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2021 Vol. 36,No. 8Published:03 August 2021
Study and Reform of Chemical Education
  • Exploration and Practice of Comprehensive Model of Polymer Chemistry Teaching for Non-Polymer Major Students
  • Yi Liu, Quan Lin, Kun Liu, Hao Zhang, Wenlong Song, Zuosen Shi, Zhanchen Cui, Kai Zhang, Junhu Zhang
  • Since the outbreak of COVID-19 at the beginning of 2020, students are unable to come back to study on campus. Under this situation, College of Chemistry at Jilin University organizes the online teaching of polymer chemistry for students with chemistry major (non-polymer major), followed by the offline teaching plus the construction of course ideology and politics in polymer chemistry. According to the basic knowledge and characteristics of students with chemistry major, teachers pay more attentions on developing their interests in polymer instead of just telling them to remember the knowledge, realizing the combination between ideological and political education and knowledge system education. By taking the advantages of online teaching, offline teaching and ideological and political education, the teaching quality is improved and the teaching task is completed successfully.

  • 2021, 36 (8): 2011017. DOI: 10.3866/PKU.DXHX202011017
  • Construction and Reform of the Course System of Principles of Chemical Engineering under the Background of Engineering Education Certification
  • Caihong Tao, Baoyong Liu, Li Sheng, Yang Lei, Jieqiong Cai
  • The curriculum system of principles of chemical engineering includes three segments: principles of chemical engineering, laboratory of principles of chemical engineering and curriculum design of principles of chemical engineering. This course is of great significance to guide students to establish cultivate scientific engineering thinking methods and engineering consciousness. It is also very important for improving students' engineering practice skills and engineering quality, the two essential abilities for engineering technicians. Starting from the above three segments, this paper discusses the methods of curriculum reform for three courses under the background of engineering education certification and new engineering construction, so as to fundamentally improve the teaching quality of chemical engineering principle curriculum system and train qualified engineering students who can really solve the practical problems of Engineering.

  • 2021, 36 (8): 2012044. DOI: 10.3866/PKU.DXHX202012044
  • Teaching Practice of Analytical Chemistry in Literature Reading
  • Ying Wu, Li Yao, Daming Gao, Kunhong Hu
  • In order to meet the training objectives of applied universities, the practice of literature reading is introduced in the teaching of analytical chemistry. This paper explores the selection of literature content, teaching methods and grading methods, which can help students understand the application of the principles of various analysis methods in practical production and scientific research, promote the effective integration of students' theoretical knowledge and practical ability, and improve students' comprehensive ability.

  • 2021, 36 (8): 2103004. DOI: 10.3866/PKU.DXHX202103004
  • Preliminary Exploration of Course Ideology and Politics Teaching of Physical Chemistry Experiments under the Background of New Era
  • Yue Sun, Zuan Yang
  • Taking the School of Chemistry and Chemical Engineering, Liaoning Normal University as an example, under the background of the new era, thought was excavated to improve students' political accomplishment. Through the attention of experimental teaching content, students' sense of social responsibility was cultivated. At the same time, based on experimental teaching, students' rigorous and realistic scientific attitude were developed in the college. In addition, the stories of scientists were introduced into teaching for students to learn. Meanwhile, the research and design experiments were valued by teachers to strengthen students' innovative spirit and team consciousness. A preliminary exploration on the ideological and political education in physical chemistry experiments teaching was made in this paper, which would be a reference for the implementation of ideological and political education reform in University experiment teaching.

  • 2021, 36 (8): 2103054. DOI: 10.3866/PKU.DXHX202103054
Survey of Chemistry
  • Recent Progress on the Concepts of Aromaticity
  • Baolei Huang, Hao Sun, Xinye Li, Yuting Fan, Tao Tao
  • Aromaticity is a key concept in organic chemistry. It dated back to Faraday's discovery of benzene in 1825 and Kekulé's famous alternating-double-bond structure of 1865, and is still evolving in recent years. At present, some examples of anti-Hückel's rule have been proposed gradually, including Möbius aromaticity rule and Baird's rule. In particular, scientists put forward new concepts of 3D aromaticity and global aromaticity. This review not only introduces the experimental and theoretical criteria of aromaticity, but also summarizes several new aromaticity systems through porphyrin nanoring, macrocyclic polyradical and polycyclic π-conjugated system. In addition, it covers the applications of aromaticity and briefly discussed recent progress on the concepts of aromaticity.

