物理化学教材中各类化学反应等温式的完整导出和介绍

本文介绍在物理化学教材中,以化学势为主线,籍此系统而又完整地导出各类化学反应的等温式。一方面可进一步巩固和强化学生对各类物质化学势及其表达式的理解和应用,另一方面还可以非常直接地明晰各类化学反应等温式的来龙去脉,并帮助学生正确理解和计算各类化学反应标准摩尔Gibbs自由能Δ_r G_m^?、标准平衡常数(又称热力学平衡常数) K^?和反应商Q,从而有助于取得较好的教学效果。     

基础化学教学中科学理解“化学平衡常数”的几点看法

在高中化学和大学普通化学等基础化学教学中,常常基于化学反应速率引入经验平衡常数,也有基于热力学理论引入标准平衡常数。经验平衡常数比较具体、形象,标准平衡常数比较抽象,但2者本质是一致的。经验平衡常数因存在多种形式及量纲等问题,相对复杂;标准平衡常数严格、规整,数值唯一,具有“大道至简”的特征。建议在教学中更多地从热力学角度来理解、概括化学平衡和平衡常数,在定量计算中尽可能统一使用标准平衡常数。     

化学反应平衡常数

化学反应平衡常数是化学中一个重要的物理量,在过去的教学中曾有不同的认识,许多文章对此进行了讨论.1982年我国颁布了一系列国家标准(以下简称GB标准),其中GB3102.8-82《物理化学和分子物理学的量和单位》对化学反应平衡常数作了明确的定义和规定,可以统一目前对平衡常数的不同认识,如:有哪些平衡常数?它们的表达式怎样?平衡常数有无量纲?平衡常数只是温度的函数,还是同时是温度、压力、浓度的函数?     

不同标态下标准电极电势间关系的热力学解释

利用标准吉布斯自由能变化ΔrGm与标准电极电势和标准反应平衡常数间的联系,分析不同标态下电极标准电极电势间的关系。根据这一思想,以水解离平衡为例,讨论了设计原电池求化学反应平衡常数的一般方法。     

Clausius-Clapeyron方程在解题中的应用

叙述Clausius—Clapeyron方程在自发过程判定,计算溶液气、液相组成,计算化学反应的标准平衡常数及开尔文公式中的应用     

关于Van't Hoff公式与温度对化学反应方向的影响的讨论

说明温度对化学反应的平衡常数K的影响决定于该反应的标准焓变化△■. 若△■是正值     

《化学反应原理》中与化学平衡常数有关的几个问题

论证了中学教材为什么要引入化学平衡常数,讨论了中学教材中的化学平衡常数是经验平衡常数还是标准平衡常数,指出了应用平衡常数表达式进行计算时须遵循的规则。重现了人教版、鲁科版和苏教版《化学反应原理》教材中与化学平衡常数有关的几道例题及其解题过程,分析了解题过程中存在的问题,并提出了解决问题的策略。     

热力学在无机化学“四大平衡”教学中的应用

利用化学反应吉布斯自由能变化?_rG_m~?来计算无机化学"四大平衡"的平衡常数,解释诸如沉淀-溶解平衡教学中为什么要求微溶强电解质等问题,并从化学反应等温式类推了电极反应的等温式,推导了复杂电极的标准电极电势与其简单电极的标准电极电势之间的关系,拓展了热力学在现行基础化学教学上的应用范围。     

勒夏特列原理和化学平衡常数学习现状的调查分析和教学反思

1问题的提出化学平衡是化学反应原理的一个重要课题,新课程更不例外,但新教材引入了平衡常数,课程标准要求学生知道平衡常数的含义。那么现在学生在解决化学平衡问题时是更习惯用传统的勒夏特列原理还是新引入的平衡常数呢?平衡常数的引入能否     

有关固体颗粒分散度与化学反应平衡常数关系的探讨

从表面化学的一道习题出发,探讨固体颗粒分散度与其化学反应平衡常数之间的关系,借助高度分散系统的热力学基本方程及化学反应平衡判据,推导出在一般性的固态纯物质与理想气体的复相反应中,是否考虑固体反应物分散度时两种平衡常数之间的定量关系式。     

Thermodynamic derivations of conditions for chemical equilibrium and of Onsager reciprocal relations for chemical reactors

For an isolated chemical reactor, we derive the conditions for chemical equilibrium in terms of either energy, volume, and amounts of constituents or temperature, pressure, and composition, with special emphasis on what is meant by temperature and chemical potentials as the system proceeds through nonequilibrium states towards stable chemical equilibrium. For nonequilibrium states, we give both analytical expressions and pictorial representations of the assumptions and implications underlying chemical dynamics models. In the vicinity of the chemical equilibrium state, we express the affinities of the chemical reactions, the reaction rates, and the rate of entropy generation as functions of the reaction coordinates and derive Onsager reciprocal relations without recourse to statistical fluctuations, time reversal, and the principle of microscopic reversibility.     

