NOTES
Aug., 1956 as the boiling point.3 This cut had a refractive index of 1.3413 a t 25" as compared with 1.34163 given in the literature.' The specific gravity was 0.7756 25/25 compared with 0.7839 20/20 given by Carbide and Carbon.a An Abbe refractometer and a Westphal balance were used for the refractive index and specific gravity measurements, respectively. As a further test for the purity of the acetonitrile, the infrared spectrum for this cut was compared with that of Eastman spectrograde acetonitrile on a Rsird infrared spectrometer. The spectra were almost identical. The indications were that the cut was, if anything, slightly more pure than the Eastman spectrograde material. Experimental and Discussion A standard Othmer still supplied by the Emil Greiner Company was used for the determination. The insulated still was operated until 4 checking samples, taken 15 minutes apart, were obtained. This took 2 to 6 hours. The comositions of the liquid and vapor samples were determined gy specific gravity using the Westphal balance. Values of specific gravity a t various compositions are given in Table I. TABLE I SPECIFIC GRAVITY 25/25 OF ACETONITRILE-WATER SOLUTIONS Acetonitrile, wt. %
Sp. gr.
4.75 9.62 14.53 18.72 19.63 29.70 39.15
0.9902 .9816 ,9737 .9636 ,9622 ,9395 ,9170
25/25
'
Acetonitrile, wt. %
Sp. gr.
59.96 78.77 87.02 92.43 95.86 100.00
0.8678 ,8242 .8037 .7921 .7848 ,7765
25/25
The results of these determinations are shown in Table I1 and Fig. 1. These data were obtained a t a total pressure of 760 mm. with a possible variation of f 1 5 mm. According to Othmer and Josefowitz, a pressure variation of 1 1 5 mm. a t this total pressure would cause a deviation of about f 0 . 2 wt. % acetonitrile in the azeotrope composition range. TABLE I1 ACETONITRILE-WATER LIQUID-VAPOR EQUILIBRIUM EXPERIMENTAL DATA (Pressure 760 f 15 mm.) B.P., OC.
90.3 84.2 80.9 80.7 78.0 77,2
... 76.8 77.2 77.0 76.8 77.0 78.1 79.4
Li uid composition Acetonitrile Wt. Mole
%,
6.8 11.8 20.7 21.7 35.2 64.5 65.4 79.0 56.5 83.2 85.8 90.2 95.5 98.4
3.1 5.4 10.3 10.5 19.2 44.3 45.3 62.2 36.3 68.5 72.5 80.2 90.3 96.4
Vapor concn. % Acetonitrile Wt. Mole
48.5 65.9 73.5 73.9 77.3 78.0 80.9 82.4 79.4 81.2 84.0 86.3 91.5 95.5
28.5 45.8 54.9 55.4 59.8 60.9 65.0 67.2 68.4 69.1 69.7 73.3 82.5 90.3
0
1147
20
40
60
80
MOL FRACTION ACETONITRILE IN THE
Fig. 1.-Acetonitrile-water
100
LIQUID.
liquid-vapor equilibrium; 760 mm.
shown by Othmer is high by approximately 2.3 wt. %. It is believed that the Carbide and Carbon data and the data determined in this work are correct. As has been pointed out,a the specific gravity of the pure acetonitrile used by Othmer indicates their sample may have contained about 2.5 wt. yo water instead of being 100% acetonitrile. When this is allowed for, the Othmer azeotrope composition fits the others very closely.
TABLE I11 ACETONITRILE-WATER AZEOTROPE A T 760 MM.
This work Carbide and Carbon Chemicals Co. Othmer and Josefowitz
B.P., OC.
Acetonitrile Wt. Mole % %
76.8
83.5
69.0
76.5 76.0
83.7 85.8
69.2 72.6
The equilibrium curve was calculated from the azeotrope using the Van Laar equations in order to test their applicability to this system. The Calculated curve was quite close to the experimental one. For mole fraction acetonitrile from 0 to 0.4, the deviation of the calculated curve was about 10% low. For the remainder of the range, 0.4 to 1.O, the calculated curve was within 1 5 % . The experimental curve, Fig. 1 , shows it is relatively easy to separate acetonitrile from water in concentrations up to the azeotrope.
Acknowledgment.-The authors wish to thank C. Cenerizio, E. Kupski and E. Miley for making the measurements in this work. A DETERMINATION OF THERMODYNAMIC PROPERTIES OF LIQUID 3-METHYLTHIOPHEXE BY THE ULTRASONIC METHOD
The azeotrope boiling point and composition are given in Table I11 compared with those quoted by Carbide and Carbon and Othmer.' The azeotrope boiling point and composition were determined by graphical inter olation of the bracketing data presented in Table I. T i e comparison of the data of this work with those of Carbide and Carbon is quite good. On the other hand, the composition
Contribution from the Department of Physics and Astronomy, I'anderbilt University, Nashville, Tennessee Received February $0,1966
(3) Carbide and Carbon Chemicals Co., private communication, Dec. 28, 1955. (4) The Dow Chemical Co., "Physical Properties of Chemical Substances," Serial No. 2081, 4-23-52;
Sound velocity ,and density values have been determined in 3-methylthiophene at five degree intervals over the temperature range -10 to 50°,
BY GEORGEM. CAMPBELL
NOTES
1148
These values were combined with the specific heat a t constant pressure (C,) data of the American Petroleum Institute' and several other important thermodynamic values calculated. The 3-methylthiophene sample was purchased from the American Petroleum Institute, Carnegie Institute of Technology, to insure a high degree of purity. It wab of 99.97 i 0.03 mole % ' purity. Experimental Work The sound velocity measurements were made by the interferometer method. The interferometer used was the same as the one used by Gilbert and Lagemanna with one significant modification. Instead of using a conducting foil to maintain electrical contact to the to of the quartz crystal, the bottom of the polytetraffuoroetlylene reservoir was coated with silver conducting paint. A conducting wire attached to a copper ring around the reservoir and touching the paint, completed the circuit to the interferometer housing. The frequency of the oscillator was adjusted to that of the National Bureau of Standards Station WWV at 500 kc./sec. Sound velocity measurements were repeated on methyl alcohol as a check on the over-all apparatus. The interferometer was immersed in a thermostated water-bath and the temperature measured by a thermometer calibrated by the National Bureau of Standards. The density measurements were made using a pycnometer similar to the one described by M. R. Lipkin, et UZ.,~ with a volume of three milliliters. The procedure also was that followed by Lipkin. At temperatures where the density had been previously determined**' the agreement wm very good.
