Activation Energy Table

name         Christian
status       student
grade        9-12
location     Denmark

Question -   Hi, I have done an experiment looking at the 
reaction between sodium thiosulphate and hydrochloric acid; now 
by varying the temperature I have registered some data and made 
an Arrhenius plot.
From this I determined the activation energy for the reaction to 
be 52 kJmol^-1.
Now I have been looking ALL around for an accepted value, but have 
been unsuccessful.
Could you please help me by indicating either a source that 
contains the accepted Ea or could you provide me with the value?
---------------------------------------------------------------------
I found one source from which you might be able to compute their 
value of the activation energy:

http://physics.slss.ie/downloads/ch_me_6.2teacher.doc

    However, remember that the concept of activation energy is 
empirical and a gross oversimplification of the temperature 
behavior of most chemical reactions. There are several problems: 1. 
The mechanism may involve several paths, and activation energy 
assumes a single "simple" path. 2. There is a constant in the equation:
k = A*(exp^-Ea/RT) the so called "pre-exponential factor, A" which 
is also a function (usually not known) of the temperature. 3. When 
you plot the ln(k) vs. 1/T(kelvins) to determine Ea, the activation 
energy you frequently find that the activation energy, Ea, appears 
to be a function of temperature!! That is the plot isn't linear. And 
even if it is linear it is not clear what it is you are measuring 
because very complicated reaction mechanisms often produce simple 
appearing concentration and temperature behavior.
   Too frequently, all of the limitations of the concept of 
activation energies are not spelled out for students. It's 
empirically good for estimating the rate of a reaction at a 
different temperature, but don't read a lot into its fundamental importance.

Vince Calder
====================================================================