This pact was led by the United States and since that agreement, the ozone hole started filling up. They have a consensus to periodically eliminate the production and consumption of primary ODS. In 1987, 27 nations signed a pact to ban the use of ozone-depleting substances (ODS). The sources of chlorine gases are given below: can destroy 100,000 molecules of ozone (O 3).The sources of chlorine-free radicals have a major role in ozone depletion. Among them, CFCs are the most abundant ones. There is a variety of gases that go into the stratosphere and release chlorine-free radicals (Cl For, example, B romochlorodifluoromethane (CF 2 ClBr) extensively used in fire extinguishers (Halon 1311) is now considered the most dangerous in this category with an ODP value of 10.Ĭhlorine source gases in the stratosphere ODS are classified as per their potential to damage the ozone. These free radicals damage the ozone O 3. Here the UV light breaks them to form chlorine (Cl) and bromine (Br) free radicals. They are relatively inert in the troposphere and get activated upon reaching the stratosphere. The chemical substances that destroy or damage ozone are termed ozone-depleting substances (ODS). CFCs can be prepared by the free radical substitution of alkanes.ĬHFCl 2 + F 2 → CF 2Cl 2 Ozone-depleting substances (ODS) of General Motors, as safer chemicals for refrigeration purposes in 1928. Synthesis of CFCsĬhlorofluorocarbons were first introduced by Thomas Midgley Jr. On the right side, there’s less ozone, so UV rays enter the atmosphere. On the left side, it shows the normal ozone layer which filters out the harmful UV rays. The normal concentration of ozone in the stratosphere is 300 dobson units. These holes allow UV rays to reach Earth’s surface, eventually causing health problems. CFCs break down ozone molecules which leads to holes in the ozone layer. It is present in the stratosphere and blocks out harmful UV rays coming from the sun that can cause skin cancer and other health problems, if not filtered right there. The ozone layer is a protective layer with a thickness of around 0.12 inches. The figure below shows the impact on ozone in 2004 over Antarctica. one single chloride, free radical can reduce up to 3 million ozone molecules. These free radicals generate more free radicals and the cycle continues. Free radical chlorine reacts with ozone to form oxygen and another free radical in the form of oxychloride radical. Here they interact with electromagnetic radiations, especially ultraviolet radiation to produce free radical chlorine (Cl Concepts Berg Chemistry of Chlorofluorocarbons (CFCs)Ĭhlorofluorocarbons (CFCs) diffuse up to the stratosphere as they are relatively inert.effects of Chlorofluorocarbons on the environment.Chlorine source gases in the stratosphere.Chemistry of Chlorofluorocarbons (CFCs).
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |