# Entropy in isothermal expansion

1. Nov 8, 2014

### cytr

Air:
V1= 0,1 m3
P1= 1 MPa
T1= 20 C
After isothermal expansion P2= 0,1 MPa

I had to find T2, M, V2, L, Q and found all those (T2=20 C; M=1,1927 kg; V2=1 m3; L=Q=230258 J) but need s (enthropy) for creating illustration in T-s
I cant find how its possible to calculate s1 and s2, is it possible at all or is it possible to find only delta s?

2. Nov 9, 2014

### cytr

I already found the solution. :)
S2 with same formula, just had to change P with P2 (if finding S1, then P=P1), Cp was 1000, P0 is normal pressure (760 mm HG), T0 is normal temperature (273,15 K)