同品种影响不同。     

变色瓶子实验褪色时间影响因素探究

变色瓶子实验是常见的有机物氧化还原反应,根据亚甲基蓝以及臧红T这两种有机物其氧化态及还原态不同颜色变化而设计的变色实验称为变色瓶子实验.文章主要探究上述两个变色实验过程中碱溶液浓度、反应温度、搅拌速度以及连续变色实验反应时间对于变色时间的影响.     

有机化合物的氧化还原反应及其配平

氧化还原反应是化学反应中的一种重要类型。物质被氧化,就必然有物质被还原,二者总是相伴而生的。在无机化学中,任何一个氧化还原反应都有电子的转移,其中供电子物质是还原剂,得电子物质为氧化剂;在有机化学中,有机物分子多是共价健,其碳原子一般总保持四价,在反应过程中并无电子的得失,因此有机化合物的氧化或还原和典型的无机化合物的反应有所不同。     

Solar chemistry of metal complexes

Electronic excited states of certain transition metal complexes undergo oxidation-reduction reactions that store chemical energy. Such reactions have been extensively explored for mononuclear complexes. Two classes of polynuclear species exhibit similar properties, and these complexes are now being studied as possible homogeneous sensitizer-catalysts for hydrogen production from aqueous solutions.     

Experiments and simulations of ion-enhanced interfacial chemistry on aqueous NaCl aerosols

A combination of experimental, molecular dynamics, and kinetics modeling studies is applied to a system of concentrated aqueous sodium chloride particles suspended in air at room temperature with ozone, irradiated at 254 nanometers to generate hydroxyl radicals. Measurements of the observed gaseous molecular chlorine product are explainable only if reactions at the air-water interface are dominant. Molecular dynamics simulations show the availability of substantial amounts of chloride ions for reaction at the interface, and quantum chemical calculations predict that in the gas phase chloride ions will strongly attract hydroxl radicals. Model extrapolation to the marine boundary layer yields daytime chlorine atom concentrations that are in good agreement with estimates based on field measurements of the decay of selected organics over the Southern Ocean and the North Atlantic. Thus, ion-enhanced interactions with gases at aqueous interfaces may play a more generalized and important role in the chemistry of concentrated inorganic salt solutions than was previously recognized.     

Chemical reactions of anions in the gas phase

Anions of many types, both organic and inorganic, farmiliar and exotic, can be generated in the gas phase by rational chemical synthesis in a flowing afterglow apparatus. Once formed, the rates, products, and mechanisms of their reactions with neutral species of all kinds can be studied, not only at room temperature but at higher energies in a drift field. These completely unsolvated ions undergo a large number of reactions that are analogous to those they undergo in solution, as well as some that are less familiar. New types of ions, for which there are no counterparts in solution, can be produced and their chemical reactions explored.     

Ground water redox reactions: an analysis of equilibrium state applied to eh measurements and geochemical modeling

Computer modeling of 611 high-quality analyses of normal ground waters from diverse geographic areas reveals that aqueous oxidation-reduction reactions are generally not at equilibrium. Multiple redox couples present in individual samples yield computed Nernstian Eh (redox potential) values spanning as much as 1000 millivolts. The computed Eh values do not agree with each other, nor do they agree with the single "master" value measured in the field with a platinum electrode. Because of internal disequilibrium, the use of any measured Eh value as input to equilibrium hydrogeochemical computer models will generally yield misleading results for normal ground waters.     

多媒体技术在无机化学元素部分教学中的应用

元素化学是无机化学的重要组成部分。由于元素化学涉及的内容繁杂，化学反应很多，历年来是教学的难点。本研究结合无机化学元素部分多媒体教学实践，从课前准备，课堂教学，课后总结进行了探讨，指出多媒体技术的引入，提高了教学效果。     

Planetary probe: origin of atmosphere of venus

The high temperatures and chemical composition, as determined by space probe and terrestrial observation, suggest that the present atmosphere of Venus has formed by chemical interaction with the lithosphere. Although the precise reactions have not been identified, good theoretical approximations to the molecular abundance may be obtained from reactions applicable to terrestial rocks. The high temperatures and chemical reactivity create conditions on Venus which are fundamentally different from those on the cooler terrestrial planets where the attainment of equilibrium is prevented by kinetic barriers.     

不同有机无机肥对烤烟生长发育及产质量的影响

[目的]为筛选适合抚州烟区生态条件的有机无机肥料。[方法]通过大田试验方法,对6种有机无机肥进行效果对比。[结果]各种有机无机肥对烟株长势的影响不明显。[结论]施用镇江贝斯特有机无机肥、湖南金叶有机无机肥可提高烟叶产量,同时可增强烟叶内在化学成分的协调性,提高烟叶的吸食品质。     

Selenium biochemistry

The toxicity of selenium to animals and plants has been known and extensively documented since the 1930's, but it is only during the past 15 years that selenium has also been shown to be an essential micronutrient for animals and bacteria. Very little is known about the specific role or roles of selenium and, to date, there are only three enzyme-catalyzed reactions that have been shown to require the participation of a selenium-containing protein. These are the reactions catalyzed by (i) formate dehydrogenase of bacteria, (ii) glycine reductase of clostridia, and (iii) glutathione peroxidase of erythrocytes. The common denominator of these selenium-dependent processes is that they are all oxidation-reduction reactions. A fourth selenoprotein has been isolated from skeletal muscle of sheep but its catalytic function has not been identified. The form in which selenium occurs in these selenoproteins is unknown. The selenoprotein of clostridial glycine reductase contains selenium in a covalently bound form. Studies in progress indicate that this may be an organoselenium compound not previously detected in nature. Identification of the chemical nature of selenium in proteins participating in electron transport processes should enable us to determine its specific role and to understand the basic defects in certain cardiac and skeletal muscle degenerative diseases which are selenium-deficiency syndromes. The greater availability and ease of isolation of the selenoprotein of the bacterial glycine reductase system makes this the biological material of choice for studies on the mechanism of action of selenium. An added attractive feature of this system is that it can conserve the energy made available by the reductive deamination of glycine in a biologically useful form by synthesizing ATP.