NOTES
408
Vol. 61
TABLE I THEHEATOF COMBUSTION OF YTTRIUM Mass Y burned, g.
Wt. Mg,
Wt. YzOa,
ing.
g.
Joules/deg., totals
1.2237 1.1507 1.1454 1.0926 1.1571 1.1400 1.1945
7.11 7.03 7.06 6.43 7.20 7.51 7.94
40. I 31.4 31.9 52.9 39.8 39.8 42.2
10037.1 10033.4 10033.6 10042.6 10037.0 10037.0 10038.0
4T
Firing,
OK.'
j.
1.2812 1.2054 I . 1999 1.1425 1.2131 1.1953 1.2523
Energy from
Y,
j./g.
11.2 11.2 13.0 '10.5 10.4 12.5 13.1 Av.
10356.2 10350.0 10347.7 10346.5 10360.3 10350.4 10348.8 10351.4 Stand dev.
Dev. from mean
4.8 1.4 3.7 4.9
8.9 1.0 2.6 3.9 1.9
uncertainty introduced in the correction for the as they are able to acquire some pure scandium impurities6 which is estimated to be 0.11%. The metal. determination of the uncertainty in the correctioii Acknowledgments.-The authors wish to acfor impurities also includes the possibility that the knowledge the valuable assistance of D. Pavone, ratio of YO to Yz03may be as high as 3 and as low F. H. Ellinger, 0. R. Simi and E. Van Kooten in as the anaIytica1 work. The combined uncertainty is 12.8 joules/g. which They also appreciate the courtesy of Dr. F. H. does not include the possibility that the GOz, HzO Spedding of the Ames Laboratory, A.E.C., through and NOz react with the Yzo3. The value for the whom the metal was obtained. heat of combustion gives for the reaction in the = - 1901.4 f 2.3 kj./mole. bomb a value of AE2s.o~ Composition of the Yttrium Oxide.-The oxide THE LIQUID DENSITY, VAPOR PRESSURE AND CRITICAL TEMPERATURE AND formed was light tan in color. An X-ray pattern showed it to be the cubic form with a calculated PRESSURE OF PERCHLORYL FLUORIDE'~2 density of 5.03 g./cc. Analysis by the method of BY ROQERL. JARRY Barthauer and Pierce1' showed no oxygen above Psnnsyluania Ball Manufacturing Company Research and Development that necessary for the sesquioxide. Department, Whilemarsh ReseaTch Laborhtories, Wyndmoor , 1% Heat of Formation of Yz03.-Using methods of Received October 1 1968 calculation reported elsewhere6 the heat of formaPerchloryl fluoride (C1o3F)was first prepared by tion of Y203, AHz60 = -1905.6 f 2.3 kj./mole. In defined calories this is -455.45 f 0.54 kcal./ Engelbrecht and Atzwanger,3 and in the cited article mole. Two estimated values in the literature are and in a later one by the same authors4information those of Brewer,l2 -420 A 9, and Roth and on the physical and chemical properties is given. Becker, l 3 - 440 kcal./mole. This high value, The infrared spectrum has been examined by Lide Barth-Wehrenalp6 reviewed the -151.82 f 0.18 kcal./g. atom 0, appears to and Mann.6 methods of preparation of perchloryl fluoride. deserve some comment. The only other oxides known to have heats of The current study has extended the range of formation greater in magnitude than. - 150 kcal./g. measurements reported by Engelbrecht and Atzand presents data of a higher precision. atom 0 are CaO (-151.79 f 0.21 k ~ a l . / m o l e ) ~wange1-3,~ ~ and Procedure .-The density was measured and Erz03 (-151.20 i 0.15 kcal./g. atom O).8 in Apparatus a glass dilatometer consisting of a 4 bulb and 10 em. Dysprosium oxide, Dy203,is close, having a heat of of 2 mm. i.d. capillary tubing. This apparatus and its formation of -148.61 f 0.31 kcal./g. atom 0.' operation were described in a previovs publication.' The The other rare earth sesquioxides which have been only change in procedure was in filling the dilatometer; this case the perchloryl fluoride was charged from a stormeasured have values for the heat of formation in age cylinder and the amount obtained by weight differfnce. around -144 kcal./g. atom 0.2-7Since yttrium Vapor pressures to two atmospheres were measured in an has an ionic radius and chemical properties similar all-metal system which was described in previous publications.788 Pressures were read on a mercury manometer by to those of dysprosium and erbium the heat of for- means of a cathetomet,er to a precision of S0.05 mm. The mation of its oxide would probably be expected to be vapor pressure to the critical region was measured in a metal of the same order of magnitude. Also, since the heat (1) Presented before the Fluorine Symposium, Division of Indusof formation of the alkali and alkaline earth oxides trial and Engineering Chemistry, 130th National Meeting of the Ameriincrease in each series as the atomic weight de- can Chemical Society, September 20. 