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Homework Help: Following first order rxn

  1. Feb 27, 2009 #1
    OK if we are given the following first order rxn:

    [tex]2N_2O_5 - > 4NO_2 + O_2[/tex]

    The rate constant is [tex]k[/tex]. Now how would we express the rate law for the decomposition of [tex]N_2O_5[/tex].

    [tex]- d[N_2O_5]/dt = k[N_2O_5][/tex]


    [tex]- d[N_2O_5]/dt = 2k[N_2O_5][/tex]

    I think it is the latter but I see all books use the former.zzz

    Its urgent.
  2. jcsd
  3. Feb 27, 2009 #2


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    Science Advisor
    2017 Award

    Re: Kinetics

    Well, the rate is equal to -(1/2) d[N2O5]/dt. You cannot, however, say a priori that the reaction will be first order with respect to the concentration of N2O5 without knowing the reaction mechanism.
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