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结合多元酸碱滴定的教学实践经验,指出正确表述多元酸碱滴定的可行性判据和明确其准确度要求,对学习多元酸碱滴定的原理和解决实际问题具有重要的指导意义。 相似文献
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一、问题的提出 滴定分析是分析化学的主要内容,而对滴定突跃理论的研究在滴定分析中又占有十分重要的地位。其原因是滴定突跃的特征与滴定误差有着直接的联系,对于滴定突跃的研究,目前一般书中采用计算滴定曲线的方法来处理。在酸碱滴定中使用酸碱平衡公式,作一些近似处理,用代数方法进行计算(称代数计算法)。这种方法只适用于处理简单的滴定问题.如强酸碱滴定,强酸碱滴定弱酸碱等等。但对于较复杂的滴定如多元酸碱滴定常常会遇到以下几种难以解决的问题: 1、代数计算法很难证明强酸碱滴定弱酸碱的滴定条件为CKi≥10~(-8);二元酸碱分步滴定的条件K_1/K_2≥10~5 相似文献
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酸碱滴定是以酸碱中和反应为基础的常用容量分析法,其终点通常是借助于指示剂的颜色变化而指示的。由于指示剂常选用有机弱酸或弱碱,有自己特定的 pH 变色点与变色范围,因而对不同的酸碱中和滴定,必须根据等当点的 pH 值来选择适当的指示剂,且要参照视觉对颜色的敏感性来科学地确定合理的滴定顺序,才能取得满意的实验结果。弱酸,特别是多元弱酸,因有其特殊性,酸碱滴定过程较为复杂,对终点及以上要求更为严格,若有不 相似文献
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酸碱滴定可行性的经典理念及其存在的问题 总被引：2，自引：0，他引：2
王趁义 《湖州师范学院学报》2005,27(1):41-43
酸碱滴定可行性的经典理念是以终点误差为根据，以弱酸的平衡浓度Csp和离解常数Ka来表征酸碱滴定可行性，并把CspKa≥10^-8作为表征酸碱滴定反应可行性的判据．这种观点是片面的，只有根据终点观测误差推导酸碱滴定可行性才有实际意义，即根据平衡浓度Csp和酸与碱之间滴定反应的平衡常数Kt来表征酸碱滴定可行性．相应地，表征酸碱滴定反应可行性的判据应该是CspKt≥10^6． 相似文献
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运用质子平衡式,提出了对多元强酸强碱、缓冲溶液、酸碱滴定体系进行处理的新思想。在符合分析化学理论基础上,数学推导严密,结论正确。 相似文献
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酸碱滴定是分析化学中定量分析的基础,是定量分析的重要组成部分.酸碱滴定方法的撑握与否直接影响今后配位滴定、氧化还原滴定、沉淀滴定等滴定分析方法的学习.用"Titration"软件的滴定演示功能和动态曲线图形贯穿酸碱滴定整章教学过程,尤其是酸碱滴定曲线和指示剂的选择的教学,使抽象的概念变得生动、形象,提高了学生学习分析化学的兴趣. 相似文献
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罗济文 《广西师范大学学报(哲学社会科学版)》1995,(Z1)
滴定曲线是容量分析理论最基本的内容之一,酸碱滴定曲线的绘制,国内外分析化学教材和有关文献均有详细讨论。目前,多数教材都是将整个滴定过程分为若干阶段讨论,不同的阶段使用不同的计算公式,经近似处理后再代入数据计算。对于多元酸碱,则只计算各化学计量点的数据并用其他方法直接给出曲线。本文从溶液的物料平衡和电荷平衡出发,给出一种能推导出适用于滴定全过程的计算公式的方法。该方法可应用于不同类型的酸碱滴定。 1 计算公式的基本推导方法 以一元强碱NaOH滴定酸为例说明该法。设酸和碱的原始浓度分别为C_A~O和C_B~O,酸的原始体积为V_A~O,在滴定过程中某一时刻已加入的碱的体积为V_B,在该时刻稀释后,酸和所加入碱的分析浓度分别为C_总和C_B,滴定分数为a则 相似文献
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申双龙 《晋东南师范专科学校学报》2001,18(3):35-37
运用质子平衡式，提出了对多元强酸强碱、缓冲溶液、酸碱滴定体系进行处理的新思路。在符合分析化学理论基础上，数学推导严密，结论正确。 相似文献
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We investigated students' initial and final understanding of acid-base concepts and their concurrent thought processes and actions during the process of acid-base titrations. Here we report students' actions and thought processes while titrating. Different levels of information were presented by three technologies: chemical indicators, pH meters, and microcomputer-based laboratories. We speculated that the level of information would influence students' actions and thought processes, as expressed in verbal commentary. Data were collected from 14 secondary chemistry students. Each student used one technology to titrate a strong acid, a weak acid, and a polyprotic acid with a strong base. They verbalized their thoughts while titrating. Students then graphed pH versus volume of base and discussed the titration with the investigator. Verbal commentaries were coded and analyzed for patterns in actions and for frequency of statement categories. Drawings were analyzed for shape, scale, and direction; discussions were analyzed for understanding of acid-base neutralization. We found that the technology's level of information affected the focus of students' observations. The microcomputer group focused primarily on the graph; other groups exhibited multiple foci. We speculate the screen display functions as an auxiliary short-term memory. The discussion data also reveal that students held three main ideas about how acids and bases behave when mixed. Implications for instruction are discussed. 相似文献
