Liquid-solid Equilibrium Position and Critical Point for Benzene

Abstract

Using a specially constructed experimental apparatus, the freezing thermograms of benzene at increasingly higher constant pressures and temperatures were determined. The isotherm reversible freezing of liquid benzene, which metastabilizes irreversibly through super cooling and isentalpic transformation steps, is studied in detail. In addition to the temperature and pressure changes, it was determined that the step times decreased rapidly due to increasing pressure and temperature and reached zero. Where these quantities are zero, 356 K and 2230 bar are considered as the temperature and pressure of the critical point of the liquid-solid equilibrium line, respectively. The liquid-solid equilibrium line for the variation of pressure with temperature between this critical point and the triple point is precisely determined. A pressure-temperature phase diagram with the critical point and this test line is arranged for benzene. The irreversible metastabilization of liquid benzene has been studied thermodynamically. It has been determined that enthalpy, entropy, volume and internal energy changes and work done on the system decrease rapidly with temperature and pressure as they gradually increase and approach zero at critical values.