ABSTRAKT

Experimentally determined tensile strength of water can be measured mainly by two methods: by the application of high-intensity ultrasound or by the cooling of liquid-filled inclusions. The tensile strength around room temperature given by the two methods differs remarkably; for the ultrasonic method it is around –30 MPa, while for the inclusion method it is around or below –100MPa. The controversy can be explained by assuming the effect of an already vanished low-temperature critical point, i.e., the existence of a second Widom region observable only under negative pressures. This Widom region is responsible for the increase of the isothermal compressibility, which—being the response function for pressure perturbations—can cause unexpected homogeneous nucleation in a region, still far enough from the near-spinodal metastable liquid states. Therefore—depending on the experimental paths—one can obtain nucleation in very deep negative pressures (near-spinodal region) or in a much higher pressure values, related to this new Widom region. A quintic equation of state (where quantic means that the highest term in volume is V⁵), similar to the van der Waals equation is proposed, which can qualitatively describe the expected anomalies.