How Do I Calculate Molar Solubility From KSP?

Molar solubility can be calculated from KSP by writing the chemical equation for the substance and then dissolving and dissociating so that the KSP expression can be written and then the concentration of each individual ion can be added and multiplied out. Molar solubility is the number of moles that are dissolved per liter of solution.

KSP is known as the solubility product constant. It is the equilibrium constant for solid substances that are being dissolved in aqueous solutions. KSP represents the level that a solute dissolves at in a solution and the more that a substance dissolves, the higher the KSP rating will be for that substance, whereas the less time that it takes for a substance to dissolve, the lower the KSP rating will be for that substance. There is something known as the “salt effect” where the KSP value is increased if uncommon ions are present. Uncommon ions are ions other than the ions that are involved in the equilibrium process. There is also something known as the “common ion effect.” This is where a common ion leads a substance to a lower KSP.

An example of a soluble substance is NaNO3 (sodium nitrate), which has a high molar solubility with 10.0+ moles per liter of solution most of the time. An example of an insoluble substance, AgBr (silver bromide), has a minuscule molar solubility with the value being close to 5.71 x 10 to the -7 moles per liter.