5. Equations for Chemical Mass in Liquid System

Try these first

1. 1.

   Define mass balance in terms of chemical systems.

   Hint

   Think about how you account for resources in a closed system.

2. 2.

   What does porosity refer to?

   Hint

   Consider what allows water to pass through soil.

3. 3.

   What does the term 'mass balance' refer to in sediment systems?

   • Tracking mass over time
   • Chemical reaction rates
   • Solid volume measurements

   Hint

   Consider how flow can impact mass tracking.

4. 4.

   True or False: Effective diffusivity is the same as regular diffusivity.

   • True
   • False

   Hint

   Think about why diffusion might slow down in porous media.

5. 5.

   Consider a hypothetical sediment system with a high porosity of 0.5 and a diffusivity of 1 × 10^-5 m²/s. Calculate the effective diffusivity using Millington-Quirk's equation.

   Hint

   Use the formula correctly, remembering to calculate φ raised to the power.

6. 6.

   Construct a mass balance equation for a contaminated river sediment. Assume the sediment has 10% saturation with a contaminant concentration of 200 mg/L and assess the risk of leaching.

   Hint

   Pay attention to how leaching would be calculated in your mass balance.