When writing an equilibrium constant expression, do I include aqueous reactants and products or only gases?
Yes aqueous reactants and products are included in equilibrium constant expressions
We actually have 2 types of equilibrium constants,
Let's have an example to differentiate
For the below reaction:
A(aq) + 2B(g) = 3C(s) + 4D(aq)
Concentration of a solid is equal to its density which is always a constant term, so it'll just be part of K and therefore not in the K expression.
Hope this clarifies!