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2023 Volume 38 Issue 8
2023, 38(8): 1-8
doi: 10.3866/PKU.DXHX202208069
Abstract:
The conditions and shortcomings of the curriculum of general chemistry laboratory are analyzed and studied. The principles for reformation includes visualization of chemical processes, materialization of experimental results and virtual reality of chemical theories. The students' perspective and view of observation will be changed by application of digital imaging technique. Practical products will be obtained from the experiments. The microstructure of materials will be presented by means of software, handicraft and 3D printing. With these novel techniques and new ideas on reforming of laboratory teaching, the aspect of the curriculum of general chemistry laboratory will be improved substantially. The students will expand the horizons and boost their innovation skills. Thus, the chemical education and teaching will receive more and more recognition and passion from the students.
The conditions and shortcomings of the curriculum of general chemistry laboratory are analyzed and studied. The principles for reformation includes visualization of chemical processes, materialization of experimental results and virtual reality of chemical theories. The students' perspective and view of observation will be changed by application of digital imaging technique. Practical products will be obtained from the experiments. The microstructure of materials will be presented by means of software, handicraft and 3D printing. With these novel techniques and new ideas on reforming of laboratory teaching, the aspect of the curriculum of general chemistry laboratory will be improved substantially. The students will expand the horizons and boost their innovation skills. Thus, the chemical education and teaching will receive more and more recognition and passion from the students.
2023, 38(8): 9-14
doi: 10.3866/PKU.DXHX202208146
Abstract:
Starting from the background of "Three All-Round Education", this paper expounds the importance of chemistry and society in curriculum reformation. This paper explores the methods of course ideology and politics of Chemistry and Society:discusses the specific measures of curriculum political thinking from the aspects of teaching objectives, teaching content, teaching methods and means, diversified assessments and finally summarizes the learning effect. These practices can achieve the teaching goal of value shaping, knowledge transfer and capacity development.
Starting from the background of "Three All-Round Education", this paper expounds the importance of chemistry and society in curriculum reformation. This paper explores the methods of course ideology and politics of Chemistry and Society:discusses the specific measures of curriculum political thinking from the aspects of teaching objectives, teaching content, teaching methods and means, diversified assessments and finally summarizes the learning effect. These practices can achieve the teaching goal of value shaping, knowledge transfer and capacity development.
2023, 38(8): 15-21
doi: 10.3866/PKU.DXHX202208031
Abstract:
Based on standard teaching practice, we propose a blended teaching mode called "three Integration, three transformation" for chemical separation engineering course. This mode was designed in accordance with ideological and political education principles and the engineering education certification. The integration of online and offline teaching allows teachers to take advantage of online teaching resources such as "Rain Classroom". Meanwhile, there is potential to develop a more scientific evaluation system of the overall learning process. The integration of ideological and political education and professional education is conducive to the completion of the fundamental task of "establishing morality and cultivating people". Furthermore, to meet the requirements of the emerging engineering education, we actively mobilized offline practical teaching resources to improve students' engineering practical literacy. Preliminary teaching trials show that this model can stimulate students' interest in learning and innovation potential and improve their higher-order thinking skills. The overall learning outcomes were also significantly improved.
Based on standard teaching practice, we propose a blended teaching mode called "three Integration, three transformation" for chemical separation engineering course. This mode was designed in accordance with ideological and political education principles and the engineering education certification. The integration of online and offline teaching allows teachers to take advantage of online teaching resources such as "Rain Classroom". Meanwhile, there is potential to develop a more scientific evaluation system of the overall learning process. The integration of ideological and political education and professional education is conducive to the completion of the fundamental task of "establishing morality and cultivating people". Furthermore, to meet the requirements of the emerging engineering education, we actively mobilized offline practical teaching resources to improve students' engineering practical literacy. Preliminary teaching trials show that this model can stimulate students' interest in learning and innovation potential and improve their higher-order thinking skills. The overall learning outcomes were also significantly improved.
2023, 38(8): 22-30
doi: 10.3866/PKU.DXHX202209060
Abstract:
Rearrangement reaction is one of the important but unique teaching contents in organic synthesis course, as it seems very different from the basic organic reactions, such as substitution reactions, addition reactions, elimination reactions, oxidation and reduction. In fact, rearrangement reactions are involved in many chapters of organic chemistry course, which makes it hard for the students to get a deep understanding of these types of reactions and clarify the relationship between them. Therefore, the development of teaching practice in a deep leaning manner is of significant importance. Based on the characteristics of this course and the current teaching situation, we focused on the four characteristics of deep learning, and took teaching clips as an example to illustrate the application of deep learning theory in organic synthesis.
Rearrangement reaction is one of the important but unique teaching contents in organic synthesis course, as it seems very different from the basic organic reactions, such as substitution reactions, addition reactions, elimination reactions, oxidation and reduction. In fact, rearrangement reactions are involved in many chapters of organic chemistry course, which makes it hard for the students to get a deep understanding of these types of reactions and clarify the relationship between them. Therefore, the development of teaching practice in a deep leaning manner is of significant importance. Based on the characteristics of this course and the current teaching situation, we focused on the four characteristics of deep learning, and took teaching clips as an example to illustrate the application of deep learning theory in organic synthesis.
2023, 38(8): 31-37
doi: 10.3866/PKU.DXHX202208077
Abstract:
Organic chemistry is an important basic course for chemistry and related majors, but many reactions, esoteric mechanisms and complex synthesis make it one of the most difficult courses in science and engineering colleges. In the teaching of organic chemistry, we use the comparative teaching method to explain the knowledge that is easy to be confused and difficult to understand and remember. Through concept comparison, structure and property comparison, reaction condition comparison, mechanism comparison, synthesis method and other multi angle analysis and comparison, we can grasp the main contradictions of things, help students clarify the similarities and differences of knowledge, stimulate students' interest in learning, and improve the quality of teaching.
Organic chemistry is an important basic course for chemistry and related majors, but many reactions, esoteric mechanisms and complex synthesis make it one of the most difficult courses in science and engineering colleges. In the teaching of organic chemistry, we use the comparative teaching method to explain the knowledge that is easy to be confused and difficult to understand and remember. Through concept comparison, structure and property comparison, reaction condition comparison, mechanism comparison, synthesis method and other multi angle analysis and comparison, we can grasp the main contradictions of things, help students clarify the similarities and differences of knowledge, stimulate students' interest in learning, and improve the quality of teaching.
2023, 38(8): 38-43
doi: 10.3866/PKU.DXHX202208079
Abstract:
There exist some problems in cultivating talents in local colleges and universities, such as the inadaptation between talent cultivating objectives and locally economic development needs, the lack of effective measures and reasonable assessment and evaluation mechanisms for cultivating students' application abilities, the loose integration of professional education and humanistic education, and the lack of in-depth integration of industry and education. In response to these problems, the teaching team at the school of chemistry and chemical engineering, Linyi University has built the student-centered "four-in-one" talent cultivating model, which is guided by moral education, supported by practical platform, and driven by scientific and technological projects. The school has taken some measures of resetting the talent training program, optimizing the double-qualified teachers, strengthening the hierarchical and progressive training, and establishing an incentive-oriented assessment and evaluation mechanism to highlight the cultivation of application ability. The whole-process education of all staff has been realized, and gratifying results have been achieved.
There exist some problems in cultivating talents in local colleges and universities, such as the inadaptation between talent cultivating objectives and locally economic development needs, the lack of effective measures and reasonable assessment and evaluation mechanisms for cultivating students' application abilities, the loose integration of professional education and humanistic education, and the lack of in-depth integration of industry and education. In response to these problems, the teaching team at the school of chemistry and chemical engineering, Linyi University has built the student-centered "four-in-one" talent cultivating model, which is guided by moral education, supported by practical platform, and driven by scientific and technological projects. The school has taken some measures of resetting the talent training program, optimizing the double-qualified teachers, strengthening the hierarchical and progressive training, and establishing an incentive-oriented assessment and evaluation mechanism to highlight the cultivation of application ability. The whole-process education of all staff has been realized, and gratifying results have been achieved.
