Student Answers krishna-agrawala Student Chlorofluorocarbons CFC are a group of synthetic organic chemicals composed of carbon, oxygen, chlorine and fluorine.
Derivatives of this anion are explosive and must be stored at cryogenic temperatures. Ozonides for all the alkali metals are known. Ozone will also detoxify cyanides by converting them to cyanates.
This IR band is also used to detect ambient and atmospheric ozone although UV based measurements are more common.
There, unstructured absorption bands are useful for detecting high ambient concentrations of ozone, but are so weak that they do not have much practical effect. The study of ozone concentration in the atmosphere started in the s. However, even in this "layer", the ozone concentrations are only two to eight parts per million, so most of the oxygen there is dioxygen, O2, at aboutparts per million by volume.
This conversion of UV light into kinetic energy warms the stratosphere. The oxygen atoms produced in the photolysis of ozone then react back with other oxygen molecule as in the previous step to form more ozone.
The termination reaction is catalysed by the presence of certain free radicals, of which the most important are hydroxyl OHnitric oxide NO and atomic chlorine Cl and bromine Br. In the second half of the 20th Century the amount of ozone in the stratosphere was discovered to be declining, mostly because of increasing concentrations of chlorofluorocarbons CFC and similar chlorinated and brominated organic molecules.
The concern over the health effects of the decline led to the Montreal Protocolthe ban on the production of many ozone depleting chemicals and in the first and second decade of the 21st Century the beginning of the recovery of stratospheric ozone concentrations.
Ozone-oxygen cycle and Ozone depletion Importance to surface-dwelling life on Earth[ edit ] Levels of ozone at various altitudes and blocking of different bands of ultraviolet radiation.
The small unabsorbed part that remains of UV-B after passage through ozone causes sunburn in humans, and direct DNA damage in living tissues in both plants and animals. Nevertheless, enough of UV-B radiation at similar frequency reaches the ground to cause some sunburn, and these same wavelengths are also among those responsible for the production of vitamin D in humans.
Low level ozone[ edit ].The world is filled with beautiful women. They are prominetly featured in television shows, movies and magazines all the time.
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CFC and SF 6 tracer-derived age of ocean water. Chlorofluorocarbons (CFCs) are anthropogenic compounds that have been released into the atmosphere since the s in various applications such as in air-conditioning, refrigeration, blowing agents in foams, insulations and packing materials, propellants in aerosol cans, and as solvents.
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