ENST 202, 3rd homework for Rich Kamens, Due Thurs. April 15,2008
1a. Write the reactions for the formation of PAN.
1b. How does the PAN reaction pathway tie up NO2 when it is cool, or give NO2 back to
the atmosphere when it is warm?
2. Although we did not spend a lot of time on loss reactions, the formation of nitric acid
(HNO3) is consider a removal (or termination) reaction of nitrogen oxides from the
atmosphere, where:
OH + NO2 HNO3
How does this reaction slow down the formation of O3?
3. ROO behaves like HO2 in that it quickly oxidizes NO NO2.
Where do ROOs come from?
4. What is the chemical structure for ethylene?, Toluene?
5. O3 can often be calculated from the following photo-stationary steady state expression:
[O3] = [NO2]*k1/([NO]*k2)
were [O3], [NO2] and [NO] are in parts per million or ppm and k1 and 2 are reaction
rate constants
What would the predicted O3 concentration in the atmosphere be if you measured NO2 at
0. 3ppm, NO at 0.03 ppm and k1 was 0.5 min-1 and k2 was 25 ppm-1 min-1? Would you be
exceeding the ambient air quality standard for O3 if this concentration persisted for 8
hours. If so, by how much?
6. What does it mean to compile a mechanism?
7. To control O3 what two kinds of emissions can be controlled.
8. Is the formation of O3 a linear process? Why or why not?
9. In class, we used formaldehyde to represent hydrocarbons going into our
photochemical mechanism. In the class simulations, what was the effect on O3 of
reducing initial formaldehyde from 1 to 0.5 ppm. We then reduced initial NO from 0.3 to
0.1 ppm and NO2 from 0.05 to 0.02 ppm. What was the combined effect of reducing
both formaldehyde and oxides of nitrogen?