An analytical approach to the anomalous specific heat of water

• Published in: Journal of molecular liquids Vol. 371; p. 121049
• Main Authors: Simões, M., Steudel, A., Yamaguti, K., Cobo, R.F., Santos, A.P.R., Amaral, R.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2023
• Subjects: Analytical description; Anomalous behavior; Excluded volume; Specific heats; Two-liquid model; Water; Water; Anomalous behavior; Analytical description; Specific heats; Excluded volume; Two-liquid model
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2022.121049

•The two-liquid model and the thermal-dependent excluded volume.•Reconsidering the Van der Waals’ approach to an equation of state.•Invariance of water specific heat at constant volume with the excluded volume.•Dependence of water specific heat at constant pressure with the excluded volume.•An analytical description of the anomalous behavior of water specific heats. In this paper, we use the recent confirmed water two-liquid model to give an analytical description of the observed anomalous behavior of water specific heats. We will show how the two-liquid model implies that water net excluded volume, ve, can not be taken constant but depends on the sample thermal conditions. Combining these ideas, it will be shown that, at constant volume, the specific heat (CV) is invariant with changes of ve. Otherwise, at constant pressure, the specific heat (CP) changes with the changing ve, giving CP a very characteristic shape. This is how our model explains the physical origin of the contrast between the ”normal” behavior of CV and the non-usual behavior observed in CP and CP – CV. Finally we give an analytical form to these issues that agree with the experimental data.