*.1 '4Rt.E I! IIoIality of
€IC1
( i . 002(iO
0 .11)12
I llti
II ,
002cio
0.1042
1.043
Temperature,
oc.
c,v1ts
I3rown (;e0 25.0 0.690 .675 19.0 31.0 .TO7 25.0 .519 19.6 ,514 .'3, 3 ,521;
0.381
.:391
25.ll 2 1 .e02. Combining this with the above heat yields A S o = f.t.7 k 3.1 e.u. By estimating Sa = 1:3 e.u. for G e 0 2 (using Latimer's tables") we calculate the cntropy of F12Ge03(ac1)to be 34.3 i-4.0 e.u. For the oxidation of GeT2to GeOzby triiodide
+
21120
-t GeI?(s)
we calculate AIIO
+ It-
= GeOJ(s)
= - 29.3 &
+ 4T-I- + ,?I-
1.4 kcal./mole.
(9) R Schwari arid R H i i f . Z. nnovg Chem , 203, 1 0 - 1 11'471) (10) C Winkler, J p r a l l Chein , [ Z ] 34, 2 1 1 (1880) (11) tV hI L,itimer TI115 I U I J R U ~73, I , 1480 (1'1711
(ill??)
[COXTRIBUTION FROM 'TIE DBP.4RTMRST
RADIATIOU LABORATORY,
O F CHEMISTRY AND CIIEMICAI. ENGINEERING, AND T;NIVERSITY O F CALIFORNIA
1
The Vapor Pressure of Germanic Iodide. The Entropies of Germanic Halides. The Disproportionation of Germanous Iodide RY WILLIAIIL. JOLLY^ AND WENDELL 31. LATIMER RECEIVED JULY 7, 1932 Germanic iodide sublimes readily a t temperatures in the neighborhood of loo", and in this research the vapor pressure has been measured over a range of 55'. These data have been employed t o calculate AF" and A H D for the sublimation. Since there are no values for the entropy of GeIl(g), the method of Hildebrand has been employed t o estimate the vibrational frequencies and hence calculate the entropy. The vapor pressure of GeI,(g) over mixtures of Ge and GeI2 has been measured over a range of 100". These data have been employed to calculate AF' and A H o for the disproportionation of GeI?.
The Vapor Pressure of Ge14(s).-A saturated vapor flow-method was employed. Germanic iodide crystals were placed in a horizontal glass tube which was heated to a constant temperature while n steady stream of argon was passed through the tube. By assuming that the gas was saturated with GeIr vapor in passing through the tube, the amount of GeI4 which condensecl out on the cooler portions of the tubing was taken as n nit'asure of the vapor pressure. I
Experimental Procedure.-Germanic iodide was prepared by the method of Foster and Williston.2 The product w a ~ purified by r e c r p l l i z a t i o n frnrn chloroform followed by air drying at 80 . Two methods for heating the tube containing the GeId were used. I n two low temperature experiments the tubing was heated by a vapor-jacket similar to that used in Abderhalden driers. The vapors of boiling benzene and of boiling water were used to maintain the temperatures 79.8 and 99.8', respectively. Higher temperatures were maintained by heating the tubing in a horizontal tube furnace. A "Celectray" electronic controller (C. J. Tagliabue Mfg. (1) Taken from a thesis presented by William L. Jolly for partial satisfaction of the requirements of the P h . D . degree, University of
California. 1962. i Z ) L. S . Poster ~ n r lA. 1'. WilliPtoo. I m r ~ S. y n l l m s ~ s 9 . , 112 (1040).
Co.) was u\ed in conjunction with a chromel-alumel thermocouple t o keep the temperature of the furnace constant to kt.7". The thermocouple was calibrated at the boiling point of water and the melting points of ice, tin and cadmium. A sheath of nickel foil was wrapped around the tubing where the GeIl was contained. Linde argon was freed of oxygen and water by passing the gac consecutively through hot copper turnings arid magneiium perchlorate. The total volume of gas passed in a ruii was determined by collecting the gas over water a t the end of the flow system. ( I t wai necessary to correct for the vapor pressure of water ) The runs were timed with a n TABLE
I
VAPORPRESSURE OF GeId(s) Total ~. .~.
Run T , OK.
Time, min.
Flow rate, mole A/min.
99.7 1OR 0.74F X I3 393 206 0.387 X c 393 47 1.69 x 10-3 0 (extrap.) 393 D 408 75 0.527 X lo-* E 379 203 .774 x 10-8 I' 873.0 215 ,735 x 1 0 - 3
A
c;
3&?.0
3uo
,634
x
10.'
pressure in tube, Calcd. vapor presatm. snre of GeIi, a t m .
0.999 1.007 1.008 1.010 1.000 1.002 O.OQQ
8 . 2 x 10-4 8 . 4 X lo-' 7 . 1 x 10-4 8 . 7 x 10-4 1.79 X 2 . 9 x 10-4 2.20 x io-' 4.7
x lo-'
