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Leaded or unleaded? Homemade microscale tin electroplating 有铅的还是无铅的?自制微型电镀锡
Pub Date : 2022-03-01 DOI: 10.1515/cti-2021-0024
Maite R. Herrera-Loya, L. M. Cervantes-Herrera, Sofia Gutierrez-Vallejo, J. G. Ibanez
Abstract Social distancing measures due to the SARS-CoV-2 virus have profoundly challenged the educational experimental work. We have sought to remediate this issue by designing a series of low cost, low risk, quick, and qualitative electrochemistry and corrosion experiments to be performed in the student’s homes at the microscale with a kit provided by the teacher. One such experience is the electroplating of Sn from an aqueous chloride solution using readily available soldering wires (e.g., Sn–Pb alloy, or Sn–Ag–Cu alloy). This process catches students’ attention due to its simplicity and variety of possible applications that include corrosion protection, fabrication of electronic components, plating of cooking utensils, lithium batteries, etc.
摘要严重急性呼吸系统综合征冠状病毒2型导致的社交距离措施对教育实验工作提出了深刻挑战。我们试图通过设计一系列低成本、低风险、快速、定性的电化学和腐蚀实验来解决这个问题,这些实验将在学生家中用老师提供的试剂盒进行微型电化学和腐蚀试验。其中一种经验是使用现成的焊丝(例如,Sn–Pb合金或Sn–Ag–Cu合金)从氯化物水溶液中电镀Sn。这一过程因其简单性和各种可能的应用而引起学生的注意,包括防腐、电子元件制造、炊具电镀、锂电池等。
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引用次数: 5
Incorporating research literature and chemistry textbooks in 5E instructional model to reveal ambiguous oxidation state formalism of CuS for pre-service science teachers 在5E教学模式中结合研究文献与化学教科书,揭示职前科学教师cu的歧义氧化态形式
Pub Date : 2022-03-01 DOI: 10.1515/cti-2022-0001
Irudhayaraj Savarimuthu, Margaret Susairaj
Abstract This paper implements the 5E instructional model to reveal authentic concepts in chemistry, in particular the ambiguous oxidation state formalism of copper sulfide (CuS) for pre-service science teachers (PSTs). We discuss the process and outcomes of learning phases of the 5E (engage, explore, explain, elaborate, and evaluate) for authentic chemistry learning. The puzzle activity of engage phase demonstrate PSTs prior-knowledge, understanding, problem-solving skills in the fundamental concepts of chemistry. However, we observed misconceptions in chemistry concepts, in particular the oxidation state formalism of CuS. Next, the explore phase describe how the scientific evidence from research literature give insight into whether the PSTs conceptions are in accordance with research evidence. The research evidence from collaborative literature review revealed the uncertainty in the oxidation state formalism of CuS. In the explain phase, we explained the complex electronic structure of CuS. In the fourth phase, the elaborate phase, we involve the PSTs in the book review to elaborate and analyze the uncertain concept. The results of the book review provide insight into the coverage of oxidation state formalism of CuS in nine chemistry textbooks. Finally, in evaluate phase, the results of questionnaire describe the PSTs perspectives and experiences in the student-centered chemistry learning.
摘要本文实现了5E教学模式,以揭示真实的化学概念,特别是为职前科学教师(PSTs)提供的硫化铜(CuS)的模糊氧化态形式。我们讨论了真实化学学习的5E(参与、探索、解释、阐述和评估)学习阶段的过程和结果。参与阶段的益智活动展示了PST在化学基本概念方面的先验知识、理解和解决问题的技能。然而,我们观察到化学概念上的误解,特别是CuS的氧化态形式。接下来,探索阶段描述了研究文献中的科学证据如何洞察PSTs概念是否与研究证据一致。来自合作文献综述的研究证据揭示了CuS氧化态形式的不确定性。在解释阶段,我们解释了CuS的复杂电子结构。在第四阶段,即阐述阶段,我们在书评中引入了PST来阐述和分析不确定性概念。该书评的结果提供了对九本化学教科书中CuS氧化态形式主义的理解。最后,在评估阶段,问卷结果描述了PST在以学生为中心的化学学习中的观点和经验。
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引用次数: 0
Student explorations of calcium alginate bead formation by varying pH and concentration of acidic beverage juices 学生探索海藻酸钙珠的形成通过改变pH值和浓度的酸性饮料果汁
Pub Date : 2022-02-23 DOI: 10.1515/cti-2021-0027
J. Buenaflor, Cassandra K. Lydon, Aaron Zimmerman, Olivia L. DeSutter, Jane E. Wissinger
Abstract Teaching experiments involving edible, biodegradable calcium alginate beads serve as an attractive model system to introduce upper secondary age students to core chemistry topics through innovations in sustainable consumer products. A teaching experiment is described that engages students with the synthesis of calcium alginate hydrogel beads from sodium alginate and calcium lactate, two food-safe and renewable materials. The beads’ outer membranes are a result of ionic interactions between carboxylate groups from alginate strands and the divalent calcium cations between them, thus forming cross-linked polymers. Protonation of the carboxylate groups on the alginate strands decreases crosslinking density affecting bead formation. First, various concentrations of citric acid are used to lower the pH of the sodium alginate solution and the effect on the calcium alginate bead formation is observed. A correlation between pH and bead shape and firmness is derived. This information is then used to explore juices with varying natural acidities. The experiment is amenable to implementation in the classroom or as an at-home activity. Learning outcomes include acid-base reactions, chemical bonding, polymer structures, and green chemistry concepts. Students consider the environmental challenges of traditional plastics used in packaging and how innovative new commercial products are attempting to provide solutions.