  • 2021, 36 (8): 2009060. DOI: 10.3866/PKU.DXHX202009060
  • From Solvent Cage to Molecular Cage
  • Yue Li, Wenjuan Ruan
  • In physical chemistry, the model of solvent cage is used to describe the relationship between reactant and solvent. In this model, the reactant molecule is surrounded by the cage constructed with solvent molecules. The solvent cage is flexible, and its size and shape are determined by the central reactant molecule. The encounter, collision and reaction between reactant molecules proceed in solvent cages. With the advancement of synthetic techniques, molecular cages, which are constructed by covalent and coordination bonds, are developed. Relative to the solvent cages connected with van der Waals force, molecular cages show much higher rigidity, thus, their effects on the reactions is expected to be more remarkable. Different from traditional catalysts that participate the reaction through the binding with reactants or intermediates, molecular cages could affect the reaction through a physical manner. By enriching reactants, altering the configuration of reactants, changing the structure of intermediates and limiting the growth of products, molecular cages could exert a profound influence on the rate and selectivity of the reaction. The research on this field is significant for the elucidation of reaction mechanism and the modulation of reaction proceeding.

  • 2021, 36 (8): 2011027. DOI: 10.3866/PKU.DXHX202011027
  • Old Reaction, New Understanding: An Important Reaction of Diborane with Ammonia
  • Huizhen Li, Yunhui Li, Huifen Zhuang, Liting Chen, Yingmin Liang, Siyuan Yi
  • Although at first glance, the old reaction of B2H6 (diborane) with NH3 seemed to be simple, it has been shown that the reaction was complex and had perplexed boron chemists for decades. The reaction was highly sensitive to the experimental conditions, and one or the mixture of the products, such as diammoniate of diborane (DADB, [NH3BH2NH3][BH4]), ammonia borane (AB, NH3·BH3), aminodiborane (ADB, NH2B2H5), could be obtained. It was known that the asymmetrical cleavage of the double bridge bond of B2H6 produced the ionic product DADB, whereas symmetrical cleavage afforded the covalent product, AB. The different cleavage patterns of B2H6 under particular conditions attracted interest to study the key points of the selectivity including steric effect, inductive effect, solvent effect, and dielectric constant, but it is still not possible to predict the products of the reactions of B2H6 with Lewis base. B2H6 was present in THF as the THF·BH3 adduct, and the products of the reactions of Lewis bases with THF·BH3or B2H6 were of the same types. The formation mechanisms of AB and DADB were explored by an ingenious design using THF·BH3 as a proxy for more reactive B2H6, and the reaction of THF·BH3 with NH3could be carried out under mild conditions. It was found that dihydrogen bonds played a critical role in the competing formation of AB and DADB. Both experimental and computational results demonstrated that dihydrogen bond was the dominant factor in the complex formation mechanism of ADB.

  • 2021, 36 (8): 2012019. DOI: 10.3866/PKU.DXHX202012019
Chemistry Laboratory
  • Experimental Design and Implementation of Decolorization of Dye by Persulfate Activation
  • Xiaoyan Wang, Yong Liu, Baoquan Chen
  • An exploratory analytical chemistry experiment "decolorization of dye by persulfate activation", has been designed, and the students' initiative to participate actively have been stimulated through obvious experimental phenomena and application of different analytical methods. Students are led to consult the relevant reference to design the open experimental plan and exploration. In addition, different teaching plans were adopted for different levels of students, and students' laboratory skills, ability to solve practice problem and capacity to innovate was cultivated step by step.

