explain at least two methods in brief for the purification of solid organic compounds.
Answers
Answer:
explain at least two methods in brief for the purification of solid organic compounds.
Explanation:
Purification means the removal of unwanted impurities present in an organic compound. The general methods of purification are:
Sublimation
Crystallisation
Distillation
Differential Extraction
Chromatography
Methods of Purification
Sublimation
Some solids can directly pass to the vapour state without going through the liquid phase. The purification technique which exploits this property is called sublimation. It is helpful in separating sublimable compounds from non-sublimable ones. The substance is heated in a china dish above which an inverted funnel is kept to collect the sublimable compounds. The funnel is kept cool so as to hasten the process. Vapours of the substance solidify on the funnel.
Crystallisation
The principle here is that the compound and the impurities have different solubilities in a solvent. A solvent is chosen where the compound to be purified is sparingly soluble, that is, it is sparingly soluble at lower temperature and soluble at a higher temperature. The solution is heated to get a saturated solution, and on cooling, the crystals of the compounds are removed via filtration.
For example, crystals of benzoic acid can be crystallised with water. Benzoic acid is sparingly soluble in cold water and soluble in hot water.
If the mixture contains impurities that have the same solubility as of the compound to be purified, repeated crystallisation is performed.