A Modular Laser Apparatus for Polarimetry, Nephelometry, and Fluorimetry in General Chemistry

In most chemistry departments general chemistry students are the widest audience for engaging public understanding of the wonders and importance of the discipline of chemistry. Use of lasers for medical, commercial, and scientific purposes has increased, yet students often have to wait until upper-level courses to gain experience with lasers. We present an apparatus suitable for multiple uses in the general chemistry laboratory including polarimetry, fluorescence, and nephelometry. The main advantage of the instrument is its modular nature; the students assemble the instrument themselves for each laboratory exercise, thereby developing an understanding of the apparatus and the measurements made using the device. The open design of the instrument also decreases the chance that students will contract the "black-box syndrome" that seems to develop when using instruments that only provide the final data in an experiment without showing how the measurements are obtained. This apparatus is well suited for use in organic, biochemistry, and physical chemistry classes. In addition, we present suitable experiments adapted for the instrument: determination of the kinetics of acid-catalyzed hydrolysis of sucrose, determination of sulfate ion concentration in tap water using nephelometry, and fluorescence-probed kinetics of protein denaturation.