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2018 Volume 33 Issue 8
2018, 33(8): 1-4
doi: 10.3866/PKU.DXHX201802023
Abstract:
The current instrumental analysis course is difficult for the students to learn and reduces the enthusiasm for learning, because the theoretical knowledge is generally abstract, boring and incomprehensible. We propose to apply the teaching mode of flipped classroom to instrumental analysis teaching. By pre-learning before lectures, acquisitioning and internalizing knowledge in classes, doing posting assignments or extended learning tasks after classes, and student-teacher online and offline interactions, this teaching mode enhances students' interests in learning instrumental analysis, cultivates students' abilities for self-motivated study, independent and innovative thinking. Moreover, this teaching mode is applicable to multi-ethnic students.
The current instrumental analysis course is difficult for the students to learn and reduces the enthusiasm for learning, because the theoretical knowledge is generally abstract, boring and incomprehensible. We propose to apply the teaching mode of flipped classroom to instrumental analysis teaching. By pre-learning before lectures, acquisitioning and internalizing knowledge in classes, doing posting assignments or extended learning tasks after classes, and student-teacher online and offline interactions, this teaching mode enhances students' interests in learning instrumental analysis, cultivates students' abilities for self-motivated study, independent and innovative thinking. Moreover, this teaching mode is applicable to multi-ethnic students.
2018, 33(8): 5-9
doi: 10.3866/PKU.DXHX201803013
Abstract:
Taking the determination of optical rotation of carbohydrate as an example, the paper explores the application of flipped classroom in the laboratory teaching of organic chemistry in medical colleges. The instructional design includes designing the learning task list, making the teaching video and documents, finding the relevant literature, organizing class activities and evaluating the teaching effect. In general, the application of flipped classroom in laboratory teaching improves the status that pre-class preparation is a mere form, cultivates students to learn on their own initiative, and stimulates medical students' interest in basic organic chemistry experiments.
Taking the determination of optical rotation of carbohydrate as an example, the paper explores the application of flipped classroom in the laboratory teaching of organic chemistry in medical colleges. The instructional design includes designing the learning task list, making the teaching video and documents, finding the relevant literature, organizing class activities and evaluating the teaching effect. In general, the application of flipped classroom in laboratory teaching improves the status that pre-class preparation is a mere form, cultivates students to learn on their own initiative, and stimulates medical students' interest in basic organic chemistry experiments.
2018, 33(8): 10-13
doi: 10.3866/PKU.DXHX201801002
Abstract:
The evaluation system of the fundamental chemistry laboratory courses is explored from the aspects of expert evaluation and student assessment, and has been used to evaluate systemically the teaching quality. In addition, the corresponding reward and punishment system is accordingly established. The practice has shown that the scientific and reasonable evaluation system can inspire the teachers to put more enthusiasm into the fundamental chemistry laboratory courses, and thereby improve the teaching quality of fundamental chemistry laboratory courses greatly.
The evaluation system of the fundamental chemistry laboratory courses is explored from the aspects of expert evaluation and student assessment, and has been used to evaluate systemically the teaching quality. In addition, the corresponding reward and punishment system is accordingly established. The practice has shown that the scientific and reasonable evaluation system can inspire the teachers to put more enthusiasm into the fundamental chemistry laboratory courses, and thereby improve the teaching quality of fundamental chemistry laboratory courses greatly.
2018, 33(8): 14-18
doi: 10.3866/PKU.DXHX201802001
Abstract:
The teaching mode for traditional chemistry laboratory course, especially for the fundamental one, is listening to the instructors and following the manuals. This mode neglects both the independent study and the innovation ability of the students. In order to improve their enthusiasm, cultivate their creation ability and promote the teaching effectiveness,a new three-step teaching mode was created,which can solidify the laboratory ability, increase the comprehension level and highlight the innovation ability. The five-years practice shows that this mode has a strong effect on teaching quality.
The teaching mode for traditional chemistry laboratory course, especially for the fundamental one, is listening to the instructors and following the manuals. This mode neglects both the independent study and the innovation ability of the students. In order to improve their enthusiasm, cultivate their creation ability and promote the teaching effectiveness,a new three-step teaching mode was created,which can solidify the laboratory ability, increase the comprehension level and highlight the innovation ability. The five-years practice shows that this mode has a strong effect on teaching quality.
2018, 33(8): 19-25
doi: 10.3866/PKU.DXHX201712043
Abstract:
The catalytic system and reaction mechanism of asymmetric dihalogenation of olefins, as well as the application in the synthesis of natural products are discussed, based on the textbook knowledge of olefinic dihalogenation reaction and the mechanism of dibromination reaction of alkenes. The enthusiasm of students to learn organic chemistry will be inspired by improving the teaching method, enriching the content of teaching, increasing the interest of teaching. The aim is to lead students to discover new problems from basic knowledge, think about the method for solving problems, train students' innovation thoughts and improve their problem-solving abilities.
