Critical point (thermodynamics)

  1. Subcritical ethane, liquid and gas phase coexist.
  2. Critical point (32.17 °C, 48.72 bar), displaying critical opalescence.
  3. Supercritical ethane, fluid.[1]

In thermodynamics, a critical point (or critical state) is the end point of a phase equilibrium curve. One example is the liquid–vapor critical point, the end point of the pressure–temperature curve that designates conditions under which a liquid and its vapor can coexist. At higher temperatures, the gas comes into a supercritical phase, and so cannot be liquefied by pressure alone. At the critical point, defined by a critical temperature Tc and a critical pressure pc, phase boundaries vanish. Other examples include the liquid–liquid critical points in mixtures, and the ferromagnet–paramagnet transition (Curie temperature) in the absence of an external magnetic field.[2]

  1. ^ Horstmann, Sven (2000). Theoretische und experimentelle Untersuchungen zum Hochdruckphasengleichgewichtsverhalten fluider Stoffgemische für die Erweiterung der PSRK-Gruppenbeitragszustandsgleichung [Theoretical and experimental investigations of the high-pressure phase equilibrium behavior of fluid mixtures for the expansion of the PSRK group contribution equation of state] (Ph.D.) (in German). Oldenburg, Germany: Carl-von-Ossietzky Universität Oldenburg. ISBN 3-8265-7829-5. OCLC 76176158.
  2. ^ Stanley, H. Eugene (1987). Introduction to phase transitions and critical phenomena. New York: Oxford University Press. ISBN 0-19-505316-8. OCLC 15696711.