Question

Molar flux consist of ______________

(a) Molar flux = partial flux + diffusion

(b) Total flux = bulk motion + diffusion

(c) Molar flux = solid motion + flow rate

(d) Total flux = partial flux + flow rate

This question was addressed to me during an online interview.

My question is from External Mass Transfer topic in section Heterogenous Reactions of Bioprocess Engineering

Answer 1

The correct option is (b) Total flux = bulk motion + diffusion

The best explanation: Molar flux consists of two parts:

– Bulk motion of the fluid, BA

– Molecular diffusion flux relative to the bulk motion of the fluid produced by a concentration gradient, JA

– WA = BA + JA (total flux = bulk motion + diffusion).