Question

What is the difference between solubility equilibrium and dynamic equilibrium?

Answer 1

Solubility equilibria are a subset of dynamic equilibria.

Explanation:

The dissolution of a sparingly soluble salt is certainly an equilibrium reaction. Of course, the concentration of the insoluble solid is a meaningless concept, and does not appear in the solubility equilibrium. Given an "insoluble" solid in water the rate of solute dissolution is equal to the rate of solid deposition.