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Need help, Activation energy determination from this reaction. Is this possible?

  1. Feb 2, 2012 #1
    Need help, Activation energy determination from this reaction. Is this possible??

    i did an experiment, i noted the tempreture and found rate constant.
    My friend did the same experiment and she found rate constant and noted the tempreture.. The tempreture differs by one degree. Can i calculate tempreture like this...?

    S2O82-(aq) + 2 I-(aq) -->SO42-(aq) + I2(aq)

    Friend: K1: 0.0594 at t1: 21oC = 294 K
    Ours = K2: 0.06 and t2: 22oC. 295 K


    In (0.0594 /0.06) = Ea / 8.314 x ( 1/ 294- 1/295 )
    -0.01 = Ea / 8.31 x (1.153x10-5)
    Ea= 0.01x 8.31 / 1.153x10-5)
    Ea = 7207.28 J/mol

    = 7.207 KJ mol

    Is this possible?

    please help me!! :( So for this reaction is the Ea 7.207

    I would have done Just used my rate constant and tempreture to wwork out Ea but I dont know the Frequency factor A! I cant find this anywhere...
     
  2. jcsd
  3. Feb 2, 2012 #2

    Borek

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    Staff: Mentor

    Re: Need help, Activation energy determination from this reaction. Is this possible??

    Your approach looks perfectly sound to me. Not that I believe in the result. 1 deg C is a very low temperature difference, especially for a typical lab thermometer. Think errors/accuracy.
     
  4. Feb 2, 2012 #3
    Re: Need help, Activation energy determination from this reaction. Is this possible??

    Really ? This is my friends results it was done on a different day. The only reason I had to use this method was because I did not know frequency factor. Do you know anywhere I can get frequency factors or known rate constants for particular reactions?
     
  5. Feb 2, 2012 #4
    Re: Need help, Activation energy determination from this reaction. Is this possible??

    thank you very much for your reply!
     
  6. Feb 2, 2012 #5

    Borek

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    Staff: Mentor

    Re: Need help, Activation energy determination from this reaction. Is this possible??

    Doesn't matter. Experimental errors don't care about date.

    They are determined with the same approach you just used. No idea where to look for the data - the best approach I know is to go to the chemistry dept library at University and ask librarian for help.
     
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