Naphthalene is a volatile solid and is best purified by which among the following?

The correct answer is Sublimation.

Key Points

• Sublimation is a process where a solid changes directly into a gas without passing through the liquid phase.
• Naphthalene, being a volatile solid, can easily undergo sublimation due to its high vapor pressure at relatively low temperatures.
• This method is particularly effective for purifying substances like naphthalene that can sublime, as impurities do not usually sublime at the same temperature.
• Sublimation allows for the separation and purification of naphthalene by heating it until it turns into vapor and then cooling the vapor to get the purified solid.

Additional Information

• Crystallization: A process of forming solid crystals from a homogeneous solution. Suitable for substances that have impurities with different solubilities.
• Distillation: A method of separating mixtures based on differences in their volatilities in a boiling liquid mixture. Not suitable for solids like naphthalene.
• Steam Distillation: A separation process for temperature-sensitive materials such as natural aromatic compounds. Not applicable to naphthalene.
• Volatile Solids: Substances that easily vaporize at relatively low temperatures. Naphthalene is an example of a volatile solid.
• Vapor Pressure: The pressure exerted by a vapor in equilibrium with its solid or liquid phase. High vapor pressure facilitates sublimation.