The physical meaning of the energetic parameter, chi(12), that is characteristic of Flory theory is explored in connection to the random mixing hypothesis. It is known that, if such a hypothesis is valid, chi(12) is independent of the concentration (x(1)). Here, deviations from the random mixing hypothesis are attributed to an excess of interactions between like molecules (if chi(12)(x(1)) > chi(12)(x(1) = 0.5)) or of interactions between unlike molecules (if chi(12)(x(1)) < chi(12)(x(1) = 0.5)). Binary mixtures of the type hydroxyether + dibutyl ether, or + 1-alkanol, or + 2-methoxyethanol have been investigated studying the chi(12) variation with x(1). Toward this end, we provide a new expression for chi(12) which makes possible the exact determination of this magnitude at any composition if the corresponding molar excess enthalpy, H-mE, is known. Orientational effects are present in the studied solutions, although the model can represent the H-m(E) for hydroxyether + 1-alkanol or + 2-methoxyethanol, where the mentioned effects are weaker. The excess molar volumes, V-m(E), are only described for the systems with two cellosolves, due to the existence in the remainder mixtures of structural effects. Results from the Kirkwood-Buff formalism, applied to 2-ethoxyethanol + dibutyl ether, or + 1-butanol, systems are in agreement with those obtained using Flory theory.