Fe3+在水溶液中的水解平衡和配位平衡

通过实验研究Fe3 在水溶液中存在的水解平衡和配位平衡,探讨温度的改变对上述平衡移动的影响,并澄清了中学教学对Fe3 颜色、水解平衡移动等问题的认识误区。     

平衡施肥与农作物的平衡吸收

叙述了平衡施肥对农作物生长的重要意义，分析了平衡施肥与农作物平衡吸收的矛盾，提出了促进农作物平衡吸收的措施。大量的实践表明，只有农作物真正平衡吸收所需的营养元素，才能有效提高农作物的产量和质量，提高肥料的利用率，减少化肥对环境的污染，提高农民的投入与产出比。     

一般反应的平衡移动

一般反应的平衡移动张世民（湖南大学化学化工系，长沙４１００１２）本文对一般恒温恒压反应的平衡移动进行了高度概括和清晰的讨论，把温度、压力、反应组分的初始摩尔数和惰性组分的初始摩尔数对平衡的影响概括到了一个公式中，并指出，当向平衡体系中加入反应组分或惰...     

多功能汽液平衡测定仪的研究

研制了一种多功能液平衡测定仪－－CS-Ⅱ型VLE测定仪，阐述了该仪器的设计思想，该仪器兼有沸点仪和平衡釜的特点和功能，作为沸点仪，它具有泵结构搅拌器，可适用于拟静态法；作为平衡釜,它具有新型的汽液相取样结构和液相区冷却功能，可适用于安全互溶体系、部分互溶体系和高沸点差体系VLE的测定，本文给出了有关详细的实验考核结果。     

压力对合成氨反应中[N_2]的影响

在一定温度下,一个化学反应平衡体系受总压改变的影响,平衡被破坏,体系将调整反应物和产物浓度值,重新建立平衡。对题述平衡体系增大(或减小)压力时,根据勒夏特列原理可以推断,重新建立平衡时,氨的浓度要增大(或减小)。而氮及氢的浓度变化情况较为复杂。本文对这个问题做一讨论。设某浓度时,理想气体反应体系N_(2(g))+3H_(2(g))→2NH_(3(g))在反应进度为ξ时达平衡;平衡体系中氮、氢及氨的物质的量分别为x(mol)、y(mol)及,z(m(?));平衡体系的体积力V(m~3);平衡体系中氮、氢及氨的浓度分别为[N_2](mol.m~(-3))、[H_2](mol.m~(-3))及[NH_3](mol.m~(-3));以浓     

等效平衡的判断及应用

等效平衡是解决化学平衡问题的重要方法,也是教学过程中的难点,从研究等效平衡的外界条件、适用范围、等效条件、等效内容4个方面来建立等效平衡并进行应用.     

论化学平衡中的独立等量关系

物料平衡等式(MBE)、电荷平衡等式(CBE)和质子平衡等式(PBE)是化学平衡定量解析中的常用等量关系。本文从理论上证明了CBE可以由MBE导出,因此在计算中不是一个必不可少的独立条件。由于H~+来源的多样性,在涉及酸碱的化学平衡中,CBE比MBE的计算效率更高。这些结论与计算实践相一致,即在配位平衡、氧化还原平衡和沉淀平衡的计算中,MBE为主,CBE起辅助作用;在酸碱平衡计算中,CBE为主,MBE为辅。PBE也不是一个独立等量关系,而且仅适用于酸碱平衡,可以完全被效率更高的CBE代替。本研究明确了化学平衡中的独立等量关系,不仅有助于提高化学平衡定量解析的效率,而且使其理论结构更加简洁明晰。     

平衡移动原理在盐类水解题中运用的一个误区

在盐类的水解中,存在水解平衡,水解平衡也是一种化学平衡,它同样遵循化学平衡移动原理,我们应该将化学平衡移动原理准确运用于盐类水解平衡,不可断章取义。[题目]25℃时,等体积等物质的量浓度的NaF和NaCl溶液中离子总数相比()A.前者多B.后者多C.一样多D.无法确定(注:原题出自任     

