How do I explain this in kinetic terms how this change occurs?

Question

A characteristic of gases is that they spread throughout the space available to them

Answer 1

Chucky50 has a way with words or other noisy events. Gas molecules have a kinetic motion, and move in all directions. If there are less molecules in a given volume in a certain direction, the molecules in there will tend to spread. This process will continue until the molecules are bounded by a closed volume.

Answer 2

if i fart would you want an explanation or be getting the heck out the area ?