摘要涉及可食用、可生物降解的海藻酸钙珠的教学实验是一个有吸引力的模式系统,通过可持续消费产品的创新,向高中生介绍核心化学主题。介绍了一项教学实验,让学生参与由海藻酸钠和乳酸钙这两种食品安全和可再生材料合成海藻酸钙水凝胶珠。珠子的外膜是海藻酸盐链中的羧酸根和它们之间的二价钙阳离子之间离子相互作用的结果,从而形成交联聚合物。藻酸盐链上羧酸根的质子化降低了影响珠粒形成的交联密度。首先,使用不同浓度的柠檬酸来降低藻酸钠溶液的pH,并观察对藻酸钙珠形成的影响。推导了pH值与珠状和硬度之间的相关性。这些信息随后被用于探索具有不同天然酸度的果汁。这个实验可以在课堂上进行,也可以在家里进行。学习成果包括酸碱反应、化学键合、聚合物结构和绿色化学概念。学生们考虑包装中使用的传统塑料对环境的挑战,以及创新的新商业产品如何试图提供解决方案。
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引用次数: 4
Development and validation of customized pedagogical kits for high-school chemistry teaching and learning: the redox reaction example 高中化学教学定制工具包的开发与验证:氧化还原反应实例
Pub Date : 2022-02-07 DOI: 10.1515/cti-2021-0022
Enas Easa, R. Blonder
Abstract In this paper, we describe the structure, development, and validation process of customized pedagogical kits (CPKs) for differentiated instruction (DI) in chemistry. The CPKs rely on the DI approach, comprising varied pedagogical activities (e.g., games, inquiry activities, puzzles, simulations, models) designed as treatments, to help chemistry teachers personalize their teaching according to students’ misconceptions. The kits are based on the response to intervention (RTI) model, where the teacher applies an ongoing evaluation to meet the individual student’s needs within an evolutionary flexible process of learning. Each kit includes a diagnostic task, its characterization, pedagogical treatments for diagnosed misconceptions, and an assessment task, to evaluate the effectiveness of the treatments implemented in the classroom. The kits are developed along relevant literature criteria for using DI strategies and are based on constant validation and ongoing assessment, as demonstrated in the Redox-reaction CPK development. The validation and impact of the CPK on students’ achievements are supported by 25 chemistry teachers that implemented the full kit in their classrooms. Furthermore, the CPKs developed in the present research have succeeded in resolving many of the difficulties and challenges mentioned in the literature as obstructing the implementation of DI.