多组分体系单级萃取平衡的Newton-Raphson算法

提出了一种多组分体系串级萃取动态仿真中的单级萃取平衡和物料计算的新同了有机相萃取量,水相洗涤量和混合萃取比等限制条件下两相组成关系的２λ元非线性方程组,构造以水相中某一组分的平衡含量为变量的目标函数,采用Ｎｅｗｔｏｎ－Ｒａｐｈｓｏｎ迭代求解,并以萃取平衡和物料平衡得到该级其它所有组分在两相的含量。     

多元弱酸(碱)平衡体系中平衡型体浓度的精确数值解法

提出了在多元弱酸(碱)平衡体系中各种平衡型体浓度精确求解的新处理方法。抽象出一般性精确浓度数值解法的数学模型和算法框图。计算过程实用、新颖。     

铝壶煮沸的饮用水中铝的形态分析

用过滤、离子交换和光解氧化分离自来水和经铝壶煮沸的饮用水中铝的形态,以石墨炉原子吸收光谱法测定铝的浓度,采用化学平衡模式计算铝的形态分布。实验结果表明：经铝壶煮沸１ｍｉｎ的饮用水中颗凿态铝量比自来水降低了３．３倍,可交换态、不可交换有机态、不可交换无机态铝量分别２增加了１．４、０．５和１．２８倍,可交换态和不可交换无机态是铝的主要存在形态。随着煮沸时间的增加,可交换态、不可交换有机态、不可交换无机     

Speciation of aluminum in acidic natural water equilibria with mineral phase kaolinite by chemical equilibrium calculation

Aluminum is largely associated with aluminosilicate minerals such as kaoliniteAl,Si,Os(OH), within the earth's crustl. During the weathering, especially when the acidrain hastens the process, aluminum is released and thus becomes available tobiogeochemical processes. The elevated concentrations of aqueous aluminum causedetrimental consequences to plants, aquatic organisms and humans. Therefore, there havebeen considerable growing concerns in the aqueous chemistry of aluminum these years.'In …     

Membrane equilibria in concentrated polymer solutions

Membrane equilibria in concentrated polymer solutions are investigated. A three-component system (solvent, a polymer and an arbitrary solute) is considered. Starting with the virial expansion of the osmotic pressure, the Gibbs-Duhem equation for the system is integrated and the chemical potentials of the different components are evaluated. From the latter the equilibrium conditions are derived for a variety of experimental situations. The treatment is extended to the study of partition equilibria in gels, using a concentrated polymer solution as a model for the gel.     

结合PBL的思维导图法在大学化学“四大平衡”教学中的应用

Taking the chemical equilibria including acid-base equilibrium, complexation equilibrium, precipitation equilibrium and redox equilibrium as an example, the application of the mind mapping combined with problem-based learning in university chemistry teaching is introduced.     

Durability of aluminum cooling system in electric power plants

The final step in gas turbine electric power production plants is the cooling of water after the turbine expansion. In some thermal plants, the temperature reduction of the recycling fluid is partially obtained by heat exchanging with the atmosphere by passing the fluid through huge aluminum heat exchangers. From the corrosion point of view, most critical is the starting step of the power plant, when the aluminum cooling system comes in contact with water for the first time and reaches a surface condition in dynamic equilibrium with the liquid. This paper describes a systematic study of aluminum surface evolution in the cooling system of an electric power plant during the first weeks of operation. Some aluminum samples were placed inside the cooling system in significant locations and removed after scheduled times. The surface conditions of the samples were characterized using surface analyses, electrochemical techniques and microscopic observations. At the same time, the chemical conditions of the recycling fluids were monitored. The obtained results describe the corrosion resistance of the aluminum surface as a function of the conditioning time, proving the growth of a partially protective layer able to produce corrosion decrease during the service time of the energy production plant. Copyright © 2009 John Wiley & Sons, Ltd.     

