DETERMINATION OF ACTIVITY COEFFICIENTS AT INFINITE DILUTION FROM DEW POINT AND/OR BUBBLE POINT CURVES

A new method for determining activity coefficients at infinite dilution from dew point and/or bubble point data in binary systems is proposed. The extrapolated values of dew point and bubble point parameters, respectively, defined as D≡ a1a2/(1 - a1) (1 - a2) and B≡ (1 - b1) (1 - b2)/b1b2, agree thermodynamically with the activity coefficients at infinite dilution. The values of ''a'' and ''b'', respectively, can be calculated by a≡ γ× = (π/P)y from dew point data and by b≡ (y/γ) = (P/π)× from bubble point data, where x, y, P, π and γ, respectively, express mole fraction in liquid phase, that in vapor phase, vapor pressure, total pressure and activity coefficient.