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Why is CN stable in low pressure but unstable otherwise?

  1. Aug 28, 2015 #1
    Here's the question:
    The CN molecule has been observed spectroscopically in comets where pressure has been estimated to be as low as 10–10 mm Hg. Draw a Lewis structure for CN. Suggest an explanation as to why this species can persist in a comet but is unstable under normal terrestrial conditions.

    The only progress I could make was to realize that CN is a free radical since it has 1 unpaired valence electron. And if I understand the question correctly, CN is stable under conditions of extremely low pressure but unstable at normal conditions of higher pressure, and its asking why this is, and I'm kind of clueless. Please help! Thanks.
     
  2. jcsd
  3. Aug 28, 2015 #2

    Bystander

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    ... and, what happens to free radicals at higher pressures? Think about collision frequencies, kinetic theory of gases, mean free path ....
     
  4. Aug 28, 2015 #3
    They're unstable at higher pressures?
     
  5. Aug 28, 2015 #4

    Bystander

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    What do unpaired electrons do?
     
  6. Aug 28, 2015 #5
    well, the atom with an unpaired electron would be highly reactive
     
  7. Aug 29, 2015 #6

    Borek

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    Why do you stop here? Try to draw conclusions from what you just wrote and from what Bystander wrote in the post #2.
     
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