Studiot

I couldn't find that problem in my rather old B, S & L (1960 edition) do you have a page number? And has the reference system changed? You seem to have the problem in both chapters 18 and 19. It would seem more appropriate to my 18.

I know I said before that the rate of solution of C is greater than the rate of solution of A but in fact it should have been greater than or equal to and you can take the equality to obtain an equation for part (1) since the rate of solution of A then = rate of diffusion of C into the liquid

I remember my Chem Eng flatmate getting a First back then. He used to go everywhere muttering

Input = Output plus Accumulation

For (2) the accumulation (of the sphere of A) is negative.