TEMPERATURE AND PRESSURE EFFECT ON THE THERMODYNAMIC COEFFICIENT (@V/@T)OF WATER

On the basis of literature data, the temperature and pressure dependences of the thermodynamic coefficient (aV/aT)p for liquid water have been calculated and analyzed. The obtained results are compared with the relevant data for argon. Taking the principle of corresponding states into account, the existence of a region, where the thermodynamic similarity between water and argon takes place, is confirmed. At the same time, there is a region, where the indicated similarity is not observed, and the thermodynamic properties of water demonstrate a peculiar behavior. In particular, an inflection point at a temperature of (91.0 +/- 0.2) circle C is observed in the temperature dependence of the curve (aV/aT)p for water, but not for argon, along the liquid-vapor equilibrium curve. The existence of inflection point in the dependence (aV/aT)p for water leads to the presence of negative values of (aV/aT)p at temperatures below 3.98 circle C, as well as to the intersection of the temperature dependences of isobars (aV/aT)p in water at a temperature of (42.0 +/- 0.2) circle C. On the contrary, the temperature dependences of the curves (aV/aT)p for argon along the liquid-vapor equilibrium curve do not have a corresponding inflection point.