This extreme stability allows cfcs to slowly make their way into the stratosphere most molecules decompose before they can cross into the stratosphere from the troposphere. Ib chemistryenvironmental chemistry wikibooks, open. Protecting the ozone layer department of the environment. National aeronautics and the ozone hole space administratio n. The chemistry by which cfcs break down ozone is an extremely complicated process. Sherwood rowland, mario molina rowlands postdoc at the time, and paul crutzen and in 1995 they received the nobel prize for their work. Basic ozone layer science ozone layer protection us epa. Ozone depletion consists of two related events observed since the late 1970s. Humans have introduced gases and chemicals into the atmosphere that have rapidly depleted the ozone layer in the last century. Over the last 30 years manmade cfcs have been the main cause of stratospheric ozone depletion. The lower most atmospheric layer is troposphere extending upto 8 to 10 km at poles and 16 to 18 km at equator. The latter phenomenon is referred to as the ozone hole. The ozone layer flashcards in a level and ib chemistry.
Publications about the ozone depletion theory of global. Models of stratospheric chemistry have been primarily directed toward an understanding of the behavior of stratospheric ozone. It was only until recently, 1990s in fact, that the chemistry of ozone creation and destruction was developed by f. Delocalizationof electron resonance structuresozone resonance structure 1 resonance structure 2 resonance hybrid all bond oo are identical in length strength hybrid of 2 resonance structure no oo single or oo double bonds found only o o bond intermediate in character bet single and double bond. Effects of ozone depletion ozone depletion is affecting the human health and environment negatively, as it allows the penetration of uv radiations to reach the earth. This depletion makes humans more vulnerable to the uvb rays which are known to cause skin cancer as well as other genetic deformities.
The ozone layer is a region of the atmosphere where there is an equilibrium between molecular oxygen and ozone gases. Ib chemistry on resonance, delocalization and ozone destruction slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Causes of ozone depletion source impact cfcs the increase in the size of the hole in the ozone layer is directly linked to increased production of cfcs since the 1950s in aerosols, plastic foam, fast food packaging and. Application of ozone in water treatment was performed in 1893 in holland. Ozone depletion in the stratosphere biology discussion.
Air pollution not only harms buildings and plant life, but it negatively impacts human health as well. Ozone depletion and industrial output ozone depletion and industrial output for years, we have heard about the ozone crisis. For more information about legal and policy issues, see the books by benedick and litvin, and the following web sites. The thinning of the ozone layer has increased the risk that australians already face from overexposure to. The natural distribution of ozone around the earth is. Companies are finding substitutes for cfcs, and people in general are becoming more awareness of the dangers of ozone layer depletion.
The energy required to promote one of the double bond electrons in oxygen, making a diradical, is considerably higher that the corresponding energy required to promote an electron in. Causes of ozone layer depletion and its effects on human. The ozone layer prevents most ultraviolet uv and other highenergy radiation from penetrating to the earths surface but does. Chemistry of ozone depletion fire protection association nz. Ozone depletion is largely a result of manmade substances. To acquire the knowledge of terms, concepts, processes, techniques and principles related to the subject. Ozone in the ozone layer is formed by the action of solar ultraviolet light on oxygen. The ozone depletion potential odp of a chemical compound is the relative amount of degradation to the ozone layer it can cause, with trichlorofluoromethane r11 or cfc11 being fixed at an odp of 1. To help foster a continued interaction, this component of the scientific assessment of ozone depletion. Ozone layer depletion is one of the major environmental issues which is getting thinner day by day as a result of increasing pollution. List of books and articles about ozone layer online. Scientific assessment of ozone depletion 2006 twenty. Ozone depletion potential an overview sciencedirect topics. These processes regulate a balance of ozone and form the ozone layer.
From wikibooks, open books for an open world chemistry and impacts on free shipping on qualified orders. Pdf causes of ozone layer depletion and its effects on. Cfcs are highly reactive and so will react violently with ozone which is dangerous. International baccalaureate chemistry, an interactive ib syllabus.
Ozone depletion also explains much of the observed reduction in stratospheric and upper tropospheric temperatures. Depletion of this layer by ozone depleting substances ods will lead to higher uvb levels, which in turn will cause increased skin cancers and cataracts and potential damage. Ozone can be produced in the lab using a machine called an ozonator. The first manmade threat to the ozone layer was noted by harold johnston 1971. Though generally thought of as an urban dilemma, it poses a health threat in rural areas as well. Initially this interest reflected the diagnostic role of ozone in the understanding of atmospheric transport processes.
