Journal of Chemical Education最新文献

In this laboratory activity, students were tasked with determining the heat of combustion for each of three common sugar substitutes: saccharin, aspartame, and sucralose. The heats of combustion were determined via three different methods: bomb calorimetry, heats of formation derived from semiempirical calculations, and tabulated average bond energies. Students were then tasked with writing a single laboratory report that combined and compared the results obtained from all three techniques. This gave them an experience more representative of writing a journal article than traditional laboratory reports that typically focused on outcomes from a single laboratory technique. The results from the two theoretical methods were compared via percent error and error analysis with the experimentally determined results. The comparison of the experimentally determined heats of combustion and the semiempirically derived heats of combustion all yielded errors of less than about 20%, while the comparisons of the experimentally determined heats of combustion and the bond-energy-derived heats of combustion yielded errors of 20–50%. In addition to the experience with writing the more complex laboratory report, students gained experience working with process hazards that involved elevated and changing gas pressure, performing computational calculations, and applying skills learned in previous chemistry courses. This laboratory activity is presented so that it will allow adoption by others, including student handouts for the bomb calorimetry and theoretical determination activities and notes for the instructor.

Titration is an important experimental skill that every chemistry educator and learner must master. Titration is often the method of choice in the science laboratory courses in secondary and postsecondary schools. During acid–base titration, chemistry learners are always told about salt formation. However, a practical visualization of the salt formed is not actually done. The evasion from the visualization of salt formed in acid–base titrations may prevent students from learning some key concepts of isolation, purification, quantification, and identification of salts. In view of the importance of titrations and salt formation therein, we demonstrate the titration of sodium hydroxide with hydrochloric acid with special focus on the visualization of the formation, isolation, purification, and identification of sodium chloride formed during the titration. The identification of sodium chloride was done by solubility studies and silver nitrate and flame tests. The approach serves as a unique and effective pedagogical method for understanding acid–base titrations and formation, isolation, purification, quantification, and identification of salts formed during acid–base neutralization reactions.

A laboratory experiment that involves the aqueous and solid phase synthesis, characterization, and solvatochromic properties exploration of red complex [Ni(Mei₃en)(acac)]BPh₄ has been developed for first-year undergraduates in the College of Chemistry and Chemical Engineering at Xiamen University. In contrast to previously reported synthesis methods (Fukuda, Y. Studies on mixed chelates─II Mixed nickel(II) chelates with N,N,N′,N′-tetramethylethylenediamine and β-diketones. J. Inorg. Nucl. Chem. 1972, 34, 2315–2328; Funasako, Y. Thermochromic and solvatochromic Nafion films incorporating cationic metal-chelate complexes. Chem. Comm 2013, 49, 4688–4690; Hosokawa, H. Colorimetric Humidity and Solvent Recognition Based on a Cation-Exchange Clay Mineral Incorporating Nickel(II)-Chelate Complexes. Langmuir 2015, 31, 13048–13053; Nguyen, T. N. Studies on Mixed Chelates. VII. Mixed Nickel(II) Chelates Containing N,N′- or N,N-Dialkylethylenediamines and Acetylacetone. Bull. Chem. Soc. Jpn. 1977, 50 (1), 154–157; Wei, X. J. Vis-Spectrum Investigation of Thermo-Solvatochromic Behaviors of a Mixed Diamine and β-Diketonate Ligand Ni(II) Complex in Different Alcoholic Solutions. Acta Phys.-Chim. Sin. 2009, 25 (7), 1449–1454; Inorganic and Analytical ChemistryExperiment Test of The 10th Chinese National Undergraduate ChemistryLaboratory Tournament https://chemlabs.nju.edu.cn/DFS/file/2019/08/26/20190826132901247mmvyr5.pdf?iid=2382 (accessed November 2023).), which using a large amount of organic solvents, the aqueous and solid phase synthesis methods described here are remarkably green, environmentally friendly, high efficiency and highly reproducible, and the complex [Ni(Me₃en)(acac)]BPh₄ showing a remarkable reversible solvatochromic phenomenon, so this experiment is very suitable as a classroom demonstration for first-year undergraduates in inorganic chemistry or general chemistry. By performing this experiment, students will gain experience in solid phase synthesis, purification, and UV–vis characterization of the complex. In addition, students will gain appreciation of how solvatochromism and thermochromism (in acetone) of the complex Ni(Me₃en)(acac)]BPh₄ and their mechanisms, and progress in the understanding of the effect of the configuration of a complex on crystal field splitting, and the effect of crystal field splitting on color.