  • 2021, 36 (8): 2009058. DOI: 10.3866/PKU.DXHX202009058
  • Preparation of Flower Soaps: A Recommendation of a Comprehensive Chemistry Experiment
  • Xianbo Ma, Xinhan Li, Fuqin Zhang, Minghong Chen, Yanqin Ye, Chao Huang
  • A comprehensive chemistry experiment was introduced, which involved the extraction of active ingredients of natural products and the preparation of daily chemical products by saponification reaction. This experiment systematically and coherently combined the basic knowledge of university organic chemistry, basic laboratory skills and life to prepare flower soaps. Through the experiment, students' interests and understanding of the knowledge of organic chemistry will be stimulated. Meanwhile, their ability of innovation will be improved.

  • 2021, 36 (8): 2009017. DOI: 10.3866/PKU.DXHX202009017
  • Improving Kinetic Measurements of Aspirin Hydrolysis
  • Shenghong Zhang, Chuansong Qi, Hua Rong, Liangfa Gong, Wei Li
  • The kinetics of aspirin hydrolysis is the critical content of theoretical physical chemistry for both medical and pharmaceutical students. The experiment is usually conducted by monitoring aspirin's hydrolysis product (salicylic acid, SA) with a spectrophotometer after reaction with soluble Fe3+ salts. However, the kinetic measurement of aspirin hydrolysis has not been widely implemented in physical chemistry laboratory, because of the complicated procedures and the long testing period required to perform the reaction. In this work, the ultraviolet absorbance of SA at a wavelength of 296 nm has been employed to determine the kinetics of aspirin hydrolysis in a phosphate buffer (pH = 6.85). Compared with the traditional method, these improvements simplify the experimental procedures significantly, avoid the formation of liquid acidic wastes, and shorten the reaction time, thus, turn the hydrolysis of aspirin into a practical kinetic experiment for medical and pharmaceutical college students.

  • 2021, 36 (8): 2010054. DOI: 10.3866/PKU.DXHX202010054
  • Application Research of Mobile Phone Thermal Imaging Technology in Chemical Laboratory
  • Jiang Liu, Junhua Hong, Lijiao Wang, Ningdong Zhao, Huaichun Xu, Jun Liu
  • Chemical reaction is often associated with the energy changes. The chemical laboratory data of energy changes was recorded on the thermal imaging device made by the phone thermal imaging plug-in FLIR One Pro and smart mobile phone component. The dynamic temperature distribution in the capillary method for the determination of the melting point of naphthalene, the distillation method for the determination of the boiling point of ethanol and the dehydration reaction of concentrated sulfuric acid with paper were visualized. The images of temperature change with time in different reactions were obtained, and the color change of the images represented the energy change information of different reaction processes. This device can quickly, accurately obtain the system temperature without contact, and provides a visualization of the temperature changes invisible to the human eyes.

  • 2021, 36 (8): 2009035. DOI: 10.3866/PKU.DXHX202009035
  • Experimental Design and Teaching Effect of Maltose Syrup Preparation
  • Yuzi Huang, Maosheng Jiang, Yuexu Lin
  • To improve comprehensiveness, innovation and exploratory of chemistry experiments for teaching, an experiment "preparation of maltose syrup by starch catalytic hydrolysis" was designed. The amylase was prepared and applied as catalyst in the starch hydrolysis process. The reaction had enzyme-catalyzed characteristics, with optimal catalytic temperature 55 ℃. The experiment design featured agriculture and forestry university discipline. Not only did it integrate theoretical teaching with practice to help cultivate the students' scientific spirit, but also was a profound ideological and political course.

  • 2021, 36 (8): 2011034. DOI: 10.3866/PKU.DXHX202011034
  • Quantum Chemistry Research on the Absolute Hardness: Introduction to a Computational Chemistry Experiment
  • Song Yang, Yihan Tang, Jiawei Xu, Ruoxi Liu, Bing Xue, Zhihui Zhang
  • The experimental design of quantitative research on the absolute hardness of compounds in Hard and Soft Acid and Base (HSAB) rule using Gaussian software is introduced, which involves geometry optimization and high-level single point energy calculation. Through the experiment, students will grasp basic steps of using quantum chemistry to calculate the absolute hardness, deepen their understanding of the theory of HSAB, and lay the foundation for future research work.

