1. The problem statement, all variables and given/known data Hi! My problem : There is given substance for which (dV/dT)_p =ap^2,where V-volume,T-temperature,p-pressure,a-const. How much the entropy S will increase if T=const and pressure changes from p1 to p2? 2. Relevant equations 3. The attempt at a solution So 1) Mathematically the question of this excersie could be represented as dS=Int [(dS/dp)_T dp] from p1 to p2 2) The next step should be to use Gibs potential : dG=Vdp-SdT From Gibbs potential i should derive something like this (dV/dT)_p = -(dS/dp)_T (*) But i can go as far as dG=(dG/dp)dp -(dG/dT)dT -> (dG/dp)_T=V ;(dG/dT)_p=-S I think that the problem is mathematical: i can't figure out how from dG i can get (*) Could someone can,please help me? P.S. I'm sorry about the equations, i cant find any option for equation builder.