Excess partial molar entropy of alkane-mono-ols in aqueous solutions at 25 degrees C

In the preceding paper, we reported the values of model-free chemical potentials for aqueous methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 1-hexanol at 25degreesC over the entire compositional region. Using alcohol excess partial molar enthalpies, H-AL(E), determined earlier in this laboratory (Can. J. Chem. 74, 713 (1996)), we have calculated excess partial molar entropies for the alcohols, S-AL(E), where AL stands for an alcohol. We then calculated, numerically, the entropic interaction, S-AL-AL(E) = N(partial derivativeS(AL)(E)/partial derivativen(AL))(p,T,nW), where n(AL) is the amount of AL, n(W) is the amount of H2O, and N is the total amount of solution. S-AL-AL(E) signifies the effect of addition of AL upon the entropic situation of existing AL in solution. Using these quantities, the mixing schemes in aqueous alcohols have been studied. The earlier conclusions, which used H-AL(E) and H-AL-AL(E) alone, are confirmed. Furthermore, the order of the relative hydrophobic nature of alcohols is established from the behaviour of S-AL-AL(E) and of H-AL-AL(E) as methanol < ethanol < 2-propanol < 1-propanol.