Chemical reactions
In this exploration, we will discover the link between chemical reactions and probability to
compare the kinetics of fundamental reactions.
If we assume that the sugar molecules (N) are randomly distributed throughout the flask,
what is the probability that a sugar molecule is at "Site A"?
For a reaction they need to collide with sufficient energy and make contact in just the right
orientation.
Step 1:
To determine the probability that a molecule occupies a single position, we can divide the
number of available molecules by the number of available positions:
p = N/V
Using this connection, we can draw some important conclusions about changes in
concentration that affect how reactions work.
Step 2:
For example, adding more water to the flask increases the number of available positions for
the sugar molecules already in the flask. Chemists would say that this reduces the
concentration of sugar molecules in the flask.
Since the number of sugar molecules has not changed, there is now a much lower
probability that any molecule will be at Site A and, as we will see, this has real
consequences for chemical reactions.
Concentration:
This probability also has a more common name: concentration. The higher the concentration
of a molecule in a flask, the more molecules there are per unit volume. If we want a more
concentrated sugar solution, we simply add more sugar molecules to the solution without
changing the amount of water.
In general, both the number of molecules and the number of locations in a flask are such
large numbers that it is not useful to think about them directly; the ratio is much more
practical.
The concentration of a molecule (B).
"B" is represented by:
[B] = N*B/V
What is the probability that a molecule (C) and a molecule (D) are both at location A?
p = [B]×[C]