2023, 38(8): 44-48
doi: 10.3866/PKU.DXHX202208151
Abstract:
Inspired by the fundamental task of strengthening morality education, we integrate ideological and political theory into physical chemistry course after analyzing the teaching situation and reforming current courses. Taking "Fundamentals of Chemical Dynamics-Simple Order Reactions" as an example, this paper expatiates the strategy of integrating ideological and political materials in the teaching process, leading students to feel the scientific spirit through chemical history and realize social responsibility from Chinese culture. A blended educating method is explored in teaching practice to impart knowledge and cultivate moral values simultaneously. On these bases, we establish parallel education of the physical chemistry core curriculum and ideological and political theory, enabling close cooperation of specialized course and ideological education eventually.
Inspired by the fundamental task of strengthening morality education, we integrate ideological and political theory into physical chemistry course after analyzing the teaching situation and reforming current courses. Taking "Fundamentals of Chemical Dynamics-Simple Order Reactions" as an example, this paper expatiates the strategy of integrating ideological and political materials in the teaching process, leading students to feel the scientific spirit through chemical history and realize social responsibility from Chinese culture. A blended educating method is explored in teaching practice to impart knowledge and cultivate moral values simultaneously. On these bases, we establish parallel education of the physical chemistry core curriculum and ideological and political theory, enabling close cooperation of specialized course and ideological education eventually.
2023, 38(8): 49-54
doi: 10.3866/PKU.DXHX202208081
Abstract:
Organic chemistry is a basic course which has close relationship with the philosophy concept such as "theory with practice", "unity and opposites", etc. In the organic chemistry course at our school, we try to introduce the philosophy of dialectical materialism to reorganize the contents. We aim to change the students' "isolated, partial, static" understanding from rigid memory, and try to build the "interrelated, comprehensive, developing" philosophic understanding of organic chemistry.
Organic chemistry is a basic course which has close relationship with the philosophy concept such as "theory with practice", "unity and opposites", etc. In the organic chemistry course at our school, we try to introduce the philosophy of dialectical materialism to reorganize the contents. We aim to change the students' "isolated, partial, static" understanding from rigid memory, and try to build the "interrelated, comprehensive, developing" philosophic understanding of organic chemistry.
2023, 38(8): 55-60
doi: 10.3866/PKU.DXHX202208035
Abstract:
Taking the content of "Atomic Structure and Periodic Table of Elements" as a specific case, the combination of "course ideology and politics" and the teaching process of general chemistry in college is explored. Carrying ideological and political teaching is aimed to merge students' ideological and political concepts, scientific literacy and subject way of thinking, and in-depth excavation by full use of college general chemistry courses in knowledge transfer, ability cultivation and value guidance. On the basis of condensing the ideological and political elements in general chemistry, we explore and practice the effective combination of the teaching content of "atomic structure and periodic table of elements" with ideological and politics of general chemistry under the concept of "course ideology and politics".
Taking the content of "Atomic Structure and Periodic Table of Elements" as a specific case, the combination of "course ideology and politics" and the teaching process of general chemistry in college is explored. Carrying ideological and political teaching is aimed to merge students' ideological and political concepts, scientific literacy and subject way of thinking, and in-depth excavation by full use of college general chemistry courses in knowledge transfer, ability cultivation and value guidance. On the basis of condensing the ideological and political elements in general chemistry, we explore and practice the effective combination of the teaching content of "atomic structure and periodic table of elements" with ideological and politics of general chemistry under the concept of "course ideology and politics".
2023, 38(8): 61-68
doi: 10.3866/PKU.DXHX202209055
Abstract:
The analytical chemistry course plays an important role in cultivation of talents for chemistry majors and students' innovation ability and scientific research training. According to the course content of analytical chemistry, the ideological and political elements were excavated based on the cultivation of the correct abilities of analysis. And the course ideology and politics were integrated into the whole teaching process, leading to the formation of the system of ideological and political elements and the goal of moral education.
The analytical chemistry course plays an important role in cultivation of talents for chemistry majors and students' innovation ability and scientific research training. According to the course content of analytical chemistry, the ideological and political elements were excavated based on the cultivation of the correct abilities of analysis. And the course ideology and politics were integrated into the whole teaching process, leading to the formation of the system of ideological and political elements and the goal of moral education.
2023, 38(8): 69-76
doi: 10.3866/PKU.DXHX202210018
Abstract:
Environmental inorganic and analytical chemistry is an important basic course of environmental science. Under the background of "new college entrance examination", the teaching of environmental inorganic and analytical chemistry is facing great challenges due to the different chemical knowledge reserves of students. This paper proposes the teaching mode of student-centered and closed-loop teaching with teacher-directed and student-oriented, dig the relationship between professional content and ideological moral education, and then design and practice curriculum ideological and political teaching cases, expecting to realize knowledge imparting and value leading in the same direction.
Environmental inorganic and analytical chemistry is an important basic course of environmental science. Under the background of "new college entrance examination", the teaching of environmental inorganic and analytical chemistry is facing great challenges due to the different chemical knowledge reserves of students. This paper proposes the teaching mode of student-centered and closed-loop teaching with teacher-directed and student-oriented, dig the relationship between professional content and ideological moral education, and then design and practice curriculum ideological and political teaching cases, expecting to realize knowledge imparting and value leading in the same direction.
2023, 38(8): 77-84
doi: 10.3866/PKU.DXHX202303066
Abstract:
Aiming at shortcomings of traditional inorganic chemistry laboratory teaching such as the single teaching mode and content, incomplete laboratory assessment and evaluation, and insufficient combination of laboratory teaching with information technology. The inorganic chemistry laboratory platform based on cloud desktop has been constructed, the cloud open teaching mode of "cloud guidance, cloud assistance, cloud promotion" has been discussed online and offline, and the application effect and practice feedback of the laboratory teaching mode have been analyzed. Practice has proved that this laboratory teaching mode effectively solves the problems of students' weak participation, insufficient interaction between teachers and students, and insufficient personalized learning. It plays an important role in cultivating students' independent learning ability, practical application ability and innovation and entrepreneurship ability.
Aiming at shortcomings of traditional inorganic chemistry laboratory teaching such as the single teaching mode and content, incomplete laboratory assessment and evaluation, and insufficient combination of laboratory teaching with information technology. The inorganic chemistry laboratory platform based on cloud desktop has been constructed, the cloud open teaching mode of "cloud guidance, cloud assistance, cloud promotion" has been discussed online and offline, and the application effect and practice feedback of the laboratory teaching mode have been analyzed. Practice has proved that this laboratory teaching mode effectively solves the problems of students' weak participation, insufficient interaction between teachers and students, and insufficient personalized learning. It plays an important role in cultivating students' independent learning ability, practical application ability and innovation and entrepreneurship ability.
2023, 38(8): 85-94
doi: 10.3866/PKU.DXHX202208060
Abstract:
The COVID-19 pandemic has caused significant losses and suffering around the world. Although the SARS-CoV-2 vaccine has largely controlled the spread of the virus, the scientific and sustainable treatment of COVID-19 patients is still necessary to truly end the pandemic. Small-molecule drugs against COVID-19 have attracted the attention of the scientific community and industry owing to their unique advantages such as a simple delivery method, relatively high output, and immune response with lower probability. Fortunately, in the last three years, some potentially effective drugs have been proposed, and have achieved good results in clinical trials. This paper briefly introduces the research progress on small-molecule drugs since 2020 to provide reference for future SARS-CoV-2 research.
The COVID-19 pandemic has caused significant losses and suffering around the world. Although the SARS-CoV-2 vaccine has largely controlled the spread of the virus, the scientific and sustainable treatment of COVID-19 patients is still necessary to truly end the pandemic. Small-molecule drugs against COVID-19 have attracted the attention of the scientific community and industry owing to their unique advantages such as a simple delivery method, relatively high output, and immune response with lower probability. Fortunately, in the last three years, some potentially effective drugs have been proposed, and have achieved good results in clinical trials. This paper briefly introduces the research progress on small-molecule drugs since 2020 to provide reference for future SARS-CoV-2 research.
