The gibbs function of a thermodynamic system is defined by: g h - ts. if the system is consisting of two phases 1 and 2 of a single substance and maintained at a constant temperature and pressure, the equilibrium condition for the coexistence of these two phases is that the specific gibbs functions are equal consider now a first-order phase change between the phase 1 and the phase 2. at the phase boundary, the equilibrium condition for the two phases for the state a at tand p is given by gi(tp)g2lt, p) and for the neighboring state b at (t+dt) and (p+dp) is given by gi(t+dtp+dp)g(t+dtp+dp). 1- show that the specific volume of the phase i is given by: vi - 2- show that the specific entropy of the phase i is given by: s(-1 or 2).