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

#### himynameis

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...

#### Borek

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.

#### himynameis

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.
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?

#### himynameis

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.
thank you very much for your reply!

#### Borek

Mentor
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.
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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