2023, 38(8): 95-100
doi: 10.3866/PKU.DXHX202208102
Abstract:
Herein, a comprehensive experiment was carried out to study the macrocyclic molecules of semithiobambus[6]uril (stBU[6]), involving the preparation, characterization, and performance testing. Through a series of fluorescence tests, the students are guided to understand the mechanism of ion transmembrane transport, familiarize themselves with large-scale instruments, and broaden their horizons to lay a good foundation for improving their comprehensive practical skills.
Herein, a comprehensive experiment was carried out to study the macrocyclic molecules of semithiobambus[6]uril (stBU[6]), involving the preparation, characterization, and performance testing. Through a series of fluorescence tests, the students are guided to understand the mechanism of ion transmembrane transport, familiarize themselves with large-scale instruments, and broaden their horizons to lay a good foundation for improving their comprehensive practical skills.
2023, 38(8): 101-107
doi: 10.3866/PKU.DXHX202208121
Abstract:
An analytical chemistry experiment at an intermediate level is presented in this work, achieving the detection of chemiluminescence (CL) on a paper-based device. Using copper nitrate and benzene-1,3,5-tricarboxylic (BTC) acid in a metal-organic frameworks (MOFs) synthesis reaction, Cu-BTC with a catalytic effect was synthesized and loaded onto the paper's surface. Due to the catalytic effect of Cu-BTC in a luminol-H2O2 CL system, trace H2O2 can be detected. This exercise can train students' practical ability in comprehensive experiments. It can also improve the intuitive ability of normal students to better grasp experimental data processing.
An analytical chemistry experiment at an intermediate level is presented in this work, achieving the detection of chemiluminescence (CL) on a paper-based device. Using copper nitrate and benzene-1,3,5-tricarboxylic (BTC) acid in a metal-organic frameworks (MOFs) synthesis reaction, Cu-BTC with a catalytic effect was synthesized and loaded onto the paper's surface. Due to the catalytic effect of Cu-BTC in a luminol-H2O2 CL system, trace H2O2 can be detected. This exercise can train students' practical ability in comprehensive experiments. It can also improve the intuitive ability of normal students to better grasp experimental data processing.
2023, 38(8): 108-117
doi: 10.3866/PKU.DXHX202208073
Abstract:
With the goal of developing high-quality applied talents, a comprehensive experiment, "Preparation and capacitive properties of porous carbon materials", has been designed to cultivate the practical and innovative abilities of students. The experiment consists of multiple parts, including formulating a scheme, preparing and characterizing materials, measuring the performance, processing data, and writing a paper based on the basic theory and preparation principles of porous carbon materials that the students have mastered. After this training, students will be familiar with scientific research ideas and will have mastered the experimental methods and skills to operate a tube furnace; conduct scanning electron microscopy, X-ray powder diffraction characterization, N2 adsorption-desorption, and capacitance performance analyses; and perform data processing. Thus, the goal of nurturing students' scientific research interest, cultivating awareness on sustainable development, and inculcating an innovative spirit will be realized.
With the goal of developing high-quality applied talents, a comprehensive experiment, "Preparation and capacitive properties of porous carbon materials", has been designed to cultivate the practical and innovative abilities of students. The experiment consists of multiple parts, including formulating a scheme, preparing and characterizing materials, measuring the performance, processing data, and writing a paper based on the basic theory and preparation principles of porous carbon materials that the students have mastered. After this training, students will be familiar with scientific research ideas and will have mastered the experimental methods and skills to operate a tube furnace; conduct scanning electron microscopy, X-ray powder diffraction characterization, N2 adsorption-desorption, and capacitance performance analyses; and perform data processing. Thus, the goal of nurturing students' scientific research interest, cultivating awareness on sustainable development, and inculcating an innovative spirit will be realized.
2023, 38(8): 118-127
doi: 10.3866/PKU.DXHX202208052
Abstract:
With the ongoing developments in the graphene industry, the discharge of wastewater is increasing. It has the characteristics of strong acidity and high concentration of fluoride and metal ions. In this experiment, graphene simulated wastewater were treated by four methods, including single coagulation, neutralization coagulation, coagulation flocculation, and neutralization coagulation and flocculation. These methods were compared to remove contaminants such as fluoride and metal ions. The ion content and sediment in the wastewater were analyzed using ion chromatography and X-ray powder diffraction. The results show that the combination of sodium hydroxide, calcium hydroxide, and flocculant has the best fluoride removal effect. The removal rates of fluoride and metal ions reached 98% and 99.5%, respectively. Compared with the traditional process, the sediment is reduced by over 50%. The experiment was easily operated and observed. The experimental content highlights that combining practice and theory methods enriches the teaching design of experimental courses and guides students to understand the current situation of industrial production, improve their awareness of environmental protection, and master the usage of chemical software and ability of data analysis and processing. This satisfies the requirements of cultivating students' comprehensive ability in applied undergraduate colleges.
With the ongoing developments in the graphene industry, the discharge of wastewater is increasing. It has the characteristics of strong acidity and high concentration of fluoride and metal ions. In this experiment, graphene simulated wastewater were treated by four methods, including single coagulation, neutralization coagulation, coagulation flocculation, and neutralization coagulation and flocculation. These methods were compared to remove contaminants such as fluoride and metal ions. The ion content and sediment in the wastewater were analyzed using ion chromatography and X-ray powder diffraction. The results show that the combination of sodium hydroxide, calcium hydroxide, and flocculant has the best fluoride removal effect. The removal rates of fluoride and metal ions reached 98% and 99.5%, respectively. Compared with the traditional process, the sediment is reduced by over 50%. The experiment was easily operated and observed. The experimental content highlights that combining practice and theory methods enriches the teaching design of experimental courses and guides students to understand the current situation of industrial production, improve their awareness of environmental protection, and master the usage of chemical software and ability of data analysis and processing. This satisfies the requirements of cultivating students' comprehensive ability in applied undergraduate colleges.
2023, 38(8): 128-135
doi: 10.3866/PKU.DXHX202208108
Abstract:
Performing chemistry experiments is an important way for students to develop practical skills and understand the process of scientific inquiry. Using research results, a comprehensive experiment was designed for the electrochemical synthesis of selenium-containing heterocycles. The experiment teaches students about chemical synthesis, analytical techniques, and structural analysis through the preparation of substrates, electrochemical synthesis and analysis, the spectral characterization of compounds, and crystal culture and analysis, among other processes. Learning about electrochemical synthesis enhances students' awareness of green chemistry and stimulates their interest in the scientific process.
Performing chemistry experiments is an important way for students to develop practical skills and understand the process of scientific inquiry. Using research results, a comprehensive experiment was designed for the electrochemical synthesis of selenium-containing heterocycles. The experiment teaches students about chemical synthesis, analytical techniques, and structural analysis through the preparation of substrates, electrochemical synthesis and analysis, the spectral characterization of compounds, and crystal culture and analysis, among other processes. Learning about electrochemical synthesis enhances students' awareness of green chemistry and stimulates their interest in the scientific process.
2023, 38(8): 136-144
doi: 10.3866/PKU.DXHX202208074
Abstract:
Owing to time consumption and waste liquid production constraints, the optimization of separation conditions is not involved in high performance liquid chromatography (HPLC) experiments in colleges. In these experiments, students complete only the operation practice of "prescription preparation", and their practical ability of constructing an HPLC analysis scheme for specific objects is ineffectively cultivated. Therefore, we propose an improved procedure:the chromatographic injection practice and determination of rhubarb anthraquinone compounds are organically combined, and the chromatographic conditions are optimized using the virtual simulation software HPLC Simulator without prolonging the class time. Retention data under different temperature and mobile phase compositions were obtained in the injection practice experiment, and the data were shared by all students. The green optimization of the chromatographic conditions was then realized using HPLC Simulator. The optimal chromatographic conditions simulated were verified in a second experiment. This improved experiment transfers the boring chromatographic injection practice into an exploratory experiment that stimulates students' learning enthusiasm. It can help students master the green optimization of chromatographic conditions in limited class hours, cultivate their ability to solve practical problems using information technology, and improve the experimental teaching quality under the informatization background. In addition, the sharing of experimental data may cultivate students' teamwork spirit.