  • 2021, 36 (8): 2010036. DOI: 10.3866/PKU.DXHX202010036
  • Study on the Controlled Preparation, Analysis and Catalytic Properties of Cu2O Crystals
  • Chuanfeng Liu, Jiacheng Liu, Peihong Gao, Junyan Liang, Yanhong Bai, Wen Zhang, Dan Xiang, Min Hu
  • In order to let students understand the general synthesis method of nanomaterials and instill the concept of controllable synthesis of nanomaterials, the green synthesis method is used to prepare Cu2O microparticles of different colors by the liquid phase reduction method. In this experiment, glucose was used as the reducing agent, and the Bancol reagent was used to react under alkaline conditions. The cuprous oxide sol of different sizes and morphologies was successfully synthesized, and the morphology of the sample was characterized by a biological microscope. The control mechanism of Cu2O morphology was explored by shape model of Cu2O to realize the effective control of the morphology and particle size. The degradation performance of Cu2O as a visible light catalyst on the organic dye methylene blue was evaluated. This experiment involves the synthesis, control and application of nanomaterials, which is conducive to cultivating students' ability to observe, analyze and solve problems. At the same time, the application of nanomaterials to the sewage treatment of organic dyes will help cultivate students' environmental awareness and professional power.

  • 2021, 36 (8): 2011015. DOI: 10.3866/PKU.DXHX202011015
  • Improvement on Measuring the Intrinsic Viscosity of Cellulose by the Copper Ethylenediamine Method
  • Peng Liu, Hongbin Zhang, Sinong Wang, Boxu Gao, Yueer Yan, Yi Tang
  • An improved experiment for determining the intrinsic viscosity of cellulose through the copper ethylenediamine method is introduced. In this method, lignin has a great impact on determination of the intrinsic viscosity of cellulose. In order to explore this issue, a cellulose-lignin model was constructed to discuss the influence of lignin content on intrinsic viscosity of cellulose. Moreover, an improved calculation method was used for cellulose in this model to obtain a more accurate intrinsic viscosity and degree of polymerization of cellulose. In addition, the impact of different dissolution times on the intrinsic viscosity of cellulose copper ethylenediamine when in contact with air was also discussed. This experiment is a basic characterization experiment of cellulose-related materials. By learning this experiment, students can understand the basic properties and dissolution mechanism of cellulose, as well as the determination of viscosity of polymer materials and the use of viscometer. They can also learn to build a simple model to explore the influence of different components.

  • 2021, 36 (8): 2010068. DOI: 10.3866/PKU.DXHX202010068
  • Preparation and Application of Fluorescent Carbon Dots
  • Yaru Yang, Feng Lu, Min Hu, Youshen Wu, Dan Xiang, Peihong Gao, Wen Zhang
  • The paper designed a chemical experiment based on carbon dots which own excellent fluorescence properties. Students need to synthesize blue and green carbon dots through "bottom-up" method, search the relationship between fluorescence excitation spectra and fluorescence emission spectra, measure the fluorescence quantum yield by comparing with a reference fluorophore, explore the changes of fluorescence spectra at different concentrations and pH, and apply the carbon dots to anti-counterfeit materials. All these will make students have a good command of fluorescence principle, such as fluorescence excitation spectrum, fluorescence emission spectrum, fluorescence quantum yield, Stokes shift and the factors that influence fluorescence. We also encourage students to apply the knowledge they have learned to their daily life.

