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B2H6 formation

  1. Apr 9, 2014 #1
    2BH3(g)->B2H6(g)

    Which is true?
    a) Reaction is always spontaneous.
    b) Reaction is always non-spontaneous.
    c) Reaction is sometimes spontaneous sometimes not.
    d) Reaction is endothermic.
    e) Two of the above are true.


    I know DSsystem is negative. But I would need more information on DH to say anything else. Please help me!
     
  2. jcsd
  3. Apr 9, 2014 #2
    http://www.nist.gov/data/PDFfiles/jpcrd544.pdf [Broken]
     
    Last edited by a moderator: May 6, 2017
  4. May 9, 2014 #3
    Chestermiller, we cannot have access to these ressources in exams. We should do it without references. Can we say for sure that the reaction is exothermic since the reaction is a synthesis reaction?
     
  5. May 9, 2014 #4
    Sorry. I can't help you on this, if that is the case. Please check with Borek who is very knowledgeable.

    Chet
     
  6. May 10, 2014 #5

    Borek

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    Staff: Mentor

    No idea, which is why I have not commented earlier. Perhaps the data were given in other parts of the test?
     
  7. May 10, 2014 #6

    AGNuke

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    Gold Member

    If this is asked in test, from my experience, you just have to consider that Borane, being electron deficient molecule, tried to remove the deficit by dimerizing (making bond). Hence you could say that the change in Enthalpy is negative. However, it is difficult to say about the spontaneity all by itself, except it can be below certain temperature.

    Remember, if this is just a test, my reasoning is a valid flying guess (at least in the type of tests I gave during my college entrance preparations)
     
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