For the dissolution of AgCl, which is the correct Ksp expression and which factor would increase its solubility?

For the dissolution of AgCl, which is the correct Ksp expression and which factor would increase its solubility?

• A. Ksp = [AgCl]; Increasing temperature
• B. Ksp = [Ag+]; Increasing temperature
• C. Ksp = [Ag+][Cl-]; Increasing temperature
• D. Ksp = [Ag+][Cl-]; Decreasing temperature

Answer: (C)

The key idea is how the solubility product is defined and how temperature affects solubility for this dissolution. For AgCl(s) dissolving to Ag+(aq) and Cl−(aq), the Ksp expression is the product of the two ion concentrations, with the solid’s activity omitted: Ksp = [Ag+][Cl−]. At saturation, if the solubility is s, then [Ag+] = [Cl−] = s and Ksp = s^2. Temperature dependence comes in because the dissolution is endothermic. When temperature rises, the equilibrium shifts to dissolve more solid, increasing the concentrations of both ions and, consequently, the value of Ksp. So increasing temperature increases solubility for this salt. That’s why the correct choice reflects the product form [Ag+][Cl−] and identifies increasing temperature as the factor that increases solubility. The other forms don’t represent the proper Ksp expression, since the solid isn’t included and a single ion concentration isn’t the full product.

The key idea is how the solubility product is defined and how temperature affects solubility for this dissolution. For AgCl(s) dissolving to Ag+(aq) and Cl−(aq), the Ksp expression is the product of the two ion concentrations, with the solid’s activity omitted: Ksp = [Ag+][Cl−]. At saturation, if the solubility is s, then [Ag+] = [Cl−] = s and Ksp = s^2.

Temperature dependence comes in because the dissolution is endothermic. When temperature rises, the equilibrium shifts to dissolve more solid, increasing the concentrations of both ions and, consequently, the value of Ksp. So increasing temperature increases solubility for this salt.

That’s why the correct choice reflects the product form [Ag+][Cl−] and identifies increasing temperature as the factor that increases solubility. The other forms don’t represent the proper Ksp expression, since the solid isn’t included and a single ion concentration isn’t the full product.