1034
PRODYOT ROY,RAYMOXD Id. ORR .\si)R.ILPII HLTLTGREN
J701.G4
bond dissociation cnergies of the tli>ulfidec (RSSR) are given by c, 'ollp
I1
E
-F -H
1 04 1 00 0 97 0 92 1 08 1 05 1 os I 03 101 0 05 1 44 1 42
-c1 -Br
-I -CS
-O€I -SH2 -0Et -0CEI -SH -SCH7 -0OH -SCH212Hj
T.IBLEI1 Atom !XI C F €I Paiiiing'selectroneastiritS(E) 2 . 5 4 . 0 2.1 C-X boml distanw 0,) 1 . 3 2 1 10 v% i,. 1 32 1 . 3 3 e 1 . 4 9 1 32
C1 Br I 3.0 2 8 2.4 1 . 7 9 1 94 2 14 0.98 0 . 8 0 0 . 7 3 1 04 0 . 8 i i 0 1;s
=
84€~€.
and ESR
= 0
73 f 0.21ER
The bond dissociation energy equations for hydrazines (R2K-SR2), and nitroso or nitro compounds (ONX or 02SX)appear to be D = 5 4 ~ 1 ~ 2 and D = 7 0 € , ~respectively. ~, There is considerable uncertainty in these two series, however, hecause of the very limited number of reliable data and consequently the corresponding X constants may require correction at a later date when more data become available. The validity of these equations can be seen froin the examples shown iii Fig. 8. The bond dissociation energies for the diatomic inolecules Hq, F?,C12, Brz, I? do not fall into a general series having a comnion X. On the contrary, each has a X characteristic of the element in question :tnd its isotopes. It is interesting to notice that the €-values for F, H, C1, Rr and I may be related to Pauling's electroiiegatis-ity E.S The quantity E is given almost exactly by y ' z / r where I* is the correspondiiig C-X bond length. (See Table 11.) This is c~ousi~tent with the observations of Glocklerg who reported that the hoiid dissociation energy of 11-S in the series, n-here X is F,C1. Br and I (but not H) is inversely proportioiial to the C-X bond clistance. The present correlation accounts for the earlier anomalous hehavior of 13. I t is also noted that the expre=ioii for calculating ep, for the group RlR2R C, i y very nearly equal to
THE THERPIIODYS,IRIICS O F BISMUTH-LEAD ALLOYS' BY PRODYOT ROY,RIYMOYD L. O m C'ontrihvtion .from the Department
0.f
AID
R ~ L P HYLTGREN H
Jlzneral Technolog?,, ~'niwrsatyof Calffornia, Berkeley, Cal
R . B. Ger;laium, Z/ ui. Piz. Khzm., 37, 1973 (1957). L 2nd I t . Brnnewitz, Arch. Eisenhi~tlen~o., 29, G G 3
(1958). ( 5 ) C . Tvzack and G . C . Raynor. d r l a CrvsL., 7, 505 (1953). (13) 31. & p s i , ' V i p p o n K i n k . Oakk.,3 , 123 (1939). i i i W. B. Pe:irson. "A Handbook of Lattice Sparings end Struct n v s of l l e t n l s and Alln Pergan,on Press, New York, N . Y., 1958. ( 8 ) R . L . O n , A . (:oldberg and R . Tliiltpren, Rev. Sci. I n s l r . . 28, 767 (19,57). (9) D. 13. S t i l l and 13. C'. Siiike, "Tlicrmodynaniic Properties of the Elements," .Imerican Chemical h c i e t y , Washington. D. C., 195G. (10) R. Hultg-en, P. Newconib, R. L. Orr a n d L. Warner, Proceedings, Symposium No. 9, National Physical Laboratory: The Physical Chemistry of :.lctdlic Solutions and Intelmetallic Compounds, H.ll.S.O., Londcm. 1!339, Paper 113.
xPb.
Fig. l.-Pliaw
diagram of the hismiith-lrad s w t m
700
0
PRESENT INVESTIGATION
0
O E L S E N 8. BENNEWITZ"'
600
500
r:
0 t-
a 400 a \ J
a V
-
I
300
Q 200
IO0
0
0.5
0.6
0.7
0.8
0.5
I .o
XPb.
