AllChemicals — The Online Chemical Glossary | https://allchemicals.info/chemical/439-fractional-crystallisation
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Also Known As
Recrystallisation (related), zone refining (related), crystallisation purification
What is Fractional Crystallisation?
A purification technique that separates mixtures of solids based on their different solubilities at various temperatures. As the solution cools, the less soluble substance crystallizes first and is collected by filtration. The process is repeated to increase purity.
Properties & Characteristics
Fractional crystallisation is a purification technique in which a mixture of solutes is separated by exploiting their different solubilities at different temperatures. The mixture is dissolved in hot solvent, then slowly cooled to crystallise the less soluble component first. The filtrate (mother liquor) contains the more soluble impurities. Repeated cycles improve purity. Alternatively, solvent evaporation is used when solubility differences at different temperatures are small.
Uses & Applications
Fractional crystallisation is used in: purification of organic compounds (recrystallisation), industrial separation of potassium nitrate from sodium chloride, purification of sugars, preparation of pure chemical standards, and in geological processes (magmatic differentiation — minerals crystallise from magma in sequence).
Safety Information
Handling hot saturated solutions requires appropriate heat-resistant glassware (borosilicate) and protection from sudden crystallisation that can cause localised boiling. Some compounds crystallise with sharp edges that present laceration hazards when handling the solid product.
Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.
SynonymsRecrystallisation (related), zone refining (related), crystallisation purification
Frequently Asked Questions
A purification technique that separates mixtures of solids based on their different solubilities at various temperatures. As the solution cools, the less soluble substance crystallizes first and is collected by filtration. The process is repeated to increase purity.
Fractional crystallisation is used in: purification of organic compounds (recrystallisation), industrial separation of potassium nitrate from sodium chloride, purification of sugars, preparation of pure chemical standards, and in geological processes (magmatic differentiation — minerals crystallise …
Handling hot saturated solutions requires appropriate heat-resistant glassware (borosilicate) and protection from sudden crystallisation that can cause localised boiling. Some compounds crystallise with sharp edges that present laceration hazards when handling the solid product.
Editorial standards: Chemical data is sourced from peer-reviewed literature,
CAS Registry, NIST WebBook, and PubChem. Safety information reflects guidance from OSHA, ECHA,
and IAEA. For educational purposes only — always consult official SDS documentation and qualified
professionals before handling chemicals.