  • 2021, 36 (8): 2009038. DOI: 10.3866/PKU.DXHX202009038
  • Synthesis and Specific Rotation Determination of (-)-Menthone: A Research-Oriented Fundamental Organic Chemistry Experiment
  • Jie Han, Wenbin Chen, Yuxin Li, Rujiang Ma, Zhengjie He
  • (-)-Menthone has been prepared by oxidation of (-)-menthol with sodium dichromate in dilute sulfuric acid or sodium hypochlorite in acetonitrile, and the preparation methods have been reviewed briefly. The specific rotation of (-)-menthone was determined and discussed with respect to the epimerization between (-)-menthone and (+)-menthone, which was corroborated by gas chromatography. This experiment covers the training in fundamental experimental skills such as reflux, distillation, extraction, filtration, gas chromatography characterization and specific rotation determination, and may help the undergraduates improve their integrative abilities and learn the knowledge of chiral compounds.

  • 2021, 36 (8): 2010060. DOI: 10.3866/PKU.DXHX202010060
  • Semiconducting Polymer Nanoprobe for Ratiometric Detection of Reactive Oxygen Species: A Comprehensive Experiment
  • Guosheng Song, Shiyi Liao, Youjuan Wang, Shuangyan Huan
  • This works introduces a comprehensive research experiment about the synthesis and characterization of nanoprobes for detecting reactive oxygen species (ROS). In this experiment, organic semiconducting polymer nanoprobes were prepared using nano-coprecipitation method. Those nanoprobes can be employed for ratiometric detection of ROS, using semiconductor polymer (PFODBT) as the reference and fluorescent molecules (IR775s) as responsive unit. Specifically, the content of ROS (ClO- and ONOO-) can be measured by calculating PFODBT-to-IR775s absorbance ratio. Moreover, based on the principle of fluorescence resonance energy transfer (FRET) between PFODBT and IR775s, the ratio of fluorescent emission of PFODBT/IR775s can also be used for fluorescence ratiometric detection of ROS. This experiment is comprehensive and feasible, and benefited for training the solid experimental skills and scientific research ability for students.

  • 2021, 36 (8): 2011032. DOI: 10.3866/PKU.DXHX202011032
  • Improvement on Preparation of Cyclohexanone from Cyclohexanol
  • Wenbin Chen, Yueyang Chen, Bo Chen
  • In this paper, the organic chemistry experiment "cyclohexanol oxidation to cyclohexanone" was improved by two green oxidants: potassium bisulfate (Oxone) and trichloroisocyanuric acid (TCCA). A by-product was found in the oxidation with Oxone, and the structure of the by-product was determined by GC-MS. The contents of the target product and by-product under different conditions were studied. When TCCA was used as oxidant to prepare cyclohexanone from cyclohexanol, the higher pure target product was obtained (93%), which can be used to replace the original sodium dichromate oxidation of cyclohexanol to cyclohexanone. Through the introduction of the concept of green chemistry, the students can learn the importance of green chemistry in organic synthesis, and be stimulated the interest in scientific research. It is more important to guide students to pay attention to new discoveries in chemical experiments and to search for the causes or processes of new discoveries, and find out new solutions.

  • 2021, 36 (8): 2011045. DOI: 10.3866/PKU.DXHX202011045
  • Preparation of Magnetic Material and Its Application in Wastewater Treatment: A Comprehensive Experiment Based on Blended Teaching
  • Shilong Guo, Min Hu, Shuai You, Haoyu Wen, Yaru Yang, Wenbin Liu, Peihong Gao, Dan Xiang, Wen Zhang
  • Based on the adsorption characteristics of activated carbon and the magnetic properties of nano-Fe3O4, a recyclable and low-cost nano-Fe3O4 was designed to circumvent the problem that traditional water treatment materials cannot be reused and easily remained in water. This experiment is problem-based using Fe3O4@C composite materials as the carrier, to help students master the basic preparation of inorganic nano materials, performance characterization methods, improve students' ability of data processing and interpretation. This experiment provides a new comprehensive laboratory teaching mode, and the online teaching is adopted through the introduction, use and data software in learning of large instruments, while the offline practice is adopted for material preparation and wastewater treatment performance evaluation. This experiment overcame the weakness in traditional inorganic chemistry laboratory teaching, such as weak characterization methods and data processing training. This experiment can be used as a comprehensive experiment for inorganic chemistry, modern instrumental analysis and other theoretical courses.

