What is crystallisation? What is use of this process?

 What is crystallisation? What is use of this process?

This is the most common method used for the purification of solids. The impure compound is the least soluble of the solvent in which the compound is more soluble in heat than in cold. Impurities are removed by filtering the hot solution. Once the crystals of the pure compound are obtained, the filtrate solution is allowed to cool. The crystals are separated by filtration and recrystallized if necessary. Very fine large-size crystals are obtained if the filter is allowed to cool slowly. mother liquor left after the separation of the crystals concentrated to get another crop of crystals. The process of retrieving the maximum amount of pure compound has been repeated many times.

Crystallisation meaning in Hindi: क्रिस्टलीकरण

Crystallisation diagram:

The process of crystallization chemistry involves the following steps:

Crystallisation experiment:

(a) Selection of suitable solvent: A suitable solvent is selected by hit and trial method. Only solvents that do not dissolve or dissolve the compound in very small amounts in cold but are soluble in large quantities when heated or boiled. If no single solvent is found suitable. A combination of two or more solvents can be used.

(b) Preparation of solution: The impure compound is heated in a circular bottom flask connected by an air condenser and dissolved in a suitable solvent.

 (c) Removal of impurities and undesirable colors: Insoluble impurities are removed by filtration. If the raw compound contains pigment impurities, it may affect the appearance and properties of the crystals: these can be removed by boiling the hot solution of the compound in well-operated animal charcoal and then filtering the hot solution. The color impurities are absorbed by the animal's charcoal, and pure decolorized crystals of the substance separate out on cooling.

(d) Separation of crystals and drying: The crystals are separated by filtration through a bucker funnel and washed with a small amount of solvent. The crystals are dried by pressing between layers of filter paper or heated in an electric oven. Crystals can also be dried in a desiccator or vacuum desiccator. The compounds are dried in a desiccator without the risk of decomposition.

Crystallisation applications And USES

• Purification of salt that we get from seawater and
• Separation of crystals of alum from an impure sample.

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