@article {2012, title = {Thermodynamic phase transitions and shock singularities}, journal = {Proc. R. Soc. A 8 March 2012 vol. 468 no. 2139 701-719}, number = {arXiv:1107.0394;}, year = {2012}, publisher = {The Royal Society}, abstract = {We show that under rather general assumptions on the form of the entropy\\r\\nfunction, the energy balance equation for a system in thermodynamic equilibrium is equivalent to a set of nonlinear equations of hydrodynamic type. This set of equations is integrable via the method of the characteristics and it provides the equation of state for the gas. The shock wave catastrophe set identifies the phase transition. A family of explicitly solvable models of\\r\\nnon-hydrodynamic type such as the classical plasma and the ideal Bose gas are\\r\\nalso discussed.}, doi = {10.1098/rspa.2011.0459}, url = {http://hdl.handle.net/1963/6090}, author = {Giuseppe De Nittis and Antonio Moro} }