2.2. Resistance in Mass Transfer

Try these first

1. 1.

   Define mass transfer resistance in your own words.

   Hint

   Think about the factors affecting pollutant transfer.

2. 2.

   What is mixing height?

   Hint

   Relate it to how pollutants would behave once released.

3. 3.

   What does mass transfer resistance refer to?

   • A barrier to energy transfer
   • A barrier to pollutant transfer
   • A type of fluid mechanics

   Hint

   Think about what limits pollutant exchange.

4. 4.

   True or False: Higher mixing heights generally result in lower pollutant concentrations at ground level.

   • True
   • False

   Hint

   Consider how pollutants spread with height.

5. 5.

   A pollutant is released into a lake. After one hour, its concentration is measured at 300 mg/L in the water. If the evaporation rate is 10 mg/L per hour, calculate the rate of accumulation and prepare the mass balance equation.

   Hint

   Remember to identify all terms in the mass balance equation.

6. 6.

   Consider a scenario where pollutant x evaporates from a still lake surface at a concentration of 200 mg/L. If the ambient air concentration is zero, and kA2 = 0.25 m/s, calculate the flux and explain its implications.

   Hint

   Identify concentration gradients as driving forces for mass transfer.