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Spontaneous "back-and-forth" chemical reactions

  1. May 13, 2018 #1
    I was wondering if there is a good example of a chemical reaction cascade that reverses itself, or does a "loop" in nature outside of life?

    First thing that came to mind was water evaporating and coming back down from clouds, but that is not really a chemical reaction. Or would it be considered one?

    Thanks for any feedback.
     
  2. jcsd
  3. May 13, 2018 #2
  4. May 13, 2018 #3

    HAYAO

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    I didn't know of this, despite being a chemist. Thank you Asymptotic.
     
  5. May 14, 2018 at 12:41 AM #4
    That is totally it! Thank you!
     
  6. May 14, 2018 at 1:55 AM #5

    Borek

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    Note: it is not a real oscillator, working indefinitely. It is a process that goes from some initial state to some final state, it just doesn't go there straight, but through oscillations.
     
  7. May 14, 2018 at 10:35 AM #6
    Thanks for pointing that out Borek.

    Would there be an example of this kind of non-living oscillator that is fed by an energy source, and just keeps going? And whether this exists and can be found somewhere on Earth at all?

    Also, would it be fair to say the same thing of living organisms as they all have some form of an expiry date and are in essence are a complex form of an "oscillating mechanism"?
     
  8. May 14, 2018 at 10:45 AM #7

    Borek

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    Every oscillator that dissipates energy must stop when the available energy is all used out.

    Radio transmitter converting electric energy into radio waves. Clock that uses spring energy.
     
  9. May 14, 2018 at 10:50 AM #8
    I’m curious about the existence of any spontaneous non-living chemical events that do this on Earth.
     
    Last edited: May 14, 2018 at 12:04 PM
  10. May 14, 2018 at 12:29 PM #9

    hilbert2

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    It has to be noted that, even though the concentration of one chemical species can oscillate in some chemical reactions, the total entropy has to be monotonously increasing. This requires that the concentration of some of the chemical species participating in the reaction has to be monotonously increasing/decreasing.
     
  11. May 15, 2018 at 4:21 AM #10

    mjc123

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    "Monotonically". Unless, of course, you find chemistry boring...
     
  12. May 15, 2018 at 11:02 AM #11
  13. May 16, 2018 at 2:36 AM #12

    hilbert2

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    Oh, sorry, confused the similar terms. :p
     
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