Dynamic Reactions

Energy AnalysisEarth’s atmosphere contains 3 billion metric tons of ozone (O3).Earth’s stratospheric ozone plays a critical role in shielding us fromthe high-energy ultraviolet radiation (UV-C and most of UV-B) emitted bythe sun. Life on Earth would be much harsher for most living organismswithout this protection. Several decades ago, scientists identified ahole in the ozone. It was determined that specific synthetic chemicals,chlorofluorocarbons (CFCs), were degrading our ozone layer. Once in theatmosphere, these CFCs react to release chlorine free radicals, whichare very reactive. You can see the current status of the ozone hole at NASA’s Ozone Watch. (Links to an external site.)The natural level of ozone in the stratosphere is maintained through a dynamic equilibrium, referred to as the Chapman Cycle. Ozone forms when sunlight splits molecular oxygen (O2) into two oxygen radicals. Oxygen radicals are very reactive. Among other reactions, they can either join together to reform O2 or one can join O2 to form O3.Ozone can then react with an additional oxygen radical to reformmolecular oxygen, or it can react with sunlight to form molecular oxygenand an oxygen radical. Ozone is constantly being created and destroyedthrough these reactions within the stratosphere. This reaction withsunlight is how we are protected from the harmful UV-B and UV-C!Step 1: hv + O2 –> 2O∙Step 2: O2 + O∙ –> O3Step 3: O3 + O∙ –> 2O2orO3 + hv –> O2 + O∙However, ozone destroyed by catalyzed decomposition from chlorineradicals (and other chemicals) shifts the natural dynamic equilibrium,resulting in more high-energy light reaching Earth’s surface.Consider: Choose one (1) of the following to respond to with your initial post:Evaluate the enthalpy diagram for the catalyzed and uncatalyzeddecomposition of ozone. Identify eight accurate and significant piecesof information, explained in 1–3 paragraphs (in your own words).The rate of formation and destruction of ozone depends upon theintensity of sunlight. Comment on how ozone production varies 1) over aday and 2) over Earth’s seasons. Specifically, identify and explain therate equations for the Chapman Cycle.Using key ideas from kinetics (e.g.catalysts), and equilibrium (e.g.LeChatelier’s principle), explain why CFC usage has been banned in manycountries. Specifically, consider the balance between the Chapman Cycleand CFC destruction of ozone. Specifically state the equilibriumexpression that relates to the concentration of ozone and molecularoxygen.