Binary nucleation of water-sulfuric acid system: A reexamination of the classical hydrates interaction model

It is shown that the hydration correction for the free energy of cluster formation in the classical binary nucleation theory is not applicable for the thermodynamic data of the water-surface acid system commonly used in nucleation calculations. A new form of the hydration correction is presented. For the commonly used thermodynamic data the nucleation rates of the new hydration correction are in the temperature range of 248-323 K, and at a relative humidity greater than 40%, 10(3)-10(6) times lower, respectively, than the nucleation rates of the former theory. The predictions of acid-water nucleation rates of the thermodynamically consistent version of the classical binary homogeneous theory [G. J. Wilemski, Chem. Phys. 80, 1370 (1984)] with the new hydration correction are in accordance with experimental results [B. E. Wyslouzil, J. H. Seinfeld, R. C. Flagan, and K. J. Okuyama, Chem. Phys. 94, 6842 (1991)] obtained at 298 K and with experimental results CD. Boulaud, G. Madelaine, D. Vigla, and J. Bricard, J. Chem. Phys. 66, 4854 (1977)] obtained at 293 K, but at a given number concentration of acid and relative humidity, they predicted nucleation rates are rather more stronger functions of temperature than the experimental rates. The theoretical nucleation rate of water-sulfuric acid vapor is due to the hydration correction sensitive to the thermodynamic properties of dimers and timers. (C) 1998 American Institute of Physics. [S0021-9606(98)51244-5].