混合离子的沉淀准确滴定

用沉淀滴定的林邦滴定曲线方程推导滴定突跃的绝对值,用滴定突跃的绝对值推导混合离子准确滴定的条件。     

用滴定突跃的绝对值推导四大滴定分析的直接准确滴定条件

建立了四大滴定分析"滴定突跃绝对值"的概念;用滴定突跃绝对值推导出四大滴定分析直接准确滴定的条件。     

强碱滴定一元弱酸突跃范围的计算

针对现有教材及文献对弱酸滴定计量点附近某些不甚合理的简化处理过程以及某些值得商榷的结论,根据滴定弱酸计量点附近溶液的实际组成,推导了合理的、适用任何情况的强碱滴定一元弱酸的突跃范围计算公式,从而给出了一元弱酸被准确滴定的判据。     

一元强碱滴定二元弱酸的林邦滴定曲线方程及pH_(sp)计算

用质子条件式PBE、物料平衡式MBE、副反应系数和条件稳定常数等知识,推导出一元强碱滴定二元弱酸溶液的林邦滴定曲线方程,并用其推导出第一、第二化学计量点pH_(sp1)和pH_(sp2)的计算公式。     

基于滴定突跃的计算探讨多元弱酸分步滴定的准确条件

多元弱酸分步滴定的准确条件一直是酸碱滴定中的一个教学难点。基于分布分数的分析指出了当前分析化学教材中有关探讨磷酸分步滴定的某些错误结论,并在此基础上,通过滴定突跃大小的计算,对多元弱酸分步滴定的准确条件进行了探讨分析。结果表明：若人眼判断滴定终点时有±0.2pH的不确定性时,滴定误差控制在0.5%,强碱滴定多元弱酸时,分步滴定的准确条件是：Kai/Ka(i+1)≥105.0;cKai≥10-8.7。     

关于一元酸准确滴定判据的商榷

化学分析教科书中给出的弱酸能被准确滴定的条件是cKa≥1.0×10-8。本文根据这一判据的来源(滴定突跃≥0.3pH单位),对一元酸体系的滴定情况进行了严格数学处理。计算结果表明,只有同时满足弱酸的浓度c1.0×10-3mol/L和cKa≥1.0×10-8条件下,弱酸才能被准确滴定。对于浓度极稀的酸溶液(c≤1.4×10-4mol/L),无论强酸还是弱酸都不能被准确滴定。对教材很少涉及的不同浓度酸碱互相滴定的情况也给出了有价值的结论。     

一元强碱滴定混合一元弱酸的林邦滴定曲线方程及pHsp的计算

用物料平衡式MBE、质子条件式PBE、副反应系数和条件稳定常数等知识,推导出一元强碱滴定混合一元弱酸溶液的林邦滴定曲线方程并用其推导出第一、第二化学计量点pHsp1和pHsp2的计算公式.     

聚苯胺修饰电极酸碱示波电位滴定法——Ⅰ.水溶液中的酸碱滴定

示波电位滴定具有终点直观、仪器便宜、操作简便、快速、准确等特点。本文将对氢离子响应敏锐、使用寿命长、制备简单的聚苯胺修饰电极(PAME)^[4,5]应用于酸碱示波电位滴定中,使电位突跃更加明显,化学计量点更易判断(与双铂电极体系比较),可滴定多元弱酸、弱碱、混合酸和混合碱.与pH玻璃电极比较,具有阻抗低,响应灵敏、迅速,终点电位突跃大,不易损坏,不需预处理,制备简单等特点.     

对络合返滴定过程的理论探讨

推导了络合返滴定曲线方程 ,绘制了络合返滴定曲线和计算了pN突跃。并利用双曲正弦函数的性质 ,提出了内含最大敏锐指数的络合返滴定误差计算公式 ,从而获得了计算络合返滴定pN突跃范围的公式。     

利用滴定曲线方程和Origin精确绘制滴定曲线*

滴定曲线是滴定分析原理的重要内容。它显示了滴定过程中平衡体系性质的变化,可以获知化学计量点和滴定突跃信息,从而指导准确滴定判别或指示剂的选择。滴定曲线方程是滴定过程中体系的某种性质X(例pH)与滴定分数a(或滴定剂体积V)的关系方程,解析方程可获得函数X=f(a)的表达式。对一些较复杂的体系,推导函数X=f(a)较困难,但多数情况下反函数a=g(X)的推导更容易,表达式也更简洁。本文对酸碱、配位、氧化还原和沉淀滴定曲线方程进行了系统总结,并对不同情况下的函数X=f(a)或反函数a=g(X)进行了推导,拓展了教材内容。根据函数关系,在Origin中利用其函数绘图功能可直接绘制出滴定曲线,不用先生成数据点再绘图,方便快捷。用反函数绘图时增加数据点即可获得高精度的滴定曲线,可直接从滴定曲线上查找化学计量点和滴定突跃信息。     

Comparison of Two Approaches to Processing Titration Curves of a Dibasic Acid

Two approaches to processing titration curves of dibasic acids based on the use of sets of equations characteristic for dibasic acids and for a mixture of two monobasic acids were compared. With an example of processing of titration curves of glutamic, oxalic, and succinic acids using logarithmic relationships, it was demonstrated that the first approach provides a higher sensitivity to the influence of different factors. Recommendations were given for the use of the studied approaches for solving analytical problems.     