  • 2021, 36 (8): 2010012. DOI: 10.3866/PKU.DXHX202010012
  • Laboratory Teaching Results and Discussions of "Determination of Kinetic Constants of the Hydrolysis Reaction of trans/cis-[Co(en)2Cl2]Cl Complexes"
  • Chunyan Zhang, Xiaoqing Ouyang, Chanzi Ruan, Yinyun Lü, Rui Pan, Yuhua Weng, Zhiqiang Dong, Zhenling Xu, Shunü Peng, Huamin Li, Yanping Ren
  • This paper mainly introduces the laboratory teaching implementation results and discussions of "determination of kinetic constants of the hydrolysis reaction of trans/cis-[Co(en)2Cl2]Cl complexes", which has been carried out for 10 years and particularly designed for top-talented chemistry-majored students at Xiamen University. Students were guided to discuss and explore the effects of reaction medium and temperature on the hydrolysis reaction of trans/cis-[Co(en)2Cl2]Cl, based on the dynamic experimental data and results. In light of this, students could directly understand the differences in the hydrolysis reaction kinetics behavior of trans/cis isomer with different structure, and the meaning of "structure decides the nature". Their ability of induction, summary, analysis, judgment and critical thinking can be cultivated.

  • 2021, 36 (8): 2011035. DOI: 10.3866/PKU.DXHX202011035
  • Improvement on Preparation of Na2CO3 and Innovative Design on Purification of Salt
  • Xueru Liu, Ronglan Zhang, Bin Cui
  • In this experiment, the purification of crude salt, the preparation of soda and the determination of sodium carbonate content in mixed alkali were integrated, and a comprehensive and designed experiment of university chemistry was developed. Students' independent design was introduced in the part of the purification of crude salt, and Hou's soda production system was introduced in the part of the preparation of soda. The experiment can make the students to consolidate the basic operation skills such as vacuum filtration, crystallization, titration, mastering a large number of chemical reaction principles and methods involved in the preparation of the soda ash, to exercise the ability of comprehensive application of knowledge, and improve the comprehensive innovation quality. Meanwhile, combining with ideological education, it can also help stimulate students' patriotic feelings and interest and enthusiasm of chemistry discipline, and cultivate students' awareness and ability to solve practical problems.

  • 2021, 36 (8): 2012027. DOI: 10.3866/PKU.DXHX202012027
  • Synthesis of Carbon Quantum Dots and the Application in Biothiol Detection
  • Ying Guo, Yonghui Shang, Minyan Zheng
  • A comprehensive chemical experiment is introduced in the paper, including the synthesis, characterization of carbon quantum dots and the fluorescence detection of biothiol. This experiment not only makes students understand the hot spots in the frontier of science, but also enables students to master the structures, principles and operational skills of UV-Vis and fluorescence spectrometers, which are helpful for the innovative consciousness and comprehensive application ability training.

  • 2021, 36 (8): 2105020. DOI: 10.3866/PKU.DXHX202105020
Between Teacher and Student
  • Kekule's Structure of Benzene and the Resonance Structures of Benzene
  • Zhanhui Yang, Xufan Shen
  • A variety of domestic and international organic chemistry textbooks hold the standpoint that the two resonance structures of benzene are Kekulé structures. By introducing the research history of benzene structures and the structural characteristics of Kekulé's benzene, we propose that the above standpoint should be reconsidered. We also suggest that the two resonance structures should be named as "Pauling's structure" or "Pauling benzene".

