In creating general education chemistry courses for nonscience students, a key challenge is effectively demonstrating the reliance of scientific investigations on numerical measurements. In many instances, students in such courses are often so overwhelmed by dealing with numbers they fail to connect them to the physical or chemical phenomenon being probed. One approach to solving this problem is for students to apply a quantitative scale to a material property which they are already comfortable describing qualitatively; an excellent example is color, given a common vocabulary exists to define it, several quantitative scales have been created for measuring it, and it can act as a harbinger of chemical change. This tactic has been employed, in a general education course based on the chemistry of artist's materials, to develop an experimental project for studying changes in the color of paint caused by light-induced fading. Prior to the project, preliminary experiments introduce students to the chemical nature of color and the approaches to measuring it, as well as leading them through the synthesis of lake pigments and the production of their own paint from these pigments. The project commences with students creating swatches of their paint and subsequently fading them in homemade light boxes, using either fluorescent lights or black lights. The progress of fading is monitored by periodically imaging the swatches on a flatbed scanner and extracting numerical information from these images to characterize changes in the hue, saturation and lightness of the paint. Each student is required to graph these temporal changes using Excel�, and to incorporate them in a final report explaining how well the quantitative results correlate with qualitative descriptions of the color changes observed.

Monitoring the fading of paints made from lake pigments: An experimental project for a �chemistry and art� general education course

246th National Meeting (2013)

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