粒度对纳米体系化学反应热力学性质的影响

为了研究纳米粒子的粒度对化学反应热力学性质的影响规律, 以球形原子簇来模拟纳米金刚石颗粒, 用量子化学方法对粒度不同的金刚石纳米粒子与氧气反应的热力学性质进行了计算. 结果表明, 粒度对多相反应的标准摩尔反应焓△rH0m、标准摩尔反应熵△rS0m、标准摩尔反应吉布斯函数△rG0m和标准平衡常数K0均有明显的影响, 随着反应物粒径的减小, △rH0m、△rS0m和△rG0m均降低,而K0增大. 这些影响规律与实验结果基本一致.     

流动注射分析系统中的化学动力学研究

运用对流－扩散模型研究了流动注射分析系统中的化学动力学，基于无化学反应时试样分散的浓度分布公式，运用数学归纳法导出了在一定条件下一级和二级反应的产物浓度分布公式，所得解析解便于计算机模拟产物生成曲线。解释了双峰的产生，并讨论了相关的动力学信息。     

计算机模拟在化学理论与实验教学中的应用

With the help of PHREEQC program,we introduced the application of computer simulation in theoretical and laboratory teaching of chemistry.Accordingly,reaction models for the chemical process of acid-base neutralization,complexation reaction,precipitation-dissolution equilibrium,and chemical kinetics were established.These models can greatly help the students understand chemistry,improve the teaching quality,enrich modern teaching methodology,develop students' creativity,and establish a scientific and efficient research method.     

Chemical braking exhibited by ethynylhelicene (M)-nonamer in solution: Competitive reaction system of self-catalysis to form double-helix and approach towards equilibrium to form random-coil

Chemical braking occurs in a dilute solution during a structural change of ethynylhelicene (M)-nonamer from the metastable double-helix state to the random-coil state, being at equilibrium, where the reaction is initially rapid and then substantially retard. The chemical braking is derived from the competitive chemical reaction system in dilute solution: An energetically uphill self-catalytic reaction to form double-helix and the downhill reaction to form the random-coil.     

Determination of thiosulfate concentrations by gravimetric analysis: A desirable experiment for chemical education

An electrochemistry-based gravimetric method of analysis for the determination of thiosulfate concentrations in aqueous solutions and its application in chemical education are introduced. Nine standard aqueous thiosulfate solutions with triplicate concentrations of 0.02 M, 0.03 M, and 0.04 M were prepared in 1.0 M hydrochloric acid. The elemental sulfur produced in each sample was recovered by filtration, and the mass of the recovered elemental sulfur and the electrochemically determined equilibrium constant of the reaction at 25°C (K_eq = 3.5) were used to determine the concentration of thiosulfate in each standard solution. The method % Error is 4.9 ± 3.0, which means that the average method % Error is less than 5.0.     

Growth and Chemical Thermodynamics Analysis of SiC Film on Si Substrate by Heating Polystyrene/Silica Bilayer Method

SiC films were prepared by modified heating polystyrene/silica bilayer method on Si (111) substrate in normal pressure flowing Ar ambient at 1300 o C. The films were investigated by Fourier transform infrared absorption, X-ray diffraction, and scanning electron microscopy measurements. The chemical thermodynamics process is discussed. The whole reaction can be separated into four steps. The carburizing of SiO is the key step of whole reaction. The main reaction-sequence is figured out based on Gibbs free energy and equilibrium constant. Flowing Ar is necessary to continue the progress of whole reaction by means of carrying out accumulating gaseous resultants. The film is very useful for application in a variety of MOS-based devices for its silica/SiC/Si(111) structure, in which the silica layer can be removed thoroughly by the standard RCA cleaning process.     

非线性化学反应在低维介质中的动力学行为

通过数值模拟对３分子自催化反应Ａ＋２Ｘ＝３Ｘ在一维和二维介质中的动力学行为进行了研究。发现在一维和二维情形下，如果施以不同的微观反应规则，该反应的渐近行为既可能偏经典化学反应动力学（平均场理论）所预言的平衡极限行为，也可能与之一致。