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Ionizationconstantsofpolyproticweakacidsarebasicthermodynamicsdata .Undermanycircumstances ,measurementsofionizationconstantsofpolyproticweakacidsareroutinelynecessary ,e .g .,fornewcompounds ,forwell establishedcompoundsatagiventemperaturewherepreviousdataareunavailable,andindifferentsol ventsystems.ThemainmethodsfordeterminationofionizationconstantsreportedinRefs.[1]— [4 ]arecon ductometricmethod ,potentiometrictitrationmethod ,NMRmethodandspectrophotometricmethod .Inthispaper,anewmethodf… 相似文献
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王克强 《韩山师范学院学报》1992,(3)
本文用严格的数学方法从理论上系统探讨了弱酸混合酸的分步滴定问题和总酸量的滴定问题,提出了在允许误差ε=0.2％、突跃范围ΔpH=0.6条件下的混合酸准确滴定判据。 相似文献
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返滴定法确定混合碱第一计量点的探讨 总被引：3，自引：0，他引：3
阎俊英 《商丘师范学院学报》2001,17(6):85-87
采用滴定剂HCl稍过量，NaOH标准溶液返滴定过量HCl的方法，较准确地确定混合碱第一计量点。并通过分光光度测定，对该法进行了对比验证。通过实际样品测定，滴定误差均在0．5％以下。 相似文献
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用磷酸二铵和硫酸钾对公酿一号葡萄品种进行不同时期、不同比例施肥,然后采用滴定等方法对其进行分析测定,结果发现,生长期施磷钾肥能明显提高果实可溶性固形物含量,降低可滴定酸含量,从而提高固酸比,同时作物产量有所提高. 相似文献
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The purposes of this study are: to apply the ARCS model in designing an acid and bases unit, and to assess a single class
of 11th graders for motivation and achievement outcomes before and after ARCS instruction. Four essential strategies for designing
motivation instruction in the ARCS model were: Attention, Relevance, Confidence, and Satisfaction. We used the ARCS model
in designing a 10-hour acids and bases lesson for one class of 11th graders with low interest and motivation in chemistry
learning. Both the Students' Motivation toward Science Learning questionnaire (SMTSL) (Tuan, Chin & Shieh, in press) and a
teacher-designed achievement test were implemented before and after instruction. In addition, students' self-reporting on
time engagement in learning before and during the instruction was also collected. The results of the study indicated that
both students' motivation and achievement in the acids and bases unit increased significantly (p<0.05) after the ARCS instruction. Students' time engagement during the ARCS lessons had increased from before. Findings of
the study showed that using the ARCS model to teach acids and bases unit could improve low motivated students' level of motivation
and achievement. The implications for chemistry teaching will be discussed in the paper. 相似文献
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Chia-Ju Liu I-Lin Hou Houn-Lin Chiu David F. Treagust 《Research in Science Education》2014,44(1):133-154
This study explored factors of students’ mental states, including emotion, intention, internal mental representation, and external mental representation, which can affect their learning performance. In evaluating students’ mental states during the science learning process and the relationship between mental states and learning achievement, valid, reliable, and scalable measures of students’ mental states and learning achievement are needed. This paper presents the development of the Mental State Conceptual Learning Inventory (MSCLI) to identify students’ mental states before and after learning about acids and bases. This instrument is time efficient and convenient and can be administered to large student samples so that teachers and researchers can gain profound insights into their students’ learning of acids and bases in science class. The results of this study indicate that students’ mental states are highly correlated with their achievement. As a whole, low-achieving students tended to have negative emotions and low intentions, were not good at internal visualization, and were unable to interpret graphics and draw pictures. In contrast, high-achieving students had positive emotions and intentions when learning life-related topics about acids and bases, and were good at internal visualization and drawing and interpreting graphics. 相似文献