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Haloalkanes and Haloarenes
Polyhalogen Compounds: Freons
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Concepts tested
- CFCs and ozone depletion
All Questions
2004 AIPMT 1 question
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Which of the following is responsible for depletion of the ozone layer in the upper strata of the atmosphere :-Freons are chlorofluorocarbons (CFCs) such as $CCl_2F_2$ (freon-12), used in refrigerators, air conditioners and aerosol sprays.
They are very stable, so they slowly diffuse unchanged into the stratosphere. There, ultraviolet radiation breaks them to give chlorine free radicals:
$CF_2Cl_2 \xrightarrow{h\nu} \dot{C}l + \dot{C}F_2Cl$
$\dot{C}l + O_3 \rightarrow Cl\dot{O} + O_2$
$Cl\dot{O} + O \rightarrow \dot{C}l + O_2$
The chlorine radical is regenerated, so one radical can destroy thousands of ozone molecules.
Ferrocene (an organometallic sandwich compound) and fullerenes (carbon allotropes) do not cause ozone depletion.
So freons are responsible for the depletion of the ozone layer.