Common Ion Effect on Solubility

$$K_{sp} = [A^+][B^-] = S'(S' + C) \approx S' \cdot C \implies S' = \frac{K_{sp}}{C}$$

Concept: Suppression of solubility of a sparingly soluble salt AB in the presence of a common ion concentration C

Notation:

• $$\text{Notation: } K_{sp} = \text{Solubility product constant}$$
• $$\text{Notation: } S' = \text{Molar solubility in the presence of common ion}$$
• $$\text{Notation: } C = \text{Molar concentration of the common ion}$$