Meteo 532 Atmospheric Chemistry

Problem set #2

assigned: 27 September, 2002

due: 4 October, 2002

The following web-sites will give you the information you need for rate coefficients. You can download the JPL kinetics data. Please be sure to get the full document (12) as well as the revisions (13).

http://jpldataeval.jpl.nasa.gov

http://kinetics.nist.gov/index.php

I recommend that you use the JPL data for most problems.

In Finlayson-Pitts and Pitts, the answers to some of the problems are in the back of the book. Therefore, please be sure to show all of your work.

1. Finlayson-Pitts and Pitts, Chapter 3, problem 1, for State College, PA.

2. Finlayson-Pitts and Pitts, Chapter 3, problem 6, for CH₃ OOH.

3. Finlayson-Pitts and Pitts, Chapter 4, problem 1.

4. Finlayson-Pitts and Pitts, Chapter 4, problem 6. Do the same calculations for the upper troposphere at 12 km altitude and 40^o N latitude in June, where the water vapor mixing ratio is ~200 ppm. One source for the approximate temperature and pressure at 12 km is at: ftp://nssdcftp.gsfc.nasa.gov/models/atmospheric/cira/cira86ascii .

5. Exothermic and endothermic reactions. The enthalpy table is in an appendix in Finlayson-Pitts and Pitts.

a. Calculate the enthalpy change for each of the following reactions. State if the reaction is exothermic or endothermic.

i.) O + H₂O -> 2OH

ii.) O(¹D) + H₂O -> 2OH

iii.) O₃ + C₂H₆ -> C₂H₅ + OH + O₂

iv.) Cl + C₂H₆ -> C₂H₅ + HCl

v.) OH + C₂H₆ -> C₂H₅ + H₂O

vi.) NO₂ + O₃ -> NO₃ + O₂

b. By ranking the reactions by their reaction rate coefficients at 298 K, show that greater exothermicities do not mean faster reaction rate coefficients.