The catalytic system and reaction mechanism of asymmetric dihalogenation of olefins, as well as the application in the synthesis of natural products are discussed, based on the textbook knowledge of olefinic dihalogenation reaction and the mechanism of dibromination reaction of alkenes. The enthusiasm of students to learn organic chemistry will be inspired by improving the teaching method, enriching the content of teaching, increasing the interest of teaching. The aim is to lead students to discover new problems from basic knowledge, think about the method for solving problems, train students' innovation thoughts and improve their problem-solving abilities.
2018, 33(8): 26-31
doi: 10.3866/PKU.DXHX201801031
Abstract:
The effects of pH on the synthesis experiment of BiVO4 pigment were studied with improved experimental installation. Under the selected experimental conditions, the product was a mixture of a tetragonal phase, which dominated and a monoclinic one. pH of reaction system had significant influence on product color. Under acidic condition, the product was dark khaki. Under basic condition, product presented bright yellow. The pH=9 reaction system was recommended, because the product had a better bright yellow tone.
The effects of pH on the synthesis experiment of BiVO4 pigment were studied with improved experimental installation. Under the selected experimental conditions, the product was a mixture of a tetragonal phase, which dominated and a monoclinic one. pH of reaction system had significant influence on product color. Under acidic condition, the product was dark khaki. Under basic condition, product presented bright yellow. The pH=9 reaction system was recommended, because the product had a better bright yellow tone.
2018, 33(8): 32-36
doi: 10.3866/PKU.DXHX201801041
Abstract:
The chemical laboratory in the universities is a place with a frequent flow of large student populations under the opening management for laboratory teaching, research and training professional talents. However, the precursor chemicals are widely used in the chemical laboratory and the safety management is a challenge. Focusing on the existing problems in the current management of precursor chemicals, this study suggests building the scientific, effective and simple management system of precursor chemicals, the establishment of precursor chemicals warehouse, the implementation of special charge and the distribution pattern of follow up. At the same time, the account book of the precursor chemicals has been set up for each teacher, and a regular inspection is implemented. Moreover, effective supervision of the whole process of precursor chemicals usage is performed. These actions not only assure the rational need of teaching and research, but also prevent the illegal use.
The chemical laboratory in the universities is a place with a frequent flow of large student populations under the opening management for laboratory teaching, research and training professional talents. However, the precursor chemicals are widely used in the chemical laboratory and the safety management is a challenge. Focusing on the existing problems in the current management of precursor chemicals, this study suggests building the scientific, effective and simple management system of precursor chemicals, the establishment of precursor chemicals warehouse, the implementation of special charge and the distribution pattern of follow up. At the same time, the account book of the precursor chemicals has been set up for each teacher, and a regular inspection is implemented. Moreover, effective supervision of the whole process of precursor chemicals usage is performed. These actions not only assure the rational need of teaching and research, but also prevent the illegal use.
2018, 33(8): 37-42
doi: 10.3866/PKU.DXHX201801004
Abstract:
A new polymer chemical comprehensive experiment, "synthesis, characterization and properties of conjugated polymer containing fluorine", was recommended for undergraduates. This experiment included the synthesis of conjugated polymer by Sonogashira coupling reaction, structure characterization by nuclear magnetic resonance spectroscopy and infrared spectroscopy, and the investigation of its optical and thermal properties by ultraviolet-visible spectrometry, fluorescent spectrometry and thermogravimetric analysis. This experiment combined knowledge points of polymer chemistry and polymer instrumental analysis and characterization; thus it was recommended to be included in the advanced polymer chemical comprehensive experiment course.
A new polymer chemical comprehensive experiment, "synthesis, characterization and properties of conjugated polymer containing fluorine", was recommended for undergraduates. This experiment included the synthesis of conjugated polymer by Sonogashira coupling reaction, structure characterization by nuclear magnetic resonance spectroscopy and infrared spectroscopy, and the investigation of its optical and thermal properties by ultraviolet-visible spectrometry, fluorescent spectrometry and thermogravimetric analysis. This experiment combined knowledge points of polymer chemistry and polymer instrumental analysis and characterization; thus it was recommended to be included in the advanced polymer chemical comprehensive experiment course.
2018, 33(8): 43-46
doi: 10.3866/PKU.DXHX201802007
Abstract:
A semi-microscale organic chemistry experiment for the efficient synthesis of acetylsalicylic acid is designed, and the synthesis starts from salicylic acid and acetic anhydride with HZSM-5 as the catalyst at room temperature or heating conditions. Compared with the classical experimental method, the new experiment possesses the advantages of easy operation, high product yield and low pollution, which is more in line with the educational concepts of green chemistry.
