Acceleration of the effect of solute on the entropy-volume cross fluctuation density in aqueous 2-butoxyethanol, 1-propanol, and glycerol: the fourth derivative of Gibbs energy.

Using a differential pressure perturbation calorimetry developed by us recently [K. Yoshida, S. Baluja, A. Inaba, K. Tozaki, and Y. Koga, "Experimental determination of third derivative of G (III): Differential pressure perturbation calorimetry (II)," J. Solution Chem. (in press)], we experimentally determined the partial molar S-V cross fluctuation density of solute B, (SV)δ(B) , in binary aqueous solutions for B = 1-propanol (1P) and glycerol (Gly). This third derivative of G provides information about the effect of solute B on the S-V cross fluctuation density, (SV)δ, in aqueous solution as the concentration of B varies. Having determined (SV)δ(B) by better than 1% uncertainty, we evaluated for the first time the fourth derivative quantity (SV)δ(B-B) = N(∂(SV)δ(B) ∕∂n(B)) for B = 1P and Gly graphically without resorting to any fitting functions within several percent. This model-free quantity gives information about the acceleration of the effect of solute B on (SV)δ. By comparing fourth derivative quantities, (SV)δ(B-B) , among B = 1P, Gly, and 2-butoxyethanol obtained previously, the distinction of the effect of solute on H(2)O becomes clearer than before when only the third derivative quantities were available.