4.2. Effective Diffusivity in Porous Media

Try these first

1. 1.

   Define effective diffusivity.

   Hint

   Think about how the environment might affect diffusion.

2. 2.

   What role does porosity play in diffusion?

   Hint

   Consider how a sponge might allow liquid to flow more easily.

3. 3.

   What is effective diffusivity?

   • The rate of diffusion in solids
   • The rate of diffusion in fluids
   • The rate of diffusion adjusted for interactions in porous media

   Hint

   Think about how materials interact with the medium.

4. 4.

   True or False: Higher porosity leads to a slower rate of diffusion.

   • True
   • False

   Hint

   Restrict your thoughts to space availability.

5. 5.

   A sediment column has a porosity of 0.45, and the retardation factor is calculated at 2.5. Calculate the effective diffusivity if the original diffusivity of the substance is known as 1.0 cm²/s.

   Hint

   Focus on how retardation affects the effective rate.

6. 6.

   Analyze how changes in bulk density could affect the effective diffusivity in a sediment analysis environment where porosity is altered.

   Hint

   Consider what density means for the volume available.