Owing to time consumption and waste liquid production constraints, the optimization of separation conditions is not involved in high performance liquid chromatography (HPLC) experiments in colleges. In these experiments, students complete only the operation practice of "prescription preparation", and their practical ability of constructing an HPLC analysis scheme for specific objects is ineffectively cultivated. Therefore, we propose an improved procedure:the chromatographic injection practice and determination of rhubarb anthraquinone compounds are organically combined, and the chromatographic conditions are optimized using the virtual simulation software HPLC Simulator without prolonging the class time. Retention data under different temperature and mobile phase compositions were obtained in the injection practice experiment, and the data were shared by all students. The green optimization of the chromatographic conditions was then realized using HPLC Simulator. The optimal chromatographic conditions simulated were verified in a second experiment. This improved experiment transfers the boring chromatographic injection practice into an exploratory experiment that stimulates students' learning enthusiasm. It can help students master the green optimization of chromatographic conditions in limited class hours, cultivate their ability to solve practical problems using information technology, and improve the experimental teaching quality under the informatization background. In addition, the sharing of experimental data may cultivate students' teamwork spirit.
2023, 38(8): 145-155
doi: 10.3866/PKU.DXHX202208129
Abstract:
Realizing high-efficiency H2 production under practical, mild conditions is essential to meet the requirements to develop this source of ideal clean, alternative energy; thus, this attracted wide spread interest. Catalytic decomposition of formic acid-formate is one of the most widely studied options to achieve this. Herein, we demonstrate H2 production from HCOOK over Pd/C catalysts, in which a flexible content is allowed by modulating the catalyst preparation conditions, reaction conditions, and catalytic characterizations. This experiment not only includes basic chemical kinetics but also guides students to accumulate innovative consciousness through thinking about the structure-activity relationship of catalysts by structural characterization. In addition, this experiment enriches teaching content, improves teaching efficiency, and exercises students' cooperation ability through modular design and group teaching. This project relies on the National Demonstration Center for Experimental Education to build an inter-school resource sharing platform to realize the sharing of experimental data and characterization results that colleges can then use to freely select the required information to enrich students' experiment reports.
Realizing high-efficiency H2 production under practical, mild conditions is essential to meet the requirements to develop this source of ideal clean, alternative energy; thus, this attracted wide spread interest. Catalytic decomposition of formic acid-formate is one of the most widely studied options to achieve this. Herein, we demonstrate H2 production from HCOOK over Pd/C catalysts, in which a flexible content is allowed by modulating the catalyst preparation conditions, reaction conditions, and catalytic characterizations. This experiment not only includes basic chemical kinetics but also guides students to accumulate innovative consciousness through thinking about the structure-activity relationship of catalysts by structural characterization. In addition, this experiment enriches teaching content, improves teaching efficiency, and exercises students' cooperation ability through modular design and group teaching. This project relies on the National Demonstration Center for Experimental Education to build an inter-school resource sharing platform to realize the sharing of experimental data and characterization results that colleges can then use to freely select the required information to enrich students' experiment reports.
2023, 38(8): 156-163
doi: 10.3866/PKU.DXHX202208016
Abstract:
This paper describes an experiment for synthesizing MOF-5 using the principles of coordination chemistry and green chemistry. Zinc acetate dihydrate was used as the starting material, and the product was self-assembled with terephthalic acid by deprotonation of the organic amine. The purity, structure, and stability of the product were characterized by infrared spectroscopy, thermogravimetric analysis (TGA), and powder X-ray diffraction (PXRD). The adsorption properties of the product with common dyes were studied by UV-Vis spectrometry. By studying and conducting this experiment, students can strengthen their understanding of coordination chemistry theory, master the use of large-scale instruments and equipment, master the adsorption principle, and gain an understanding of green chemistry regarding caring for the environment. This experiment has mild reaction conditions, high yield, stoichiometric chemistry, and green chemistry and is pollution-free. It allows for a compact teaching schedule, which is very suitable for teaching experiments in structural chemistry, physical chemistry, and other courses.
This paper describes an experiment for synthesizing MOF-5 using the principles of coordination chemistry and green chemistry. Zinc acetate dihydrate was used as the starting material, and the product was self-assembled with terephthalic acid by deprotonation of the organic amine. The purity, structure, and stability of the product were characterized by infrared spectroscopy, thermogravimetric analysis (TGA), and powder X-ray diffraction (PXRD). The adsorption properties of the product with common dyes were studied by UV-Vis spectrometry. By studying and conducting this experiment, students can strengthen their understanding of coordination chemistry theory, master the use of large-scale instruments and equipment, master the adsorption principle, and gain an understanding of green chemistry regarding caring for the environment. This experiment has mild reaction conditions, high yield, stoichiometric chemistry, and green chemistry and is pollution-free. It allows for a compact teaching schedule, which is very suitable for teaching experiments in structural chemistry, physical chemistry, and other courses.
2023, 38(8): 164-169
doi: 10.3866/PKU.DXHX202209007
Abstract:
The ether preparation experiment is important in organic chemistry experiments. "The preparation of methyl tert-butyl ether" and "The preparation of n-butyl ether" are the corresponding experiments in the textbook. Studying these ether preparation experiments is important for a comprehensive understanding of the chemical properties of alcohols and the SN1 and SN2 mechanisms of nucleophilic substitution reactions. However, there are still many issues in "The preparation of methyl tert-butyl ether" based on the SN1 mechanism in the textbook, such as the requirement of a stoichiometric amount of the sulfuric acid catalyst, difficult reaction monitoring, challenging purification of the product, and low yields. Herein, a non-flammable solid, diphenylmethanol, and ethanol were used as starting materials, and anhydrous ferric chloride was used as the catalyst to prepare the desired benzhydryl ethyl ether. After simple washing extractions, the desired benzhydryl ethyl ether product could be purified and obtained in 88%-90% yields and 95%-97% purities. Notably, the reaction mechanism of this experiment is the same as that of methyl tert-butyl ether preparation; however, the catalyst amount is significantly reduced, product separation and purification steps are greatly simplified, and product yield is significantly improved. This experiment is helpful for students to comprehensively understand basic theories, including the properties of carbocation intermediates, organic Lewis acid-base theories and their applications, and the SN1 mechanism. Further, it can cultivate students' appreciation of green chemistry principles.
The ether preparation experiment is important in organic chemistry experiments. "The preparation of methyl tert-butyl ether" and "The preparation of n-butyl ether" are the corresponding experiments in the textbook. Studying these ether preparation experiments is important for a comprehensive understanding of the chemical properties of alcohols and the SN1 and SN2 mechanisms of nucleophilic substitution reactions. However, there are still many issues in "The preparation of methyl tert-butyl ether" based on the SN1 mechanism in the textbook, such as the requirement of a stoichiometric amount of the sulfuric acid catalyst, difficult reaction monitoring, challenging purification of the product, and low yields. Herein, a non-flammable solid, diphenylmethanol, and ethanol were used as starting materials, and anhydrous ferric chloride was used as the catalyst to prepare the desired benzhydryl ethyl ether. After simple washing extractions, the desired benzhydryl ethyl ether product could be purified and obtained in 88%-90% yields and 95%-97% purities. Notably, the reaction mechanism of this experiment is the same as that of methyl tert-butyl ether preparation; however, the catalyst amount is significantly reduced, product separation and purification steps are greatly simplified, and product yield is significantly improved. This experiment is helpful for students to comprehensively understand basic theories, including the properties of carbocation intermediates, organic Lewis acid-base theories and their applications, and the SN1 mechanism. Further, it can cultivate students' appreciation of green chemistry principles.
