THERMODYNAMIC PROPERTIES OF TERNARY MIXTURES .2. EXCESS VOLUMES OF MIXING OF TERNARY MIXTURES OF CYCLOHEXANE, AROMATICS, AND HALOMETHANES
Rastogi, RP; Nath, J; Das, SS
The excess volumes of mixing of seven ternary mixtures, viz., (i) carbon tetrachloride (CCl4) + benzene + p-xylene, (ii) cyclohexane + CCl4 + toluene, (iii) cyclohexane + CCl4+ p-xylene, (iv) cyclohexane + chloroform (CHCl3) + toluene, (v) cyclohexane + CHCl3 + p-xylene, (Vi) cyclohexane + methylene dichloride (CH2Cl2) + toluene, and (vii) cyclohexane + CH2Cl2 + p-xylene, have been measured over a wide concentration range. The results have been fitted to an equation of the type VE123= VE12* + VE23* + VE31* + x1x2x3|A +Bx1(x2−x3) + Cx12(x2−x3)2] where VE123 is the excess volume of mixing per mole of the ternary mixture in which mole fractions of components 1, 2, and 3 are x1,x2, and x3, respectively. A, B, and C are constants which are characteristic of a ternary system and the quantities VE12*, VE23*, and VE31* are given by VE12* = x1x2[A12 + B12(x1−x2) + C12(x1−x3)2|,VE23* = x2x3[A23 + B23(X2−x3) + C23(x2−x3)2|, and VE31* = x1,x2[A31+B31(x1−x3) + C31(x1−x3)2], where A12, B12, C12, etc. are constants which are determined from the data on excess volumes of mixing for the binaries. The deviations, ΔVE, of the experimental values of VE123 from the appropriate quantities of the three binary systems have been calculated by using the relation ΔVE = VE123-½[(X1 + X2)VE12 + (X2 + X3)VE23 + (X3 + X1) VE31], where X1, X2, and X3 refer to the number of moles of components 1, 2, and 3 in the ternary system, and the quantities etc. refer to the excess volumes of mixing per mole of a binary mixture in which mole fraction of component 1 is X1(X1+ X2) and of component 2 is X2/(X1 + X2) etc. The values of ΔVE have been found to be positive in the case of all the ternary systems. It is suggested that this is due to weakening of halomethanearomatic interaction by the third component. 1977, American Chemical Society. All rights reserved.