Question

42. What is sublimation ? How is naphthalene
sublimated ? How does the process of sublimation
help in purifying an impure sample ?
❤️❤️ please give a proper definition ❤️❤️​

Answer 1

Sublimation is a technique used by chemists to purify compounds. ... Under this reduced pressure, the solid volatilizes and condenses as a purifiedcompound on a cooled surface (cold finger), leaving a non-volatile residue of impurities behind.

Answer 2

Sublimation is the transition of a substance directly from the solid to the gas phase, without passing through the intermediate liquid phase.

Naphthalene is a solid that sublimes at standard atmospheric temperature with the sublimation point at around 80 °C or 176 °F. At low temperature, its vapour pressure is high enough, 1 mmHg at 53 °C, to make the solid form of naphthalene evaporate into gas.

The purification of organic compounds is necessary, though complex, step after its extraction from a natural source or synthesis in the laboratory. The method of purification of the organic compound depends mainly on the nature of the compound and the impurities present.

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.