In this section, we delve into the concept of solubility product constant (Ksp) for sparingly soluble salts, defining Ksp as the product of the equilibrium concentrations of ions in a saturated solution. Using the dissolution equation of salts like barium sulfate, we show how Ksp can be calculated based on molar solubility. For instance, the equilibrium expression Ksp = [Ba2+][SO42–] represents barium sulfate's dissociation in water. Additionally, we highlight the common ion effect, emphasizing how the introduction of a common ion decreases the solubility of ionic compounds. Ksp values for several common salts provide a framework for further application in predicting solubility and understanding precipitation reactions.