V O L U M E 23, NO. 1 2 , D E C E M B E R 1 9 5 1 LITERATURE CITED
(1) Bone, W. A,, Parsons, L. G. B., Sapiro, R. H., and Groocock, C. M., Proc. Roy. SOC.(London), 148A,492-522 (1935). (2) .Juettner, B., J. Am. Chem. Soc., 59, 208, 1472 (1937). ( 8 ) Juettner, Smith, and Howard, Ibid., 59, 236-41 (1937).
1883 (4) Smith, L. I., and Byrkit. G. D., Ibid.,55, 43058 (1933). (6) Smith, R. C., Tomarelli, R. C., and Howard, H. C., Ibid., 61, 2398-2402 (1939). RECEIVED February 9. 19.51.
Polarographic Determination of Nickel and Zinc in Copper-Base Alloys W. E. ALLSOPP' AND THEODORE E. ARTHUR Fenn College, Cleveland, Ohio Z I S C and nickel are ~ i ~ u a ldetermined, ly in control analysis of copper-base alloys, h y time-consuming precipitations. Copper a n d lead are determincd eIwtrolyti(:a11y after tin is precipitated a s metastannic acid. The authors felt thxt this procedure, might be shortencd i f a ~)ol:irographicdetermination of nic.ki.1 and zinc could he coniIjincBd wit,h the routine procrdu~rsfor the other three metals. A review of the litrniture rwealed that Lingane ( 3 )had made a systematic polarographic. drtrrmination of zinc, nickel, lead, ant1 tin in copper-base alloys, but t o accomplish this, he used constant potential r~lectrolyticapparatus, two samples, and two different, supporting electrolytw. Sherman (6) developed a polarographic method for the determination of zinc in copperalloys; the othrr mctals w('re only sepnratcd arid not quailt itvt ively determined. Folloiving the litrrature searvh, an investigation of polarographic analysis of the filtrate after the electrolytic separation and determination of copper and lead showed that the polarographic method is entirely feasible and saves much tinie over the earlier precipitation methods for zinc and nickel. Copper, lead, tin, z i n c , and nickcl can be determined with this method in 3 hours. APPARATUS
A Model XI1 Snrgent photographic recording polarograph with a dropping mercury cathode having a drop time of approximately 4 seconds per drop. The dropping mercury elect,rode was held with a holder previously desrril,ed (I). II-type polarographic caellf with a saturated calomel electrode ( 2 ) . Tank nitrogen, purifictl 1)y passing through a solution of vanadous sulfate (4). . h i isothermal bath regulated :It 30.0" i .0.1" C. .-\ Fisher Electro Analyzer w a s uped for the electrol~sis. PRELIMINARY RESEARCH
The linear relationship between the diffusion currents and the concentrations of zinc and nickel in a supporting electroll-te consisting of 0.4 A1 ammonium nitrate and 1.5 fi'. ammoniuni hydroxide was confirmed with standardized solutions of zinc and nichel. Tin was removed as metastannic acid, copper and lead were determined siniult aneously by the constant current electrolytic method, and zinc and nickel were determined polarographically. iln unsuccessful effort u-as made t o determine zinc and nickel polarographically in the filtrate from the electrolysis of copper and lead when fluoride ion was used t o hold tin in solution as used by Ravner ( 5 ) . PROCEDURE
Dissolve a 1.0-gram sample with 12 ml. of concentrated nitric w i d in a 250-1111. beaker and after the action has ceased evaporate the solution t o dryness. (If the copper alloy contains more than Present address, National Spectrographio Laboratories, Inc., Cleveland, Ohio. I
__
_-
Table I. Sainple 124a
-_
~-~ --
-
-~
___
_.
inalyses of Vatioiial Bureau of Standards Samples Zinc, LiO ?*'ickel. % Present 5.25
Found
Present
3 . 15
Found
Kot rPp0rtP.d
5 .15 5 15 3 . 15 5.15 5.15 63a
0.61
0.64 0.63
0.63 0.63 0.64 52
1.88 1,88 1.88
1,88
1.88
1,88 52a
3.17
3,l5 3,15 3.17 3.19 3.19
37c
27.22
27.04 27,OO
0.58
0.59 0.58
G2b
37.97
37.90 37.3
0.27
0.27 0.27
8yotin, evaporat,e the solution to approximately 5 ml. to avoid loss of tin by splattering.) Add 12.5 ml. of concentrat,ed nitric ncid and boil t o bring the salts into solution. Add 100 ml. of water and digest for 30 minutes. Filter with the aid of paper pulp, keeping the solution hot. \\'ash the precipitate with hot 2% nitric acid. The metastannic acid may be ignited, weighed, and calculated to per cent tin in cont,rol mirk. Add 1 drop of 0.1 S hydrochloric acid t,o the filtrate and dilute to 150 nil. with water. Copper and lead are plated on platinum elect,rodes, the anode being rotated, n-it4ha current of 1.5 amperes following the usual eleotrolyLic technique. After 15 minut'es t h e current may be raised t80 2.5 amperes unt,il deposition is complete. Copper IS deposited on the cathode and lead peroxide on the anode. Under t,he above conditions copper and lead may be determined simultaneously. Transfer t8hefiltrate from the electrolysis t,o n 250-ml. volumetric flask and dilut,e to the mark with nat,er. Take a 50-ml. aliquot, and transfer to a 100-ml. volumetric flask. Add 4.0 nil. of 0.5% gelatin solution and 1Q ml. of concentrated amrnrinium hydroxide. Dilute t o the mark wit.h wat'er. Transfer a portion to the polarographic cell. Remove the dissolved oxygen from t8he solution with pure nitrogen and obtain a polarogram over the range 0 to -2.0 volts I ' S . the saturated calomel electrode. lfeasure t,he height of the polarographic waves occurring a t half-wave potentials of -1.15 and -1.38 volte vs. S.C.E. a t 30" C. and relate t8histo the concentration of nickel and zinc. DISCUSSION O F RESULTS
The results obtained on six National Bureau of Standards copper-base alloy samples are shown in Table I. They indicate t h a t the proposed polarographic method will
1884
ANALYTICAL CHEMISTRY
M.. and Linmne. J. J.. "Polaropraphy," P. 215, New York. Interscience Publishers, 1941. (3) L i n w e . J. J.. IND.ENG.CHEM.,~ I L ED.. . 18.429 (1946). CHEM..20,984 (1948). (4) Meitea, L.. and Meites, T., .4ar~. ( 5 ) Ritvner. H.. IND.ENG.CHEU..ANAL.ED.. 17,41-3 (1945). (6) Sherman. M., Foundru, 78, 94 (1050) (2) Koithoff, I.
