A singular thermodynamically consistent temperature at the origin of the anomalous behavior of liquid water
Abstract
The density maximum of water dominates the thermodynamics of the system under ambient conditions, is strongly Pdependent, and disappears at a crossover pressure P_{cross} ~ 1.8 kbar. We study this variable across a wide area of the TP phase diagram. We consider old and new data of both the isothermal compressibility K_{T}(T, P) and the coefficient of thermal expansion α_{P}(T, P). We observe that K_{T}(T) shows a minimum at T* ~ 315+/5 K for all the studied pressures. We find the behavior of α_{P} to also be surprising: all the α_{P}(T) curves measured at different P cross at T*. The experimental data show a ``singular and universal expansivity point'' at T* ~ 315 K and α_{P}(T*) ~= 0.44 10^{3} K^{1}. Unlike other water singularities, we find this temperature to be thermodynamically consistent in the relationship connecting the two response functions.
 Publication:

Scientific Reports
 Pub Date:
 December 2012
 DOI:
 10.1038/srep00993
 Bibcode:
 2012NatSR...2E.993M