Chapter 6 homework

1 and 2

3. How well does the following equation work for the compounds in Table 5.2 ()below, page 80 old version, Schwarzenbach) compared to values given in the Appendix starting on page 1202 new book, see, –log Csati,w (or page 620 old book); use a spread sheet if you like; note that for most compounds xi sat is very small but for say octanol, it is appreciable


3. A Fugacity problem (first some additional theory )

In a compartment, Ci, the rate of decay in moles m-3 year-1 for a given process, j, is

rateCi = kj[Ci]

where kj = bio degradation

photolysis
hydrolysis
oxidation
advection
etc.

rateSCi= kB[Ci]+ kP[Ci]+ kH[Ci]+ kOX[Ci]+ kA[Ci]

rateSCi = [Ci] Skj = [Ci] kT

in moles per year the total rate in a compartment of volume Vi is:

rateSTi = [Ci] kT Vi

if the system is at steady state in each compartment, the total input rate for all the compartments in moles/ year will equal the amount reacted in moles/year

I = S([Ci]kT Vi) = SZi fi kT Vi) and

I = fi S Zi kT Vi); why?

so

fi= I / S(Zi kT Vi)

Assume three compartments air, water and sediment (sed) in equilibrium with one another and a total input rate of 1000 moles/year goes into the entire system. From the following rate constant data (years-1), calculate for each compartment the fugacity, the resulting concentration (moles/m3), the total decay rate (moles/year) and the total #moles in each compartment. Use Z values and volumes from the class example. From the total decay rate, where does most of the degradation take place? where does most of the mass end up?


Rate constants (years-1)

Biodeg. Photolysis hydrolysis oxidation advection kT

Air 0 130 0 0 50 180
water 100 100 100 0 200


Sed. 0.1 0 0 0 0