The slowest process is the adsorption
of nitrogen to give adsorbed nitrogen atoms, Nads, not
so much because of the activation energy, but because of the low
probability that nitrogen molecules collide with an active site
and are bonded.
Question
Think about the entropy changes involved
in the process of adsorbing nitrogen gas molecules and chemically
binding them to the catalyst surface. Will it be positive or negative?
How will this affect the probability
of the process occurring?
Answer
Negative
Will make process less likely. The direction of spontaneous change is
to increase in entropy.
The catalyst surface adsorbs nitrogen and
hydrogen, increasing the likelihood they will react. This diagram
illustrates the process.
