Find the bubble-point and dew-point temperatures of a mixture of 0.4 mole fraction toluene (1) and 0.6 mole fraction n-butanol (2) at 101.3kPa. The K-values can be calculated from (2-72), the modified Raoult's law, using vapor-pressure data, and γl and γz from the van Laar equation of Table 2.9 withAI2 = 0.855 and A2l = 1.306. If the same mixture is flashed at a temperature midway between the bubble point and dew point, and 101.3kPa, what fraction is vaporized, and what are the compositions of the two phases?

Table 2.9 Empirical and Semitheoretical Equations for Correlating Liquid-Phase Activity Coefficients of Binary Pairs Equation for Species 2 Name Equation for Species 1 logyi = Ax logy = Ax} (1) Margules x[21 + 2x2 (12 21)] log yi = xA 12 + 2x1(21 12)] (2) Margules (two-constant) log y2 = A12 A21 In y, = [1 + (x1A12)/(x2A21)] Iny, = -In(x1 + A12x2) In y2 = [1+ (x2A21)/(x1A12)J In y2 = -In (x2 + A21X1) (3) van Laar (two-constant) (4) Wilson (two-constant) A12 A21 A12 A21 +x2 x1 + Aj2x2 x2 + A21X1, -x1 \x1 + A12x2 x2 + A211, xiT12G12 (x2 + XG12)? X3721G21 In y (5) NRTL (three-constant) In y2 = (x1 +X2G21)? (x2 + XG12) (x1 + x,G21) exp(-ajty) = exp (-ajTj) Gij Gij 02 In y, = In X1 In y2 = In- X2 In 2 In (6) UNIQUAC (two-constant) +v (4-) -4, la (0, + 0,T12) +V2 (1 -2) - q In (0, + 02T21) - q2 In (02 + 0, T 12) r2 T21 01 + 02T21 T12 T12 T21 +0291 + 0,92 02 + 0,T12 01 + 02T21. 02 + 0,T12,