This Is the Time

Overview At any given moment, dozens of chemical reactions are taking place in the atmosphere. Some of the most common reactions involve molecules of oxygen or ozone, both of which contain oxygen atoms and are highly reactive. Breathing ozone can damage the lungs. Schoenbein paper tests for the presence of ozone in the air through a reaction between ozone and potassium iodide that produces a purple color. By making their own Schoenbein paper, students will test for ozone and the conditions that lead to its formation. A: As a result of activities in grades 5 – 8, all students should develop abilities to do scientific inquiry and understandings about scientific inquiry. Design and conduct a scientific investigation: Students should develop general abilities, such as systematic observation, making accurate measurements, and identifying and controlling variables. Science in Personal and Social Perspectives: Natural environments may contain substances (for example, radon and lead) that are harmful to human beings. Maintaining environmental health involves establishing or monitoring quality standards related to use of soil, water, and air. Time Two class periods (40 – 50 minutes) and overnight/8-hour exposure of Schoenbein Paper Materials 1 Potassium iodide (5g (one teaspoon) will be plenty) 1 Distilled water (must use distilled water) 1 Spray bottle filled with distilled water (must use distilled water) 1 Filter paper 1 Heat source (preferably a hot plate) e Identify the layers of the atmosphere. r Define ozone and locate where it can be found within the layers of the atmosphere. t Explain that the Schoenbein paper detects ozone by an oxidation reaction wit potassium iodide. u Demonstrate that by using Schoenbein paper they can determine variations in the amount of ozone present in the troposphere from day to day and from place to place. i Draw conclusions about ozone levels of the air based on test results. 1 Glass stirring rod (do not use metal) 1 Small paint brush 1 250 ml beaker 1 Glass Pyrex plate 1 Hot pad or mitt for removing the beaker from the heat source 1 8-1/2 x 11-inch paper for drying filter paper 1 Map of city or school building 1 Air tight containers 1 Scissors 1 Sealable plastic bags Vocabulary OZONE — highly reactive gas containing three atoms of oxygen Schoenbein paper —paper saturated with potassium iodide that can show the presence of ozone in the air TROPOSPHERE — area of the atmosphere from the …