Build Your Own Photometer: A Guided Inquiry Experiment to Introduce Analytical Instrumentation.
A guided inquiry project designed to teach students the basics of spectrophotometric instrumentation at the second year level is presented. Students design, build, program, and test their own single wavelength, submersible photometer using low cost light emitting diodes (LEDs) and inexpensive household items. A series of structured prelaboratory assignments guide students through the processes of researching background information, designing a photometer device, and developing their own procedure to test the performance of the device. Students also learn basic skills of data acquisition by programming an easy to use LabVIEW interface for their device. Using a colorimetric indicator dye, students use their photometers and LabVIEW interfaces to determine the endpoint of an acid base titration and compare the linear response of their device against that of a commercially available spectrophotometer. Students who completed the experiment indicated that the experience improved their understanding of spectrosco.