Notes On Organic Compounds: Methods Of Purification - I - CBSE Class 11 Chemistry
Based on the nature of the organic compounds and the impurities present in them, organic compounds can be purified using five different methods. Organic compounds are purified by five different methods: sublimation, crystallization, distillation, differential extraction and chromatography.

Sublimation is a process which involves the conversion of a solid directly into vapour without any intermediate liquid. Sublimation is used to separate sublimable compounds from non-sublimable impurities.



Crystallisation is a process of purification of solid organic compounds. It is one of the most commonly used techniques for the purification of solid organic compounds. It is based on the difference in solubilities of the compound and the impurities in a suitable solvent.

Distillation is used when the liquids in the mixture differ appreciably in their boiling points. Distillation helps to separate liquids from impurities (or) other liquids. Simple distillation is commonly used for liquids that are sufficiently stable at their boiling points and contain non-volatile impurities.

Fractional distillation is used to separate liquids with a very small difference in their boiling points.



Liquids that decompose at (or) below their boiling points and liquids with very high boiling points are separated using distillation under reduced pressure. Reducing the pressure on the liquid surface reduces the boiling point of the liquid.

Steam distillation is used to separate substances that are steam volatile and water insoluble.

Summary

Based on the nature of the organic compounds and the impurities present in them, organic compounds can be purified using five different methods. Organic compounds are purified by five different methods: sublimation, crystallization, distillation, differential extraction and chromatography.

Sublimation is a process which involves the conversion of a solid directly into vapour without any intermediate liquid. Sublimation is used to separate sublimable compounds from non-sublimable impurities.



Crystallisation is a process of purification of solid organic compounds. It is one of the most commonly used techniques for the purification of solid organic compounds. It is based on the difference in solubilities of the compound and the impurities in a suitable solvent.

Distillation is used when the liquids in the mixture differ appreciably in their boiling points. Distillation helps to separate liquids from impurities (or) other liquids. Simple distillation is commonly used for liquids that are sufficiently stable at their boiling points and contain non-volatile impurities.

Fractional distillation is used to separate liquids with a very small difference in their boiling points.



Liquids that decompose at (or) below their boiling points and liquids with very high boiling points are separated using distillation under reduced pressure. Reducing the pressure on the liquid surface reduces the boiling point of the liquid.

Steam distillation is used to separate substances that are steam volatile and water insoluble.

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