1. The problem statement, all variables and given/known data Specify at least two ( physical or chemical), real world, processes for each of this cases: a) Internal energy is constant b) Entalpy is constant c) Gibbs free energy is constant d) Helmholtz free energy is constant 2. Relevant equations a) dU = TdS - pDV = 0 b) dH = TdS + VdP = 0 c) dG = dH - tdS = 0, or dG =vDp -SdT = 0 ??? d) dF = -(pdV + SdT ) = 0 3. The attempt at a solution b) Joulle-Thompson effekt ...and this is all what I found... Thanks for any help !