Salting-Out

Salting-Out 

the liberation of a dissolved substance from solution by the addition of another substance (usually a salt) with greater solubility.

Two instances of salting-out are differentiated: (1) salting-out of electrolytes by electrolytes, and (2) salting-out of nonelectrolytes by electrolytes. In the first case the electrolyte used for salting-out has the same ion as the substance salted out. Thus, sodium chloride (NaCl) can be displaced from an aqueous solution by magnesium chloride (MgCl₂). Here the solubility product gives a quantitative estimate. In the second case the substance used for salting-out unites with the solvent, thus in effect reducing the amount of solvent for the substance being salted out. Salting-out is used both in analytical chemistry and in industrial chemistry (salting-out of soap or dyes; in radiochemistry, the chlorides of barium and radium, BaCl₂ and RaCl₂, are salted out by the addition of hydrochloric acid, HC1).