Free Expansion Theory

Free Expansion Theory describes how gases expand into a larger space without any external force or confinement. When a gas is suddenly allowed to expand into a vacuum, its molecules spread out to fill the available volume, resulting in an increase in entropy (disorder). During this process, no work is done on the surroundings, and there’s no heat exchange. It’s an idealized way to understand how gases behave when they expand freely, highlighting the natural tendency of systems to move toward higher disorder and greater volume without energy cost.