1956. creases, it might be expected that yttrium oxide ( 2 ) This paper represents the results of one phase of research carried would have a higher heat of formation than lantha- out under Contract No. 18(600)-761, supported by the United States num oxide. I n this connection, the heat of forma- Air Force through the Air Force Office of Scientific Research of the and Development Command. tion of scandium oxide, SCZO,,should be very inter- Air(3)Research A. Engelbrecht and H. Atzwanger, Ilfonalsh. Chem., SS, 1087 esting, and the authors hope to measure it as soon (1952). ,
W.
(11) G . L. Barthauer and D. Pierce, Ind. Eng. Chem., 18, 479 (1946). (12) L. Brewer, Chem. Reus., 5 2 , 1 (1953). (13) W. A . Roth and G. Becker, Z.phZ/&k. Chem., AlB9, 1 (14) E. J. Huber, -Jr., and C. E. Holley, Jr., THISJOURNAL,60, 498 (1956).
(1932).
(4) A. Engelbrecht and H. Atswanger, J . Inorg. Nuclear Chem., 2, 348 (1956). ( 5 ) D. R. Lide, Jr., and D. E. Mann, National Bureau of Standards Report #4399, Nov. 1, 1955. (6) G. Barth-Wehrenalp, J . Inorg. Nuclear Chem., 2 , 266 (1956). (71 R. L. Jarry and H. C. Miller, THISJOURNAL, 60, 1412 (1956). (8) R. L. Jarry and H. C. Miller, J. A m . Chem. Soc., 78, 1552 (1956).
NOTES
April, 1957 system immersed in a constant temperature bath. The lines to the bourdon gage as well as the gage itself were kept a t a temperature above that in the bath. The 1000 p.s.i.g. bourdon gage used in these measurements had a stated accuracy of of 1%. Critical temperature was measured on samples sealed in 2 mm. i.d. capillary tubing. The tube was placed directly into a constant temperature bath and observations made on the disappearance and reappearance of the meniscus. Temperature was measured during the density and precise vapor pressure determinations either by means of a platinum resistance thermometer or by means of thermocouples which have been compared with the thermometer. The thermometer had been compared with the National Bureau of Standards temperature scale. During the equilibrium periods of 15-20 min. during which measurements were taken, the temperature drift in the metal system or the dilatometer was no more than 0.002'/min. and 0.004'/min., respectively. For the critical temperature and high vapor pressure determinations a mercury in glass thermometer calibrated by the National Bureau of Standards was used. Material.-The perchloryl fluoride for these measurements was prepared and purified by A. Engelbrecht at this Laboratory. Purification was accomplished by fractional distillations. Purity was assayed by infrared analysis and by mass spectrometer analysis kindly furnished by the staff of the National Bureau of Standards. The mass spectrometer analysis showed a purity of 99.9+ mole %.
Results and Discussion.-The data obtained for the liquid density are given in Table I, and are represented by the equation d = 2.266
- 1.603 X
10-8T
- 4.080 X 10-8T'
(1)
where d is the density in g./cm.3 a t the absolute temperature T. Deviations between the experimental and values calculated using equation 1 are given in column 3 of Table I. TABLE I THEDENSITY OF LIQUIDPERCHLORYL FLUORIDE BETWEEN 131 AND 234°K. (OOC. = 273.16"K.) T,OK.
Density, gJcrn.8
131.31 144.46 149.58 154.79 159.84 164.66 169.62 174.50 179.52 184.54
1.989 1.950 1.935 1.920 1.905 1.891 1.877 1,862 1.846 1.831
Deviation obsd. oalcd.
