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A simple method for measuring ground-level ozone in the atmosphere
Knudsen, G., Seeley, S. K., Seeley, J. V., Bull, A. W., Fehir, R. J., & Cornwall, S. (2005). A simple method for measuring ground-level ozone in the atmosphere. Journal of Chemical Education, 82(2), 282. https://doi.org/10.1021/ed082p282
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.
