Which expression represents the solubility product (Ksp) for BaSO4?

Which expression represents the solubility product (Ksp) for BaSO4?

• A. [BaSO4]
• B. [Ba2+]+[SO4^2-]
• C. [Ba2+][SO4^2-]
• D. [Ba2+]-[SO4^2-]

Answer: (C)

Solubility product is the equilibrium constant for the dissolution of a sparingly soluble salt into its ions. For BaSO4, the solid dissolves to give Ba2+ and SO4^2− in solution: BaSO4(s) ⇌ Ba2+(aq) + SO4^2−(aq). At equilibrium, Ksp is defined as the product of the concentrations (more precisely, activities) of the ions. In dilute solutions, activities are well approximated by concentrations, so Ksp = [Ba2+][SO4^2−]. Because the dissolution yields a 1:1 ratio, each ion appears to the first power. The solid itself is not included in the expression, and you multiply the two ion concentrations rather than adding or subtracting them. This product stays constant at a given temperature, guiding how changes in ion concentrations shift the system toward dissolution or precipitation.

Solubility product is the equilibrium constant for the dissolution of a sparingly soluble salt into its ions. For BaSO4, the solid dissolves to give Ba2+ and SO4^2− in solution: BaSO4(s) ⇌ Ba2+(aq) + SO4^2−(aq). At equilibrium, Ksp is defined as the product of the concentrations (more precisely, activities) of the ions. In dilute solutions, activities are well approximated by concentrations, so Ksp = [Ba2+][SO4^2−]. Because the dissolution yields a 1:1 ratio, each ion appears to the first power. The solid itself is not included in the expression, and you multiply the two ion concentrations rather than adding or subtracting them. This product stays constant at a given temperature, guiding how changes in ion concentrations shift the system toward dissolution or precipitation.