-
0.004 .001 ,000
.ooo
,000 ,000
.OOl ,000 ,000 ,000
T,OK.
Density, g./cm.*
189.50 194.44 199.38 204.34 209.21 214.21 219.15 224.11 229.23 234.22
1.816 1.801 1.786 1.770 1.751 1.734 1.718 1.701 1.684 1.667
Deviation obsd. calod.
-
0,001 .001
.002 ,002 - ,001 ,001
,000 - ,001 ,000 .003
499
TABLE I1 THEVAPORPRESSURE OF PERCHLORYL FLUORIDE (O'C. = 273.16"K.) Devia-
tion,
Temp., OK.
mm. Pressure, obsd. mrn. calcd.
-
152.81 3 . 0 8 -0.15 157.67 5.53 - .03 162.58 9.31 - .05 167.50 14.97 .02 172.33 23.19 - .10 177.40 35.73 - .03 182.33 53.05 - .01 187.31 77.13 .02 192.25 109.48 .12 197.19 151.77 .23 202.11 207.50 .38 207.19 279.66 - .35 212.20 370.73 .08 217.13 481.49 - .20 222.13 619.33 - .10 227.09 785.44 1.00 232.04 980.28 -0.97 237.14 1220.89 -0.80 242.09 1496.31 1.20
-
Temp., OK.
227.09 232.04 237.14 242.09 251.99 262.07 272.04 282.10 292.13 292.24 302.17 312.21 322.33 332.41 342.50 352.66 362.92
Pressure, atm.
Deviation, atm. obsd. cnlcd.
-
1.033 -0.008 1.290 - ,006 1.606 - .001 ,004 1.969 2.891 ,025 4.048 - ,041 5.748 .086 .lo8 7.789 10.170 - ,027 10.177 ,050 ,074 13.361 17.034 .012 21.388 - .122 26.490 - .285 32.782 - .127 39.959 - ,066 48.259 .024
-
2 is 226.40"K. The data to the critical region are represented by the equation logloP(atm.) = 4.46862
1010.81 -T
Deviations between the experimental and calculated values for these two equations are given in column three of Table 11. Temperature was known in these measurements to *0.05° for the data to 2 atmospheres and to f0.10" for the data to the critical region. The heat of vaporization a t the normal boiling point calculated using equation 2 and a gas imperfection correction of -3.21%, derived from the Bethelot equation, is 4609 cal./mole. The critical temperature was determined to be 368.33 f 0.10"K. From this value the critical pressure was calculated using equation 3 to be 53.0 atm. absolute. Acknowledgments.-The author wishes to express his appreciation to Dr. J. J. Fritz of the Pennsylvania State University and Mr. H. C. Miller of the Pennsylvania Salt Manufacturing Company for their advice during the course of this work. He also wishes to thank Dr. A. Engelbrecht, now at the University of Innsbruck, for purifying the sample of perchloryl fluoride, and Mr. Gordon E. Webb of the Pennsylvania Salt Manufacturing Co. for his excellent assistance.
The uncertainty of the measurements is estimated to be f O . l % . Temperature was known to f0.05O . The volume values for the dilatometer were corrected using the expansion coefficient data of Buffington and Latimer.g Corrections were applied for the quantity of material in the dead space POLYMORPHISM I N MONOCHLOROACETIC above the liquid. ACID The vapor pressure data are given in Table 11. The data to two atmospheres have been fitted by BY R. E. KACARISE the equation Naval Research Laboratory, Washington 86, D. C . log,oP(mm.) = 18.90112
1443 467 - 4.09566 logloT -A T
(2)
The normal boiling point calculated using equation (9) R. 19. Buffington and W. M. L,atimer, J . A m . Chem. SOC.,4 8 , 2305 (1926).
Received October 86, 1966
It is well known that monochloroacetic acid exists in at least three distinct crystalline varieties-l Re(1) "Beilsteins Handbuch der Organischen Chemie," J u l i u s Springer, Berlin, Fourth Edition, H2, 194, 1920; E.12, 87 (1929); E112, 187 (1942).
