Question

A hazardous chemical was spilled into a quiescent pond. The chemical is immiscible with water and has a density of 0.9 g cm−3. A haz mat team estimated that there is a layer of the chemical on the pond surface that is 2 cm in thickness. Measurements made with a portable gas chromatograph show that the vapor film layer above the surface of this chemical layer is about 0.5 cm in thickness. The diffusivity of this chemical in air is known to be 0.03 cm2 s−1. Since the pond is in a remote location, it has been decided to just let the chemical evaporate into the air. Assuming the concentration of the chemical in the bulk air is so low that it can be neglected, estimate how many days this will take. The saturation concentration of the chemical in the air is 6.73 × 10−5 g cm−3.

Answer 1

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