The activation energy of UV color changing beads (Educational Innovations, UV-750) is determined by measuring the first-order rate constant in a temperature range of 10 to 45�C. Using a tungsten lamp and a visible spectrometer with fiber optic input, the reflectance spectrum of a bead can be monitored as it decays from its excited state (color) back to the ground state (white). By fitting the natural log of the maximum absorbance value versus time, the first-order rate constant is determined. The corresponding activation energy is found by using making Arrhenius plots of the natural log of the rate constant versus 1/Temperature. This presentation demonstrates a low-cost, green alternative for measuring reaction energies.

Determining the activation energy of UV color changing beads

243rd National Meeting (2012)

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