Table I. Determination of Azide in Synthetic Sodium Azide Mixture Aiide Concn., Relatlvr lIg./lOO 111. Error hmplt. Present Found i < 1 4.!I 4.9 0 0 9.6 2 4 2 ‘38 5.9 6.1 :3 , 4 3.6 J 2.9 3.0 Precirion (on 10 detnp.) :3 4
lu = 1 0 08
3 4 5 . $1 3 5
me.
mp and a pH of 2.2. Spectrophotomet,ric determination of the empirical formula of the complex gave a 1 to 1 ratio of ferric to azide ion. EXPERIMENTAL
Instruments. A Beckman q u a r t z sy)cctrophotometer Model DL- with a IO-mm. Cores or silica absorption ccll was used for absorbance mcssiii~ements. All measurements n-erc~made :tt the maximum sensitivity of th(’ instrument. I Beckman Model G p H rnet,er was used in adjusting t,he p H of d l solutions. Reagent Solutions. A reagent solotion 0.011M in iron(II1) was prepared liy dissolving 0.6142 grain of electrolytically pure iron wire in 7 5 inl. nf 6.051 perchloric acid. T h e solution nxs heated below boiling until the volunie \vas reduced t o 25 ml., t’raiisf e r i ~ t lto a 1-liter volumetric flask. and diluted to t h e mark with dist,illed water, giving a solution 0.01 1-1.2 in iron (111). Tests for iron(I1) and for chloride with potassium ferricyanide and silvrr nitrate, respectively, were npg:itive. Li solution 0.01131 in azide was prvp a r d by dissolving 0.7150 pram of
192.
commercial sodium azide in 1 liter of clistilled water. Procedure. Pi-Det 25 ml. of 0.11-%f fcwic perchlorateAsolutioninto a 2501111. beaker previously marked t o indi(.ate t h e 100-nil. level and add 25 ml. of dist.illed water. Adjust t h e p H t o 2.2 with 0 . 1 s perchloric acid or 0 . 1 s sodium hydroxide (carbonate-free!, using t,he Beckman pH meter. A i d da sample containing no more th:in 10 mg. of azide. Agitate the solution and dilute to 90 ml. with distilled watcr. Check the pH once more, quantitativeljtransfer the solution to a 100-ml. volumetric flask, and dilute t’othe mark. Measure the absorbance a t 454 nip ngainst a ferric perchlorate blank. Calculate the amount of azide in the sample from a calibration curve made from standard sodium azide solutions ranging from 0.5 to 10.0 mg. of azide per 100 nil. Effect of p H and Stability. l‘hc fcirric azide complex will form in this I” range from 1.7 t o 2.7. A t p H 3 : i i i d higher t h e solution beconiw c,loudy because of the formation of n qi.spensioii of hydrated ferric osidv. .In intermediate pH of 2.2 was chosw for t h e analysis. T h e solution will gi,adually fade if exposed to the air in (ither the dark or light. The color hding is caused by the liberation of hydrazoic acid from the solution. Solutions should be read immediatcly :ifter the complex is formed. Empirical Formula of Complex. ’ l h slope ratio and the continuow wriations methods ( I ) indicated ferric. ion-azide ion ratios of 1 to 1.1 and of 1 to I, respectively, confirmi-g the work of Ricca (3’). Interference of Diverse Ions. The following ions did not interfere in
concentrations exceeding 50 m g . per 100 ml.: ammonium, barium, lead. lithium, potassium, sodium, acetate, ea1 bonate, chloride, cyanide, nitrate, and perchlorate. Thiocyanate in vonerntrations of more than 1 mg. per 100 ml. nil1 interfere. Determination of Unknowns. ,4 wries of solutions comprising a wide range of sodium azide concentrations TI as prepared and issued as unknon ns t o one investigator. Table I indicates t h a t t h e relative error varies from 0 t o 6% and t h a t the standard d r w a tion is t0.08mg. of azide LITERATURE CITED
(1) Harvey, A. E., hlanning, D. I,,,J . Am. Chena. SOC.72, 4488 (1950). (2) Labruto, G., Randisi, D., - i r i n . chivs. ~ p p l 22, . 319-24 (1932). (~:3) Ricca, B., Gam. ch,it)a. ital. 75, 71-7 (3945). (4)
Robcrson, C. E., ilustin, C. h l . >-%SAL.