摘要本文介绍了化学差异化教学定制教学套件(CPKs)的结构、开发和验证过程。cpk依靠DI方法,包括各种教学活动(例如,游戏,探究活动,谜题,模拟,模型)设计为治疗,以帮助化学教师根据学生的误解个性化教学。该工具包是基于干预反应(RTI)模型,其中教师应用一个持续的评估,以满足个别学生的需求,在一个进化灵活的学习过程。每个工具包包括一个诊断任务,它的特征,诊断错误观念的教学治疗,和一个评估任务,评估在课堂上实施的治疗的有效性。该试剂盒是根据使用DI策略的相关文献标准开发的,并基于不断的验证和持续的评估,如氧化还原反应CPK开发所示。25名化学教师在他们的课堂上实施了完整的工具包,支持CPK对学生成绩的验证和影响。此外,本研究中开发的cpk成功地解决了文献中提到的阻碍DI实施的许多困难和挑战。
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引用次数: 6
Development of teaching material for green and sustainable chemistry in Japan 日本绿色可持续化学教材的开发
Pub Date : 2022-01-31 DOI: 10.1515/cti-2021-0029
Izumi Imai, Y. Tsuchiya, K. Ogino, Keiji Ueno, Hitoshi Tomita, K. Makide, Kenichi Tominaga
Abstract This study first developed content for a series of textbooks on green and sustainable chemistry (hereinafter referred to as GSC) targeted for university use. The textbooks focus on technology and products that have been awarded prizes in recognition of their contribution and performance toward GSC promotion. We also supplemented the textbooks with a video teaching material on dyeing systems that do not use water. We then surveyed aspiring secondary school teachers about the developed teaching materials using the questionnaire method. The results from university students’ questionnaires showed that 82% understood the importance of GSC and were interested in the subject. Second, we developed a series of leaflets on GSC targeted for use in upper secondary schools. Specifically, the content emphasizes the relationship between high school chemistry textbooks and daily life, other subjects, society, and the global environment. The results showed that approximately 60% of the senior high school students’ first impression of the leaflet was “interesting.” Twenty years after GSC has been defined, it has still not become completely pervasive in Japan. In the future, it will be necessary to foster instructors capable of teaching GSC in secondary education.
本研究首先开发了面向大学使用的绿色和可持续化学(以下简称GSC)系列教材的内容。教材集中介绍了为促进GSC做出贡献和表现而获得奖励的技术和产品。我们还制作了一套不用水的染色系统的视频教材作为教科书的补充。然后采用问卷调查法对有抱负的中学教师就所开发的教材进行调查。大学生问卷调查结果显示,82%的大学生了解GSC的重要性,并对这一学科感兴趣。其次,我们制作了一系列针对高中使用的GSC传单。具体而言,内容强调高中化学教科书与日常生活、其他学科、社会和全球环境的关系。结果显示,约60%的高中生对传单的第一印象是“有趣”。在GSC定义20年后,它仍然没有在日本完全普及。在未来的中学教育中,有必要培养能够教授GSC的教师。
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引用次数: 1
Simple and easy way for students to develop a dynamic model on Excel sheet 简单方便的方法,让学生在Excel表格上开发动态模型
Pub Date : 2022-01-27 DOI: 10.1515/cti-2020-0035
M. Kamata, Asuka Kamata
Abstract Radioactive decay is not only important in the field of radiochemistry but also useful as a teaching material for chemical kinetics. Although differential equations are often used to explain how decay rate changes over time, there are many students even in college or university who are not very good at mathematics and have difficulty in solving differential equations. Those students are expected to appreciate institutive and schematic illustrations using Excel sheets. In this paper, a water and tank model to demonstrate how radionuclides decay and decrease over time is presented as an example of the model that the students can develop or rearrange by themselves. Therefore, only four arithmetical operations were used in the sheet, so that the students can easily grasp the basic concept of a decay curve or radioactive equilibrium even if they do not have great knowledge of differential equations. In addition, only “Record Macro” and built in “Charts” were used on the sheet, and therefore, no knowledge or skill in graphic programming, such as Visual Basic, is needed to make and use the sheet. A brief online survey indicated the model was interesting to high school students. Since Excel is widely used all over the world, the sheets we have developed can be used in many countries without additional expense.
放射性衰变不仅在放射化学领域具有重要意义,而且作为化学动力学的教材也很有用。虽然微分方程经常被用来解释衰减率是如何随时间变化的,但有很多学生甚至在大学里也不是很擅长数学,很难解微分方程。这些学生应该能够使用Excel表格欣赏制度和原理图。在本文中,一个水和水箱模型展示了放射性核素如何随着时间的推移而衰变和减少,作为一个例子,学生可以自己开发或重新排列模型。因此,在表格中只使用了四种算术运算,使学生即使不太了解微分方程,也能很容易地掌握衰变曲线或放射性平衡的基本概念。此外,在工作表上只使用了“Record Macro”和内置的“Charts”,因此,制作和使用工作表不需要图形编程的知识或技能,例如Visual Basic。一项简短的在线调查显示,高中生对这种模式很感兴趣。由于Excel在世界各地广泛使用,我们开发的表格可以在许多国家使用,而无需额外费用。
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引用次数: 0
Balancing redox equations through zero oxidation number method 用零氧化数法平衡氧化还原方程式
Pub Date : 2022-01-13 DOI: 10.1515/cti-2021-0031
Shengping Zheng
Abstract Many high school students and first-year undergraduate students find it difficult to balance redox reactions. A method using zero oxidation number to balance redox equations is presented herein. This method may shorten the balancing time and lessen the effort. It is a helpful complement to the traditional oxidation number method and half-reaction method.
