1344
NOTES
slight shoulder a t 7.28 EL and the broadening of the 7.93 EL band are due to the presence of phenoL4 I n addition to the work described above the authors also have determined that it is possible to detect phenol in aqueous solution a t a concentration of 0.45y0 using the band a t 8.15 p, and phenoxide ion a t 0.63Y0 using the band a t 7.93 p . There are experimental indications that it is possible to detect phenoxide ion a t concentrations as low as approximately 0.2% in water.6 (4) An approximation of the apparent dissociation constant for phenol can be obtained by plotting the decrease in intensity of the 7.28 AI band (which decreases in intensity on increasing the phenoxide ion concentration) verws the observed pH. When such a plot is made, i t is seen t h a t the mid-point of the curve is a t pH 10, which is close to the known value for this ionization.6 Although only three points have been used to obtain this value, the authors feel t h a t these points are significant. An attempt will b e made in the future t o refine these mea8urements. (5) C. M. Judson and M. Rilpatrick, J . A m . Chem. Soc., 71, 3113
(1949).
(6) The quantitative determination of phenol in water by infrared spectrophotometric methods is being explored in the authors’ Laboratory.
LATTICE CONSTANTS OF AMMONIUM CHLORIDE-AMMONIUM BROMIDE SOLID SOLUTIONS B Y VINCENT e. A N S E L M O A N D NORMAN 0. SMITH Departmeat of Clremisfw, Fordham University, Ne% Y o r k , N . Y . Received January 88,1969
The need for a convenient means of aiialysiiig solid solutions of ammonium chloride in ammonium bromide led to the measurement of the variation of their lattice constant with composition. The lattices of both components are of the interpenetrating simple cubic type at room temperature, and a complete series of solutions is possible between the two. Only one isolated measurement of a lattice constant of such a solid solution has ever been reported.’
Vol. 63
Table I, and are believed accurate to 0.005 A., considering the inaccuracy of the wedge technique and the lack of temperature control. The values for the pure components, viz., 3.875 and 4.059 A. for the chloride and bromide, respectively, agree satisfactorily with those of the National Bureau of Standards,4,53.876 and 4.059 A . at 26’.
TABLE I LATTICECONSTANTS OF NHaC1-NH4Br SOLID SOLUTIONS Compn,, mole fraction of NHaBr
0.00 .04
.OB .I1 .23
Lattice constant,
A. 3.875 3.875 3.882 3.883 3.907
Dev. Compn., Dev. from adLattice from admole ditivity, fraction constant, ditivity, A. X 103 of NH4Br 8. 8. X 103 ,
,
-7 -8 -12 -10
0.47 .70 .00 1.00
3.963 4.000 4.060 4.050
$2 $5 $3
...
It seems clear that the U.S.P.materials in the present work contributed no error greater than that introduced by the X-ray technique itself. Table I also gives the deviation of the lattice constants from Vegard’s rule of additivity. It is seen that the solid solutions follow Vegard’s rule within experimental error except for those with high ammonium chloride content, which exhibit negative deviations. (4) H. E. Swanson and E. Tatge, “Standard X-Ray Diffraction Powder Patterns,” Vol. 1, National Bureau of Standards, 1953, p. 59. ( 5 ) H. E. Swanson and R. K. Fuyat, ref. 4, Vol. 2, p. 49.
THE USE OF DIFFERENTIAL THERMAL ANALYSIS FOR INVESTIGATING THE EFFECTS OF HIGH ENERGY RADIATION ON CRYSTALLINE AMMONIUM PERCHLORATE BYELI S. FREEMAN .4ND DAVID A. ANDERSON Pyrotechnics Chemical Reseaick Laboratory, Picatinnu Arsenal, Dover, New Jersey Received January 6, 1069
Differential thermal analysis (d.t.a.) involves the continuous measurement of temperature difExperimental ferences between a sample and thermally inert U.S.P. grade :iinnioniuin chloride and ilnin~oniuinbro- reference compound as a function of sample or mide were used without further purification. The solid reference temperature and/or time, as both the solutions were made by mixing hot concentrated aqueous solutions of the coinponcnts with stirring and allowing to sample and reference compound are heated siniulcool. Stirring was continued for a t lcast 48 hours to im- taneously a t a predetermined rate. This techprove the homogeneity of the resulting crystals. The nique has been used to characterize and to study latter were filtered, dried overnight and stored in a desic- the high temperature physico-chemical behavior cator. They were then analyzed potcntion~etrically(silver and calomel electrodes and standard silver nitrate) with the of clays, minerals, inorganic and organic systems’ help of an adaptntiou of the method of McAlpine.2 Total as well as for investigating reaction kinetic~.~,3 lialide was det,ermined, and then chloride alone, after dc- In this paper we are reporting on the application stroying bromide with permanganate. The accuracy of the of differential therinal analysis to the study of the method, estitblished by analyzing synthetic mixtures of ammonium chloride and bromide, g;tvc mole fractions of effects of radiatioii on crystalliiie ammonium perNH4Br within 0.01 for low bromide contents and within chlorate. 0.003 for high. X-Ray powder photographs were talcen a t A powdered saniple of C.1’. aiiinioiiium perchloroom temperature as described in an earlier study3 and the rate was irradiated with an OEG-50 X-ray tube, in lattice constants evaluated therefrom. The sharpness of the lines indicated that the solids were essentially homogene- air, for 100 hours at 40 kv. and 20 ma. a t a distance ous. Only the last five lines of greatest glancing angle were of 1 em. from the tungsten target. The total used for the calculation of each constant, but, for each dosage of radiation was approximately lo7 rosolid, the mean deviation of these was usually less than 0.002 entgens. The differential thermal analysis apA . and, a t the most, 0.004 A . (mole fract,ion of NH4Br paratus was similar to that previously reported* 0.23). The lattice constants for each composition are shown in with the exception that a two pen Leeds and (1) R. S. Havighurst, E. Mack, Jr., and F. C. Blake, J . A m . Chem. ~ o c .47, , 29 (1925). (2) R. K. McAlpine, ibid., 61, 1065 (1929). (3) E. T.Teatum and N. 0. Smith, THISJOURNAL,61, 697 (1957).
(1) C. B. Murphy, Anal. Chem., S O , 867 (1958). (2) E. S.Freeman and B. Carroll, THISJOURNAL, 62, 394 (1958). (3) H. J. Borchardt and F. Daniels, J . A n . Chem. Soc., 79, 1102 (1957). (4) S.Gordon and C. Campbell, Anal. Chem., 27, 1102 (1955).
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