A semi-microscale organic chemistry experiment for the efficient synthesis of acetylsalicylic acid is designed, and the synthesis starts from salicylic acid and acetic anhydride with HZSM-5 as the catalyst at room temperature or heating conditions. Compared with the classical experimental method, the new experiment possesses the advantages of easy operation, high product yield and low pollution, which is more in line with the educational concepts of green chemistry.
2018, 33(8): 47-51
doi: 10.3866/PKU.DXHX201802012
Abstract:
In the paper, the history of "yesterday, today and tomorrow" of analytical chemistry is briefly discussed. The "yesterday of analytical chemistry", which is based on the physical chemical principles, detects chemical changes by visual observations, thus, is called "chemical analysis". The "today of analytical chemistry" is mainly instrumental analysis based on physical methods, therefore, it is often said that "the chemistry is going out of analytical chemistry". The "tomorrow of analytical chemistry" will come back to the chemistry field. I hope that, the role of analytical chemistry is not limited to provide data and report for others, but to solve practical problems and even to produce new products.
In the paper, the history of "yesterday, today and tomorrow" of analytical chemistry is briefly discussed. The "yesterday of analytical chemistry", which is based on the physical chemical principles, detects chemical changes by visual observations, thus, is called "chemical analysis". The "today of analytical chemistry" is mainly instrumental analysis based on physical methods, therefore, it is often said that "the chemistry is going out of analytical chemistry". The "tomorrow of analytical chemistry" will come back to the chemistry field. I hope that, the role of analytical chemistry is not limited to provide data and report for others, but to solve practical problems and even to produce new products.
2018, 33(8): 52-57
doi: 10.3866/PKU.DXHX201802013
Abstract:
A mixture of monobasic strong acid and monobasic weak acid was chosen to derive the universal criterion for evaluating the feasibility of accurate stepwise titration of equimolar mixture with indicators. It is found that with an acceptable maximum relative error of 0.1%, the accurate stepwise titration can't be achieved unless two requirements are satisfied:the concentration of each acid is no less than 0.544 mol·L-1, and the pKa of weak acid is in the range of 5.6-8.3. The requirements vary with the acceptable maximum relative error.
A mixture of monobasic strong acid and monobasic weak acid was chosen to derive the universal criterion for evaluating the feasibility of accurate stepwise titration of equimolar mixture with indicators. It is found that with an acceptable maximum relative error of 0.1%, the accurate stepwise titration can't be achieved unless two requirements are satisfied:the concentration of each acid is no less than 0.544 mol·L-1, and the pKa of weak acid is in the range of 5.6-8.3. The requirements vary with the acceptable maximum relative error.
2018, 33(8): 58-65
doi: 10.3866/PKU.DXHX201802008
Abstract:
This paper compares and analyzes outliers related contents in analytical chemistry textbooks which are widely used nowadays, and explains the significance of the detection of outliers. Several common methods for testing outliers are introduced and compared, and the data treatment methods of dealing with confirmed outliers are also compared and discussed. All kinds of methods have their own advantages and disadvantages, thus we should choose different methods or a variety of methods, in accordance with the actual situation, to achieve better detection and treatment of outliers.
This paper compares and analyzes outliers related contents in analytical chemistry textbooks which are widely used nowadays, and explains the significance of the detection of outliers. Several common methods for testing outliers are introduced and compared, and the data treatment methods of dealing with confirmed outliers are also compared and discussed. All kinds of methods have their own advantages and disadvantages, thus we should choose different methods or a variety of methods, in accordance with the actual situation, to achieve better detection and treatment of outliers.
2018, 33(8): 66-72
doi: 10.3866/PKU.DXHX201801015
Abstract:
This paper summarizes the UV curing technology and the progressing of UV curable coatings. Taking the products of BASF company which won the American President Green Chemistry Award in 2005 as an example, this paper introduces the green refinish primer's composition, curing mechanism and influencing factors by comparing with traditional products. At the end of the paper, the outlook on UV-curable paint's usage in green refinish primer field is provided.
This paper summarizes the UV curing technology and the progressing of UV curable coatings. Taking the products of BASF company which won the American President Green Chemistry Award in 2005 as an example, this paper introduces the green refinish primer's composition, curing mechanism and influencing factors by comparing with traditional products. At the end of the paper, the outlook on UV-curable paint's usage in green refinish primer field is provided.
2018, 33(8): 73-85
doi: 10.3866/PKU.DXHX201710004
Abstract:
2018, 33(8): 86-90
doi: 10.3866/PKU.DXHX201801007
Abstract:
The structures of P4 and its derivatives are one of the hot subjects in chemistry contests. This paper introduced the growth of P4. The problems in recent chemistry contests for high school students were resolved, and some teaching advices were provided.
The structures of P4 and its derivatives are one of the hot subjects in chemistry contests. This paper introduced the growth of P4. The problems in recent chemistry contests for high school students were resolved, and some teaching advices were provided.
