Question

How can solids and liquids diffuse when there is intermolecular force between them ?

Answer 1

Diffusion is the process of a substance spreading out to evenly fill its container or environment. This is the process where the particles move from high concentration to low concentration.

The reasoin is explained below:

All molecules, whether in solod state, gaseous state or liquid state are in random motion. This motion leads to collisions between the molecules. These collisions increase the kinetic energy of the molecules. The rate of collision increases when temperature increases, because molecules move at higher speed. (That's why at higher temperatures gases diffuse quickly.) When the molecules attain enough energy to break the intermolecular force, they will diffuse.

The freedom of motion of molecules is very low in solids and liquids. So the molecules require more collisions to gain enough kinetic energy to break the intermolecular forces in solids and liquids. This is the reason behind the lower rate of diffusion in solids and liquids.

But in gases this collision will be high, so more kinetic energy for molecules and higher rate of diffusion.