Chemistry – States of matter - Diffusion | e-Consult

The diffusion of a gas is faster than that of a liquid at the same temperature because of the differences in intermolecular forces and the relative kinetic energies of the particles. Both gases and liquids have particles with kinetic energy related to temperature, but the nature of the particles and the forces between them differ significantly.

In a gas, the particles are widely separated and the intermolecular forces are very weak (essentially negligible). This allows the particles to move freely and independently, with minimal resistance to their motion. The kinetic energy of the gas particles is therefore almost entirely converted into translational motion, resulting in rapid diffusion.

In a liquid, the particles are much closer together and experience stronger intermolecular forces (e.g., van der Waals forces, hydrogen bonding). These forces impede the movement of the particles, requiring more energy to overcome them. While the kinetic energy of the liquid particles is the same as that of the gas particles at the same temperature, a greater proportion of that energy is used to overcome intermolecular forces rather than to contribute to translational motion. This results in a slower rate of diffusion compared to a gas.

Therefore, the weaker intermolecular forces and greater freedom of movement in gases allow for faster diffusion compared to liquids, even at the same temperature.