What is meant by solubility product?

Solubility product:

• Solubility product is defined as the product of the concentration of the ions which is in equilibrium with the solid compound in a saturated solution.
• It is denoted by$K_{\mathrm{sp}}$.
• The value of the solubility product depends upon the solubility of the substance.
• The lesser the solubility product, the lesser will be the solubility and vice versa.

For example:

The equilibrium between Barium sulfate and the ions in a saturated solution can be represented by the equation:

${\mathrm{BaSO}}_4\left(\mathrm{aq}\right)\rightleftharpoons {\mathrm{Ba}}^{2+}\left(\mathrm{aq}\right)+{{\mathrm{SO}}_4}^{2-}\left(\mathrm{aq}\right)$

The equilibrium constant can be given as:

$\mathrm{K}=\frac{\left[{\mathrm{Ba}}^{2+}\right]\left[{{\mathrm{SO}}_4}^{2-}\right]}{\left[{\mathrm{BaSO}}_4\right]}$, For a pure solid substance, the concentration remains constant.

Thus, it can be written as:

$K_{\mathrm{sp}}=\mathrm{K}\left[{\mathrm{BaSO}}_4\right]=\left[{\mathrm{Ba}}^{2+}\right]\left[{{\mathrm{SO}}_4}^{2-}\right]$, The experimental value of $K_{\mathrm{sp}}$ in above equation at 298K is $1.1\times {10}^{-10}$.