Problem 3

C

Phase, a

Phase

B

C₂

Phase, a

Consider the above figure on the left, in which a species is

diffusing from phase a through a thin film of a different phase B.

The thickness of the thin film is . An approximate concentration

profile is also shown in the schematic. The diffusivity of the species

in these two phases (a and B) are Da and DB, respectively. What

will be flux (J) of the species in term of C and C₂ ? You need

other parameters to solve the problem. It is up to you to figure

them out.