New Considerations Around the Singular Water Temperature Explaining the Anomalous Behavior of Liquid Phase

Area of Science:

• Thermodynamics
• Physical Chemistry
• Water Science

Background:

• Water's unique thermodynamic properties stem from its hydrogen bonding (HB).
• Polydispersity significantly influences water's structure and dynamics.
• Fundamental thermodynamic functions exhibit singular behavior at a specific temperature.

Purpose of the Study:

• To investigate the universality of a characteristic temperature (T*) in water's thermodynamic properties.
• To analyze thermal properties including density, specific heat, and self-diffusion around T*.
• To explore the role of low-density liquid (LDL) and high-density liquid (HDL) phases in supercooled water.

Main Methods:

• Analysis of isothermal compressibility (KT) and isobaric expansivity (αP) isobars.
• Examination of density (ρ), specific heat (CP), and self-diffusion (DS) isobars.
• Investigation of average intermolecular distance (dOO) in the P-T phase diagram.

Main Results:

• A singular temperature T* ≈ 315±5 K was identified for isothermal compressibility and isobaric expansivity.
• Universality characteristics of T* were suggested through analysis of density, specific heat, and self-diffusion.
• The observed phenomena in supercooled water are linked to the ratio of LDL and HDL phases.

Conclusions:

• The temperature T* ≈ 315±5 K represents a universal feature in water's thermodynamic behavior.
• Water's structural and dynamic properties are intrinsically tied to hydrogen bond characteristics.
• The interplay between LDL and HDL phases governs supercooled water's unique properties.