The chemistry education research community values and emphasizes the role of constructing explanations and mechanistic reasoning to support students’ learning of organic chemistry. Emerging large language model (LLM) and generative artificial intelligence (GAI) technologies are uniquely equipped to advance the teaching and learning of chemistry. GAI-based chatbots, such as ChatGPT, have the potential to help students learn mechanistic reasoning through their generated responses. This study investigates the extent to which 255 ChatGPT-generated responses are accurate explanations of 85 different reaction mechanisms and exhibit mechanistic reasoning as categorized by the levels of explanation sophistication framework. The study also explores the effects of prompt engineering on mechanism accuracy and explanation sophistication through three types of prompt cueing. Study findings show that (1) a quarter of responses are fully accurate explanations of reaction mechanisms and the majority contain predominantly accurate explanations of chemical phenomena and identification of nucleophiles and electrophiles, (2) responses exhibit high levels of explanation sophistication, and (3) prompt engineering plays a significant role in eliciting high levels of explanation sophistication but not mechanism description accuracy. Results are situated in mechanistic reasoning and prompt engineering frameworks with a focus on how these new technologies can be integrated into the chemistry classroom.

This paper describes an interdisciplinary collaboration of faculty and students from chemistry and mathematics to develop and implement an activity showcasing the relevance of calculus in chemistry to first-semester calculus students. The activity focuses on using calculus optimization methods to maximize the ground-state radial probability distribution function for the hydrogen atom and verify that the Bohr radius gives the desired maximum. Broader goals include encouraging further mathematics study by chemistry students, enhancing awareness of calculus applications to the sciences, preparing students for physical chemistry, and cultivating scientists and mathematicians with broader and deeper backgrounds.

The lateral flow immunoassay (LFIA) is a simple and cost-effective rapid diagnostic test designed for the on-site detection of disease biomarkers. In the context of introducing this technique to undergraduate biotechnology students, we propose a comprehensive 5 h laboratory experiment. This experiment covers various aspects, including the bioconjugation of gold nanoparticles with antibodies, optimization of the bioconjugation procedure using the gold aggregation test, lab-scale manufacturing of the test strips, and the detection of the human protein biomarker lactate dehydrogenase as a proof of concept. Several strategies are employed to assess student learning in the context of this laboratory experiment. These strategies include pre-lab and post-lab discussions, a rubric for practical skills, observation and feedback, and a post-lab assessment requiring students to answer three in-depth questions on the material, procedure, and fundamentals covered, concluding with an end-of-lab report. The main goal of this experiment is to highlight the pedagogical potential inherent in utilizing cost-effective and accessible laboratory tools, specifically lateral flow immunoassays. The aim of integrating these methodologies is to provide students with a concrete and experiential understanding of analytical chemistry, biosensing, and nanotechnology, which are continually evolving fields.

In response to the great challenge that the teaching of basic sciences currently entails in the new generations of young people and seeking to awaken the interest of our students in chemistry and its areas of influence, we developed an innovative card game named “Amino-structure” which served as a key tool to implement an active learning strategy in the study of the 20 amino acids in biochemistry classes. In this paper, we describe the results of this proposal, evaluated after the completion of three (3) phases: presentation of the game, implementation, and validation. 201 university students, from academic programs in science and engineering, participated in this fun activity, and through them, we evaluated the effectiveness of this pedagogical strategy which was carried out during their studies in the above-mentioned disciplines. The analysis of the results regarding parameters such as usability, playability, and satisfaction with the game showed a high degree of acceptance by most of the participants. In the final part of our study, through a quiz with two open-ended questions, we evaluated the learning objective. The analysis of the results, based on the responses of the participants, showed that 82.1% passed the knowledge test, which suggests that a high percentage of approval of the game as a pedagogical, guiding, and motivating tool was obtained.