2023, 38(8): 170-176
doi: 10.3866/PKU.DXHX202208028
Abstract:
“Determination of calcium content in dolomite by potassium permanganate method” is a classical analytical chemistry experiment to train students' comprehensive experimental ability, including dissolution of dolomite ore sample, preparation and washing of calcium oxalate precipitate, concentration calibration of potassium permanganate solution and titration of calcium oxalate precipitate. Because of the complexity of the experiment process and the many influence factors, it is very difficult that students control the measurement error within 3‰ in the experiment. Therefore, we guide students to precipitate calcium oxalate from acid-dissolved dolomite solution under different experimental conditions, investigate the relationship between the particle size and surface morphology of calcium oxalate precipitate and the determined calcium contents, and thus revealing the control factors affecting the accuracy of calcium content determination. It not only deepens the students' understanding to the experimental process, but also stimulates their interest in learning chemical experiments, improving their experimental ability and strengthening their confidence in scientific research.
“Determination of calcium content in dolomite by potassium permanganate method” is a classical analytical chemistry experiment to train students' comprehensive experimental ability, including dissolution of dolomite ore sample, preparation and washing of calcium oxalate precipitate, concentration calibration of potassium permanganate solution and titration of calcium oxalate precipitate. Because of the complexity of the experiment process and the many influence factors, it is very difficult that students control the measurement error within 3‰ in the experiment. Therefore, we guide students to precipitate calcium oxalate from acid-dissolved dolomite solution under different experimental conditions, investigate the relationship between the particle size and surface morphology of calcium oxalate precipitate and the determined calcium contents, and thus revealing the control factors affecting the accuracy of calcium content determination. It not only deepens the students' understanding to the experimental process, but also stimulates their interest in learning chemical experiments, improving their experimental ability and strengthening their confidence in scientific research.
2023, 38(8): 177-185
doi: 10.3866/PKU.DXHX202208135
Abstract:
In this study, a method for identifying residual antibiotics in food was developed based on chromium black T and europium ion as colorimetric and fluorescent probes (EBT/Eu3+) coupled with pattern recognition in machine learning. The changes in color and fluorescence of four antibiotics with the addition of EBT/Eu3+ were obtained using smart phone and fluorescence measurements. Assisted by pattern recognition, the four antibiotics in honey were successfully identified. This experiment is highly comprehensive; it integrates multiple knowledge points, such as two-channel probe preparation, color recognition based on smart phone, fluorescence measurements, machine learning, and identification of various antibiotics.
In this study, a method for identifying residual antibiotics in food was developed based on chromium black T and europium ion as colorimetric and fluorescent probes (EBT/Eu3+) coupled with pattern recognition in machine learning. The changes in color and fluorescence of four antibiotics with the addition of EBT/Eu3+ were obtained using smart phone and fluorescence measurements. Assisted by pattern recognition, the four antibiotics in honey were successfully identified. This experiment is highly comprehensive; it integrates multiple knowledge points, such as two-channel probe preparation, color recognition based on smart phone, fluorescence measurements, machine learning, and identification of various antibiotics.
2023, 38(8): 186-191
doi: 10.3866/PKU.DXHX202209057
Abstract:
An extended instrumental analysis experiment "In situ high-temperature X-ray diffraction study of titanium dioxide phase transformation" is recommended for undergraduates. In this experiment, the phase transformation of TiO2 was carefully investigated using in situ high-temperature X-ray powder diffraction. The structural changes, including the composition, quantification, lattice constant, grain size, and lattice strains, were analyzed during the phase transformation process. Theoretical knowledge of the basic crystal material structure and a variety of X-ray diffraction analysis skills were combined with the experiments. It is useful for students to acquire knowledge on application, scientific research, and innovation.
An extended instrumental analysis experiment "In situ high-temperature X-ray diffraction study of titanium dioxide phase transformation" is recommended for undergraduates. In this experiment, the phase transformation of TiO2 was carefully investigated using in situ high-temperature X-ray powder diffraction. The structural changes, including the composition, quantification, lattice constant, grain size, and lattice strains, were analyzed during the phase transformation process. Theoretical knowledge of the basic crystal material structure and a variety of X-ray diffraction analysis skills were combined with the experiments. It is useful for students to acquire knowledge on application, scientific research, and innovation.
2023, 38(8): 192-199
doi: 10.3866/PKU.DXHX202208043
Abstract:
A comprehensive chemical synthesis experiment, that is, hydrophobic modification of inorganic perovskite quantum dots and LED applications, is introduced in this article. The SiO2 aerogel was prepared with tetraethyl orthosilicate as the raw material, and the hydrophobicity and toughness of SiO2 aerogel were enhanced by trimethylchlorosilane and mullite fibers, respectively. Finally, CsPbX3@SiO2 aerogel composites were obtained by adsorption of inorganic perovskite quantum dots on hydrophobic SiO2 aerogel. The successful modification of the SiO2 aerogel was characterized by contact angle, infrared spectroscopy and X-ray diffraction, and the LED devices were fabricated. This experiment involves synthesis, characterization, and application of materials. It can be used as a comprehensive chemistry experiment for undergraduates majoring in chemistry and applied chemistry, which helps to improve students' scientific literacy and stimulate their interest in scientific research.
A comprehensive chemical synthesis experiment, that is, hydrophobic modification of inorganic perovskite quantum dots and LED applications, is introduced in this article. The SiO2 aerogel was prepared with tetraethyl orthosilicate as the raw material, and the hydrophobicity and toughness of SiO2 aerogel were enhanced by trimethylchlorosilane and mullite fibers, respectively. Finally, CsPbX3@SiO2 aerogel composites were obtained by adsorption of inorganic perovskite quantum dots on hydrophobic SiO2 aerogel. The successful modification of the SiO2 aerogel was characterized by contact angle, infrared spectroscopy and X-ray diffraction, and the LED devices were fabricated. This experiment involves synthesis, characterization, and application of materials. It can be used as a comprehensive chemistry experiment for undergraduates majoring in chemistry and applied chemistry, which helps to improve students' scientific literacy and stimulate their interest in scientific research.
2023, 38(8): 200-208
doi: 10.3866/PKU.DXHX202209058
Abstract:
Experiments on matrix effects in the fluoride selective-electrode-based potentiometric methods were performed to expand students' theoretical knowledge and deepen their understanding of matrix effects in the potentiometric method in the chemistry laboratory course. Complex matrices were simulated by doping ethanol or acetic acid gradiently into a standard solution. Comprehensive and systematic empirical verification and theoretical analysis of the matrix effects were conducted. Moreover, the standard curve and addition methods determining fluoride in different matrices were investigated and compared. The experimental results showed the matrix effects and the characteristics of the different quantitative analysis methods. This study provides students with an enhanced sense of experimental principles and expands their scientific thinking, which eventually helps achieve improved teaching and learning.
Experiments on matrix effects in the fluoride selective-electrode-based potentiometric methods were performed to expand students' theoretical knowledge and deepen their understanding of matrix effects in the potentiometric method in the chemistry laboratory course. Complex matrices were simulated by doping ethanol or acetic acid gradiently into a standard solution. Comprehensive and systematic empirical verification and theoretical analysis of the matrix effects were conducted. Moreover, the standard curve and addition methods determining fluoride in different matrices were investigated and compared. The experimental results showed the matrix effects and the characteristics of the different quantitative analysis methods. This study provides students with an enhanced sense of experimental principles and expands their scientific thinking, which eventually helps achieve improved teaching and learning.
2023, 38(8): 209-215
doi: 10.3866/PKU.DXHX202209074
Abstract:
A virtual simulation software, which is also called "electronic book" for experimental teaching of capillary electrophoresis has been independently developed. It was programmed in Web development language. Other auxiliary tools such as Photoshop, Flash and 3D Max software were used to make a realistic interactive three-dimensional model of virtual instruments. The mentality of designing, function module, applied method and teaching efficiency of this virtual simulation experimental software were also introduced and discussed. This "electronic book" contained the detailed steps of the experimental process, i.e., the experimental principle, introduction to instruments, sample preparation, parameter setting, sample testing, data analysis and experimental report writing. Because it completely matches the current real experiment and textbook in paper form, the online-merge-offline hybrid experimental efficiency and the combination of "real experiment" with "virtual experiment" can be achieved. Through rich and colorful pictures, animation, 3D drawing in electronic book, it greatly helps students master the relevant knowledge of the instrument analytical testing items in an all-round way, effectively solving the current problems of traditional experimental teaching. Moreover, it motivates the students' enthusiasm and consciousness, and enhances the interest and efficiency of experimental teaching.
