Question

What is the unit of diffusion flux “J” in the Fick’s law equation?

(a) mol m^−2 s^−1

(b) mol m^2 s^−1

(c) mol m^2 s^1

(d) mol m^−2 s^1

This question was addressed to me in my homework.

My doubt stems from Molecular Diffusion topic in chapter Mass Transfer of Bioprocess Engineering

Answer 1

Right choice is (a) mol m^−2 s^−1

Explanation: J is the “diffusion flux,” of which the dimension is amount of substance per unit area per unit time, so it is expressed in such units as mol m^−2 s^−1. J measures the amount of substance that will flow through a unit area during a unit time interval.