许多高中生和大一学生发现很难平衡氧化还原反应。本文提出了一种用零氧化数来平衡氧化还原方程的方法。这种方法可以缩短平衡时间,减少工作量。它是对传统氧化数法和半反应法的有益补充。
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引用次数: 1
Exploring the relationships among stoichiometric coefficients, number of transferred electrons, mean oxidation number of carbons, and oxidative ratio in organic combustion reactions 探索有机燃烧反应中化学计量系数、转移电子数、碳平均氧化数和氧化比之间的关系
Pub Date : 2021-12-28 DOI: 10.1515/cti-2021-0020
Pong Kau Yuen, C. M. Lau
Abstract Combustion reactions, stoichiometry, and redox reactions are some of the basic contents in chemistry curriculum. Although the counting of transferred electrons is critical in redox reactions, assigning mean oxidation number of organic carbons (ONc) is not always easy. Even though the relationship between the oxidative ratio (OR) and ONc is known, the relationship between the number of transferred electrons (Te−) and OR has not been thoroughly studied. The H-atom method has already been developed to balance and deduct organic combustion reactions. It can be used further to help establish the relationships among the stoichiometric coefficients (SC), the number of transferred hydrogens (TH), and Te−. This article uses the procedures of the H-atom method for balancing and deducting, and the known relationships among SC, TH, and Te− for exploring the relationships among SC, Te−, ONc, and OR in organic combustion reactions. By integrating three sets of relationships: (i) SC and Te−, (ii) Te− and ON, and (iii) SC and OR, the interconversions among SC, Te−, ONc, and OR can be mathematically formulated. Furthermore, Te−, ONc, and OR can be assigned by SC and the general molecular formula of CxHyOzXw.
燃烧反应、化学计量学和氧化还原反应是化学课程的基本内容。虽然转移电子的计数在氧化还原反应中是至关重要的,但确定有机碳的平均氧化数(ONc)并不总是那么容易。尽管氧化比(OR)与ONc之间的关系是已知的,但转移电子数(Te−)与OR之间的关系尚未得到深入研究。h原子法已经发展到平衡和扣除有机燃烧反应。它可以进一步用于帮助建立化学计量系数(SC)、转移氢数(TH)和Te−之间的关系。本文利用已知的SC、TH和Te−之间的关系,利用h原子法进行平衡和推导,探讨了有机燃烧反应中SC、Te−、ONc和OR之间的关系。通过整合三组关系:(i) SC和Te−,(ii) Te−和ON,以及(iii) SC和OR, SC、Te−、ONc和OR之间的相互转换可以用数学公式表示。此外,Te−、ONc和OR可以通过SC和CxHyOzXw的一般分子式进行分配。
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引用次数: 3
A simple theoretical, quantitative approach to help understand the titration of weak acids and bases 一个简单的理论,定量的方法,以帮助了解滴定弱酸和弱碱
Pub Date : 2021-12-28 DOI: 10.1515/cti-2021-0021
M. Arocena
Abstract What happens at the very beginning of the titration of a weak acid or base is a question sometimes asked by undergraduate students when introduced to the concept of buffer solution. To attempt to answer this question, a simple quantitative approach is developed, which also allows explaining more general properties of the weak acid or weak base titration process, while serving as well as an introduction to the theoretical, quantitative treatment of this subject. Using this approach, it can be shown that, at the beginning of the titration, the reaction between a weak acid (base) and a strong base (acid) does not occur on a one to one ratio when very small amounts of the strong base (acid) are added.
当介绍缓冲溶液的概念时,大学生有时会问弱酸或弱碱滴定开始时会发生什么。为了试图回答这个问题,一种简单的定量方法被开发出来,它也允许解释弱酸或弱碱滴定过程的更一般的性质,同时也为这个主题的理论和定量处理提供了介绍。使用这种方法,可以证明,在滴定开始时,当加入极少量的强碱(酸)时,弱酸(碱)和强碱(酸)之间的反应不会以一比一的比例发生。
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引用次数: 0
Frontmatter Frontmatter
Pub Date : 2021-12-01 DOI: 10.1515/cti-2021-frontmatter4
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引用次数: 0
期刊
Chemistry Teacher International : best practices in chemistry education
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