Since activity coefficients are difficult even for good students to understand from the normal presentations in undergraduate physical chemistry, the author has reanalyzed this concept and presents a new way for introducing it. A practice problem (with solution) is included. (JN)

Examines the volume distribution of electrical charge and charge thickness on the surface of a metallic sphere, and compares the results with a sphere made of a perfect insulator. (JM)

By using a computer program to identify bacteria, students sharpen their analytical skills and gain familiarity with procedures used in laboratories outside the university. Although it is ideal for identifying a bacterium, the program can be adapted to many other disciplines. (Author)

Presents an internally consistent set of 63 substituent constants developed for use with the Schoolery Relationship to predict the chemical shifts of methylene protons of acyclic compounds. Chemical shift data used in deriving the constants were taken mainly from primary sources of HNMR (nuclear magnetic resonance) spectra. (JN)

A versatile point system for grade assignments that allows students to choose the type of performance to be evaluated is described. Features and advantages of using the grading system in both graduate and undergraduate courses are noted. (JN)

Clarifies where in the scheme of modern chromatography high performance thin layer chromatography (TLC) fits and why in some situations it is a viable alternative to gas and high performance liquid chromatography. New TLC plates, sample applications, plate development, and instrumental techniques are considered. (JN)

Discusses characteristics of crystal systems, comparing (in table format) crystal systems with lattice types, number of restrictions, nature of the restrictions, and other lattices that can accidently show the same metrical symmetry. (JN)

Deduces the relationship between reduced velocity and molar fractions for productive enzyme complexes; obtains the mathematical expression of molar fractions for an enzyme with two specific binding sites per molecule; and proposes a useful plot to follow the dependence of enzyme molar fractions with the concentration of one of its ligands. (JN)

Presents an overview of the glass-to-rubber transition, what it is, why it is important, and the major factors that influence it. Indicates that this information should be incorporated into chemistry curricula. (JN)

Reports on the development of an equation that relates, quantitatively and continuously, bond order and bond length for any homo- and heteronuclear bond. (JN)

Reviews analogies used to try to capture the concept of the magnitude of Avogadro's number, including analogies related to small/tiny objects, counting, people, water, and money. Also presents several new ones which are based on modern computers and printers. (JN)

Prolog is one of the most successful "very high level languages." Describes this programming language (a product of artificial intelligence research) and attempts to show how it functions by using some short examples to illustrate its essential features. (JN)

The unit basis approach to problem solving analyzes a question in such a way that the student clearly sees what data are needed to solve the problem. Two examples are presented to illustrate the approach. (JN)

Presents a new method of uncertainty propagation which concentrates on the calculation of upper and lower limits (the "worst cases"), bypassing absolute and relative uncertainties. Includes advantages of this method and its use in freshmen laboratories, advantages of the traditional method, and a numerical example done by both methods.…

Although many textbooks include a description of simultaneous determinations employing absorption spectrophotometry and treat the mathematics necessary for analytical quantitations, treatment of analytical wavelength selection has been mostly qualitative. Therefore, a general method for selecting wavelengths for optimum precision in simultaneous…