yield satisfactory results for nickel and zinc in copper-base alloys. N o results for the copper, lead, and tin were reported, a s t h a t of the is in daily use in foundry and familiar to moEt chemists. LITERATURE CITED
(1) Allaopp.
W.E., .4NnL. CHEM.,21, 428 (1949).
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5 1. N-Phenyl-2-naphthylamine
Sign of Douhle Refraction. Pl'egative Acute Binectrix. b = a.
C o n t r i b u t e d by W. C. MCCRONE, Armour Researoh Foundation of Illinois I n s t i t u t e .of Technology, Chicago 16, Ill.
Prinoioal Lines
PHENYG~-NAPHTHYLAMINE can be recrystallized from rnethNinol, ethanol, ether, benzene, or acetic acid. The best crystals for x-ray and optical work are obtained either from methanol or by sublimation. Recrystallization from methanol even with liberal use of deoolodaing charcoal gave reddish brown crystals; the product from sublimation, however, was colorless. There is little or no effect of the coloring material on other optical properties.
d 9.12 6.45 3.51 4.83 4.35 4.30 4.16 4.02 3.92 3.80 3.68 3.53 3.47 3.21
I/Ir 0.30 0.10 0.28 1.00 0.03 0.33 0.53 very weak 0.08 0.14 0.20 0.03 0.09 0.13
3.12 2.99 2.91 2.86 2.81 2.79 2.58 2.37 2.28 2.23 2.15 2.41 1.88 1 84
0 16 0 21 very weak 0 07 0 05 Very weak very weahvery weak very weal, Very weahvery weak very weak very weak Very weah-
e
C
I
F i g u r e l . Fusion Preparation of Phenyl-2-naphthylamine
CRYSTAL MORPHOLOQY Crystal System. Orthorhombic O r t h o g r a p h i c Proje,ction of Typical C r y s t a l of Phenyl-2-naph t h y l a m i n e
Figure 2.
,
I"I,.
Axid Ratio. a:b:e = 0.942:1:0.412. Interfacial Angles (Polar). 201 A 201 = 98'34'. 92" 34'.
X-RAYDIPFRACTION DATA Cell Dimensions. a = 17.45 A.; b Formula Weights per Cell. 8.
=
110 A i i n =
18.25 A.; e = 7.52 A.
Formula Weight. 219.27. Density. 1.237 (flotation and pycnometer); 1.226 (x-ray).
OPTICAL PROPERTIES Refractive Indexes (5893 A,; 25' C.). a = 1.636 =t 0.005 B = 1.82 0.01. Y = 1.92 =t 0.002 (cslculated). The cargille index medium 1.512 when saturated with phenyl-2naphthylamine m t o h e s the alpha refractive index of that eom-
+
nn,."'i _rY+ IIII".."
-.
0
81 ~~
~
l "
pptic Axial Angles.
Molecular Refraction ( R ) , R(aalcd.) = 70.4. R(obsi3.) FUSIONDATA.Pheuyl-Z-nitprl~nyliLlmnewnen rearysmineen from methanol several times shows a micro melting point of 107108' C. and an equilibrium melting point of 107.8" C. The melt solidifim spontaneously to give many spherites. T h e unit crystals are coarse rods and the nucleation rate rises rapidly as the temperature falls t o mom temperature. The rate of crystal gmwth is rapid at all temperatures between the melting point and mom temperature. A meltback gives broad rods showing o tie axis interference figures with 2V = 65" 1) > r, (-). A txymol mixed fusion gives well-formed rods &ith all refractive indenes ereater than thvmol. " . n_a r d~e l extinction, and a 79' profile aGgIe.
(5893 A.; 25' C.). 2V = 65'.
Dispersion. v > 1. Optic Axial Plane. 001,
2H
=
~
Cos~nrsn~rona of orystallogra~lhiodata for this section should be aent to Walter C. MoCrone. su~ervisor, AnalYtiChl Section, Armour Research Foundation oi the Illinois Institute of Technology, Chiaago 16, Ill.
