A porous cylinder, 2.5 cm in diameter and 3 cm long is saturated with 60 wt% alcohol. The void space in the solid contains sufficient pores so that the molecular diffusion can take place through the liquid in the passage. The cylinder is dropped into a large, well agitated reservoir of pure water. The agitation maintains a concentration of 1 wt% alcohol at the surface of the cylinder.
a)
Determine the concentration of alcohol (wt%) at the center of the cylinder after 10 hr if the diffusion occurs radially.
b)
Calculate the concentration of alcohol (wt%) at the center of the cylinder after 10 hr if the diffusion occurs radially and axially?
с)
How long (hr) will it take for the concentration at the midpoint to reach 50% of its initial concentration? Consider radial diffusion only.

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a Radial Diffusion The diffusion equation for a cylindrical geometry can be written as partial cpartial t D partial2 cpartial r2 where c is the concen... View the full answer