So here is an example of an insoluble salt.
It is silver chloride.
When it dissolves in water
we are going to be able to write this reaction. When it dissolves in water
we are going to be able to write this reaction.
We have, and this is the way we always will write it,
we will put the solid on the left
as a reactant,
and we will put the ions it breaks apart into as a reactant,
and we will put the ions it breaks apart into
on the right, as products.
Now this is a reversible reaction so it
could be written the other direction. Now this is a reversible reaction so it
could be written the other direction.
But we never will, because when we
start studying this
process, we are going to be using equilibrium constants that we are
going to look up in tables and they always apply to the reaction written
in this fashion.
So if we have this reaction written up at the top
you should be able to write the equilibrium constant expression
or the law of mass action, for this reaction.
So choose the right answer.
Well if you selected answer B, then you are correct.
We would not include the silver chloride
in this because it is a solid and you never
include the solids when you write these expressions.