Discusses problems and pitfalls of working with single-pan balances and methods used to advertise their accuracy. Investigated manufacturers knowledge of buoyancy effects, relating provisions and recommendations made by various companies. Provides a routine for intercalibration of weight using dummy weights of approximately known mass. (JM)

Presents an outline of group separations for a nonhydrogen sulfide analytical scheme applicable to all metallic elements (Bromide scheme). Also presents another outline of an abbreviated and modified version (Iodide scheme) designed for emphasis on nutritionally important metals, with special attention to 10 cations. (JM)

Discusses two procedures for the identification of nitrate, the standard test ("Brown Ring" test) and a new procedure using triphenylbenzylphosphonium chloride (TPBPC). Effectiveness of both procedures is compared, with the TPBPC test proving to be more sensitive and accurate. (JM)

Describes an undergraduate laboratory experiment used to illustrate the use of gas chromatography retention indices for the identification of unknown compounds, specifically for the identification of unknown compounds and for the identification of the volatile compounds responsible for the odor of the banana. Procedures, reference data, and sample…

Presents a novel approach to identification of unknown alcohols using experimental measurements of boiling point and viscosity which are easily obtained without expensive equipment of instrumentation. Provides instructions for preparing capillary viscometer, listing special hints for obtaining good results. (JM)

Describes an experiment designed to teach students to apply the same statistical awareness to instrumentation they commonly apply to classical techniques. Uses propagation of error techniques to pinpoint instrumental limitations and breakdowns and to demonstrate capabilities and limitations of volumetric and gravimetric methods. Provides lists of…

Background information, procedures, and typical results are provided for a three-part experiment involving reactions of potassium thiocynate (KNCS) with sulfuric acid. The experiment represents the final stage of structured work prior to students' research projects during their final year. (JM)

Presents three ideas to help hold costs down in purchasing and using science equipment. These include (1) use of pencils and other graphite rods as sensors in potentiometric titrations, (2) rubber bulb modification for pipetting, and (3) a heater for a glassware bath. (JM)

Outlines use of electrode potential diagrams in a simple system and in the Hill-Bendall scheme for photosynthesis to help students understand reaction mechanisms involved. Emphasizes use of arrows to depict electron transfer, concept of free-energy diagram, and that maximum heights on diagrams represent maximum work available/minimum work…

Provides background information on the development and action of the coumarin family of anticoagulants, focusing on an experimental procedure for the synthesis of dicumerol. Includes procedures used and safety considerations. (JM)

Discusses methods for reducing or eliminating waste disposal problems in the chemistry laboratory, considering both economic and environmental aspects of the problems. Proposes inventory control, shared use, solvent recycling, zero effluent, and various means of disposing of chemicals. (JM)

Describes a modular approach to help select the most effective instruments for particular applications. In the approach, an instrument is considered to be a system composed of modules, each module performing a particular function. General input/output functions of various modules, how they modify signals, and module sensitivity are discussed. (JM)

Provides a set of instructions for writing Lewis octet structures which incorporates a simple rule called the "6N+2 Rule." Discusses the importance of these structures in elementary chemistry, biochemistry, and organic chemistry courses. Also discusses non-octet structures and how they are characterized. (JM)

Points out that equilibrium binding and steady-state enzyme kinetics have a great deal in common and that related equations and error analysis can be cast in identical forms. Emphasizes that if one type of problem solution is taught, the other is also taught. Various methods of data analysis are evaluated. (JM)

Isodesmic reactions are hypothetical chemical changes in which the number of bonds of a given type are retained but change in relation to one another. Discusses use of these reactions and reaction energy to measure deviations from additivity of bond energy. Also considers relationship of enthalpies to strain and resonance stability. (JM)