Results The sound velocity data in this temperature range were found to be quite linear with the temperature. Although there was some difficulty in reaching complete temperature equilibrium between the sample and the bath, the data are believed to be accurate to approximately *0.1%. The same mathematical relationships used by Gilbert2 were used to calculate the values for the TABLE I THERMODYNAMIC PROPERTIES OF LIQUID3-METHYLTHIOPHENE
Coefficient Temp., OC.
Ultrasonic velocity, m./sec.
Density, g./cc.
of
expansion (OC.) -1 x 101
C cal.A."oc.
0.3508 1191.3 0.9895 1.071 ,3529 0.9955 1.065 1207.4 ,3550 1.059 1226.8 1.0004 .3573 1.054 1245.1 1,0058 .3596 1.049 1264.0 1.0111 ,3619 1.043 1.0164 1282.1 1.0216 .3643 1.037 1303.8 .3667 1.032 1.0268 1320.7 .3692 1.0320 1.027 10 1336.0 .3717 1.0371 1.023 5 1357.5 .3742 1.017 1.0426 0 1379.2 .3767 1.0480 1.011 -5 1396.6 .3796 -10 1415b I . 0526 1.007 "From a curve constructed from data given by McCullough, et aZ.1 b Extrapolated from -9.3'. 50 45 40 35 30 25 20 15
(1) J. P. MoCullough, 8. Sunner, H. L. Finke, W. N. Hubbard, M. E. Gross, R. E. Pennington, J. F. Messerly, W. D. Good and Guy Waddington, J . A m . Chem. SOC.,76,5075 (1953). (2) J. W. Gilbert and R. T. Lagemann, THISJOURNAL, 60, 804 (1956). (3) M. R. Lipkin, J. A. Davison, W. T. Harvey and S. S. Kurta, Jr., Ind. Eng. Chem., 16,55 (1944). (4) F. S. Fawcett, J . A m . Chem. SOC.,68, 1420 (1846).
Vol. 60
isothermal compressibility (&), the adiabatic compressibility (&), the coefficient of expansion and the specific heat a t constant volume (C,). The measured and calculated values of the various properties are listed in Tables I and 11. TABLEI1 THERMODYNAMIC PROPERTIES OF LIQUID3-METHYLTHIOPHENE Bad
Temp., OC.
50 45 40 35 30 25 20 15 10
5 0 -5 -10
Bin,
b
om.* dy'ne-1 om.' dyne-' X 10'1 10''
71.25 68.95 66.50 64.14 61.90 59.86 57.57 55.81 54.29 52.36 50.44 48.89 47.45
94.83 91.94 88.92 86.02 83.26 80.65 77.81 75.54 73.52 71.13 68.68 66.60 64.72
CP/Cv
CV, cal./g. 'C.
1.331 1.333 1.337 1.341 1.345 1.347 1.352 1.354 1.356 1.358 1.362 1.362 1.364
0.2636 .2647 ,2655 .2664 .2674 .2687 .2695 .2708 .2723 .2737 .2747 .2766 .2783
''@-TUNGSTEN" AS A PRODUCT OF OXIDE REDUCTION BY G. MANNELLA~ AND J. 0. HOUQEN Department of Chemical Enpineem'np, Ren.sealaer Polyfechncc Inatitule Troy, N . Y . Received February 8% 1068
The phase known as 0-tungsten was originally reported by Hartman, et U Z . ~ This material was later found by Charlton3 in his work on the reduction of W 0 3 with hydrogen. Recently, Hligg and Schonberg4 have suggested that 0-W is a low oxide of the metal, with a maximum oxide content corresponding to an over-all stoichiometric ratio of WaO. I n his latest work, Charlton5 has corroborated the W30 theory. A kinetics study has been carried on at Rensselaer Polytechnic Institute which has been concerned with the reduction of pelletized tungsten oxides with hydrogen. Kinetic data from this research program have appeared in another publication.6 In this research, 0-tungsten had been identified on the surface of pellets when they were partially reduced at low temperatures. By the continued reduction of a pellet at a temperature sufficiently below 600" t o preclude the formation of any a-tungsten, it was proposed t o produce a pellet of the pure p-material. Since the amount of oxide removed during the reduction may be determined gravimetrically, the composition of the final material could be established, and the oxide content could be determined. I
(1) Research Fellow, Chemical Engineering Department. (2) H. Hartman, F. Ebert and 0. Bretschnaider, Z . anorp. Che'hem., 116, 198 (1931). (3) M. G . Charlton, Nature, 169, 109 (1952); Charlton, M. G., 174, 703 (1954). (4) 0 . Htlgg and N. Schbberg, Acta Cryat., 1, 351 (1954). (5) M. G. Charlton, N a t u ~ s176, 131 (1955). (6) J. 0. Hougen, R. R. Reeves and G. Manneb, Ind. Enp. Chem., 48, 318 (1858).
z
