A significant issue facing many small chemistry departments is a lack of instrumentation for lab courses. While many labs in introductory courses do not require advanced equipment, traditionally high enrollment in these courses can exacerbate this problem for those experiments that do require some form of instrumentation. One such experiment common in freshman labs is a demonstration of Beer’s Law by graphing the absorption of a solution with an increasing concentration of a colored compound, CoCl2 in our case. To quantify this measurement and track the absorbance, a colorimeter or spectrometer is needed, which would normally cost at least a few hundred dollars for an educational model. Using a 3D printer, we were able to create a reliable and extremely portable colorimeter for under ten dollars (see figure with top removed for clarity). This cost-effective device relies on an LED for a light source, as well as another LED connected to a multimeter as a detector. The 3D printer was used to create a holder for these LEDs as well as a slot for a cuvette, while a resistor, banana socket, and several screws were the only other pieces used. During the lab, instead of recording absorbance, students recorded the voltage produced by the detector LED. The students then calculated the percent transmission and then the absorbance. This seemingly unsophisticated arrangement turned out to be beneficial because it required the students to demonstrate a greater understanding of the concepts in the lab, as opposed to simply writing down numbers.

3D printed colorimeters for use in the freshman chemistry lab

249th National Meeting (2015)

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