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2005
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February
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In the Laboratory
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A Simple Method for Measuring Ground-Level Ozone in the Atmosphere
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John V. Seeley, Arthur W. Bull, Richard J. Fehir, Jr., and Susan Cornwall
Department of Chemistry, Oakland University, Rochester, MI 48309
Gabriel A. Knudsen and Stacy K. Seeley
Department of Science and Mathematics, Kettering University, Flint, MI 48504
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February 2005
Vol. 82 No. 2
p. 282
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| Abstract |
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A standard method for measuring the ozone concentration in the lower atmosphere has been adapted for high school and college chemistry students. A simple sampling apparatus is used to bubble air through a buffered potassium iodide solution. Atmospheric ozone oxidizes iodide to produce triiodide. At the end of the sampling period, starch is added to the buffered KI solution to form a violet-colored complex with triiodide. The concentration of the complex is determined with an inexpensive homemade photometer by measuring the absorption of green light. Atmospheric ozone concentration is calculated from the volume of air sampled and the triiodide concentration. Ozone levels determined with this method agree with concentrations reported from nearby monitoring stations. This laboratory experiment applies several different fundamental concepts including oxidation–reduction chemistry, the ideal gas law, and spectroscopic analysis. In addition, students are provided with unique experiences in constructing simple instrumentation and collecting environmental samples.
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| Supplement |
Detailed documentation for the experiment is available. The documentation is divided into three sections. The first section, entitled Required Solutions and Apparatus, describes the materials and apparatus used to measure ground-level ozone. These items can be prepared by either the instructor or students. The next section, entitled Experimental Protocol, provides step-by-step instructions for making an ozone measurement. The steps are normally executed by students. The final section, entitled High School Activity, describes an adaptation of the measurement protocol that is suitable for use in a high school setting.
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 Contents |
JCE2005p0282W.doc (Microsoft Word)
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| More Information |
Citation |
Seeley, John V.; Bull, Arthur W.; Fehir, Richard J., Jr.; Cornwall, Susan; Knudsen, Gabriel A.; Seeley, Stacy K. J. Chem. Educ. 2005 82 282.
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Keywords |
Analytical Chemistry; Atmospheric Chemistry; Instrumental Methods; Quantitative Analysis
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History |
Created:
Last Updated: |
January 4, 2005
January 12, 2005
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| Home > JCE Print > Journal of Chemical Education > Issues >
2005
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February
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282
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