# Adsorption - Pre Exponential frequency factor

1. Apr 24, 2013

### dikmikkel

1. The problem statement, all variables and given/known data
I have an adsorption reaction $A+* \leftrightharpoons A^*$
Then I am to finde the rate constants and these should be given by an Arhennius relation, e.g. from left to right in the reaction:
$k_+ = f_+\exp(-\Delta E_a/k_bT)$ where the delta energy is the activation energy and f+ is the frequency factor

My question is, how do you find that pre-exponential factor? And this should be from theory and i'd rather use statistical mechanics(partition functions)

3. The attempt at a solution
I have seen it written as easy as: $f_+ = \dfrac{k_bT}{h}$
but I suspect I am missing some partition functions or so?
This is maybe chemistry but I need a physisits opinion and stringent use of units.