ozone molecule

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Today's Discussion1. Ozone in our EnvironmentOzone LayerGood Versus Bad Ozone2. Commercial Ozone Lightning In A BoxIndustry Uses of OzoneAquarium UsesEquipmentAir PreparationOzone GeneratorContact EquipmentMonitors. 1st AQUALITY Symposium, April 2 - 7, 2004, Oceanario de Lisboa, Portugal.

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4. Ozone Molecule C. F. Shoenbein, 1840 “Research on the nature of the odor in certain chemical reaction” Pungent-smelling molecule “ozone” ozein = to smell In 1840 Shoenbein reported to the Academy of sciences in Paris about the specific odor in certain chemical reactions. He was unable to determine the structure and origin of the chemical species causing that odor. But he named the mysterious pungent-smelling molecule “ozone”. Ozein in Greek mean “to smell”. A few years later Soret identified the compound as just another type of oxygen, trioxygen. The molecule of the ozone bounds 3 oxygen atoms. It is a pale blue gas and you probably have smelled it during a thunderstorm when lightning form ozone in the air. In 1840 Shoenbein reported to the Academy of sciences in Paris about the specific odor in certain chemical reactions. He was unable to determine the structure and origin of the chemical species causing that odor. But he named the mysterious pungent-smelling molecule “ozone”. Ozein in Greek mean “to smell”. A few years later Soret identified the compound as just another type of oxygen, trioxygen. The molecule of the ozone bounds 3 oxygen atoms. It is a pale blue gas and you probably have smelled it during a thunderstorm when lightning form ozone in the air.

6. Photolytic Formation O2 + h? ? O + O Ozone is created in the middle to upper stratosphere when highly energetic solar radiation hits molecules of oxygen and splits apart the two oxygen atoms. Chemical processes involving light are known as photolysis. The freed oxygen atoms have excess energy and are therefore unstable and highly reactive. In about 2 ms they react with another oxygen molecules and form ozone. Ozone is created in the middle to upper stratosphere when highly energetic solar radiation hits molecules of oxygen and splits apart the two oxygen atoms. Chemical processes involving light are known as photolysis. The freed oxygen atoms have excess energy and are therefore unstable and highly reactive. In about 2 ms they react with another oxygen molecules and form ozone.

7. UV Absorption Once created, the ozone molecule spends most of its lifetime protecting us from the UV radiation by absorbing it. Hit by energetic UV radiation, the ozone photo-dissociates to atomic and molecular oxygen. The oxygen atom may then quickly re-combine with another oxygen molecule to re-form the ozone. In this way the energy of the UV radiation is transformed to heat, and prevented from reaching the earth. Once created, the ozone molecule spends most of its lifetime protecting us from the UV radiation by absorbing it. Hit by energetic UV radiation, the ozone photo-dissociates to atomic and molecular oxygen. The oxygen atom may then quickly re-combine with another oxygen molecule to re-form the ozone. In this way the energy of the UV radiation is transformed to heat, and prevented from reaching the earth.

8. Vertical Distribution Ozone resides in the lower part of the atmosphere. Ozone resides in the lower part of the atmosphere.

9. Concentration … forms a slab 3 mm thick, just 2 stacked pennies. You see how tremendously efficient job this little amount of ozone is doing. These 3 mm thickness correspond to 300 DU. So, we may say that Dobson unit is a measure of the thickness of the ozone layer. … forms a slab 3 mm thick, just 2 stacked pennies. You see how tremendously efficient job this little amount of ozone is doing. These 3 mm thickness correspond to 300 DU. So, we may say that Dobson unit is a measure of the thickness of the ozone layer.

10. Ozone Loss Total stratospheric loading of ozone-depleting substances is expected to maximize before the year 2000. All other things being equal, the current ozone losses (relative to the values observed in the 1970s) would be close to the maximum. These are: about 6% at Northern Hemisphere midlatitudes in winter/spring; about 3% at Northern Hemisphere midlatitudes in summer/fall; about 5% at Southern Hemisphere midlatitudes on a year-round basis; about 50% in the Antarctic spring; and about 15% in the Arctic spring. Total stratospheric loading of ozone-depleting substances is expected to maximize before the year 2000. All other things being equal, the current ozone losses (relative to the values observed in the 1970s) would be close to the maximum. These are: about 6% at Northern Hemisphere midlatitudes in winter/spring; about 3% at Northern Hemisphere midlatitudes in summer/fall; about 5% at Southern Hemisphere midlatitudes on a year-round basis; about 50% in the Antarctic spring; and about 15% in the Arctic spring.

