Titration is an important experimental skill that every chemistry educator and learner must master. Titration is often the method of choice in the science laboratory courses in secondary and postsecondary schools. During acid-base titration, chemistry learners are always told about salt formation. However, a practical visualization of the salt…

Despite widespread use in general chemistry laboratories, the crystal violet chemical kinetics experiment frequently suffers from erroneous student results. Student calculations for the reaction order in hydroxide often contain large asymmetric errors, pointing to the presence of systematic error. Through a combination of "in silico"…

Volatile compounds from polymeric materials such as weatherstripping were identified by solid-phase microextraction (SPME), a solvent-free analytical method, coupled to gas chromatography-mass spectrometry (GC-MS). These compounds, originating from additives and fillers used in weatherstripping processing, were mostly polycyclic aromatic…

A study of modern genetics requires students to successfully unite the principles of Mendelian genetics with the functions of DNA. Traditional means of teaching genetics are often successful in teaching Mendelian and molecular ideas but not in allowing students to see how the two subjects relate. The laboratory module presented here attempts to…

Describes a precipitation experiment which follows a yellow powder experiment discussed in part 1 (vol 62 no 3 p238-40). Advantages of using a Petri dish to perform the experiment, laboratory procedures used, instructional strategies, and implications for chemistry curriculum and instruction are discussed. (JN)

Discusses a laboratory exercise (suitable for the day before spring vacation) involving use of a hard-boiled egg to stimulate student responses to questions on the effect of adding salt to the water, formation of iron sulfide, ease of peeling, and gas laws. Additional experiments are included. (BC)

Observations and experiments with mice, developed and tested at the Pennsylvania Advancement School with underachieving boys in grades seven and eight, are described in this teachers' guide which includes copies of student worksheets for exercises needing them. In addition to lists of materials and procedural suggestions, ideas for guiding…

Uses the subject of enzymes to illustrate the topical approach to teaching biochemistry at the secondary level. Includes the procedures for three experiments dealing with various aspects of enzymes. (JN)

Background information and procedures are provided for an experiment in which an oxidation reaction is used to distinguish saturated from unsaturated fats. Results of the experiment lead to discussions and investigations of such areas as digestion chemistry, enzymes, hydrogenation, and the relationship between heart disease and fat consumption.…

Describes a method for the extraction and bioassay of natural germination inhibitors, requiring only inexpensive equipment and minimal experimental skill. The method has been used to demonstrate qualitative/quantitative differences in germination inhibitor levels in a variety of different fruits or in different tissues within a single fruit.…

Errors in determining the effectiveness of mouthwashes, disinfectants, and other household products as antibacterial agents may result from using broth cultures and/or irregularly shaped bits of filter paper. Presents procedures for a better technique and, for advanced students, two additional procedures for introducing quantitative analysis into…

Describes a project-type experiment in which students each try to find the color indicator present in a particular flower. The philosophy of conducting such an experiment and procedures used are included. (JN)

Background information, materials needed, and procedures used are provided for potentiometric fluoride, halide, orthophosphate, and sulfate titrations. Typical results obtained are also provided for each type of titration. (JN)

Presented are procedures used to assay the activity of lipase during storage at three different temperatures. Since lipase solutions can decay even when refrigerated, it is recommended that the enzyme be freshly prepared prior to laboratory sessions in which they are used. (JN)

Briefly outlines the theoretical basis of the phenomenon of photoconductivity and describes a simple experiment which demonstrates the photoconductive properties of cadmium sulfide. (JR)