TABLE I1 YbSOc Mol. wt. = 303.28, 0°C. = 273.15"K., gbs. mole-' TkIERMOUYEAMIC PROPERTIES O F
T, OX.
5 10 15 20 25 30 35 40
45 50 55 60 70 80 $10 100 110 120 130 140 150 160 170 180 1'30 200 210 220 230 240 250 260 270 280 2'30
298.15 300 3 10 320 330
CP
S
(0.085) (0.643) 1.623 2 . 780 3,899 1.970 6.009 7.046 8.052 8,963 I). 777 10.510 11 ,750 12.818 13.703 14.408 15,235 15.984 l(i.578 17.150 17.691 18.205 18.727 19,274 19.817 20.356 20.895 21.415 '21.924 :?2,406 '22.875 !T3,3 17 :23.717 24.077 24.442 24. 667 24 717 24 995 25 277 25 555
0.028 ,223 .668 1.289 2.031 2.837 3.681 4.551 5.440 6,336 7 ,229 8.112 9.828 11.468 13,032 14.516 15.'333 17.289 18.590 19.840 21.042 22.200 23.319 24.405 2 5 . 462 26.492 27.408 28,482 29.446 30.38'3 31.313 32,219 33.107 33 , !I76 31.827 35.509 35. 660 36.475 37.273 38.053
0.021 ,167 ,490 ,913 1,400 1.906 2.418 2.932 3.445 3 ,952 4.415 -1.921 5.811 6 . 621
7.362 8.035 8.656 9.234 9.774 10.281 10.757 11.207 11.633 12.043 12.438 12.820 13.192 13.554 13.907 14.251 14.587 14.914 15 . 233 15 , 5 u 15.844 16.083 16,137 16.319 1G.6!)2 16. 057
0.007 .OS6 ,178 ,375 ,631 .'33 1 1.263 1.619 1.994 2.384 2.784 3 , 191 4.017 4.847 5.670 6.481 7.277 8.055 8.816 9.559 10.285 10.993 11.686 12.362 13.024 13.672 14.306 14.928 15.539 16. 138 16.726 17.305 17.874 18.434 18.984 19.426 10.525 20.058 20.584 21.102
(3) W. F. Giauqiie a n d R. C. Archibald, J . A m . Chem. Soc., 59, 5131 (1937). (4) W. F. Ciauque, E. W. Hornung, J. E. Kunzler and T. R. Rubin, J . A m . Che7rt. Suc.. 132, G2 (1960). 1 gbs. (gibbs) = 1 defined calorie (deg. I:&I6 (19.58); W. R. Person, R . E. HumFhrey a n d A. T. T'opov, ibid.. 81, 2 i 3 (1959).
to check the formation constant of dioxane-IC1 complex. Since preliminary results disagree with those of Lilich arid Presnikova, a more thorough study of this constant was indicated. Experimental Part The source and purity of iodine monochloride, of carbon tetrachloride. and dioxane as well as cxnerimental details of spectral measurement,s have been des;ribed in previous publications . 6 # $ I n a typical run a series of eight solut.ions was prepared cont,aining small and constant concentrat,ions of iodine monochloride and varying large excesses of dioxane. Concentration of iodinr chloride was determined by an iodometric tit'ration. Dioxane solutions were prepared by the addition of a given amount of dioxanc from a weight buret to n given volume of carbon tetrachloride and diluting to the dcsired conrentration. Solutions used for infrared measur('ments had t o be quite concentrated, and bocansc~of thv difficulties involved in morlting with concentrated iodin0 monochloride solut,ions Lrhirh wore described earlirr ,9 t.hrcmrcntrations of thrse solutions irere knoLvn otil>- with a n :muracy of itoyo. absorption spectra of ICl-dioxane niixturcs were determined in the visible and ultraviolet regions; since tht: uncomplexed IC1 showed some absorption in this region, tlie niethod of Ketelaar, et u L . , ~ ~ ~ was O used for computing tho formation constant. The data were treated b y the niethod of least squares and are summarized in Table I . TABLE 1 ABSORBANCE DATAAKD FORMATION COKYTISTOF DIOXAXE-IC1COMPLEX Ci"&
7.848 X 7.848 X 7.848 X 7.848 X 7.848 X 7.848 X 7.848 X 7.848 X ac I e Kf KW7.
C2L. ... 0.051 .I02 . I 3 ,204 ,255 ,357 ,510
355
nip
;ibsorbanrr 315 nip ~ 5 . in* j
:3rij
nip
0.022 0.025 0.048 0.120 ,370 ,500 .til3 ,695 ,460 ,635 ,755 ,865 ,520 .io5 ,Xti5 ,950 ,535 .71% ,!)I0 ,995 ,555 ,770 .!I38 1.025 ,590 ,805 !ti5 1.005 ,620 ,845 1.015 1.110 83.0 114.6 139.1 150.!) 23.86 23.12 23 07 23.03 23.27 i0 , :3-L
For thv infrared studies, solutions of dios:ine and IC1 in CC1, also were used. In one scriw of cjxpc'rinients :t solution of 0.05 31 IC1 \vas stndird with concc3ntr:~tionsof dioxane ranging from 1.0 t o 0.1 A!. I n anothvr series, the IC1 concentration was 0.1 ,If, while the dioxanc concentration was varied from 0.1 to 0.0125 M . Thew conccntrations were not the most desirable values, hiit, m - w ~ r e limited by the reactivity of the halogen t o fairly dilute solutions. However, tjhe concentration of the complex must be high enough so that its absorbance can he measured. This imposes rather narrov limits on the range of concentr:ttion which can be studied. As seen from Table I , the average valw for tlie form:rtion constant measured in t,he ultraviolet rrgiori is 23.3, n-hich is much lower than the value reported by Lilirli and Presnikova.6 However, a personal romminiic:~tio~i from Prof m o r Lilich disclosed that they also oht:iinec for Ki in a series of solutions i n whirh N vc' of dioxane was used, but :tt~t~rihiited i; to n r i c~spcrirnciit:il error. Thr results of 1,ilic.h m t l Priwiikova, :is w~ll:is t h o w of Iltissel and Hvoslofs point to n distincxt possi1)iIit). t h a t in solutions wit,h only a small excess of tiioxanr-, :L tiiox.2IC'I complex might be forming, to sonic cxtcmt at, It.ci,st,. This \vould derrea.se t>hccoriwntration of frcv iodine nionorliloridc and w-ould account for t h c higher v:rlue of thcl ca1cul:ttttl formation constant. On the other hand, ivith :i,large vxress of dioxane only the 1:l complex has a chance to form. T\-hile it might be possible to prove the existence of tho (10) A. 1. Popov, C. Castellani-Bisi and (1958).
11. Craft. ibid.. 80, 6573
