Describes an apparatus developed for photochemical studies, particularly those involving the fluorescence of halogenated acetones. The apparatus is constructed from equipment normally found in a moderately sized physical chemical laboratory. Also provides background information on some aspects of the photophysics of halogenated propanones. (JN)

Describes a set of experiments (for senior-level biochemistry students) which permit evaluation and estimation of rate and equilibrium constants involving an intermediate in the alpha-chymotrypsin mediated hydrolysis of ortho-hydroxy-alpha-toluenesulfonic acid (I). The only equipment required for the experiments is a well-thermostated double beam…

The use of a microcomputer as the basis of a multichannel analyzer (MCA) system is described. Principles of microcomputer MCA, choice of microcomputer, input-output port, data display, MCA program, and interrupt routine (with flowchart) are the topic areas considered. (JN)

Equipped with simple sensors and software, a microcomputer can become a microcomputer-based laboratory (MBL). Discusses the value of MBL's and provides three programs which preview the new MBL kits available for science classes. A list of commercially available MBL's (with product names, current prices, and other information) is also included. (JN)

Suggests a simple technique for collecting and observing human hair roots to compare structure, function, and variation. Students extract their own hair samples and view them using a 40-power microscope objective. Differences between active/inactive phases of hair growth are readily observed. (The activity can be adapted for younger students.) (DH)

Project CHEMLAB has prepared a database which focuses on laboratory experiments suitable for high school through graduate or professional school levels. The scope of the project, the structure of the database, database features, and computer searching are discussed. (JN)

The value of the genus Nematodius in teaching is not widely realized. Presented is a brief biological outline of the organism (including geographical distribution and reproductive cycle/behavior) and its use in student investigation of selective predation. (Author/JN)

A discrepant event is a happening contrary to our current beliefs. Discrepant events are said to be useful in clarifying concepts. This is one of the interesting features of current theories of constructivism. The story of Mpemba's ice cream is quite well known, but it is the educational aspects of the experiment that are of interest in this…

Discusses the nature and applications of mass-selective laser photoionization. The ionization can be done with a single intense laser pulse lasting a few billionths of a second with no molecular fragmentation. Applications focus on: (1) benzene clusters, excimers, and exciplexes; (2) metal clusters; and (3) triplet formation and decay. (Author/JN)

Free radical chlorination of methane is used in organic chemistry to introduce free radical/chain reactions. In spite of its common occurrence, demonstrations of the reaction are uncommon. Therefore, such a demonstration is provided, including background information, preparation of reactants/reaction vessel, introduction of reactants, irradiation,…

Describes an experiment on the qualitative analysis of several over-the-counter analgesic tablets. Background information, procedures used (including high pressure liquid chromatography), and typical student results are included. (JN)

Describes the nature of three types of science experiments, focusing on those designed to answer the questions: "What happens?"; "How can it be done?"; and "Which theory?". Indicates that all three have had a definite place in the school science curriculum. (JN)

The reaction between arsenite and iodate in acidic solution offers an excellent pedagogic introduction to such phenomena as traveling waves. Component reactions, traveling waves, and a mathematical model are discussed. Demonstrations described can easily be elaborated into a full laboratory experiment. (Author/JN)

A Beckmann arrangement was developed which explores the concept of stereospecificity and concurrently exposes students to synthetic, spectrophotometric, and chromatographic processes. Background information, laboratory procedures, and results are provided. (JN)

Hydantoins are a drug family lying within the broadly related ureide structural frame which encompasses many of the anticonvulsant drugs used in treatment of various types of epilepsy. Background information and experimental procedures are provided for the synthesis of the hydantoin 5,5-diphenylhydantoin. (JN)