Chemical kinetics teaching

Many books on chemical kinetics have been published, but few of these are devoted solely or even primarily to solution phase chemical kinetics. Textbooks of physical organic chemistry must deal with solution chemistry, but kinetics is only one part of their subject. From my teaching experience I have concluded that there is no current text that meets the needs, as I interpret them, of the student and practitioner of solution chemical kinetics. 

The present chapter will focus on the practical, nuts and bolts aspects of this particular CA approach to modeling. In later chapters we will describe a variety of applications of these CA models to chemical systems, emphasizing applications involving solution phenomena, phase transitions, and chemical kinetics. In order to prepare readers for the use of CA models in teaching and research, we have attempted to present a user-friendly description. This description is accompanied by examples and hands-on calculations, available on the compact disk that comes with this book. The reader is encouraged to use this means to assimilate the basic aspects of the CA approach described in this chapter. More details on the operation of the CA programs, when needed, can be found in Chapter 10 of this book. 

According to Birss and Truax (72), students are likely to experience confusion and difficulty with more advanced treatments of the subject. With regard to conceptual difficulties, the authors looked at the equilibrium potential, the reversal of sign of electrode reactions that are written as oxidations, and the differences between galvanic (electrochemical) and electrolytic cells. An approach for teaching these topics at the freshman level was then proposed. In this approach, concepts from thermodynamics and chemical kinetics are interwoven with those of electrochemical measurements. Very useful are... 

Arguments for the presentation of kinetic theory and chemical kinetics as the first topics taught in the initial physical chemistry course are presented. This presentation allows the first topic in physical chemistry to be mathematically more accessible, to be highly relevant to modem physical chemistry practice, and to provide an opportunity to make valuable conceptual connections to topics in quantum mechanics and thermodynamics. Preliminary results from a recent survey of physical chemistry teaching practice are presented and related to the primary discussion. It was found that few departments of chemistry have adopted this order of topical presentation. 

At some institutions, however, external constraints prohibit changes in the order of topics, especially if Physical Chemistry I is a service course for other departments, most notably engineering. Further, there are no textbooks in which chemical kinetics is among the first topics, certainly among the most popular textbooks currently used. Our survey of physical chemistry teaching (/)... 

Process (VIA) is the net reaction in excess arsenite ([H3As03]o/[IOJ]0 > 3) it is equivalent to (VIB) + 3 (VIC). Process (VIB), the Dushman reaction, is normally rate determining. Therefore, the net process (VIA) is autocatalytic in [I-], which causes a dramatic color change to arise at the stoichiometric point due to the sudden appearance of I2. Bognar and Sarosi exploited this fact to devise a chronometric technique for the determination of traces of iodide43. Process (VIC), the Roebuck reaction44, has played an important role in the development of chemical kinetics and teaching of physical chemistry, as it was the first multi-step reaction for which it was shown that the quotient of the independently determined forward and reverse rate laws equals the equilibrium quotient obtained from the law of mass action. 

Considerations based on the known physical phenomena can guide the choice of catalyst porosity and porous structure, catalyst size and shape and reactor type and size. These considerations apply both to laboratory as well as to large-scale operations. Many comprehensive reviews and good books on the problem of reactor design are available in the literature. The purpose of this book is to teach the reader the mathematical tools that are available for calculating interaction between the transport phenomena and true chemical kinetics, allowing optimization of catalyst performance. The discussed theories are elucidated with examples to provide training for application of the mathematics. 

Besides aetive research he very much enjoys teaching. In the Physical-Teehnieal Institute of Moseow he taught (1966-1992) general courses on Molecular Dynamics and Chemical Kinetics. In the Teehnion (since 1992) he has taught and still teaehes graduate eourses on different subjeets Advanced Quantum Chemistry, Theory of Moleeular Collisions, Kinetie Proeesses in Gases and Plasma, Theory of Fluetuations, Density Matrix Formalisms in Chemical Physics etc. 

