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2BH3(g)->B2H6(g) reaction help

  1. Feb 15, 2014 #1

    Which is true?
    a)The reaction is always non spontaneous.
    b) The reaction is always spontaneous.
    c) The reaction is sometimes spontaneous and sometimes not.
    d)The reaction is endothermic.
    e) two of the statements are right.

    I know that deltaSsystem is negative. (Less gas molecules formed)
    How do I do the rest?!!!
  2. jcsd
  3. Feb 17, 2014 #2


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    You're on the right track thinking about the ΔS of the reaction. But there is another quantity, related to ΔS that tells you whether a reaction is spontaneous or not. What is that quantity and what other information do you need to calculate it?
  4. May 9, 2014 #3
    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


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    If I had to guess, I would guess the reaction would be exothermic because it involves forming new bonds (almost always exothermic) without having to break any existing bonds. However, diborane is a sufficiently weird compound that I would not trust that inutition without looking up the heats of formation.
  6. May 10, 2014 #5


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