The density and surface tension of the air- and water-stable hydrophobic ionic liquid (IL) 1-ethyl-3-methylimizazolium tris(pentafluoroethyl) trifluorophosphate (CAS Registry No.: 377739-43-0; [C(2)mim[PF3(CF2CF3)(3)]) were measured in the range of T = (283.15 to 338.15) K. The other physicochemical properties of the IL [C(2)mim][PF3(CF2CF3)(3)] at 298.15 K were estimated in terms of empirical and semiempirical equations, as well as the interstice model theory. These properties include molecular volume, standard molar entropy, lattice energy, the parachor, molar enthalpy of vaporization, interstice volume, thermal expansion coefficient, interstice fraction, and so forth. Then, the physicochemical properties of the ILs [C(n)mim][PF3(CF2CF3)(3)] (n = 1, 3, 4, 5, 6) family were predicted in terms of the estimated values of molecular volume and the parachor.