Destruction of the upper atmospheric layer of ozone gas, caused by substances formed from breakdown of ozone depleting substances. Ozone depletion is the process of destruction of the ozone layer which can cause adverse effects on the living forms by many pollutants releases out from the vehicles, industries etc. Depletion of stratospheric ozone o3, as commonly known as the hole in the ozone layer, is an issue of international concern. The concept of ozone depletion potential odp is widely used wuebbles et al. This was also the start of intensive research into the chemistry of the atmosphere. The ozone layer is a specific area in the stratosphere of maximum ozone concentration.
Ground level ozone is a irritant its an oxidand and bad for lungs and eyes. If you continue browsing the site, you agree to the use of cookies on this website. As a result, there has been a general thinning of the ozone layer over most of the globe, including between five to nine per cent depletion over australia since the 1960s. The most commonly known ozone depletion chemicals odcs are the cfcs or chlorofluorocarbons. They break through the ozone layer and might get to outer space. Ib chemistry on resonance, delocalization and ozone. The ozone layer lies approximately 1540 kilometers 1025 miles above the earths surface, in the stratosphere. The ozone depletion was analyzed by our top scientists in our research and development lab. The problem is worsened as cfcs are a primary cause of the damage and they remain in the stratosphere for up to 100 years. From wikibooks, open books for an open world ib chemistry. To acquire skills in proper handling of apparatus and chemicals. The ozone layer is essential for complex living organisms like you and me to exist. Timeline of stratospheric ozone depletion and observations.
Cfc molecules are made up of chlorine, fluorine and carbon atoms and are extremely stable. These radiations can cause severe diseases in humans such as skin cancer, eye damage and genetic mutations etc 9. Ozone o 3 is present in stratosphere and, therefore, stratosphere is also called as ozonosphere it is rich layer of ozone that absorbs 9990 harmful ultraviolet radiations from the sun. The questions address the nature of atmospheric ozone, the chemicals that cause ozone depletion, how global and polar ozone depletion occur, and what could lie ahead for the ozone layer.
Chlorodifluoromethane r22, for example, has an odp of 0. Chemistry equations for ozone depletion the student room. Besides carbon dioxide, other greenhouse gases are methane, water vapour, nitrous oxide, cfcs and ozone. This ozone is passed through a solution of the alkene, first producing an ozonide. The questions address the nature of atmospheric ozone, the chemicals that cause ozone depletion, how global and polar ozone depletion occur, and what. Clean air, healthy children teachers guide and activities. Ozone depletion over india with so much worry about the rapid ozone depletion taking place in various parts of the earth, indian scientists are closely monitoring the ozone layer over india for possible depletion trends. Some chemicals, particularly cfcs, destroy ozone in the upper atmosphere. Most ozone is found in the stratosphere upper part of the atmosphere, more than 10 to 16 kms from the surface of the earth. When highenergy ultraviolet rays uvc strike an oxygen molecule o.
Environmental chemistry 401 carbon dioxide crosses the delicate proportion of 0. Solomon and albritton, 1992 as a measure of the effectiveness of a given compound in removing ozone, relative to a standard compound, which is taken to be cfc11. Without the ozone layer, all but very simple life forms would be destroyed by the action of ultraviolet light. Publications about the ozone depletion theory of global warming. Cfcs however, are not the only ozonedepleting chemicals. Ozone in the stratosphere forms naturally and protects us from damage that can be caused by solar radiation such as skin cancer. Chemistry of the ozone layer there are natural processes that create and destroy ozone in the stratosphere. Choose from 500 different sets of ozone depletion biology flashcards on quizlet. Environmental chemistry video centering on the information needed for the ib chemistry sl paper 3 on the topics of ozone depletion and dissolved oxygen in water. Carbon dioxide is the major contributor to global warming. Harmful radiation from the sun can reach the earths surface. The presence of small amounts of ozone in the upper atmosphere is necessary for human health.
At last, the montreal protocol has resulted in stopping additional ozone loss and investigated by 300 experts ver 4 years survey on ozone depletion earth day was first observed on 22 april 1970. Ib chemistry on resonance, delocalization and ozone destruction 1. The earths ozone layer ozone layerthe region of the stratosphere containing the bulk of atmospheric ozone. Once there they react with ozone and in the long term can lead to the depletion of ozone. Since that time, its use has spread in europe and the us due to its strong oxidizing properties, ozone is currently known as one of the most efficient and fastest microbicides breaks the cell membrane resulting in. The next layer is stratosphere extending from troposphere upto a height of 50 to 55 km. The answers are updates of those first presented in the previous ozone assessment, scientific assessment of ozone depletion. Cfc 11, or r11 has the maximum potential amongst chlorocarbons because of the presence of three chlorine atoms in the molecule.
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