Abstract

The heat of mixing of nonelectrolytic liquids is important in predicting the type of molecular interactions which exist in solutions of nonelectrolyted. The problem was to construct a calorimeter in which these heats of mixing could be measured accurately. Once constructed, the calorimeter was used to measure the heats of mixing of some binary and a ternary solutions. The systems chosen for study were the three liquid pairs formed between benzane, carbon tetrachloride, and cyclohexane, and the ternary mixture of the three. The results of the experimentation are summarized by the following equations. (1) H_12^M = X_1x_2 [103.2 + 13.1(x_1 - x_2) - 13.3(x_1 - x_2)^2] (2) H_23^M = x_2x_3 [729.6 + 102.4(x_2 - x_3)^2] (3) H_13^M = x_1x_3 [160.8 + 18.9(x_1 - x_3) - 20.2(x_1 - x_3)^2] (4) H_123^M = H_12^M + H_23^M + H_13^M + x_1x_2x_3 [128 + 161(x_1 - x_3) - 1636(x_1 - x_3)^2] where H^M stands for heat of mixing and x for mole fraction. Here, (1) is carbon tetrachloride, (2) is benzene, and (3) is cyclohexane. The value of the heat of mixing as calculated from the equation has the dimensions of caloried per mole. The measurements were all made at 25.0°C. The plots of heat of mixing against mole fraction for the three binaries are approximately symmetrical with respect to the line x + 0.500. The plot for the ternary mixture is symmetrical with respect to the line x_3 = 0.44. Furthermore, the heats of mixing of the ternary can be predicted from the binaries to within 5%.

Degree

College and Department

Physical and Mathematical Sciences; Chemistry and Biochemistry

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