11. Ozone Variations? Solar radiation; The ozone concentration varies significantly around the average value of 300 DU. Changes up to 25 % can be observed. The reasons? Everything that can change the rates of production and destruction processes. The first we can thick of are, of course, any natural changes in the solar radiation. This could be either seasonal, or diurnal changes. This could be the change of solar activity every 11 years, which may boost the ozone production by about 3%. Next, changes in the atmospheric circulation will redistribute the ozone differently. Finally, all additional sources of reactive radicals would change the rates of the catalytic cycles. One natural cause for that are volcano eruptions, which put a lot of hydrochloric acid into the stratosphere. The ozone concentration varies significantly around the average value of 300 DU. Changes up to 25 % can be observed. The reasons? Everything that can change the rates of production and destruction processes. The first we can thick of are, of course, any natural changes in the solar radiation. This could be either seasonal, or diurnal changes. This could be the change of solar activity every 11 years, which may boost the ozone production by about 3%. Next, changes in the atmospheric circulation will redistribute the ozone differently. Finally, all additional sources of reactive radicals would change the rates of the catalytic cycles. One natural cause for that are volcano eruptions, which put a lot of hydrochloric acid into the stratosphere.

12. “BAD OZONE” Surface Ozone Surface ozone can irritate the respiratory tract, cause chest pain and persistent cough, affect the ability to take a deep breath, and an increase susceptibility to lung infection. Ozone can also damage trees and plants and reduce visibility. Motor vehicles and industries are major sources of ground-level ozone. Ground-level ozone comes from the oxidation (breakdown) of VOCs found in solvents. It is also a product of reactions between chemicals produced by burning coal, gasoline, and other fuels and chemicals found in paints and hair sprays. Oxidation occurs readily during hot weather. Surface ozone can irritate the respiratory tract, cause chest pain and persistent cough, affect the ability to take a deep breath, and an increase susceptibility to lung infection. Ozone can also damage trees and plants and reduce visibility. Motor vehicles and industries are major sources of ground-level ozone. Ground-level ozone comes from the oxidation (breakdown) of VOCs found in solvents. It is also a product of reactions between chemicals produced by burning coal, gasoline, and other fuels and chemicals found in paints and hair sprays. Oxidation occurs readily during hot weather.

13. Catalytic Destruction Ozone is destroyed by catalytic cycles, proceeding in the stratosphere and involving trace chemicals. Let consider the typical form of such a catalytic cycle involving Cl radical: Reactive atomic chlorine bumps into an ozone molecule forming chlorine monoxide. The chlorine oxide then react with atomic oxygen releasing the chlorine and forming oxygen. The net result of this reactions concerns the oxygen species only. The chlorine atom mediates the outcome of these reactions, and re-forms itself. So, chlorine atom is a catalyst, and the set of reaction is catalytic cycle. Such a catalytic cycle is quite effective: one chlorine atom emerges at the end unchanged and ready to take a part in another cycle again, destroying 1000 ozone molecules before it is removed from the stratosphere. The chlorine atom here can be replaced with other reactive radicals, playing the role of catalysts. Ozone is destroyed by catalytic cycles, proceeding in the stratosphere and involving trace chemicals. Let consider the typical form of such a catalytic cycle involving Cl radical: Reactive atomic chlorine bumps into an ozone molecule forming chlorine monoxide. The chlorine oxide then react with atomic oxygen releasing the chlorine and forming oxygen. The net result of this reactions concerns the oxygen species only. The chlorine atom mediates the outcome of these reactions, and re-forms itself. So, chlorine atom is a catalyst, and the set of reaction is catalytic cycle. Such a catalytic cycle is quite effective: one chlorine atom emerges at the end unchanged and ready to take a part in another cycle again, destroying 1000 ozone molecules before it is removed from the stratosphere. The chlorine atom here can be replaced with other reactive radicals, playing the role of catalysts.

19. A decrease in the primary production of the ocean will affect all higher trophic levels. A decrease in the primary production of the ocean will affect all higher trophic levels.

25. Simplex and Duplex Series

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