Work done in a reversible adiabatic expansion

[Trowa]

Hi there!

I have to determine the work done of a reversible adiabatic expansion. Becauce the system is adiabatic: Q = 0 so $$\Delta$$U = W_rev

Becauce both the pressure and the volume changes I can't use W = p_ex$$\Delta$$V.

Homework Statement

Cv, Cp, Ti, Tf, Pi, Pf, Vi, Vf are known

The Attempt at a Solution

I thought at first that I could use $$\Delta$$U = C_V.$$\Delta$$T but the volume is not constant so I don't know if I could use it.

Who can help me find the right formula?

Thanx in Advance!

 

[Mapes]

Hi Trowa, welcome to PF.

(1) Because no heat goes in or out of the system, and because the process is reversible, one state variable remains constant. It's one that you haven't listed. What is it?

(2) $\Delta U =c_V\Delta T=(c_P-R)\Delta T$ always holds for an ideal gas, and doesn't require constant volume, constant pressure, or any other condition.

 

[Trowa]

Thanx for the fast response.