A supersaturated solution is one in which too much solute has been dissolved in a solvent. As a general rule, hot solvents can dissolve more solute than the same quantity of cold solvent. A hot saturated solution forms a supersaturated solution when cooled to a lower temperature. Because the solvent is unable to hold all the solute in solution at the lower temperature, some of solute precipitates out in the form of crystals. This process is called crystallisation.
Crystallisation is a method used to purify solids.
If one takes a solid containing a small amount of impurities and dissolves it in a suitable solvent to form a saturated solution at elevated temperature, the impurities are likely to remain in solution when the solution is cooled and the solid crystallises out. Solutions of Electrolytes Solutions of electrolytes are the electrically conducting solutions formed when salts are dissolved in water. The high electrical conductivity of the solution is due to the presence of ions from the dissociation of the salt. Solvation Solvation is the interaction of ions of a solute with the molecules of the solvent. It occurs only with polar solvents.