Liquid–Vapor Composition of the Boiling Ternary Solution Ethyl

Chem. 41, 699 (1937). COMMUNICATION TO THE EDITOR ... solution ethyl alcohol-glycerol-benzene,” published in the Journal of Physical. Chemistry 45, ...
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COMMUNICATION TO THE EDITOR

(3) BURTON, E. F.,AND BISHOP,E.: J. Phys. Chem. U,701 (1920). (4) DEMARTINI,F. E.:J. Am. Water Works Aasoc. SO, 85 (1938). E., AND SORUM, C. H.: J. Phys. Chem. 44,62 (1940). (5) FISHER, (6) HATCH,G.B., AND RICE,0.: Ind. Eng. Chem. 81.51 (1939). (7) HATCH,G.B., AND RICE,0.: Ind. Eng. Chem. 91, 1572 (1940). (8) HAZEL,F.:J. Phya. Chem. 46, 731 (1941). (9) HAZEL,F.:J. Phys. Chem. 46, 738 (1941). (10) HAZEL,F.: J. Phya. Chem. 45, 747 (1941). (11) HAZEL,F.,AND AYRES,G. H.: J. Phys. Chem. I, 2930 (1931). (12) HAZEL,F., AND AYRES,G. H.: J. Phye. Chem. I, 3148 (1931). (13) HAZEL,F., AND SORUM, C. H.: J. Am. Chem. SOC.6% 49 (1931). (14) LANOELIER, W. F.:J. Am. Water Works Aeaoc. !U, 1500 (1936). (15) LARSON,T.E., AND BUSWELL,A. M.: Ind. Eng. Chem. 31, 132 (1940). (16)RICE,O.,AND PARTRIDQE, E. P.: Ind. Eng. Chem. 91, 58 (1939). (17)ROSENSTEIN, L.: U.s. patent 20,754(1938). (18)TRAX, EDW.C.: J. Am. Water Worka Assoc. 91. 1495 (1940). (19)WEISER,H.B.:Colloid Chemistry, p. 228. John Wiley and Sons, Inc., New York (1939). (20) WILLEY,A. R., AND HAZEL,F.: J. Phya. Chem. 41,699 (1937).

COMMUNICATION TO THE EDITOR LIQUID-VAF’OR COMPOSITION OF THE BOILING TERNARY SOLUTION ETHYL ALCOHOLGLYCEROLBENZENE

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Sir : I am much indebted to Dr. Hugh J. McDonald for discussing with me a number of points in his paper, “Liquid-vapor composition of the boiling ternary solution ethyl alcohol-glycerol-benzene,’’ published in the Journal of Physical Chemistry 46,706 (1941). However, the following comments should be noted: (I) In figure 1, the residue curves are plotted with moles of each component upwards and total moles of residue out to the right; a point representing the change of residue composition during distillation (for any one component) then move8 from the upper right corner towards the origin; the motion is opposite on the distillate curves. (2) On page 711,the statement is made that the “slope of the curve a t any point is, of course, the mole fraction of each constituent in the vapor a t that point.” This is confusing. For the distillate curves, with moles of component plotted against total moles, the ratio of ordinate to abscissa is, of course, the mole fraction in the total distillate. The value of the slope has an additional term, as may be shown by simple calculus. For the residue curves, the ratio of ordinate to abscissa gives the mole fraction in the residue (as is correctly stated in the paper) ; the slope of a residue curve gives the mole fraction of that component in the “instantaneous” vapor just leaving the residue, not the mole fraction in the total distillate. (3) The curve for benzene (or either other component) in figure 1 must be

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rotated 180°, not 90°, to make it coincide, as stated on page 712. This symmetry is, of course, due to the method of plotting the data. The curve for benzene is not drawn through the experimental points, but Dr. McDonald states that other runs showed this shape for the curve. (4) In figure 2 on page 712, the points for such a y-z curve may perhaps lie approximately on a straight line, but the slope of the line (for Sample 10) is approximately eight, and not unity, aa may be shown by calculations on data read from figure 1. This higher ratio of benzene in the vapor to benzene in the liquid is more plausible, considering its relative volatility in the system. Unfortunately, other y-z curves cannot be calculated from the information in the paper, although the determination of their slopes and thence the “distribution coefficients” would be of some interest. WORDENWARING. Richardson Chemical Laboratory, The Tulane University of Louisiana, New Orleans, Louisiana. Received December 20, 1941.

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