Methodology Article
Universal Gas Transitions for Pure Substances
Beycan Ibrahimoglu
,
Beycan Ibrahimoglu Jr.*
Issue:
Volume 10, Issue 2, June 2025
Pages:
23-28
Received:
8 May 2025
Accepted:
6 June 2025
Published:
10 July 2025
DOI:
10.11648/j.aas.20251002.11
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Abstract: Classical models of phase transitions have traditionally assumed that at the critical point of a pure substance, the temperature, pressure, and density simultaneously reach unique critical values. However, experimental findings demonstrate that along the liquid–vapor equilibrium curve, only the temperature (Tcr) attains a true critical state, while the pressure and density vary depending on experimental conditions. Furthermore, for the liquid–solid equilibrium curve at high pressures, a critical point associated with the disappearance of the metastable liquid phase has been experimentally identified, leading to the definition of a critical pressure (Pcr). To comprehensively address these phenomena, a Universal Phase Transition Equation (UPTE) is proposed, extending the classical Van der Waals framework by incorporating dynamic interaction parameters dependent on both temperature and pressure. The UPTE successfully integrates the solid, liquid, gas, and plasma phases into a unified model within the pressure–temperature (P–T) diagram. By accounting for metastability, critical phenomena, and non-equilibrium behaviors, the UPTE offers a more complete and realistic framework for describing phase transitions in pure substances.
Abstract: Classical models of phase transitions have traditionally assumed that at the critical point of a pure substance, the temperature, pressure, and density simultaneously reach unique critical values. However, experimental findings demonstrate that along the liquid–vapor equilibrium curve, only the temperature (Tcr) attains a true critical state, while...
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