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

The water thermodynamics is characterized by polydispersity, which determines its structural and dynamic properties. This is due to the specifics of its characteristic bond: the hydrogen bond (HB). The isobars of the two fundamental thermodynamic functions, the isothermal compressibility (KT(P.T)) and the isobaric expansivity (αP(P,T)), show the presence of a temperature T*≃315±5 K where both have a singular behavior. In this work, by carefully considering the thermal properties of the isobars of density ρ, specific heat CP and the self-diffusion DS, we suggest the universality characteristics of this temperature. In addition, by analyzing the average intermolecular distance dOO, in the same area of the P-T phase diagram, we demonstrate that such realities are due in the supercooled liquid state to the ratio between its two characteristic phases: the low-density liquid (LDL due to HB) and the HDL (which entirely characterizes the remaining parts of the phase diagram).