9351010 Velbel A suite of microscopes equipped with thermal stages is being used to develop and calibrate a simple, innovative laboratory activity on the temperature dependence (Arrhenius activation energy) of mineral-solution reactions. The exercise is enabling students in undergraduate mineralology/geochemistry courses to directly measure reaction rates at various temperatures while simultaneously allowing them to observe the evolution of grain-surface morphology during the reaction. This is greatly improving student understanding of several basic principles of chemical kinetics directly relevant to the geological sciences, including diffusion, the temperature dependance of reaction rates, and the relationship between rate-limiting mechanisms and crystal-surface morphology. The lab exercise is generating dynamic (real-time) geochemical rate data which students then are using to augment traditional quantitative homework exercises. Furthermore, the equipment is being used to calibrate a technologically much less complicated version of the exercise. Any geology department with microscopes, hot plates, beakers, thermometers, and stopwatches can perform the same exercise without the necessity of massive investments in dedicated equipment. ***y