卡尔曼滤波光谱法用于化学平衡研究

提出了光谱法与卡尔曼滤波及因子分析相结合的新方法以研究化学平衡,将复杂的化学平衡视为特殊的多组分混合体系,其中各物种在不同介质中存在相互的平衡,卡尔曼滤波及因子分析被用作有效的化学计量学分辨工具,从光谱数据中提取信息,已用于确定所存在的物种数目和浓度以及平衡常数,本文以部分三苯甲烷试剂为例确定其酸碱平衡常数。     

Phase equilibria of the quaternary system acetic acid—ethylene glycol monoethyl ether acetate—ethylene glycol monoethyl ether—water

The synthesis of ethylene glycol monoethyl ether acetate by esterification of ethylene glycol monoethyl ether with acetic acid is of industrial interest. The following experimental determinations were carried out: vapour—liquid equilibria of the binary systems acetic acid—ethylene glycol monoethyl ether acetate and acetic acid—ethylene glycol monoethyl ether; liquid—liquid equilibrium of the binary system water—ethylene glycol monoethyl ether acetate; solubility curves of the ternary systems water—ethylene glycol monoethyl ether acetate—ethylene glycol monoethyl ether and water—acetic acid—ethylene glycol monoethyl ether acetate.The parameters of a model able to describe the phase equilibria of the whole system have been identified. Liquid—liquid, as well as vapour—liquid equilibrium data, are satisfactorily correlated with an unique choice of parameters.     

Isobaric vapor–liquid equilibria for the quaternary reactive system: Ethanol + water + ethyl lactate + lactic acid at 101.33 kPa

Isobaric vapor–liquid equilibrium (VLE) data of the reactive quaternary system ethanol (1) + water (2) + ethyl lactate (3) + lactic acid (4) have been determined experimentally. Additionally, the reaction equilibrium constant was calculated for each VLE experimental data. The experimental VLE data were correlated using the UNIQUAC equation to describe the chemical and phase equilibria simultaneously. For some of the non-reactive binary systems, UNIQUAC binary interaction parameters were obtained from the literature. The rest of the binary UNIQUAC parameters were obtained by correlating the experimental quaternary VLE data obtained in this work. A maximum pressure azeotrope at high water concentration for the binary reactive system ethyl lactate + water has been calculated.     

Experimental determination and modeling of structure II hydrates in mixtures of methane+water+1,4-dioxane

Hydrate phase equilibrium conditions were measured with a Cailletet apparatus in the pressure range 2<14 MPa. The investigated 1,4-dioxane concentrations were 1, 2, 5, 7, 10, 20 and 30 mol% relative to water. The results show that adding 1,4-dioxane up to concentrations of 6 mol%, about the stoichiometric ratio of large sII cages to water (1/17), reduced the equilibrium pressure of hydrate formation. Adding 1,4-dioxane beyond 6 mol% caused a slow increase of the equilibrium pressures. The hydrate phase equilibria data were modeled as equilibrium between a liquid phase of water and 1,4-dioxane, with a small amount of methane, and a sII hydrate of 1,4-dioxane and methane. The chemical potential of the hydrate phase was described using the van der Waals and Platteeuw theory. Activity coefficients of the liquid phase were calculated by a van Laar relation, based on literature 1,4-dioxane+water VLE data. The predicted equilibrium pressures calculated were within 5% of the data up to a concentration of 20 mol% 1,4-dioxane relative to water.     

化学平衡的多重性、稳定性和重现性

利用动力学方法讨论了非理想的化学反应体系中化学平衡态的多重性、稳定性和实验上的可重现性。分析了实验结果(化学平衡态)与初始条件以及其它动力学过程之间的依赖关系,并简略讨论了化学平衡多重性和稳定性问题在某些实际问题和工程设计中的重要性。