Laboratory Modules from Dr. Barbara Kebbekus Department of Chemistry New Jersey Institute of Technology Newark, NJ 07102

Polymers, both synthetic and natural are an enormous, varied and very important class of compounds. Synthetic polymers, plastics to most people, have contributed in major ways, both and detrimental, to modern civilization. While it is hard to imagine life without plastic packaging, synthetic clothing fibers. and manufactured building materials, these materials are also to blame for much of our solid waste disposal problem. The usefulness of polymers is due in large part to the fact that the properties of the material itself can be designed to fit exactly the needs of the application. The property of being rot-proof and long-lasting, however, makes it difficult to disintegrate these materials in landfills.

In this series of experiments, students synthesize two polymers, methyl methacrylate and a polyamide. They bring in samples of polymers and determine their composition using infrared spectroscopy . Then they carry a sample of shredded soda bottle through a separation process to show the necessary steps in producing a pure enough polymer for useful recycling. A method of hydrolyzing old nylon polyamide to produce the original monomer for recycling is also shown.

The exercise introduces infrared spectroscopy, physical separation steps (recrystallization. separation on the basis of density) and polymer synthesis. The various parts of the experiment are suitable for general chemistry(identification, synthesis, recycling of PETE), organic chemistry (synthesis, hydrolysis of nylon) and environmental science courses (identification, recycling of PETE). Each major section should take one lab period, although the hydrolysis of nylon needs a standing period of a wee; so must be spread over a two lab span.

†Professor of Chemistry, N.J. Institute of Technology: author to which correspondence should be addressed.

Is gasohol the fuel of the future? Can we obtain the chemicals needed by industry from renewable plant resources rather than from petroleum reserves? How does this new technology relate to the ancient practice of brewing alcohol from grains? This experiment allows students to explore the simple biochemistry underlying such questions by hydrolyzing cornstarch to its component sugars using a commercial enzyme preparation and fermenting the sugars to carbon dioxide and ethanol using yeast which have been immobilized in a polymer matrix. After carrying out the enzyme-mediated hydrolysis, the class will analyze the product's sugar content using refractometry, its protein content using spectrophotometry, and its water content using gravimetry. Immobilization of yeast cells in an alginic acid matrix allows easier handling of the yeast than in free suspensions; fermentation is conveniently followed by measurement of the carbon dioxide produced. Simple atmospheric distillation of the aqueous solution after filtering out the yeast beads yields ethanol (as the 95% azeotrope); alternatively, the ethanol content of the aqueous solution may be estimated by refractometry or gas chromatography.

The full experiment takes three three-hour lab periods, but selected constitutent experiments may be combined in various ways to yield shorter projects. It may be used in Organic Chemistry in connection with the chemistry of alcohols or sugars, or as an introduction to separatory and analytical techniques. It is also suitable for upper level laboratory courses. Parts of the experiment may be used in lower level courses in conjunction with the study of fuels, industrial processes, reaction catalysis, or introductory biochemistry

†Professor of Chemistry, N.J. Institute of Technology: author to which correspondence should be addressed.

This series of experiments addresses environmental concerns about air pollution, and allows students to make real-world measurements which tends to attract their interest. The group may be done as a whole or selected portions may be performed, depending on the time and equipment available. Samples are taken of airborne particulates and these are analyzed to determine the total amount of particulate in the sampled air by gravimetry, the amount of sulfate, and the amount of lead and, if desired, other selected metals. Air is also sampled for the analysis of ozone and other oxidants, and for acid gases, mostly CO₂. The experiments take from I to 2 laboratory periods of 2 hours for each determination. If the single period is available, some of the standards will have to be supplied, but doing the necessary calculations and preparing their own standards is a good experience for the students, and may-warrant taking the extra time.

Sampling for particulates is most easily done by lending out the high volume samplers in the weeks before the experiments are scheduled, so students may take samples wherever they think interesting. The gaseous samples may also be done that way, if battery powered personal sampling pumps are purchased. However, these samples may also be taken in the laboratory, of the ambient air, and analyzed immediately.

Topics covered include gas laws, conversion factor calculations, solution dilution calculations and both redox and acid base stoichiometry. Spectrometry and Beers Law are also illustrated. The experiments can be done by beginning students, with more guidance in the calculations and techniques, but upper-class students will also find them interesting, and can be given much less assistance. These may make their own standards, and other solutions and work more independently.

This experiment may be done by general chemistry students, either majors or non-majors and by environmental science classes. The gas laws are used, in doing the calculations of sample volumes. Redox titrations and stoichiometry are used in the ozone determination. Calculations using conversion factors are used in every one of the sections.

†Professor of Chemistry, N.J. Institute of Technology: author to which correspondence should be addressed.

Author Table

General Chemistry Organic Chemistry

Environmental Chemistry Liberal Arts Chemistry

Analytical Chemistry Upper Level Chemistry

Contact Professor Barbara Kebbekus with feedback on her lab modules at kebbekus@admin.njit.edu