Answer:
Free expansion is also known as the joule expansion, this happens when a gas does not have an expansion limit and its volume increases until it is allowed.
That is why as the initial volume passes at the end the pressure decreases since the molecules are more distant from each other without a barrier that stops or compresses them.
It is an irreversible process and the equation would be:
Initial pressure X Initial volume = Final pressure X Final volume
Explanation:
Where P is the pressure, V is the volume, and i and f refers to the initial and final states. Since the gas expands, Vf> Vi, which implies that the pressure drops (Pf <Pi).