text problem 4A.5

[JosephineF]

A piston confines 0.200 mol Ne(g) in 1.20L as 25C. The gas is allowed to expand through an additional 1.20 L against a constant pressure of 1.00 atm



How do we know that the expansion of the piston is irreversible expansion?

[LBacker_2E]

Since the problem tells you that the system is at constant pressure, you use Pex, which is for an irreversible system.

[Ryan Yee 1J]

For a process to be reversible, there cannot be any change in temperature or pressure in the initial and final states of the system. But since the piston confines the gas and the gas expands, then the system is irreversible because the pressure changes.

[Ivan Tadeja 1G]

If not explicitly given, just remember how any change in temperature and pressure in the final/initial values means that the equation is irreversible.