T H E SYSTEM WATER-ACETIC ACID-TOLUENE: TRIANGULAR DIAGRAM AT 25’C., WITH DEXSITIES AND VISCOSITIES O F THE LAYERS B Y ROWLAND MARCUS WOODMAN
During work on the distribution of a consolute liquid between two immiscible solvents, it was found necessary to have an accurately-determined diagram for a system containing a pair of partly miscible liquids, The present paper deals with the distribution of acetic acid, an easily-estimated liquid between water and toluene.‘
Fro.
I
The glacial acetic acid used (D 2 5 0 = 1.045)was labelled “B. D. H., A. R.,” 4 O
and, by titrating a weighed port,ion, previously diluted, against n-NaOH in the presence of phenolphthalein,*the sample was found to contain 98.96 per Waddell (J. Phys. Chem., 2 , 233 (1898)) hae investigated the system water-acetic acid-benzene by a method similar to that used here. The syptem water-acetic acidtoluene has been partially investigated by Herz and Fischer (Bcr.,37,4746; 1904~38,I 138 go$ with the view of determining the distribution of the acid between the two immiscible solvents. * Krauch: “Chemical Reagents,” 3 (1919).
WATER, ACETIC ACID, TOLUENE
TABLE I1 a = ratio of gram-moles acetic acid in I litre of aqueous phase to gram-moles in I litre of toluene phase Aqueous Layer: Wt. percent. Drnsity Viscosity of Ac-tic of Layrr of Layer Acid iD$ q 2 e 0
21.38 30.87 37.69 4 7 . 50
58.05 62 53 64.86 67.70 69.71
0.9971 0.008928 1.025 0.01116 1.035 0.01337 1.042 0.01470 1.050 0.01642 1.oj4 0.01875
'
70.jj
69.8; 69.40 66.68 65.31 58.46
1.052
1,049 1.044 1,039 1.024
1980 0.01974 0,01940 0.01904 0.01677 0 .o
1.006 0.01469 0.9757
0.01272
Toluene Layer: Viscosity Wt. percent. Dcnsity of dcstic of Liver of Liver Arid (D$ 7250
0.8600 1.374 0.8614 2.797 0.8630 4.072 0 . 8 6 5 0 6.363 0.8676 10.35 0.8730 12.98 14.98 0.8796 18.55 0.8847 2 1 .jo 0.8896 24.88 0.8952 32.96 0.9099 36.I3 40.64 0.9276 44.41 53.07 0.9588 0
0.004967 -
1
-
18.51
0.005202
I3 ' 23
0.005201 (?)
11.I j
0,005309 0.005298(?)
9.035 6.774
O.OOj441 0.005615 0.005761 0.006362
5,178 4.337 3,805 3.291 2.384
0.007263
1.779
0.01025
I. I20
0.OOjjjI
S . R. The corrc5ponding weight percents. of water and toluene can tie read off from Ill? curve.
The diagram clearly shows that the critical point lies well over on the toluene side of the curve (between the points marked a and b ) , and thus, as the percentage of acetic acid in the aqueous layer passes through a maximum on approaching this point, some diffidence might be shown as t o which side of the maximum to place several of the points corresponding to the aqueous phase, were it not for the fact that the percentage of acetic acid in the toluene layer must increase continuously in approaching the critical point. The tie-lines on being produced converge to a point; this is quite different from the systems fvater-pyridine-benzene' and lead-tin-zinc,* where there are changes in the direction of slope of the ties. The critical point should obviously be the point of contact of the tangent to the curve drawn from this point of convergence. The densities-measured by a small pyknometer-and the viscosities of the aqueous layers also pass through maxima, the values being much higher than for pure acetic acid at the same temperature; in the case of the toluene layers the densities and viscosities increase continuously as the layer ap1
Koodman and Cor) e t ' J. Chem. Yoc., 127, 2461 (1925). Wright: Proc. Foy Poc , 5 0 , 372 ( I f 9 2 ' .
