Rekryystalisaatio

Rekryystalisaatio is a Finnish term that translates to "recrystallization" in English. It is a process used in materials science and chemistry to purify solid compounds. The fundamental principle behind recrystallization is the difference in solubility of a substance and its impurities in a specific solvent at different temperatures.

The process typically involves dissolving the impure solid in a minimum amount of a hot solvent. As the solution cools, the desired compound, which is usually less soluble at lower temperatures, will begin to crystallize out of the solution. Impurities, which are either more soluble at lower temperatures or present in smaller quantities, tend to remain dissolved in the solvent. Once crystallization is complete, the pure solid is separated from the solvent, often by filtration. The collected crystals can then be washed with a small amount of cold solvent to remove any residual impurities.

The choice of solvent is crucial for successful recrystallization. An ideal solvent should dissolve the compound readily when hot but poorly when cold, and it should dissolve the impurities well at all temperatures or not at all. Common solvents used in recrystallization include water, ethanol, and acetone. This technique is widely employed in laboratories for purifying chemical compounds and in industrial processes for obtaining high-purity materials.