  • 2021, 36 (8): 2009012. DOI: 10.3866/PKU.DXHX202009012
  • Several Specious Questions in Polymer Chemistry: Developing Students' Critical Thinking, Problem Conversion Ability and Literature Consulting Awareness in Teaching
  • Lin Guo, Kunyan Sui, Hao Hu, Jiuxing Wang, Yifan Wang, Xiaoyan Zhang, Qiaohong Peng, Xin Sui
  • Five typical specious questions in polymer chemistry were discussed, including "the criterion of the spontaneity of a polymerization is △G < 0", "the activities of the two kind of active centers in an ideal copolymerization are the same", "ferrocenylmethyl acrylate (FMA) has a higher propagation rate constant of homopolymerization than 2-ferrocenylethyl acrylate (FEA)", "Methyl 3-(4-methylphenyl)-2-propenoate, or Methyl 4-methylcinnamate, can be homopolymerized into high polymer" and "α-cyanoacrylate cannot be free radically homopolymerized". Through raising and answering these questions, the students were encouraged to think, to doubt, to question, to explore, to acquire, and to understand under the teacher's inspiration and guidance. This helps to train the critical thinking skills, the problem conversion ability and the literature consulting awareness, to build the awareness and abilities of problem finding and problem raising, and to develop the ability to analyze and solve problems, in addition to acquire the right knowledge.

  • 2021, 36 (8): 2009004. DOI: 10.3866/PKU.DXHX202009004
  • Probe into the Issues about the Theory of Valence Shell Electron Pair Repulsion in Different Textbooks
  • Baoshan Li
  • This paper introduces the description in application of the theory of valence shell electron pair repulsion in textbooks at home and abroad. The main methods for determining the number of valence-layer electrons of the central atom are compared and analyzed, including the methods based on Lewis electronic determination method, the group number of the central atom and the number of electrons provided by the coordination atom, the valence electron number of the center atom in the ground state and the unpaired electron number of the coordination atom, and the total number of valence electrons of related atoms in the ground state and octet rule of coordination atoms. The theoretical basis and the physical meaning of the different methods are expounded. The main aim is to develop a consensus on this fundamental chemical theory to make it easy for the students to understand and master.

  • 2021, 36 (8): 2009044. DOI: 10.3866/PKU.DXHX202009044
  • Elementary Substance of C60 Catalog Belongs to Organic Substance
  • Zhiyong Yu
  • Organic substance has been considered as organic compound, but the author does not think it's accurate. C60 should belong to organic substance according to its structure and properties. Based on this fact, a common understanding will be formed: organic substances include both some carbonaceous elementary substances (e.g. C60) and the vast majority of carbonaceous compounds.

  • 2021, 36 (8): 2010038. DOI: 10.3866/PKU.DXHX202010038
  • Multi-Equilibrium Calculations for HF Solution and HF-F- Solution
  • Ying Zhang, Xinjun Quan
  • In HF solution and HF-F- solution, there are not only the dissociations of hydrofluoric acid but also the reactions between hydrogen fluoride and fluoride ion, so the equilibrium concentration of each component is the final product of two equilibria. Theoretically, the correct result can be obtained only if the two equilibria are considered simultaneously. However, much attention has been paid to the dissociation equilibrium of HF than to the HF-F- association in teaching, as a result students are used to take the wrong calculation method when confronting such problems. In order to develop students' comprehensive abilities to deal with the calculations of complex systems, the simple and accurate formulas for calculating the ion concentrations in HF solution and HF-F- solution are derived based on multi-equilibrium. By comparison, it is found that both equilibria must be considered in all cases, except that the concentration of HF solution is less than 1.91×10-2 mol·L-1 which can be approximately calculated as monobasic weak acid.

  • 2021, 36 (8): 2009043. DOI: 10.3866/PKU.DXHX202009043
Self Studies
  • Exploration of Transition State Search in Physical Chemistry
  • Xin Zhang, Peinan He
  • In physical chemistry, transition state theory is the key and difficult point of chemical kinetics. In this work, three methods of computational chemistry are used to search for the reaction transition state, and the reaction rate constants at different temperatures are presented. This enables students to have a more intuitive and clear understanding of transition state and reaction mechanism, and helps them learn chemical kinetics more effectively.

  • 2021, 36 (8): 2012018. DOI: 10.3866/PKU.DXHX202012018
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