A virtual simulation software, which is also called "electronic book" for experimental teaching of capillary electrophoresis has been independently developed. It was programmed in Web development language. Other auxiliary tools such as Photoshop, Flash and 3D Max software were used to make a realistic interactive three-dimensional model of virtual instruments. The mentality of designing, function module, applied method and teaching efficiency of this virtual simulation experimental software were also introduced and discussed. This "electronic book" contained the detailed steps of the experimental process, i.e., the experimental principle, introduction to instruments, sample preparation, parameter setting, sample testing, data analysis and experimental report writing. Because it completely matches the current real experiment and textbook in paper form, the online-merge-offline hybrid experimental efficiency and the combination of "real experiment" with "virtual experiment" can be achieved. Through rich and colorful pictures, animation, 3D drawing in electronic book, it greatly helps students master the relevant knowledge of the instrument analytical testing items in an all-round way, effectively solving the current problems of traditional experimental teaching. Moreover, it motivates the students' enthusiasm and consciousness, and enhances the interest and efficiency of experimental teaching.
2023, 38(8): 216-224
doi: 10.3866/PKU.DXHX202210029
Abstract:
Infrared spectroscopy has become a common method for analysis and characterization owing to its high sensitivity, high-speed measurement, and ability to obtain many information about functional groups. Although most of the experimental projects in existing textbooks focus on the qualitative and quantitative analysis of compounds, which are mainly based on infrared spectroscopy, there are few experimental investigations on infrared spectroscopy involving intermolecular hydrogen bonding and quantum chemical calculations. In this study, based on original infrared spectroscopy experiments, several common aliphatic alcohols were used as examples to investigate the infrared spectral characteristics of alcohol-carbon tetrachloride solutions with different percentages (V/V%). The hydrogen bond structures were explored in combination with quantum chemical calculations. The improved teaching method, combining macro and micro that is experimental phenomena and molecular structure respectively, may enable students to have a clearer understanding of the original frequency values of absorption peaks and the microscopic effect of intermolecular hydrogen bonds. In addition, it can significantly improve their interest in learning, broaden their horizons, and cultivate innovative thinking and critical thinking skills.
Infrared spectroscopy has become a common method for analysis and characterization owing to its high sensitivity, high-speed measurement, and ability to obtain many information about functional groups. Although most of the experimental projects in existing textbooks focus on the qualitative and quantitative analysis of compounds, which are mainly based on infrared spectroscopy, there are few experimental investigations on infrared spectroscopy involving intermolecular hydrogen bonding and quantum chemical calculations. In this study, based on original infrared spectroscopy experiments, several common aliphatic alcohols were used as examples to investigate the infrared spectral characteristics of alcohol-carbon tetrachloride solutions with different percentages (V/V%). The hydrogen bond structures were explored in combination with quantum chemical calculations. The improved teaching method, combining macro and micro that is experimental phenomena and molecular structure respectively, may enable students to have a clearer understanding of the original frequency values of absorption peaks and the microscopic effect of intermolecular hydrogen bonds. In addition, it can significantly improve their interest in learning, broaden their horizons, and cultivate innovative thinking and critical thinking skills.
2023, 38(8): 225-231
doi: 10.3866/PKU.DXHX202209048
Abstract:
Experimental teaching of polymer chemistry in science colleges mainly focuses on traditional polymerization methods, making it difficult to meet the rapid development of polymer science and the requirements of student training. We introduced atom transfer radical polymerization into the experimental course of polymer chemistry and designed a series of contents, including experimental operation, polymerization process monitoring, and instrumental characterization, which are conducive for students to understand polymer research and master the basic skills of the field. We combined cutting-edge scientific research and experimental teaching to cultivate comprehensive scientific research literacy in students, providing new ideas for training students in science colleges.
Experimental teaching of polymer chemistry in science colleges mainly focuses on traditional polymerization methods, making it difficult to meet the rapid development of polymer science and the requirements of student training. We introduced atom transfer radical polymerization into the experimental course of polymer chemistry and designed a series of contents, including experimental operation, polymerization process monitoring, and instrumental characterization, which are conducive for students to understand polymer research and master the basic skills of the field. We combined cutting-edge scientific research and experimental teaching to cultivate comprehensive scientific research literacy in students, providing new ideas for training students in science colleges.
2023, 38(8): 232-239
doi: 10.3866/PKU.DXHX202210015
Abstract:
This paper introduces a comprehensive research experiment regarding the synthesis and characterization of electrocatalysts for electrochemical water splitting. In this experiment, the electrocatalysts (Cu-MoS2/CNTs) were prepared by hydrothermal and wet chemical methods. Then, the electrochemical performance of the catalysts was evaluated by voltammetry and electrochemical impedance spectroscopy (EIS) techniques, which helped consolidate students' understanding and learning of the concepts of irreversible electrode and overpotential. They are helpful to stimulate students' scientific research interests and improve students' comprehensive experimental abilities through the synthesis and optimization of electrocatalysts.
This paper introduces a comprehensive research experiment regarding the synthesis and characterization of electrocatalysts for electrochemical water splitting. In this experiment, the electrocatalysts (Cu-MoS2/CNTs) were prepared by hydrothermal and wet chemical methods. Then, the electrochemical performance of the catalysts was evaluated by voltammetry and electrochemical impedance spectroscopy (EIS) techniques, which helped consolidate students' understanding and learning of the concepts of irreversible electrode and overpotential. They are helpful to stimulate students' scientific research interests and improve students' comprehensive experimental abilities through the synthesis and optimization of electrocatalysts.
2023, 38(8): 240-247
doi: 10.3866/PKU.DXHX202212017
Abstract:
Herein we describe a comprehensive experiment designed for laboratory teaching of analytical chemistry. The experiment was developed based on the results of one of our recent studies. Methyl viologen (MV2+) and 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (pyranine) were used as the heparin receptor and optical indicator, respectively. Once heparin was introduced in the reaction system, competitive binding led to pyranine displacement, thereby resulting in changes in the UV-Vis absorbance of the pyranine/MV2+ system. Using the changes in UV-Vis absorption as the output signal, heparin concentration can be accurately measured using the IDA-based method.
Herein we describe a comprehensive experiment designed for laboratory teaching of analytical chemistry. The experiment was developed based on the results of one of our recent studies. Methyl viologen (MV2+) and 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (pyranine) were used as the heparin receptor and optical indicator, respectively. Once heparin was introduced in the reaction system, competitive binding led to pyranine displacement, thereby resulting in changes in the UV-Vis absorbance of the pyranine/MV2+ system. Using the changes in UV-Vis absorption as the output signal, heparin concentration can be accurately measured using the IDA-based method.
2023, 38(8): 248-258
doi: 10.3866/PKU.DXHX202209026
Abstract:
Through scientific research back-feeding teaching, the two concepts of "multicomponent reaction" and "fluorinated organic compound" were integrated into undergraduate experiment teaching, and 5-(4-methylphenyl)-3-trifluoromethyl-1H-pyrazole was synthesized by the three-component reaction. This reaction features mild experimental conditions, simple operations, high yield, good reproducibility, and high safety. This comprehensive experiment integrates science and education and combines theory with practice, thus helping students to understand the new concept of step-economic synthesis and to establish the concept of green chemistry. This is a new subject suitable to introduce into the current organic experiment teaching course.
