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

AI Thread Summary
The discussion centers on determining the activation energy (Ea) for a specific reaction involving S2O82- and I- ions, based on experimental data. Two individuals conducted similar experiments, noting different rate constants and temperatures, with a one-degree Celsius difference. The user calculated Ea using the Arrhenius equation, resulting in approximately 7.207 kJ/mol. However, concerns were raised regarding the reliability of the results due to the small temperature difference, which could introduce significant experimental error. The user also expressed difficulty in finding the frequency factor (A) necessary for a more straightforward calculation of Ea. Suggestions included consulting chemistry department libraries for resources on frequency factors and known rate constants for similar reactions. Overall, the discussion highlights the challenges of accurately determining activation energy and the importance of considering experimental accuracy.
himynameis
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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 don't know the Frequency factor A! I can't find this anywhere...
 
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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.
 


Borek said:
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.

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?
 


Borek said:
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.

thank you very much for your reply!
 


himynameis said:
Really ? This is my friends results it was done on a different day.

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

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?

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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