Justi, R. S. (1997). Models in the teaching of chemical kinetics, Unpublished Ph.D. Thesis. Reading The University of Reading. 

The teaching of the conceptual schemas addressed in this Section is discussed from the point of view of research into new curricular approaches for their introduction (e.g., chemical equilibrium, electrochemistry and thermodynamics) and into the production and use of more effective teaching models (e.g., chemical kinetics and electrochemistry). 

In general, studies of chemical kinetics at the secondary level emphasise qualitative aspects. At this stage, pupils (e.g. at ages 14-16) discuss the rate of different examples and investigate the influence of temperature, concentration and catalyst on the rate of reactions. Such aspects are explained with a colliding particle model. Chemistry teaching in Australia, Brazil, the Netherlands, New Zealand, UK and USA, for instance, adopts this approach. 

Students in most, if not all, countries learn about chemical kinetics in school. It is therefore surprising that this theme has not more frequently been the focus of science education research. Indeed, there are very few studies in which the teaching of chemical kinetics has been analysed from the perspective of either teachers or students understanding at the secondary school level. 

As part of the study by Justi (1997), a written questionnaire was answered by twenty Brazilian chemistry teachers. It was found that, in general, teachers knowledge about chemical kinetics did not surpass that in the textbooks that they used in their teaching. Some of the data justified this view ... 

In the next phase of this research, a case study was conducted in a class of 15-16 years old students in Brazil. In this case study, all the twenty meetings of the class concerned with chemical kinetics were observed and video recorded. The teacher was interviewed six times, for 40 to 90 minutes on each occasion. His expressed model of chemical kinetics was characterised from the transcriptions of both the classes and the interviews with him. The textbook used in the teaching was analysed and its expressed model identified. Each of these expressed models was then compared with the eight historical models previously identified in order to estabhsh the nature of any possible relationships between them. 

The teaching of chemical kinetics at university level is often characterised by the introduction of (i) the transition state theory as a basis for explanations of the kinetic aspects of chemical reactions (ii) more complex explanations for the action of different types of catalysis than the previous key-lock model (iii) more complex mathematical models for both the rate equations and the establishment of relationships between kinetics and thermodynamical variables. For that level, the literature shows a completely different picture a few papers which discuss students difficulties as such a huge number that propose solutions to claimed problems of learning and new methodologies for the teaching of chemical kinetics. 

In his analysis of the introduction of chemical kinetics in teaching, Logan (1984) states that students difficulties are not only due to mathematical problems. He assumes that chemical kinetics is composed of two distinct lines of development the empirical and the theoretical . According to him, students have serious difficulties in learning chemical kinetics both because this fact is not discussed with them and because the two approaches are not treated as complementary to each other. 

The unique exception to these generalised studies was conducted by BouJaoude (1993) with a sample of USA first year chemistry students. The main focus of his study was on students errors when solving chemical equilibrium problems. However, as the course followed a conventional approach to the teaching of chemical equilibrium, i.e. one in which chemical equilibrium is explained in terms of kinetics, the author had to include a problem involving chemical kinetics in his research instrument. The problem... 

The main suggestions that have been made for improvement in the teaching of chemical kinetics concern the curricular models used and the production and appropriate use of specific teaching models. 

Others authors propose alternative ways to conduct or discuss an experiment that is already commonly used in the teaching of chemical kinetics. For example the presentation of a videotaped clock (iodine-azide) reaction which is suitable for videotaping and which has an easily determined mechanism (Haight Jones, 1987) the determination of a reaction mechanism of the blue bottle reaction (Engerer Cook, 1999). Others may be used to discuss thermodynamics and kinetics simultaneously, e.g., from the study of the surface of nanomaterials (such as a gold colloid monolayer) (Keating, Musick, Keefe Natan, 1999), and from the study of a chemical equihbrium in solution (Leenson, 1986). 

---