Through scientific research back-feeding teaching, the two concepts of "multicomponent reaction" and "fluorinated organic compound" were integrated into undergraduate experiment teaching, and 5-(4-methylphenyl)-3-trifluoromethyl-1H-pyrazole was synthesized by the three-component reaction. This reaction features mild experimental conditions, simple operations, high yield, good reproducibility, and high safety. This comprehensive experiment integrates science and education and combines theory with practice, thus helping students to understand the new concept of step-economic synthesis and to establish the concept of green chemistry. This is a new subject suitable to introduce into the current organic experiment teaching course.
2023, 38(8): 259-267
doi: 10.3866/PKU.DXHX202210003
Abstract:
Extraction and separation of pigments from spinach leaf is an important experiment in organic chemistry laboratory, conducted at universities. However, in experimental teaching, there have always been problems, such as the use of toxic or controlled reagents, long experiment time, cumbersome experimental steps, and poor experimental results. In this study, the conditions of thin layer chromatography were systematically explored. A variety of reagent combinations, such as n-hexane/anhydrous ethanol and n-hexane/n-butanol, were tested. It was found that the developing agent with the best separation effect was n-hexane/anhydrous ethanol solution, with a volume ratio of 10:1. The n-hexane/absolute ethanol and n-hexane/n-butanol were also used as eluents to explore column chromatography separation experiments of the pigments from spinach leaf. By using silica gel as the stationary phase, the optimal gradient elution scheme with n-hexane/absolute ethanol as eluent was obtained; whereas, the optimal gradient elution scheme with n-hexane/n-butanol as the eluent was obtained by using neutral alumina as the stationary phase. Following the improvement, the separation effect was enhanced and the amount of reagent was reduced; furthermore, more friendly reagents were used and the teaching time was shortened.
Extraction and separation of pigments from spinach leaf is an important experiment in organic chemistry laboratory, conducted at universities. However, in experimental teaching, there have always been problems, such as the use of toxic or controlled reagents, long experiment time, cumbersome experimental steps, and poor experimental results. In this study, the conditions of thin layer chromatography were systematically explored. A variety of reagent combinations, such as n-hexane/anhydrous ethanol and n-hexane/n-butanol, were tested. It was found that the developing agent with the best separation effect was n-hexane/anhydrous ethanol solution, with a volume ratio of 10:1. The n-hexane/absolute ethanol and n-hexane/n-butanol were also used as eluents to explore column chromatography separation experiments of the pigments from spinach leaf. By using silica gel as the stationary phase, the optimal gradient elution scheme with n-hexane/absolute ethanol as eluent was obtained; whereas, the optimal gradient elution scheme with n-hexane/n-butanol as the eluent was obtained by using neutral alumina as the stationary phase. Following the improvement, the separation effect was enhanced and the amount of reagent was reduced; furthermore, more friendly reagents were used and the teaching time was shortened.
2023, 38(8): 268-274
doi: 10.3866/PKU.DXHX202304001
Abstract:
In recent years, the production of laboratory chemical waste has increased rapidly. The resulting safety risks and pollution costs are also increasing simultaneously, which has become a huge problem that plagues the development of colleges and universities. The lack of social disposal ability of laboratory chemical waste and the imperfection of relevant laws and regulations are the fundamental constraints to solve this problem. Based on the analysis of the current situation of laboratory chemical wastes and their treatment in domestic laboratories as well as the corresponding experience from the foreign laboratories, some consideration and suggestions for the treatment of the laboratory chemical wastes have been put forward.
In recent years, the production of laboratory chemical waste has increased rapidly. The resulting safety risks and pollution costs are also increasing simultaneously, which has become a huge problem that plagues the development of colleges and universities. The lack of social disposal ability of laboratory chemical waste and the imperfection of relevant laws and regulations are the fundamental constraints to solve this problem. Based on the analysis of the current situation of laboratory chemical wastes and their treatment in domestic laboratories as well as the corresponding experience from the foreign laboratories, some consideration and suggestions for the treatment of the laboratory chemical wastes have been put forward.
2023, 38(8): 275-282
doi: 10.3866/PKU.DXHX202304064
Abstract:
In order to improve students' theoretical level and practical ability, a comprehensive experiment, the determination of amino acids in Cerasus humilis fruit, was designed for instrumental analysis course. The sample analysis pretreatment process was introduced to construct a complete instrumental analysis process. Through the comparison of amino acid extraction methods and the exploration of solid phase extraction technology in the process of amino acid purification, students' theoretical knowledge and practical ability can be effectively fused and improved, and the scientific literacy and comprehensive thinking ability of students can thus be improved during the process of solving practical problems.
In order to improve students' theoretical level and practical ability, a comprehensive experiment, the determination of amino acids in Cerasus humilis fruit, was designed for instrumental analysis course. The sample analysis pretreatment process was introduced to construct a complete instrumental analysis process. Through the comparison of amino acid extraction methods and the exploration of solid phase extraction technology in the process of amino acid purification, students' theoretical knowledge and practical ability can be effectively fused and improved, and the scientific literacy and comprehensive thinking ability of students can thus be improved during the process of solving practical problems.
2023, 38(8): 283-292
doi: 10.3866/PKU.DXHX202208117
Abstract:
To transform the scale of redox titration for a unified formula of the titration scale, a relative concentration of the aqueous electron Re- is proposed, and a new theory for redox titration is then developed with pRe- as its monitoring scale. This new theory addresses the balancing of the semi-redox-reaction, provides the general formula for calculating pRe-, investigates the general variation of pRe- in titration, and reintroduces the principle of an electron indicator. In this study, the titration of Ce4+ to Fe3+ solution is used as an example to deduce the following aspects:the approach for drawing titration curves, calculation for titration jump ranges, and criterion of direct and accurate titrations. Finally, the effect of Krθ', which is the conditional equilibrium constant of a redox reaction, on titrimetric analysis is discussed.
To transform the scale of redox titration for a unified formula of the titration scale, a relative concentration of the aqueous electron Re- is proposed, and a new theory for redox titration is then developed with pRe- as its monitoring scale. This new theory addresses the balancing of the semi-redox-reaction, provides the general formula for calculating pRe-, investigates the general variation of pRe- in titration, and reintroduces the principle of an electron indicator. In this study, the titration of Ce4+ to Fe3+ solution is used as an example to deduce the following aspects:the approach for drawing titration curves, calculation for titration jump ranges, and criterion of direct and accurate titrations. Finally, the effect of Krθ', which is the conditional equilibrium constant of a redox reaction, on titrimetric analysis is discussed.
2023, 38(8): 293-298
doi: 10.3866/PKU.DXHX202209021
Abstract:
The Nernst equation is the foundation of reversible cell thermodynamics and is an essential formula in electrochemistry. However, physical chemistry textbooks discuss the Nernst equationrelatively briefly and only emphasizeits applicabilityto reversible state without in-depth discussion. Students are often confused when using the equation due to the unclear restrictions in its use. Several aspects of the Nernst equation are presented in this study. The origin and development of the Nernst equation, derivation methods, restrictionsin its use, applications, and scientific heritage behind the Nernst equation are discussed. This may provide a reference for both peer and student learning.
The Nernst equation is the foundation of reversible cell thermodynamics and is an essential formula in electrochemistry. However, physical chemistry textbooks discuss the Nernst equationrelatively briefly and only emphasizeits applicabilityto reversible state without in-depth discussion. Students are often confused when using the equation due to the unclear restrictions in its use. Several aspects of the Nernst equation are presented in this study. The origin and development of the Nernst equation, derivation methods, restrictionsin its use, applications, and scientific heritage behind the Nernst equation are discussed. This may provide a reference for both peer and student learning.
2023, 38(8): 299-304
doi: 10.3866/PKU.DXHX202209092
Abstract:
The ring-opening reactions of 1,2-epoxides are important topics in organic chemistry courses. The description of the ring-opening reaction of epoxides in textbooks lacks quantitative and visual information; therefore, students usually learn it by rote and cannot fully understand the mechanisms involved. This experiment presents a prototypical example of investigating the molecular mechanism of a chemical reaction using theoretical chemistry methods. By carrying out quantum chemical calculations on the ring-opening reactions of a typical 1,2-epoxide catalyzed by an acid or base, we reveal the thermodynamic and kinetic properties of the reaction and provide an intuitive physical picture and quantitative information of the reaction for understanding the regioselectivity of the reaction. This experiment will not only help students deepen their understanding of the basic concepts and theories of chemistry but also help them broaden their horizons and expand their thinking, making them realize that theoretical calculation is an important tool in chemical research.
