Imagine you have a membrane through which oxygen can diffuse with a diffusion coefficient D = 5x10-10 m2/s. The concentration of O2 on one side of the membrane is 5x1022 atoms/m3, and on the other side it is 3.5x1022 atoms/m3. If the membrane is 2.5x10-9 m thick, what is the diffusive flux of oxygen J?

3.0x10²¹ atoms/m². s

Explanation:

The diffusive flux is the rate at the diffusion happens and can be calculated by:

J = D*ΔC/e

Where D is the diffusion coefficient, ΔC is the concentration variation and e is the membrane thickness, so:

J = 5x10⁻¹⁰m²/s x (5x10²² - 3.5x10²²) atoms/m³ / (2.5x10⁻⁹m)

J = 3.0x10²¹ atoms/m². s