Gas molecules diffuse faster than liquid molecules because they have more kinetic energy and are smaller than liquid molecules. When heat is added to a gas or liquid, the amount of kinetic energy in the molecules increases and speeds up their rate of diffusion.
Diffusion comes from the Latin word “diffundere,” which means to “spread and move outwards.” It is a method of transport for molecules. Diffusion is the process in which molecules tend to disperse from areas of high concentration to areas of low concentration. Gas molecules diffuse more quickly than liquid and solid molecules because there is more free space between gas molecules, which gives them more room to move. This causes the molecules to bounce against each other and increases the rate of diffusion.
The molecules in liquid are much closer together than those in gas. Their close proximity and the lack of available space makes it harder for them to disperse across an area and slows down their rate of diffusion. The thickness, or viscosity, of a liquid also affects the speed of diffusion. Thicker fluids tend to have slower rates of diffusion than thinner liquids. According to Biologycorner.com, once all of the molecules in an area are evenly dispersed, equilibrium is reached.