Need more insight on the keyword SITE[FR] used in Chemkin Pro
I am modelling surface reactions in chemkin pro. While going through the input manual, I came across the keyword SITE[FR].
In the manual it says, Supersedes the default units for all surface reactions which follow the REACTIONS header line for pre-exponential factors A i ; the units of surface species are site fraction and the reaction rate unit is 1/sec.
What does units of surface species mean exactly? Does this mean rate of the reaction will with respect to site fractions instead of molar concentration of that surface species?
Any help will be appreciated/