# Quick question about Gibbs Free Energy

If this isn't the correct place to ask this, please point me to where I should. I feel there are quite a few guidelines to what can be posted and what cannot, so I hope I don't break any rules!

I'm working on a problem, that deals with a superheated steam, that goes from an initial state to a final state.

I'm asked (given values for U, S, P, V for both initial and final states... all of which change) to find the maximum amount of work I can extract from the gas.

My first thought was to simply use Gibbs free energy, as that is essentially the definition of it.

However, Gibbs free energy requires constant pressure to calculate, but in this problem, the pressure changes.

If I'm dealing with changes in all of these values (H, P, S) with a constant T, should I just use the change in P?

I really appreciate any help :)