Ultraviolet radiation ozone balance

H. 10 An important role of stratospheric ozone, Os, is to remove damaging ultraviolet radiation from sunlight. One result is the eventual dissociation of gaseous ozone into molecular oxygen gas. Write a balanced equation for the dissociation reaction. 

Reactions 1 to 4 are known collectively as the Chapman mechanism (first outlined by Sidney Chapman (1) in 1930. They basically explain how ozone can exist in the stratosphere in a dynamic balance it is continuously being produced by the action of solar ultraviolet radiation on oxygen molecules and destroyed by several natural chemical processes in the atmosphere. 

Ozone combined with ultraviolet radiation (A, = 254 nm) has been shown to oxidize atrazine in water. The process can be used to oxidize different organic compounds such as volatile organochlorine substances (e.g., pesticides). Mass transfer and kinetic data have been applied to the mass balance equations of atrazine to obtain corresponding concentrations under varying... 

Considerable research was done on the application of an ozone-producing lamp for domestic refrigerators. It was necessary to find a balance between the amount of ultraviolet radiation and ozone so that mold and bacteria on the food and refrigerator wall would be destroyed, while the level of food odors and the transfer of food odors to other foods would be greatly reduced without causing reactions in certain sensitive foods. 

Convection ceases at the tropopause level, and the temperature in the stratosphere and mesosphere is determined strictly by radiation balance. At altitudes above 20 km the absorption of solar ultraviolet radiation becomes increasingly important. The temperature peak at the stratopause has its origin in the absorption of near-ultraviolet radiation by stratospheric ozone. In fact, the existence of the ozone layer is in itself a consequence of the ultraviolet (UV) irradiation of the atmosphere. The enormous temperature increase in the thermosphere is due to the absorption of extremely shortwaved and thus energetic radiation coupled with the tenuity of the atmosphere, which prevents an effective removal of heat by thermal radiation. Instead, the heat must be carried downward by conduction toward denser layers of the atmosphere, where H20 and C02 are sufficiently abundant to permit the excess energy to be radiated into space. 

Figure 1.3 Ultraviolet radiation from the Sun causes some oxygen gas (O2) to break into individual particles of oxygen (0). These individual particles combine with oxygen gas (O2) to form ozone (O3). Explain why there is a balance between oxygen gas and ozone levels in the stratosphere. 

The research of Paul J. Crutzen has been mainly concerned with the role of chemistry in climate and biogeochemistry, and in particular the photochemistry of ozone in the stratosphere and troposphere. In 1970 he hypothesized that natural ozone production by the action of solar ultraviolet radiation on molecular oxygen (O2) is mainly balanced by destraction processes, involving NO and NO2 as catalysts. These catalysts in turn result from the oxidation of N2O, a product of microbiological nitrogen conversion in soils and waters. He and Prof. Harold Johnston of the University of California, Berkeley, pointed out that NO emissions from large fleets of supersonic aircraft could cause substantial ozone losses in the stratosphere. 

Ozone plays a vital role in protecting life on Earth because it absorbs potentially harmful ultraviolet radiation and also helps to maintain a heat balance in the atmosphere. For a discussion of some ozone-producing and ozone-destroying reactions occurring in the atmosphere, and the impact made by human activities, go to the Focus On feature for Chapter 22, The Ozone Layer and Its Environmental Role, on the MasteringChemistry site. 

Stratospheric ozone is in a dynamic equilibrium with a balance between the chemical processes of formation and destruchon. The primary components in this balance are ultraviolet (UV) solar radiation, oxygen molecules (O2), and oxygen atoms (O) and may be represented by the following reactions ... 

Earth s ozone layer plays a critical role in protecting Earth s surface from the Sun s harmful ultraviolet (UV) radiation. Every ozone molecule, which consists of three oxygen atoms, has the abihty to absorb a certain amount of UV radiation. Under normal circumstances, the ozone layer, which is located in the stratosphere between 15 and 50 kilometers (9 and 31 miles) above Earth, remains in a continuous balance between natural processes that both produce and destroy ozone. 

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