12 Results
A Method of Visual Interactive Regression   
(Software, Instructional Material (1))
Over the past decade many colleges and universities have placed increased emphasis on having students develop statistical and data analysis skills in a range of disciplines. Some institutions now require that all students complete at least one course with a strong component of data analysis, whether the data are from chemical experiments, the census, or some other source. As chemists, one of our concerns should be to ensure that students view data analysis as an integral part of any quantitative experiment, and, as far as possible, do not treat this process as a black box. The authors of A Method of Visual Interactive Regression, a spreadsheet application, have developed a visual approach to linear least-squares curve fitting that drives home the idea of minimizing the sum of the squares of the deviations in order to find the best fit to a set of data that are being described by a linear relationship. For many students these visualizations are likely to persist a great deal longer than the mathematical derivations of the equation for the slope and the intercept. The visualizations will provide a useful connection between a set of equations and the buttons on a calculator or the insertion of a trendline in a spreadsheet.
A Pedagogical Simulation of Maxwell's Demon Paradox   
(Software, Instructional Material (1))
Maxwell's demon was conceived by James Clerk Maxwell in 1871 to illustrate the statistical basis of thermodynamics (1), and the concept has since formed an arena for investigation and clarification of many concepts in thermodynamics (2). Chemistry students often have difficulty developing an intuitive knowledge of some concepts in thermodynamics. A Pedagogical Simulation of Maxwell's Demon aims to help make these concepts more understandable for students. Teaching thermodynamics from the microscopic point of view can help students develop an intuitive understanding of its concepts. This program simulates, at the microscopic level, two gas chambers with an opening between them. The program allows students or their instructors to set up simulations that illustrate the thermodynamics and statistical behavior of the system. The user determines the basis for whether the demon permits or denies passage of particles through the opening using information from the microscopic level, such as specific particle velocity. Students can track and analyze how this affects particle distribution, thermal equilibrium, relaxation time, diffusion, and distribution of particle velocities.
Visualizing Numerical Methods (2)   
(Software, Instructional Material (1))
These movies are designed to help students visualize various numerical approaches to evaluating functions or solving equations. The methods themselves may be familiar to students from their mathematics courses, but they may have forgotten the material or never made the connection between a statement such as "the derivative of a curve at a given point is the slope of the line tangent to the curve at that point" and the way that one might evaluate such a derivative. All of the movies have VCR-style controls that enable the student to step through them one frame at a time and to move backwards as well as forwards.
Addition Reactions of Alkenes   
(Movie/Animation, Audio/Visual (6), Movie/Animation (1))
The Diels-Alder reaction, addition of oxygen to tetrakis(N, N-dimethylamino) ethylene, polymerization of ethylene, and addition of iodine to a-pinene are demonstrated. Molecular models of ethene are shown.
Oxidation-Reduction (Redox) Reactions   
(Movie/Animation, Audio/Visual (5))
Demonstrations exploring oxidation/reduction chemistry.
(Movie/Animation, Audio/Visual (3))
This experiment demonstrates the electrolysis of water.
Diels-Alder Visualization   
(Movie/Animation, Audio/Visual (3))
Several computer animations of a Diels-Alder reaction that were created as an undergraduate student project are presented.
Redox Titration and Animation   
(Movie/Animation, Audio/Visual (2))
A simple redox titration (hydrogen peroxide with permanganate) is performed. Also an animation demonstrates aspects of the stoichiometry.
Alkanes and Cycloalkanes   
(Movie/Animation, Audio/Visual (2))
The structures and conformations of alkanes and cycloalkanes and the vibrational, rotational, and translational motion of alkanes in the gas phase are demonstrated.
(Movie/Animation, Audio/Visual (12))
Reactions exploring electrochemical concepts.
Alkanes in Motion   
(Movie/Animation, Audio/Visual (10))
Animations of gas-phase hydrocarbon systems show the motion of molecules.
Molecular Models of DNA   
(Interactive Simulation (1))
The featured molecules this month come from the paper by David T. Crouse on the X-ray determination of the structure of DNA. Given that most students are aware of the double helix, it seems appropriate to back up a little and examine the components that give rise to this structure. Accordingly, the molecule collection includes: Purine and pyrimidine, structural precursors of the four bases found in DNA: cytosine (C), thymine (T), adenine (A), and guanine (G) The four corresponding deoxyribonucleosides The four deoxyribonucleotides (the nucleoside monophosphates) A two-base-pair fragment showing the AT and GC hydrogen-bonded complements Several small 24-base-pair DNA fragments polyAT, polyGC, and a random array of bases. The DNA fragments provide a good opportunity to have students explore features of the Jmol and Chime menus. Using the Jmol menu as an example (right-click on the structure to bring up the menu) students can use the measuring tools to get an idea of the length of a complete turn in the DNA, the relative widths of the major and minor grooves, and the diameter of the helix. They can use the coloring schemes to detect the various base pair combinations, and learn to read the code for the random sequence. In Chime they can use the Shapely coloring scheme for this same purpose. Exploring other aspects of the menu will allow students to present the molecules in the various forms, including ribbon and cartoon views. In RNA, thymine is replaced by uracil, and the sugar moiety has an axial hydroxyl group on the carbon atom adjacent to the base binding site (the 2? carbon). The structures of uracil and of uridine monophosphate are included in the molecule collection. Students can use the Web to download and examine more complex DNAs using a site such as the Nucleic Acid Database at Rutgers University.