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Anonymous asked in Science & MathematicsChemistry · 12 months ago

Chemistry help - CFCs??

Explain why the effects of CFCs on the ozone layer are seasonal?

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  • 12 months ago
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    Ozone hole....

    The effect of CFC's on ozone is ONLY seasonal in places where in certain seasons there is no sunlight. Antarctica is a case in point. During the winter there is no sunlight over Antarctica and therefore, no UV light to provide the activation energy to start the process of ozone destruction. Of course, during the Antarctic winter there is little ozone production due to reduced UV light. There is also less air circulation over the southern polar region to bring in ozone from more temperate climates. This makes the ozone hole over Antarctica more problematic. The seasonal effect is less of a problem for the Arctic winter because the weather patterns over the polar region is much more active and the air is mixed to a greater degree. Therefore, any ozone hole over the north pole is less severe. As for the rest of planet Earth, the destruction of ozone by CFC's is not seasonal.

  • 12 months ago

    In the Antarctic winter, the polar vortex isolates the Antarctic stratosphere from chemicals from the outside that could slow down the destruction of ozone. However, it does take sunlight to activate the ozone-destroying reactions of chlorine on the surfaces of polar stratospheric clouds. Thus, the ozone hole develops in Antarctic springtime as the sun begins to rise in August, and the hole continues to develop through September and October. By December, the polar vortex breaks up, and air from other regions mixes in, so the ozone hole mostly disappears in summer.

  • 12 months ago

    Chlorofluorocarbons

    Examples:-CCl3F,CCl2F2,CClF3

    Those gasses can produce Cl free radicals. Those free radicals destroy the Ozone layer because of below reaction

    O3 + Cl(free radical)---------> O-CL + O2

    O-Cl -------------------> Cl(free radical) + O(free radical)

    Because of the second reaction Cl(free radicals) don't destroy and they react with ozone continuously.

  • 12 months ago

    Basically how CFCs harm the ozone is as such.

    When the suns UV rays come in contact with a CFC the chlorine atoms come loose. Then these chlorine atoms wander around the atmosphere until they meet up with an ozone molecule. The chlorine atom and one of the oxygen atoms of ozone combine, leaving behind molecular oxygen. When a free oxygen atom contacts this chlorine-oxygen compound, the two oxygen atoms combine to form molecular oxygen, and the chlorine goes off to devastate more ozone molecules.

    The reason that during some seasons the effect of this is worse than others has to due with the tilt of Earth on its axis. (I'm using the northern hemisphere as my example) During the summer the Earth is tilted towards the sun and because of this the suns UV rays are more direct and numerous (this is also why the summer is hotter). This means there is more UV rays to impact the CFCs floating around in the atmosphere. On the other hand, in winter the Earth is tilted away from the sun resulting in fewer and less intense UV rays. Not as many rays means there won't be as many CFC damaging reactions and the ozone isn't as damaged.

    Hope this helped you out!

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