Irreversible Vs. Reversible Expansion

[Natalie LeRaybaud 1G]

Can someone please explain the difference between irreversible and reversible expansion and the effect it has when calculating entropy? I saw the diagrams of each posted on the website but now I feel a bit more confused on the subject.

[Clarisse Wikstrom 1H]

Irreversible is spontaneous in one direction, and is highly unlikely to proceed in reverse. It does less work than reversible expansion because it is typically expanding on a lower pressure. On the other hand, you can think of a reversible expansion as equally proceeding in both directions because the pressure equal. Because it is expanding on the same pressure rather than lower pressure, reversible expansion does more work than irreversible expansion.

[Lindsay Kester 2L]

However, entropy is a state function, so regardless of whether it's irreversible or reversible expansion, it's going to have the same entropy at the end, and you can use the same formulas.