AAMC FL Practice Exam

What does Ksp represent in chemistry?

1. Equilibrium constant in reactions

2. Solubility product constant for a salt

3. The concentration of a saturated solution

4. A measure of ionic strength

The correct answer is: Solubility product constant for a salt

Ksp stands for the solubility product constant, which is a specific type of equilibrium constant used to describe the saturation level of a salt in a solution. It quantifies how much of a solute can dissolve in a solvent at a given temperature until the solution reaches a state of saturation. The Ksp value is determined from the concentrations of the ions in a saturated solution of the salt when it is in equilibrium with its solid state. For a generic salt represented as \( AB \), which dissociates into \( A^+ \) and \( B^- \) ions, Ksp can be expressed as: \[ Ksp = [A^+][B^-] \] This expression indicates that the solubility product constant is based not on the concentration of the solid itself, but on the ionic concentrations that are present in solution. While the other options refer to concepts that may seem related, they do not accurately define Ksp. The equilibrium constant in reactions refers to a broader set of chemical equilibria, the concentration of a saturated solution describes the condition rather than the constant itself, and ionic strength is a measure used to describe the effect of all ions in a solution on activity coefficients, which differs from the specific intent of