Science Fair Project Encyclopedia
Fractional crystallization
In chemistry, Fractional Crystallization is a method of refining substances based on differences in solubility. If two or more substances are dissolved in a solvent, they will crystallize out of solution (precipitate) at different rates. Crystallization can be induced by changes in concentration, temperature or other means. Fractional crystallization can be used for purification or analysis.
Example: If sugar is dissolved in water and the solution partially frozen, the liquid portion will taste sweeter than the frozen portion because the sugar will be more soluble in the liquid.
A more interesting case occurs in geochemistry where elements can become separated during the slow cooling of magma as some remain dissolved while other elements separate out.
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