Question

Explain the following briefly:

Although haloalkanes are polar in character, yet they are insoluble in water.

Although haloalkanes are slightly polar, yet they are insoluble in water. Explain.

Answer 1

1. Haloalkanes contain a polar carbon-halogen (C–X) bond due to the difference in electronegativity between carbon and the halogen atom.
2. This gives haloalkanes a polar character.
3. Water is also a polar solvent and its molecules are held together by strong hydrogen bonds.
4.  To dissolve in water, a substance must be able to form hydrogen bonds with water molecules.
5. Haloalkanes cannot form hydrogen bonds with water because they lack strongly electronegative atoms like oxygen or nitrogen bonded to hydrogen.
6. Therefore, the attraction between haloalkanes and water molecules is weak.
7. The energy released when haloalkanes mix with water is not sufficient to break the existing hydrogen bonds between water molecules.

Hence, haloalkanes are insoluble in water despite being polar.