(:HEM.
29, 854-5 (1957).
AXTHONVAS TON^ JACK G. D O D D ~ AUBREYE. HARF’ET. JR. I~nivc~rsity of Arkansas Fa yet t cville, Ark. 1 Present address, Textile Fibers I k partmelit, E. I. du Pont de Kemoiirs & (’o,, Inc., Wilmington, Del. 2 Present addres?, Department of Physics, Driiry College, Springfield, Mo.
.IBSTR.KTED from a thesis submitted in the Department of Chemistry, University of Arkansas, by Anthony Anton in partial i’iilfillment of the requirements for the master of science degree. The major part of the n o r k was supported in the Ilepartment of Phvsice under Contract DA--13009-ENG-3i32 wit,h the IT.S.Army Engiiieer Research and Development 1,:)Iioratorie9, Fort Rclvoir, T’n.
X-Ray Powder Diffraction Studies of Hafnium Tetraiodide
BRIGITTE KRAUSE, A. B. HOOK, F. WAWNER, and HYMAN ROSENWASSER, United States Engineer Research and Development Laboratories, Fort Belvoir, Va.
H
TETRAIODIDE. HfI,, hac been prepared by the direet combination of elements by a method described by Corlise, Bozman. and Westfall ( 1 ) . The high purity metal was heated in an excess of iodine vapor within an evacuated generating chamher of high purity quartz. l f t e r formation of the iodide, the system was wevacuated and the sublimate driven into quartz capillaries which were flamesealed. The salt which formed ycillow-orange in color.
AFNIUM
1210
ANALYTICAL CHEMISTRY
Powder diffraction photc;graphs wew taken of the Hf14with a North American Philips Straumanis-tyFe caniera of 114.6-mm. diameter using nickel-filttxred cwpper K radiation. The average’ c’xposure time was approximately 12 hours, and the room temperature was relatively constant at 25” C. E o corrections could be made for film shrinkage. Table I contains the d- values, ohierved relative intensities, proposed indices, and calculated lattice con-
htants for HfI,. Although this diffraction pattern appears to describe a face-centered cubic lattice m-ith a lattice constant of 5.88 X.! w assume the lattice constant’s to be twice as large. This conclusion results from a romparison with patterns of other cluadrivalent halides for which the lattice constants have been established hy single crystal data. For instance, :i very close analogy can be seen in the int,ensities and line sequences of HfI4, TiBr,, and %I4. Because Si14 and TiBr4
and t h a t there are eight HI14 molecules per cell. It has been noted that the lattice constants, and thus the interatomic distances, are smaller than for other quadrivalent iodides.
Crystallographic Data for Hafnium Tetraiodide d Lattice d Lattice Values Intensity" Indices Constant Values Intensity" Indices Constant 3.394 s 222 11.76 1.470 w-ms 800 11.76 2.940 vs 400 11.76 1.350 vvw 662 11.77 2.080 s 440 11.77 11.77 1.316 ms 840 1.774 ms 622 11.77 1.199 w 844 11.75 1 697 ms 444 11.76 a Intensities are relative, visually estimated, and described in terms of the intensity scale: vs, very strong; s, strong; ms, medium strong; w, weak; vw, very weak. and vvw, very very weak. Table 1.
crystallize in the Sn14 structure (a), it is assumed t h a t Hf14 behaves siniilarly and belongs t o the space group Pa3 Thb.
HASTINGS and D. E. NICHOLSON, Humble O i l 8, Refining Co., Baytown, l e x . - - _ _ _ _ _ ~
cs-133 Slif
A
Accu-
-
or v B.L. Pts.