滴定分析

本文是《分析试验室》定期评述中“滴定分析”课题的第三篇文章,前两篇为“络合滴定”,本文扩大了内容,故改题为“滴定分析”,它述评了1987～1990年6月间国内滴定分析的进展。内容包括新方法和新技术、酸碱滴定法、络合滴定法(1988.7～1990.6)、氧化还原滴定法以及沉淀滴定法等。     

Electrochemical investigations in non-aqueous media : Part I. Investigation of the dissociation of dibasic acids

The stoichiometric dissociation constants of seven dibasic acids were determined in four alcohols by potentiometric titration; it was assumed that the acidic and neutral salts dissociate completely. A linear relationship was found between the pK_1.2 values of dibasic acids in water and those in alcohols.     

微机模拟计算各种类型酸的滴定曲线以及滴定误差

本文对三元酸滴定曲线的精确计算公式加以改进,设计出适合各种类型酸的滴定曲线和滴定误差的模拟计算程序,通过在Rainbow-100机上运行,计算结果与文献报道相符。此法简单、快速,对选择滴定条件,优化实验方法具有很重要的应用价值。     

Studies on fluorescein-IV Notes on obtaining acid dissociation constants from the titration curves of dibasic acids

Equations have been derived by which the dissociation constants of a dibasic acid can be calculated from three points on a titration curve. The equations hold irrespective of the ratio of the dissociation constants, that is, irrespective of whether an end-point break appears at one equivalent of base added per mole of dibasic acid. Conditions have also been established, under which each dissociation constant can be evaluated from a single point on the titration curve.     

复杂氧化还原滴定曲线方程的Origin解析和曲线绘制

本文首先利用物料平衡和林邦副反应思想分别推导出n1=n2和n1≠n2两种情况时的氧化还原滴定曲线方程,然后应用Origin软件对所推导的不同曲线方程进行解析,建立起以溶液电势E为因变量,滴定分数a为自变量的函数关系,并绘制其滴定曲线。     

The conductometric titration of carboxylic and phenolic acids in non-aqueous solutions: Study of the titration of dibasic acids

An experimental study has been made of the conductoinetric titration of dibasic acids in non-aqueous solvents.The factors governing the shape of the titration curve and hence determining the accuracy of the analysis of these compounds are discussed, and the conditions are given under which optimum results are obtained.     

再论滴定分析终点误差的统一计算

终点误差是高等分析化学课程的重要内容。当前分析化学教材多采用浓度定义式,并在此基础上推导出各种计算式。这种"公式化"的策略简单方便,但是没有实现统一计算,记忆负担重,而且难以解决复杂问题。本文从理论上证明了体积定义式完全等价于浓度定义式,从而为通过体积定义式统一计算终点误差提供支持,同时消除对体积定义式的误解。结果表明,体积定义式具有适用范围广、记忆负担轻、以及运算强度低的优点,能够统一四大滴定的终点误差计算。此外,对现行教材中的终点误差计算策略进行了梳理和归纳,剖析了现状,讨论了林邦公式在终点误差统一计算方面的缺陷,为相关研究提供参考。     

Homopolymerization of Four New Hydroxyamic Acids and Polycondensation of Glycerol With Dibasic Amic Acids

During the past 15 years or so, research in our laboratory has been mainly directed toward the synthesis of cyclic imides and isoimides for different purposes [1–4]. Thus a large number of substituted amic acids and bis-amic acids were prepared as intermediates. These amic acids were readily purified, crystallized, and obtained in excellent yields. In the present paper two types of amic acids are prepared. The first type is hydroxyamic acids of formula A, while the second type consisted of dibasic amic acids such as B:     

Improved linear titration plots for weak-acid titrations

Linear titration plot functions are derived for the following types of titration: weak monobasic acid-strong base, weak dibasic acid-strong base weak acid-weak base. These functions are compared with the corresponding Gran functions, where possible, and the effects of the following sources of error are discussed: the neglect of activity coefficients, errors in equilibrium constants and the presence of a hydrolysable salt.