0:00 When is it equimolar?
1:12 Shape of gradient
2:28 Example
This video explains the special case equimolar counter diffusion (in one dimension) and solves one simple example. Also explains what the concentration gradient looks like.
NOTE! If you integrate N_A=-D/delta dC_A/dz from point 1 to 2 you get N_A = -D/delta(C_A2 - C_A1). If you instead integrate from point 2 to point 1 you get N_A = D/delta(C_A2 - C_A1). The direction of the integration is the positive direction of mass transfer. A negative result means that mass transfer goes in the other direction.