(mm) AA or
Concn. /100ml length
Av
mm
-~
D. E. NICHOLSON and 5. H. HASTINGS, Humble O i l 8, Reflning Co., Baylown, Tex.
___ 13.05 0.720 1 0 . 0 6 3 ~ 1.005
benzene
-
No.1
1 1.100 0 . 0 9 9 ~ 1.005
3
1
1 5
0 . 0 8 0 , ~ 1 * 005
1,2,3,5-Tetra-~ CloHla methylbenzene
1 0-100
i
1
~
f0.6
I
11.79
0.900 0.081~
~-
Instrument: Perkin-Elmer M o d e l 1 12, NaCl prism Sample Phase: Solution in carbon disulfide Cell Windows: NaCl Absorbance Measurement: Calculation:
Base line-.
Inverse m a t r i h X Graphical--
4
~
AX or AU
Pts.
length mm
~-
~
0-100
1,3-Dimethyl- CinHlr 4-ethyl I beizene 1-Methyl-3tert-butylbenzene
C1IHIG
1,2-Dimethyl4-ethylbenzene
rf0.8 -I--
1
0-100
i
12.25 0.550 0.051~
005
~~
1
10.8 14.19 1.650 0.141~
005
~~
1
C ~ n H l r 0-100
zkO.5 1 12.21 0 . 5 5 0 I 0.051p
_ _ _ _ _ _ _ _ _ _ - _ ~I
005
~
Instrument: Perkin-Elmer M o d e l i 12, NaCl prism Sample Phase: Solution in carbon disulfide Cell Windows: NaCl Absorbance Measurement:
Point_&-
Concn.
/lo0 m l
(mm)
1 1 0 . 5 12.38 0.550 0 . 0 5 1 ~ 005
1
11.54 0.900
~
~
1
2
methylbenzene
Formula
~
2-ethylbenzene
~
I
Name
X or v 8.1.
~
l
__ 13.85
cs- 134 Slit
Accuracy
Component
12.21 0.550 1 0 . 0 5 1 ~ 1.005 benzene
CRYSTALLOGRAPHIC data for publication in this section should be sent to W. C. PIIcCrone, 501 East 32nd St., Chicago 16, Ill.
Determination of Cl0- and Cll-Alkylbenzenes
S. H.
Component
(1) Corliss, C. H., Bozman, W. R., Westfall, F. O., J . Opt. SOC.Am. 43, 398 (1953). (2) Ryckoff, R. 1J7. G., "Crystal Structures," Vol. I, Chap. V, p. 27, Interscience, New York, 1948.
It is thus concluded that the iodine arrangement approaches a cubic closepacked lattice u-ith the Hf atonis occupying l/* of the tetrahedral holes,
Determination of ClpAlkylbenzenes
~ ~ _ _ _ _ _ _
LITERATURE CITED
Calculation:
Base line-
Inverse m a t r i i Graphical-
Successive approx..----
-
Point_-X.Successive approx._
Relative AbsorbonceFAnalyticd Matrix
Relative Absorbances-Anolyticol Matrix: Component/X
1 2 3 4 5 Material Purity:
12.21~ 13.05~ 13.85~ 11.54~ 0.029 0.039 0.026 1.061 0.011 1.830 0.010 0.007 0.140 0.543 0.011 0.031 0.009 0.003 0.004 0.665 0.010 0.003 0.006 0.032
11.79~ 0.009 0.000 0.000 0.021 0.828
99.8%.
Comments: lsodurene (component 5) shows somewhat larger apparent departures from the Beer-Lambert l a w than any o f the other components o f this system. The absorptivity is 0.0828, 0.0795, and 0.0763 l i t e r l g r a m mm. when computed from solutions having absorbances of 0.400, 0.500, and 0.600.
ComponentlX 1 2 3
4 Material
Purity:
12.38~ 1.418 0.128 0.016 0.105
12.25~ 0.128
1.103 0.009 0.835
14.19~ 0.012 0.014 1.043 0.027
12.21~ 0.090 0.875 0.009 1.061
99.8Yc',.
Comments: Apparent deviations for 1 -1nethyl-3-tert-but) lbenzene are such that the absorptivity computed a t an absorbance level o f 0.600 i s 7% smaller numerically than the absorptivity calculated from solutions having an absorbance o f 0.400.
VOL. 32, NO. 9, AUGUST 1 9 6 0
1211
