Which factor does NOT affect solubility according to Ksp?

Solubility is largely determined by the equilibrium constant for solubility, known as Ksp (solubility product constant), which reflects the inherent properties of a solute and solvent system. The Ksp is impacted primarily by the type of solvent and temperature, as these aspects affect the interactions between solute particles and solvent molecules, thereby influencing how much of a solute can dissolve.

The concentration of ions in the solution is also related to Ksp because it directly influences the position of the equilibrium. As more solute dissolves, the concentration of the ions will increase until it reaches the saturation point defined by Ksp. If the ionic concentration exceeds the Ksp, precipitation could occur.

Stirring speed, however, does not affect the Ksp itself or the inherent solubility of a compound. While stirring may promote faster dissolution by enhancing interaction between solute and solvent, it does not change the solubility limit determined by Ksp. Thus, it is the only factor listed that does not have a direct effect on the solubility of a solute in a given solution under equilibrium conditions, making it the correct answer.