Abstract: The salt effect coefficients (k_s) of nonelectrolyte solute dissoving in nonaqueous electrolyte solutions, which is composed of salt (NaI,or KI) and sulfolane, was calculated by the scale particle theory. Considering the distribution behavior of the particles in solution and the forms of molecular interactions,we calculated K_s in different ways. 1. The term of hard sphere interaction (k_α) was calculated by Masterton -Lee's equation. The term of soft sphere interaction (k_β) was treated by Y. Hu's radial distribution funtion method, ie take the first coordination circle as in-order, and out of the circle as random mixing. Fur-thermore, we take the following interaction form into calculation: dipole-dipole, dipole-induced dipole, dipole-charge of ion and charge-induced dipole. The results shown that the treatment method used is better than others. 2. The molecular hard sphere diametere σ and energy parameter ∈/k were obtained from various empirical equations. These equations contain some parameters which can be got easily. By comparing the calculated k_s with the experimental results, when σ_2=0.563 nm and ion's diameter is in electronic density scale, the agreement between theory and experimental result is good.

Key words: Nonaqueous solution, Salt effect coefficients, Scale particle theory