April, 1957
COMMUNICATIONS TO THE EDITOR
511
distances of HzO, HzS and HzSeJgives 1.69 A.l1.lz the value of 51.7 e.u. calculated above. Since the bond angles for HnS and HzSe are 92.1' TABLE IV and 91.0 i 0.6", a bond angle for HzTe should be about 90 & lo. Using these data, the moments THERMODYNAMIC FUNCTIONS FOR HYDROGEN TELLURIDE IN of inertia for hydrogen telluride are 11 = 4.70 X THE IDEAL GASSTATEIN CAL./DEG./MOLE Iz = 4.78 X I 3 = 9.48 X g.cme2. H o - Hao - 'F ,jHo' T,OK. CP T S O The thermodynamic functions for HzTe to the 100 7.95 7.95 37.90 45.85 rigid rotator-harmonic oscillator approximation are 200 8.10 7.97 43.41 51.38 listed in Table IV in the range from 100' to 400°K. 250 8.29 8.02 45.19 53.21 for the ideal gas state a t one atmosphere pressure. 275 8.40 8.05 45.96 54.01 Apparently the only datum in the literature on the 298.1G 8.50 8.08 46.61 54.69 thermodynamic functions for HzTe is an estimate 300 8.51 8.08 46.66 54.74 of the entropy a t 298.16' of 56 e.ueJ9 compared with (11) M.Huggins, J . Am. Chem. Soc., 76, 4126 (1953). (12) W.Gordy, Smith and Trambarulo, "Microwave Spectroscopy," John Wiley and Sons, Inc., New York, N. Y.,1953.
325 350 400
8.63 8.75 8.99
8.12 8.16 8.25
47.31 47.91 49.00
55.43 56.07 57.25
COMMUNICATIONS TO THE EDITOR A REMARK ON SOME MEASUREMENTS OF TRANSFERENCE NUMBERS
relative amounts of sodium and potassium in both electrode compartments In some water solutions the assumption that Sir: water is a neutral particle which does not participate In view of a recent work on transference numbers in the electrical transport, fails completely Sodium by Kilpatrick and Lewis, it would seem appropriate hydroxide dissolved in water is such a case. This to recall the limitations of transference number liquid should formally be regarded as consisting measurements of a Hittorf type in a liquid. only of Na+, H + and OH- ions (or Na+, H + and Let us first consider the measurement of trans- 02-ions). It is of no consequence for our reasonference numbers of a sodium chloride solution in ing that the H + ions and the OH- ions most of the water. In the Hittorf type experiment, the change time are associated to HzO molecules as long as of the amount of sodium chloride in the cathode these ions contribute significantly to the electrical or anode compartment would be determined. transport. I n this system, which is analogous The transference number which can be determined to the mixture of fused sodium and potassium from this, refers to the center of gravity of the chloride, the Hittorf measurement will not tell water as a reference frame. This is evident, since how much of the electricity transport is carried only the ratios of the amounts of water to salt by the cations (Na+ and H+) in relationship to are determined in the electrode compartments. what is carried by the anion (OH- or 02-). A Thus it is required that the water inolecule do not consistent treatment of the results of the transtake part in the electrical transport, but simply act ference number measurement will only reveal the ratio of the transference number of sodium to that as a neutral reference frame. Without such a reference frame, transference of the proton. By arbitrarily implying that there numbers could not be determined by a Hittorf is no electricity transport by the oxygens (for intype method. In a fused salt a frame of reference stance as OH- ions) have absolute transference is lacking. A transference number measurement in numbers been obtained for such systems. What fused sodium chloride could seem to consist of an has been reported as a high OH- mobility in this observation of a change of the amount of the salt in case is more consistently described as a proton one of the electrode compartments, or in other mobility. The treatment of a system such as sodium words a displacement of the body of fused salt. But Sundheim2 has shown recently that such an fluoride dissolved in anhydrous hydrofluoric acid experiment is trivial. The results depend on the is identical with the treatment of the sodium experimental arrangement without giving any hydroxide solution discussed above. Some difficulties encountered by Kilpatrick and Lewis in information about intrinsic properties In a mixture of fused sodium chloride and potas- interpreting their experimental results on fluoride sium chloride only the ratio of the potassium systems, would vanish if the points discussed in transference number to the sodium transference this note were taken into consideration. STATE UNIVERSITY number can be determined by measuring the THEPENNSYLVANIA (1) M. Kilpatrick and T. J. Lewis, J. Am. Chem. Soc., 7 8 , 5186 (1956). (2) B. R. Sundheim, TRISJOURNAL, 60, 1381 (1956).
DEPARTMENT OF CERAMIC TECHNOLOGY T. FORLAND J. KROGH-MOE COLLEGE OF MINERAL INDUSTRIES UNIVERSITY PARK, PENNSYLVANIA RECEIVED DECEMBER 12, 1956
