In a Ksp calculation problem, the compound involved is typically in which phase?

In a Ksp calculation problem, the compound involved is typically in which phase?

• A. Gas
• B. Liquid
• C. Solid
• D. Aqueous

Answer: (C)

Solubility product describes the equilibrium between a solid salt and its dissolved ions in water. The phase involved is a solid because the Ksp expression represents the solid at the interface with the aqueous solution, donating ions to the solution. The solid’s activity is effectively constant (taken as 1), so it does not appear in the Ksp expression; only the concentrations of the dissolved ions appear. For example, a sparingly soluble salt dissolves as: solid ⇌ cations plus anions in solution, and Ksp equals the product of those ion concentrations. This is why the typical phase is solid.

Solubility product describes the equilibrium between a solid salt and its dissolved ions in water. The phase involved is a solid because the Ksp expression represents the solid at the interface with the aqueous solution, donating ions to the solution. The solid’s activity is effectively constant (taken as 1), so it does not appear in the Ksp expression; only the concentrations of the dissolved ions appear. For example, a sparingly soluble salt dissolves as: solid ⇌ cations plus anions in solution, and Ksp equals the product of those ion concentrations. This is why the typical phase is solid.