Question

To increase the overall rate of a rxn limited by internal diffusion the reaction should not ______

(a) decrease the radius R

(b) increase the concentration of A

(c) increase the radius R

(d) increase the temperature

This question was posed to me by my school principal while I was bunking the class.

This interesting question is from Internal Mass Transfer and Reaction in division Heterogenous Reactions of Bioprocess Engineering

Answer 1

Correct answer is (c) increase the radius R

The best explanation: Internal diffusion limits the observed rate when decreasing dp increases –r’A . If the rate increases when dp decreases but does not change with FT0, then larger dp is limited by internal diffusion. (where, FT0 is the particle size, dp is the diameter and –r’A is the reaction rate).