We provide data (in EXCEL and Mathematica files) on evaporation of 91% isopropyl alcohol in six different Petri dishes and one conical funnel and on evaporation of water in one Petri dish. We ask students to develop a mathematical model for the rate of evaporation for the alcohol mixture and the water, i.e. how much volume per unit of time over a given patch of surface area is lost. We suggest several differential equation models along with some elementary geometry to model the rate of evaporation in simple cylindrical configuration (Petri dish) and a more complex conical funnel situation. Finally, we seek to back out the rate of evaporation of pure isopropyl alcohol from information produced on rates of evaporation for the 91% isopropyl alcohol mixture and the rate of evaporation of pure water.
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