We
use molecular simulation to determine solvation free energies,
isochoric solvation energies and entropies, isobaric solvation enthalpies
and entropies, partial molecular volumes, and isothermal density derivatives
of the solvation free energy as a function of temperature and pressure
for hard-sphere solutes with diameters ranging from 4 to 36 Å
in TIP4P/2005 and Jagla water-like solvents exhibiting unusual thermodynamics.
An important piece of our discussion focuses on the nanometer-sized
solutes, for which simulation results are found to be accounted for
by the most basic classical thermodynamic treatment contemplating
bulk and interfacial contributions to the solvation free energy. Thus,
since water’s liquid–vapor surface tension is only special
inasmuch as it takes unusually large values, solvent’s water-like
unusual thermodynamics manifests through a term proportional to the
pressure in the solvation free energy. As a result, such solvent’s
unusual thermodynamics is found to be relevant to the temperature
and pressure dependence of the isochoric solvation energy and entropy
as well as to the isothermal density derivative of the solvation free
energy. This sharply contrasts with the findings of the first part
of this series indicating that the solvation free energy of small
hard spheres responds to temperature and pressure changes as solvent’s
density does, with such a contrasting picture embodying a “pressure–density
dichotomy.” As for the length-scale dependence, we find the
zero nominal pressure and the solvent’s temperature of the
maximum density as singular conditions for cavity surface-area size
scaling of large solutes to occur for all solvation quantities. We
finally argue that the overall study undertaken in this series suggests
that water’s unusual thermodynamics may be relevant to the
thermodynamic stability of clusters of solvophobic units in the temperature–pressure
plane. Some comments on the role of solute–solvent attractive
interactions are also depicted.