1.2. Interphase Mass Transfer – Flux and Mass Transfer Resistance

Try these first

1. 1.

   What is flux in the context of mass transfer?

   Hint

   Think about what quantity represents movement across an area.

2. 2.

   Define Fick's law of diffusion in simple terms.

   Hint

   Focus on the relationship between mass and concentration.

3. 3.

   What does Fick's law state?

   • Flux is unrelated to concentration
   • Flux is proportional to concentration gradient
   • Flux only applies to gases

   Hint

   Remember: Higher concentration differences mean greater flux.

4. 4.

   True or False: Higher viscosity decreases mass transfer resistance.

   • True
   • False

   Hint

   Think about how thick fluids behave.

5. 5.

   A river polluted by sewage shows a concentration of pollutant A at 5 mg/L. By applying the mass balance concept, how would you calculate the concentration at a downstream point 100m away if the mass transfer from sediments is estimated at 2 mg/L?

   Hint

   Use the concept of mass balance for transfer rates.

6. 6.

   Given that the diffusion coefficient of a substance is known to be 0.5 cm^2/s in water, calculate the flux if the concentration difference is 10 mg/m^3 over a distance of 0.1m.

   Hint

   Remember to apply the negative sign for flux directionality.