Question

Sometimes, Ionic product and solubility product are the same - true or false?

• A. True
• B. False

Answer 1

The correct option is A

True

If we try to dissolve a sparingly soluble salt (like $Al(OH{)}_3$, $AgCl$, etc.) in water, only a very small amount of it is dissolved in reality. At some point, a dynamic chemical equilibrium is established between the solvated ions and the insoluble solid.

$XY\left(s\right)\rightleftharpoons X^{+}\left(aq\right)+Y^{-}\left(aq\right)$

You know the drill. Derive $K_{eq}$

But here the concentration of the solid is ? Yes. It is always unity. Concentrations of pure solids never change with time.

The general product of [$X^{+}$][$Y^{-}$] is called the ionic product. At equilibrium, when the undissolved solid is in a dynamic equilibrium (for a particular temperature), ionic product = solubility product. Rather, the ionic product of a saturated sparingly soluble salt in its solution is called the solubility product.

At equilibrium Solubility product = ionic product

$K_{sp}$ = [$X^{+}$][$Y^{-}$ ] If not in equilibrium, ionic product may be greater than or lesser than the solubility product!