A dispersion parameter and an induction parameter are used to estimate this quantity in the MOSCED model. Both the NRTL and Wilson model of this quantity cannot describe its extrema, unlike a two-suffix model named after this quantity that takes a power series of Gibbs free energy over RT with respect to mole fraction and is named after Max Margules. This quantity is divided into residual and combinatorial components in the (*) UNIFAC model. The Pitzer equation gives values of this quantity in natural water. In the case of infinite dilution, this quantity can be predicted from the square root of ionic strength by the Debye-Huckel equation. This quantity equals 1 for mixtures that obey Raoult’s (-5[1])law. This quantity corresponds to the fugacity coefficient in gases. For 10 points, name this quantity symbolized gamma that measures deviations of a mixture from ideality. ■END■ (0[5])