Fig. L'.--IIr:tts
of formation of p- : ~ n de-phav B-1'1) a1lo.i-9a t 400"li.
ire calorimetcr hiit u b r 5 tliphen\-l ether in.tt~ntl of wtter ns the working mediiim.
Results The values of (WT - H2YR) n-ere determined for the &alloys at 385 and 485°K. and for the i o at. % P b €-alloy a t 385°K The measured value> indicated that heat coiiteiits were additive within a deviation of 0-5 cal./g.-atom, implying that the alloys obey Kopp's lam (AC, = 0) within t h e temperature range of present interest. This is in contrast with the results of Levi" n h o found a positive deviation from Kopp's law, undoubtedly due to precipitation at room temperature by maiiy of his specimens. The measured heats of solution for pure Bi and the alloys and the integral heats of formation evaluated a t T , are given in Table I. Also tabulated (11) A. L?vi, Atta reale u t . vrneto
6C1.
leftem ed art%,75, 627 (1916).
I’IZODYOT ROY,I? ~ Y M O U DI,. O R HA Y D R ~ L P IHULTGREV -I
1036
are thci valurs for the partial molar heat of solution of Bi(l) in Pb(1) a t infinite dilution a t 654°K. (av. == -885 cal./g.-atom) calculated from the data for pure Ri and values of H T , - FIT, evaluated from published heat content data for Ri. Since AC, = 0, the heats of formation, shown plotted ill Fig. 2 , will be independent of temperature arid thus apply to 400°K. or any other temperature of interest. Also shown are the data of Oelsen and Beniien it^,^ who measured heats of formation by pouring the pure liquid metals into a calorimeter and allowing them to solidify, assuming that homogeneous solid phases mere formed. Their data agree well with the present values in the pregion but deviate coiisiderably for the E-alloys, where a great deal of segregation during freezing mould appear unavoidable. I;or this reason it is believed thnt the present value.: are to be preferred. TABLE I O F THE:
Run no.
HEATSO F ALLOYS
66-3 67-3 66-4 67-4 66-5 67-5 66-7 67-7 66-8 67-8 66-9 67-9
AHaoin.,
ZPb
Ti.O R .
Tr,
392.7 395.3 397.6 395.8 3!V.7 396.0 3!15.0 394.6 398.0 396.4 393.0 300.7
653.8 653.6 653.9 653.6 653.9 653.7 654.0 653.7 654.4 653.7 654.4 653.7
0 95, p .95. p .90, s .90, p .83, P .83. p .TO, E
.;o,
E
.65, e .65, c .GO, E .GO. e
cal./ &-atom
O K .
9857 2828 2831 2876 2754 2759 2591 2630 2539 2570 2493 2522
FORMATIO’i
AHrmym.. 400° K.,
cal / g.-atom
113 125 139 109 241 249 516 482 584 563 691 679
(H
-
N1)Bi.1f
66-2 66-10 67-2 67-10
Pure Bi Pure Bi Piire Bi Pure Bi
392.9 303.0 404.4 405.1
653.9 654.5 653 7 653.7
3561 3548 319 1 3172
- 879 -896 -S i 6 -888
The curve drawn through the integral heats of formation of the P-phase is represented by the parabolic equations
t
AH
= 1950ZBiZr~,
Ai?,,
= 1950~~pb = 1 9 5 0 ~ ~ ~ ~
Aifpb
(1)
Within the ep1ia.e the data are best fitted by a straight line AH
= 1750-1’i90xpb
ARB,,= 1750 Agpb
than the values derived from the temperature co~ and efficients of e.m.f. determined I J Strickler Seltz.l5 The results of Kleppa and Wittig arid Huber indicate that Kopp’s lam is obeyed by the liquid alloys, hence ACp = 0. The selected free energies of formation were taken from the e.m.f. measurements of Strickler and Seltz,’s which ale in agreement with the e.m.f. values of Wagner and Engelhardt l6 aiid the vapor pressure measurements of Goiiser.li A S values for the alloys were calculated from the selected values of AH and AF. The calculated partial and integral quantities for the liquid alloys a t 700°K. are given i n Table 11. TABLE I1 PROPERTIES OF T,IQUID AI.I.OYSAT 700°K. AF,
ZPb
1fEASU12CD T f 1 : A I i O F SOLCT10’4 A Y D
(2)
= -40
Reconciliation of Thermodynamic Data Liquid Alloys.-Heats of formation measured by I
