Laboratory Modules from Dr. Mary-Ann Pearsall Department of Chemistry Drew University Madison, NJ 07940

Although catalysts are common in organic chemistry, students seldom have an opportunity to explore heterogeneously catalyzed organic reactions. This experiment teaches the effect of a common precious metal catalyst (Pd/C) on the conversion of a wide range of high boiling aldehydes to saturated and unsaturated alkanes. This involves a reaction not often discussed in standard texts. Two periods are recommended, one for reaction and another for complete data collection; students work in pairs. The experiment involves microscale reaction including thermal (noncatalytic) control, distillation, gas chromatography, IR, NMR -and GC/MS. Note: the experiment can also be performed successfully on a larger scale. Emphasis is on the discovery of new chemistry and the use of chromatographic and spectroscopic techniques in product identification and in the quantitative determination of substrate conversion and product yield.

† Assistant Professor of Chemistry, Drew University: author to which correspondence should be addressed.

This module presents an introduction to organic qualitative analysis coupled to introductions to infrared (IR) and nuclear magnetic resonance (NMR) spectrometry. The process of qualitative analysis has always been an exploratory one; this experiment, however. rather than giving the student a flow chart of reactions in advance, allows the student to develop reaction tables, correlation charts, and a flow chart in the course of the experiment, and emphasizes natural products and household chemicals as unknowns.

The first section of the experiment explores the reactivities which distinguish the classes of hydrocarbons, alkanes, alkenes, alkynes and arenes. In this section, students may also develop a simple correlation chart of important IR frequencies. The section culminates with a quantitative experiment which students must design themselves: analysis of the relative unsaturation of edible oils by a visible spectrophotometric method or by NMR.

The second part of the experiment introduces the oxygen-containing functional groups, emphasizing the analysis of the neutral groups (ketones. aldehydes, alcohols and ethers). As students apply the tests to a set of standards, they develop a flow chart of reactions which can be used to determine an unknown natural product. This process can be linked to the study of more complex IR and NMR spectra, and concludes with another self-designed experiment exploring the reactivity of pyridinium chlorochromate as an oxidizing agent.

The parts may be taken in sequence or separately to correspond to the instructor's favored order of topics in the organic chemistry course. Although the experiment is most suited to the organic chemistry course, the experiments on hydrocarbons would complement an introductory course in general. organic and biochemistry.

† Assistant Professor of Chemistry, Drew University: author to which correspondence should be addressed.

Introductory laboratory courses typically begin with a lecture on safety which students find dull and is quickly forgotten. This one-week laboratory module remedies this situation by having students investigate reactions of strong acids, strong bases, oxidizing agents, and acetone on substances which students cannot avoid bringing with them to the laboratory such as clothing (denim, cotton, and nylon fabrics), hair, contact lenses, and skin (egg white represents skin proteins). They can then see for themselves that the chemicals being tested are worthy of respect, and understand the reasons for laboratory safety procedures. Besides the safety message, the lab introduces students to the different classes and strengths of common chemical reagents, and to molarity.

The experiment requires one three-hour lab, and fits best as the first lab in a General Chemistry, Liberal Arts Chemistry, or Environmental Chemistry laboratory course.

†Assistant Professor of Chemistry, Drew University: author to which correspondence should be addressed.

The objective of this experiment is to explore the need for accuracy and precision when working in the laboratory. The topic is addressed by determining the densities of cans of soda. Students first observe the relative densities of different types of soda (e.g., diet Coke versus regular Coke) by floating the cans in water. They then postulate reasons for the difference (e.g., the sugar in regular Coke makes for a denser solution than that of diet Coke). Next they try to verify that regular Coke is denser than diet Coke by quantitatively determining densities using a procedure of their own design based on Archimedes Principle. However - to their surprise - due to the intrinsic inaccuracies of the experiment they develop, they are unable to verify the density difference! This experience is very effective in emphasizing the true meaning of significant figures.

The experiment requires one three-hour lab, and fits best early in the first semester of a General Chemistry or Liberal Arts Chemistry laboratory course. Students work in groups of four, and emphasis is placed on observation and group collaboration.

†Asistant Professor of Chemistry, Drew University: author to which correspondence should be addressed.

The purpose of this experiment is to investigate common types of chemical reactions. In the first section of the module, students test the conductivity of a variety of solutions to determine which contain an appreciable concentration of ions. In later sections examples of single displacement, double displacement (precipitation), acid-base, combination, and decomposition reactions are explored. Students run a wide variety of reactions and learn to look for evidence that a reaction has occurred. The module also gives them practice in writing formulas for compounds and balanced chemical equations for the reactions observed

This one-week module is well-suited for use early in the semester in either a general chemistry or a liberal arts chemistry course. It correlates well with the introductory chapter on chemical reactions found early on in most general chemistry texts

^†Asistant Professor of Chemistry, Drew University: author to whom correspondence should be addressed.

Author Table

General Chemistry Organic Chemistry

Environmental Chemistry Liberal Arts Chemistry

Analytical Chemistry Upper Level Chemistry

Contact Professor Mary-Ann Pearsall with feedback on her lab modules at mpearsal@drew.drew.edu