So when we looked at kinetics, what we were worried is how fast the reaction proceeds.
How long, how much time does it take
to produce a certain amount of product.
How fast are our reactants consumed.
In equilibrium, we are worried about how far the reaction proceeds
because when we first introduce th idea of chemical reactions.
We kind of assume that they go from all reactants to forming all products.
But in reality, for many reactions that is not in fact what happens. We kind of assume that they go from all reactants to forming all products.
But in reality, for many reactions that is not in fact what happens.
What we get is some portion of the reactants are converted to products But in reality, for many reactions that is not in fact what happens.
What we get is some portion of the reactants are converted to products
and then we don't see the formation of products continue to increase.
So this is when we get to the point of chemical equilibrium.
What we have to look at is how do we know we are at equilibrium?
How does that differ between different reactions.
We need understand something about that ratio
of products to reactants.
So we are going to use the term dynamic equilibrium.
The reason we use this, is that we need to make sure
clear that there is change happening. The reason we use this, is that we need to make sure
clear that there is change happening.
Because the word dynamic means just that, it means change.
But we are also looking at equilibrium, so something else also has to be equal.
The things that are equal are the rates of the
forward and reverse reaction.
When we have a reaction that is at chemical equilibrium
so say we have A goign to B.
We use this equilibrium arrow
to represent that in fact A is being converted to B
and B is being converted back to A.
If we are at the point of equilibrium and B is being converted back to A.
If we are at the point of equilibrium
the rate of the forward process, A going to B, is equal to
to the reverse process, B going back to A.
When I get to some concentration of A, we are going to find that it
doesn't change once we are at equilibrium
neither does the concentration of B.
They don't necessarily have to be the same and
in fact they are usually not the same.
So the concentration of A is constant in fact they are usually not the same.
So the concentration of A is constant
the concentration of B is constant
but the individual molecules
that are going back and forth are going to be different.
So what I see is that some molecules are
at A are being concerted to B.
At the same rate that some molecules of B
are being converted back into A.