The influence of temperature and pressure on the thermodynamic coefficient –(∂ V /∂ P ) T for water and argon

The effects of temperature T and pressure P on the thermodynamic coefficient –(∂V/∂P)T of liquid water and argon were investigated. Based on the principle of corresponding states, the existence of a region of thermodynamic similarity between these substances was confirmed. However, under certain thermodynamic conditions, this analogy breaks down, and water exhibits distinct behavior with respect to the thermodynamic coefficient –(∂V/∂P)T. In particular, for water, a characteristic temperature of T = (42.2 ± 0.20) °C was identified, at which the temperature dependence of –(∂V/∂P)T displays a pronounced minimum at the intersection with the liquid–vapor equilibrium boundary. Furthermore, minima in the temperature dependence of this coefficient along isobars are observed for water at temperatures above Tc. In addition, the pressure-dependent curves of –(∂V/∂P)T converge along isotherms at temperatures below this value. In contrast, argon does not exhibit such temperature- and pressure-dependent features in its corresponding thermodynamic coefficient.