Information • Textbooks • Media • Resources Modeling Stratospheric Ozone Kinetics, Part II: Addition of Hydrogen, Nitrogen and Chlorine: OzoneModelingPartII.mcd Erica Harvey and Robert Sweeney; Department of Chemistry; Fairmont State College; Fairmont, WV 26554
Stratospheric ozone kinetics remains an active area of research for atmospheric chemists. The basic reaction cycles are well established and a regularly updated comprehensive treatment of kinetic data is available online (1). The four-step Chapman cycle of reactions involves only oxygen-containing species. Other atmospheric constituents that participate in stratospheric ozone reactions include the NOx, HOx, and ClOx molecules (NO, NO2, HO, HO2, ClO, ClO2). “Modeling Stratospheric Ozone Kinetics with Mathcad, Part II: Addition of Hydrogen, Nitrogen and Chlorine” builds on the Chapman cycle considered in the Part I (2) document to create a more realistic model of stratospheric ozone chemistry. In this document, students are asked first in a series of leading exercises to set up and solve the system of differential equations that includes the kinetics of the NOx and HOx cycles, then to
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investigate the effects of changes in the input values. Answers to the “set-up” section are given at the end of the document, which means that students wishing to investigate chemical questions and avoid modeling details can skip the setup exercises and use the ready-made template in the answers section at the end of the worksheet. In this way, the document can function either as a bridge toward independent setup of more complex models or as a stand-alone modeling template with emphasis on chemical questions about the system and the model. Necessary data are provided for addition of the environmentally important ClOx cycle of ozone-destroying reactions; incorporation of these reactions into the model serves as a mastery exercise. Literature Cited 1. Chemical Kinetics and Photochemical Data for Use in Stratospheric Modelling; Evaluation Number 12; JPL Publication 97-4; Jet Propulsion Laboratory: Pasadena, 1997; http://remus.jpl.nasa.gov/jpl97/. 2. Harvey, E.; Sweeney, R. J. Chem. Educ. 1999, 76, 1309; http:// jchemed.chem.wisc.edu/JCEWWW/Columns/McadInChem/Mcad009/.
Journal of Chemical Education • Vol. 76 No. 9 September 1999 • JChemEd.chem.wisc.edu
