I 
 
 MDDC - 1044 
 
 UNITED STATES ATOMIC ENERGY COMMISSION 
 
 USE OF A ZINC SPIRAL IN THE TITRIMETRIC DETERMINATION OF URANIUM 
 
 by 
 
 John H. McClure 
 Charles V. Banks 
 
 Iowa State College 
 
 This document consists of 2 pages. 
 Date of Manuscript: Unknown 
 Date Declassified: June 17, 1947 
 
 1 
 
 This document is issued for official use. 
 
 Its issuance does not constitute authority 
 
 to declassify copies or versions of the 
 
 same or similar content and title 
 
 and by the same author(s). 
 
 Technical Information Division, Oak Ridge Directed Operations, 
 Oak Ridge, Tennessee 
 
USE OF A ZINC SPIRAL IN THE TITRIMETRIC DETERMINATION OF URANIUM 
 
 By John H. McClure and Charles V. Banks 
 
 A number of methods are reported in the literature for determining uranium titrimetrically by 
 reducing hexavalent uranium to the tetravalent state and titrating the latter by menas of standard 
 oxidizing agents. 
 
 Of these methods of reduction, probably the most common is the use of a Jones reductor using 
 amalgamated granular zinc as the packing material. 3 Silver, 1 lead, 6 or cadmium"' 9 packing for the 
 reductor is also used. Other methods use aluminum 5 ' 2 ' 4 or copper 7 spirals. All these methods are 
 reported as giving satisfactory results, but certain difficulties are encountered in each of them. 
 With the amalgamated zinc, the uranium has a tendency to be reduced to the trivalent state and 
 must then be oxidized to the tetravalent state by bubbling air through the solution for a few minutes. 
 Aluminum tends to give over reduction also, and after all the metal has dissolved, the solution 
 being hot, there is an appreciable amount of the tetravalent material oxidized unless air is excluded 
 during cooling. The use of a copper spiral requires the exclusion of air and long periods of boiling. 
 In the use of any reductor, a transfer of solutions is involved with the concomitant chances for error. 
 
 REAGENTS 
 
 Uranium Metal, U: Uranium metal of known purity was used. 
 
 Uranium Oxide, U 3 O b : Uranium oxide prepared by igniting ether-extracted uranyl nitrate was 
 used. 
 
 Zinc, Zn: High purity (99.99 per cent) zinc wire*, having a diameter of 0.125 inch, was used to 
 prepare the spirals. A piece of zinc wire about 700 mm long was wound on a cork borer 20 mm in 
 diameter. A length of the wire was left uncoiled, the end of which was bent into the form of a hook 
 to aid in the removal of the spiral from the flask. 
 
 All other reagents were of reagent-grade quality. 
 
 EXPERIMENTAL WORK 
 
 A tetrasulfatoceric acid solution was standardized against pure uranium oxide, U 3 O e , by the 
 conventional method using the amalgamated zinc Jones reductor 3 and also by using a zinc spiral. 
 The normality of the tetrasulfatoceric acid was found to be 0.1121 by the former method and 0.1123 
 by the latter method. These values represent the average of a series of determinations in each case. 
 
 The precision and accuracy of the proposed method was checked in the following manner. 
 Samples of uranium turnings were cleaned by placing them in dilute nitric acid until they were free 
 
 Zinc wire having these specifications can be obtained from the following sources: 
 Matthiessen and Hegller Zinc Co., La Salle, Illinois 
 
 Metallizing Company of America, Inc., 562 W. Washington Blvd., Chicago, Illinois. 
 The Piatt Brothers and Company, Waterbury 90, Connecticut • 
 
 MDDC - 1044 fl 
 
2 ] MDDC - 1044 
 
 of any oxide coating. These turnings were then carefully washed and dried. Samples of the turnings 
 were analyzed according to the recommended procedure given below. The results of these experi- 
 ments are shown in Table 1. 
 
 Table 1. Titrimetric determination of uranium after 
 reduction with a zinc spiral. 
 
 U U Error 
 
 Taken Found U 
 
 (g) (g) (mg) 
 
 0.5446 0.5448 -0.2 
 
 0.5625 0.5627 +0.2 
 
 0.5343 0.5338 -0.5 
 
 0.5716 0.5718 +0.2 
 
 0.5667 0.5669 +0.2 
 
 0.5160 0.5159 -0.1 
 
 0.5200 0.5200 0.0 
 
 0.5033 0.5027 -0.6 
 
 0.5293 0.5292 -0.1 
 
 It was found that if sulfuric acid was present, the rate of reduction was retarded and that the 
 boiling time must be increased from the usual 5 minutes to as much as 25 minutes to effect com- 
 plete reduction. 
 
 RECOMMENDED PROCEDURE 
 
 Weigh into a 500 ml Erlenmeyer flask a sample containing about 0.5 to 0.6 g of uranium, and 
 treat with 30 ml of concentrated hydrochloric acid and 10 ml of 60 per cent perchloric acid. Heat 
 the mixture on a hot plate until all the uranium is in solution and fumes of perchloric acid are given 
 off. At this point the solution should be light yellow in color. Cool the solution and dilute with a 
 mixture of 250 ml of water and 10 ml of concentrated hydrochloric acid. Place a zinc spiral in the 
 flask and boil the solution vigorously for 5 minutes. Cool the flask under running water to room 
 temperature and remove the spiral. Wash the spiral with a stream of water from a wash bottle 
 while removing it from the flask. By leaving the spiral in the solution until it is cool, oxidation of 
 the tetravalent uranium by the atmosphere is prevented. After the spiral is removed, pass a 
 current of air through the cool solution for 5 to 10 minutes. Add two drops of 0.025 M 1, 10-phenan- 
 throline ferrous sulfate indicator and titrate the solution with 0.1 A' tetrasulfatoceric acid. 
 
 REFERENCES 
 
 (1) Birnbaum, M. and S. M. Edwards, Jnd. Eng. Chem ., Anal . Ed. 12: 155 (1940). 
 
 (2) Campbell, E. D. and C. E. Griffin, J. Hid. Eng. Chem . 1: 661-664 (1909). 
 
 (3) Furman, N. E. and I. C. Schoonover, J. Am. Chem . Soc. 53: 2561-2571(1933). 
 
 (4) Griffin, C. E., Mining Eng. Wor ld, 37: 247-248 (1912). 
 
 (5) Karn, E. F., J. Am. Chem . Soc. 23: 685-726(1901). 
 
 (6) Kohlic, P., Chem . Listy 19: 1-3(1925). 
 
 (7) Scagliarini, G. and P. Pratesi, Ann, chim. applicata . 19: 85-90(1929). 
 
 (8) Treadwell, W. P., Helv. Chim . Acta , 5: 732-743(1922). 
 
 (9) Treadwell, W. D., M. Luethy, and A. H. Rheiner, Hel v. Chim. Acta, 4: 551-565 (1921) 
 
UNIVERSITY OF FLORIDA 
 
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