Question

HCl is a polar molecule, how come the intermolecular forces among its molecules consist of London dispersion force besides the dipole-dipole attraction?

Answer 1

Hint In order to find why the intermolecular force in HCl consists of London dispersion force besides the dipole-dipole interaction, we must know what are London dispersion forces and dipole-dipole interactions. It is said to be a temporary attractive force which is formed due to the formation of temporary dipoles in a nonpolar molecule.

Complete step by step solution:
Let us first understand what an intermolecular force of attraction is. Intermolecular force of attraction is the attraction present between two molecules which hold them together. Some common intermolecular forces of attraction are given below they are:
- London dispersion force.
- Dipole-dipole interactions
- Hydrogen bonding
- Ion-Ion force.
Let us now see what is London's dispersion force. London dispersion force is the weakest intermolecular force. It is said to be a temporary attractive force which is formed due to the formation of temporary dipoles in a nonpolar molecule.
Mostly atoms and molecules will have London dispersion force. HCl being a polar molecule will have dipole-dipole interaction.
$$H^{\delta +}-C{l}^{\delta -}$$
Though HCl is having London dispersion force, the dipole-dipole interaction is more. If there is no dipole-dipole interaction, then HCl cannot be soluble in water.

Additional information:
- HCl is known as Hydrochloric acid or muriatic acid.
- It is a colorless liquid.
- It has a pungent smell.
- It is a very strong acid; it dissociates completely in solution.
- Hydrochloric acid is used in the food industry as an additive and for the production of gelatin.

Note: We have to remember that intermolecular and intramolecular forces are different from one another.

INTERMOLECULAR FORCE	INTRAMOLECULAR FORCES
It is the force of attraction which can hold the molecules in a substance.	It is the force of attraction that can hold atoms in a molecule.
It is a very weak force of attraction.	It is a very strong force of attraction.
Affected strongly by a physical change	Not affected strongly by a physical change.