The ring-opening reactions of 1,2-epoxides are important topics in organic chemistry courses. The description of the ring-opening reaction of epoxides in textbooks lacks quantitative and visual information; therefore, students usually learn it by rote and cannot fully understand the mechanisms involved. This experiment presents a prototypical example of investigating the molecular mechanism of a chemical reaction using theoretical chemistry methods. By carrying out quantum chemical calculations on the ring-opening reactions of a typical 1,2-epoxide catalyzed by an acid or base, we reveal the thermodynamic and kinetic properties of the reaction and provide an intuitive physical picture and quantitative information of the reaction for understanding the regioselectivity of the reaction. This experiment will not only help students deepen their understanding of the basic concepts and theories of chemistry but also help them broaden their horizons and expand their thinking, making them realize that theoretical calculation is an important tool in chemical research.
2023, 38(8): 305-311
doi: 10.3866/PKU.DXHX202209041
Abstract:
Infrared spectroscopy is an important content of a college course "spectroscopy analysis", and the understanding of the influence of ring strain on infrared absorption frequency is a challenge. No rigorous and detailed explanation on this exists in the current textbooks, making students still confused when they accept the conclusion of the influence of ring strain on infrared vibrational frequency. Here, we use the density functional theory (DFT) to calculate the strain energy, bond length, bond angle, vibrational frequency, and orbital proportion of related bonds based on the fully optimized molecular structure. Based on the results of DFT calculation, the effect of ring strain on the vibrational frequencies of C=C and C=O double bonds is explained reasonably and in detail.
Infrared spectroscopy is an important content of a college course "spectroscopy analysis", and the understanding of the influence of ring strain on infrared absorption frequency is a challenge. No rigorous and detailed explanation on this exists in the current textbooks, making students still confused when they accept the conclusion of the influence of ring strain on infrared vibrational frequency. Here, we use the density functional theory (DFT) to calculate the strain energy, bond length, bond angle, vibrational frequency, and orbital proportion of related bonds based on the fully optimized molecular structure. Based on the results of DFT calculation, the effect of ring strain on the vibrational frequencies of C=C and C=O double bonds is explained reasonably and in detail.
2023, 38(8): 312-317
doi: 10.3866/PKU.DXHX202208064
Abstract:
Hybrid orbital theory is an important part of the chemical bond theory. The bonding ability of hybrid orbitals and the angle between two hybrid orbitals are the most important and difficult topics in the teaching and learning of hybrid orbital theory. Most textbooks usually give the relevant formulas directly and ignore their derivation, which does not meet the needs for the advanced learning of some students. This paper provides a simple derivation of these formulas to dispel students' doubts and deepen their understanding of hybrid orbital theory.
Hybrid orbital theory is an important part of the chemical bond theory. The bonding ability of hybrid orbitals and the angle between two hybrid orbitals are the most important and difficult topics in the teaching and learning of hybrid orbital theory. Most textbooks usually give the relevant formulas directly and ignore their derivation, which does not meet the needs for the advanced learning of some students. This paper provides a simple derivation of these formulas to dispel students' doubts and deepen their understanding of hybrid orbital theory.
2023, 38(8): 318-325
doi: 10.3866/PKU.DXHX202208061
Abstract:
The unique B3N3 six-membered ring is an ideal template for the investigation of non-benzene aromaticity. The B3N3 isomer with a six-membered ring was fully optimized at the B3LYP-D3(BJ)/def2-TZVP level, and frequency validation was carried out simultaneously to confirm whether the structure was local minimum. Subsequently, the LOL-π color-filled map was drawn by Multiwfn 3.7 (dev) to accurately reveal the delocalized π-electrons and non-benzene aromaticity of the six-membered ring. This innovative experiment has pronounced advantages, such as strong operability and universality, high safety, and good generality.
The unique B3N3 six-membered ring is an ideal template for the investigation of non-benzene aromaticity. The B3N3 isomer with a six-membered ring was fully optimized at the B3LYP-D3(BJ)/def2-TZVP level, and frequency validation was carried out simultaneously to confirm whether the structure was local minimum. Subsequently, the LOL-π color-filled map was drawn by Multiwfn 3.7 (dev) to accurately reveal the delocalized π-electrons and non-benzene aromaticity of the six-membered ring. This innovative experiment has pronounced advantages, such as strong operability and universality, high safety, and good generality.
2023, 38(8): 326-332
doi: 10.3866/PKU.DXHX202208134
Abstract:
This paper briefly compares the source, application scope, development history and respective characteristics of the commonly used classical models of microporous adsorption. In order to facilitate the systematic understanding and mastery of classical microporous analysis methods in physical adsorption, the methods are divided into three categories:(1) methods developed from standard isotherms, including t-method, αs-method, n-method and MP method; (2) methods based on micropore filling theory, including D-R method, D-A method and D-R-S method; (3) the currently commonly used methods include the original HK method (slit pore), HK-SF method (cylindrical pore), HK-CY method (spherical pore) and the improved HK method.
This paper briefly compares the source, application scope, development history and respective characteristics of the commonly used classical models of microporous adsorption. In order to facilitate the systematic understanding and mastery of classical microporous analysis methods in physical adsorption, the methods are divided into three categories:(1) methods developed from standard isotherms, including t-method, αs-method, n-method and MP method; (2) methods based on micropore filling theory, including D-R method, D-A method and D-R-S method; (3) the currently commonly used methods include the original HK method (slit pore), HK-SF method (cylindrical pore), HK-CY method (spherical pore) and the improved HK method.
2023, 38(8): 333-340
doi: 10.3866/PKU.DXHX202208019
Abstract:
This paper mainly introduces the inorganic and analytical chemistry laboratory project, the synthesis of the complex[Ni(Me3en)(acac)]BPh4 and the solvato/thermochromic behavior, designed by Nanjing University for "The 10th National Undergraduate Chemistry Laboratory Tournament". This paper mainly deals with the experiment implementation process, results and related issues of the solvato/thermochromic behavior in the experiment. In the paper, the detailed and intuitive experimental phenomena inspire students to explore and understand the mechanism. The law of solvato/thermochromic behavior is summarized, which allows students to intuitively understand that the structure of complexes determines their properties. In the process, students can develop the ability of analysis, judgment, induction, summarizing and critical thinking.
This paper mainly introduces the inorganic and analytical chemistry laboratory project, the synthesis of the complex[Ni(Me3en)(acac)]BPh4 and the solvato/thermochromic behavior, designed by Nanjing University for "The 10th National Undergraduate Chemistry Laboratory Tournament". This paper mainly deals with the experiment implementation process, results and related issues of the solvato/thermochromic behavior in the experiment. In the paper, the detailed and intuitive experimental phenomena inspire students to explore and understand the mechanism. The law of solvato/thermochromic behavior is summarized, which allows students to intuitively understand that the structure of complexes determines their properties. In the process, students can develop the ability of analysis, judgment, induction, summarizing and critical thinking.
2023, 38(8): 341-350
doi: 10.3866/PKU.DXHX202210022
Abstract:
The article discussed organic chemistry problems 9 and 10 in the 35th National Chemistry Olympiad Competition (Preliminary) in detail from the perspective of the fundamental theories and reaction mechanisms. The scientific backgrounds and theoretical knowledge associated with the problems were expanded to arouse the curiosity of readers in exploring chemistry..
The article discussed organic chemistry problems 9 and 10 in the 35th National Chemistry Olympiad Competition (Preliminary) in detail from the perspective of the fundamental theories and reaction mechanisms. The scientific backgrounds and theoretical knowledge associated with the problems were expanded to arouse the curiosity of readers in exploring chemistry..
