Question

The solid iodine quickly changes from a solid to gas while the solid sodiumchloride needs alot of energy to change into the liquid state. why is this so?

Answer 1

Question #57834, Chemistry / Other

The solid iodine quickly changes from a solid to gas while the solid sodiumchloride needs a lot of energy to change into the liquid state. why is this so?

Answer:

The reason is the different types of interactions between the particles of substances.

The Iodide consists of $\mathrm{I}_2$ molecules which attract to one another. These intermolecular forces, so-called Van der Waals forces, are very weak having energy is around of $0.4 - 4\mathrm{kJ / mol}$ .

Sodium chloride is an ionic compounds which contains positively charged cations( $\mathrm{Na}^{+}$ ) and negatively charged anions ( $\mathrm{Cl}^{-}$ ). These species strongly attracts to one another in comparison with iodine molecules. This is an ionic interaction with the energy being of $20\mathrm{kJ/mol}$ . Therefore NaCl needs more energy (higher temperature) to break these interionic contacts and change its physical state than the solid iodine which can easily sublimates at room temperature.