Instrumentation plays a vital role in almost every area of chemistry. As such, it is imperative that the undergraduate curriculum is designed to allow students to have opportunities to use a variety of instruments to best prepare them for careers in chemistry. Previous work has provided evidence of the types of instruments students use in undergraduate chemistry laboratories. However, little is known about employers’ expectations for specific instrument knowledge as chemistry students enter industry. With most chemistry undergraduate students entering careers in chemical industry upon graduation, the aim of this research was to determine the frequency of occurrence and value of specific instruments used in industry to help better align undergraduate chemistry laboratory curricula with the needs of industry. Additional data was also collected on the most important skills needed to succeed in industry, as well as the perceptions of the undergraduate courses where these skills are most effectively acquired. Results emphasize the need to improve how undergraduate students are taught instrumentation-specific skills and provide evidence on the best avenues in which to begin curricular improvement.

We are all users of lithium-ion batteries (LIBs), the electrochemical energy storage devices that revolutionized our life, making the diffusion of portable and wearable devices possible and now driving the switch from a combustion engine to electric vehicles in the transportation sector. These positive trends are however leading to two whiplash effects: the issue related to management of LIBs when they reach the end of their life (EoL-LIBs) and the supply of the critical raw materials (CRMs) needed to produce the essential LIBs’ components. Recycling of EoL-LIBs is the answer to these two problems, addressing the aspects of waste management while providing a secondary source of CRMs needed to produce new LIBs, in a closed-loop circular economy scheme. The proposed laboratory activity is specifically focused on the recycling of LiCoO₂, the most diffused cathode material and also the one containing the highest amount of CRMs. The students will be called to analyze the degradation procedure through acidic leaching, comparing the method today mostly exploited at industrial level (using inorganic acid) and the method recently proposed in the scientific literature (exploiting organic acids). Students will be called to consider not only quantitative chemical indicators (yields of degradation and recovery of CRMs) but also the cost, safety, and disposal of the procedure. The aim of this experience is to drive the students to critically consider all aspects related to sustainability, to present them the tools to quantitatively assess it, and to create awareness regarding a technology involved in our everyday life.

Triterpenic acids (TA), a class of triterpenoids, are widely distributed as secondary metabolites in plants. They have a pentacyclic structure and show high structural diversity. In this work, a simple but efficient method for extraction and detection of TA derivatives from apple peels is described. The method is technically straightforward and robust and can be implemented in both undergraduate laboratories and science classes or projects in school: Apple peels are (i) extracted with ethyl acetate, (ii) degreased with cyclohexane, and (iii) reconstituted in ethanol. Yields of about 2.1 g of extract/100 g of dry weight apple peel were obtained, which consisted of >70% TA (56% ursolic acid (UA), 10% oleanolic acid (OA)). The TA pattern can be evaluated by thin layer chromatography (TLC) using simple detection with a KMnO₄ solution. The separation of the different TA derivatives on normal phase TLC plates enables learning how the chemical structure affects the chromatographic separation. The whole procedure requires 3–4 h without the drying steps. The TA extraction represents suitable content for student education since they learn and discuss natural products and secondary plant metabolites. The performance of an extraction, purification of natural products, and observation of chromatographic separation and detection are also learned in this method. Using this simple procedure, up to 1 g/100 g of dry weight UA can be generated from apple peels. While only apple peel is used for the experiment, the rest of the apple fruit was eaten by the students. Thus, the experiment itself is a demonstration of how side streams of food production can be used as a source for chemical compounds.