1431
V O L U M E 2 7 , N O . 9, S E P T E M B E R 1 9 5 5 Accuracy of this method has been tested with synthetics and found to be =k2.9% with 95% confidence limit for samples containing as little as 0.1% of fluorine. Duplicate determinations of catalysts and minerals showed a standard deviation of l.2yO. ACKNOWLEDGMENT
The authors wish to express their appreciation to Ernest Solomon and J. hl. McCrea for their interest and generous hclp in preparation of this paper. LITERATURE CITED (1) Ebers, W.F., Lamb, F. C . . and Lachele, C . F: , IND. ENG.CHEM., ASAL. ED. 10. 259 (1938). (2) Haslam, J , andkhettem, S.AI. A , J . A p p l . