Chemistry students, statistics

Every chemistry student is familiar with the ideal gas equation PV = nRT. It turns out that this equation is a logical consequence of some basic assumptions about the nature of gases. These simple assumptions are the basis of the kinetic theory of gases, which shows that the collisions of individual molecules against the walls of a container creates pressure. This theory has been spectacularly successful in predicting the macroscopic properties of gases, yet it really uses little more than Newton s laws and the statistical properties discussed in the preceding chapters. 

This study used a quasi-experimental design with quantitative data (Anderson, 2000 CresweU, 2003) that used two previously designed questionnaires to solicit information related to several affective factors from second-year college chemistry students who were involved in a problem-based learning (PEL) chemistry laboratory corrrse. In order to make comparisons in particular instances, information was also solicited from a group of students enrolled in a traditional laboratory course that involved carrying out specific laboratory activities based on instructions that were provided. With the small sample size and the likelihood of non-normal distribution, any differences between the treatment and comparison groups and between pre- and posttests were analyzed with nonparametric statistics. 

Every chemistry student uses a calculator to solve chemistry problems. A suitable calculator can (1) add, subtract, multiply, and divide (2) perform these operations in exponential notation (3) work with logarithms and (4) raise any base to a power. Calculators that can perform these operations usually have other capabilities, too, such as finding squares and square roots, carrying out trigonometric functions, and offering shortcuts for pi and percentage, enclosures, statistical features, and different levels of storage and recall. 

In Chaps. 5 and 6 we shall examine the distribution of molecular weights for condensation and addition polymerizations in some detail. For the present, our only concern is how such a distribution of molecular weights is described. The standard parameters used for this purpose are the mean and standard deviation of the distribution. Although these are well-known quantities, many students are familiar with them only as results provided by a calculator. Since statistical considerations play an important role in several aspects of polymer chemistry, it is appropriate to digress into a brief examination of the statistical way of describing a distribution. 

Chemistry can be divided (somewhat arbitrarily) into the study of structures, equilibria, and rates. Chemical structure is ultimately described by the methods of quantum mechanics equilibrium phenomena are studied by statistical mechanics and thermodynamics and the study of rates constitutes the subject of kinetics. Kinetics can be subdivided into physical kinetics, dealing with physical phenomena such as diffusion and viscosity, and chemical kinetics, which deals with the rates of chemical reactions (including both covalent and noncovalent bond changes). Students of thermodynamics learn that quantities such as changes in enthalpy and entropy depend only upon the initial and hnal states of a system consequently thermodynamics cannot yield any information about intervening states of the system. It is precisely these intermediate states that constitute the subject matter of chemical kinetics. A thorough study of any chemical reaction must therefore include structural, equilibrium, and kinetic investigations. 

Textbooks and courses in general statistics are easily accessible to students of chemistry, physics, biology, and related sciences. Some of the more or less explicitly stated assumptions that one often comes across are the following ... 

The table below shows historical statistical relationships between students results on the multiple-choice portion (Section I) of the AP chemistry exam and their overall AP score. The AP score ranges from 1 to 5, with 3,4, or 5 generally considered to be passing. Over the years, around 60% of the students who take the AP chemistry exam receive a 3,4, or 5. 

It has been assumed that students have a working knowledge of the basics of analytical chemistry and its methodology. Accordingly, no attempt has been made to cover the fundamentals of analysis or of the statistical manipulation of analytical data. We will use the minimum of mathematics, and no derivations will be included. The rudiments of algebra will be sufficient. 

This work is intended to be, as the title implies, a brief introduction to the principles of quality that are important for workers in a modem industrial analytical chemistry laboratory. It is intended to be a textbook for students preparing to become technicians or chemists in the chemical process industry. It is intended to be a quick reference for new employees in an industrial laboratory as they begin to learn the intricacies of regulations and company policies relating to quality and quality assurance. It is also intended for experienced laboratory analysts who need a readable and digestible introductory guide to issues of quality, statistics, quality assurance, and regulations. 

There are other topics that might be considered, such as solid state theory and classical statistical mechanics. You must decide how much time to spend on each of your chosen topics. You can identify subtopics that you might omit or to which you can give only an introduction. One of the difficult decisions involves how much to teach about your own research area. You are obviously excited about this area, and will be tempted to spend too much class time on it. Another difficult decision is how much time to spend on topics of current interest such as nanomaterials and environmental chemistry. Your decisions should be guided by the composition of your class. If the class has a lot of premedical students and biochemistry majors in it, they are probably well served by a thorough treatment of thermodynamics and dynamics, and perhaps less well served by a thorough treatment of quantum mechanics and statistical mechanics. If the class is mostly composed of future chemistry graduate students, quantum mechanics and statistical mechanics are more important. 

Data were collected from students enrolled in three different courses. Class A was a one-semester introductory quantum mechanics course intended for junior physics majors that typically enrolled about 10 students. Class B was the second-half of a two-semester physical chemistry course for chemistry majors that typically enrolls 30-40 students. The first semester of this course focuses primarily on thermodynamics the second-half spends the first two-thirds of the semester on quantum mechanics and then concludes with a discussion of statistical mechanics. Class C is offered every semester for junior-year chemical engineering majors, and was observed three times Cl, C2, and C3. Cl and C3 were offered during the fall semester, when the mainline population of chemical engineering majors take the course and had enrollments of approximately 70 students. C2 was offered in the spring semester and is frequently taken by students who have done a "co-op" or internship in industry, which requires them to be off-campus for a semester at a time. C2 had an enrollment of around 30 students. The material in Class C is quite similar to the material offered in Class B. The first three-quarters of this class covers quantum mechanics, the remaining time is spent on statistical mechanics. 

We certainly must ask ourselves what we want our students to learn from a year of physical chemistry. There is far more material in any current textbook than one could hope to cover in any depth. Most would agree that quantum chemistry, thermodynamics, and dynamics must be covered. It is also true that statistical mechanics has increased in importance. Recently we conducted a survey of more than 400 ACS certified chemistry departments in order to... 

We have been teaching physical chemistry with a kinetics-first orientation for 13 years. Over the course of this past decade we have also examined our students using the ACS Comprehensive Standardized Exam. Form 1995 (16) was used from 1996 through 2003 and Form 2002 (17) was used in 2004 and 2005. This comprehensive exam has been administered at the end of physical chemistry II covering quantum chemistry and spectroscopy. Both versions divide the 60 multiple choice questions into the three canonical areas, T, Q, and D, with the 1995 version assigning 20 questions each to the three areas. The 2002 version assigns 15 questions to the dynamics section and 25 to the quantum section. A few statistical mechanics questions are also scattered among these sections. 

There are two main families of statistical tests parametric tests, which are based on the hypothesis that data are distributed according to a normal curve (on which the values in Student s table are based), and non-parametric tests, for more liberally distributed data (robust statistics). In analytical chemistry, large sets of data are often not available. Therefore, statistical tests must be applied with judgement and must not be abused. In chemistry, acceptable margins of precision are 10, 5 or 1%. Greater values than this can only be endorsed depending on the problem concerned. 

This book originates from a course given to the students at the IUT in Le Mans for many years. Some friends and colleagues agreed to read the text of the first edition (in 1992) and provide comments and suggestions. This, the fourth edition, has been completed with two additional chapters directed at electro-analytical methods and a chapter on basic statistics used in analytical chemistry. The translation of this text from French to English is thus directed at an even larger readership. 

Chemical Kinetics of Solids covers a special part of solid state chemistry and physical chemistry. It has been written for graduate students and researchers who want to understand the physical chemistry of solid state processes in fair depth and to be able to apply the basic ideas to new (practical) situations. Chemical Kinetics of Solids requires the standard knowledge of kinetic textbooks and a sufficient chemical thermodynamics background. The fundamental statistical theory underlying the more or less phenomenological approach of this monograph can be found in a recent book by A. R. Allnatt and A.B. Lidiard Atomic Transport in Solids, which complements and deepens the theoretical sections. 

We have tried, without being overly formalistic, to develop the subject in a systematic manner with attention to basic concepts and clarity of derivations. The reader is assumed to be familiar with the basic concepts of classical mechanics, quantum mechanics, and chemical kinetics. In addition, some knowledge of statistical mechanics is required and, since not all potential readers may have that, we have included an appendix that summarizes the most important results of relevance. The book is reasonably self-contained such that a standard background in mathematics, physics, and physical chemistry should be sufficient and make it possible for the students to follow and understand the derivations and developments in the book. A few sections may be a little more demanding, in particular some of the sections on quantum dynamics and stochastic dynamics. 

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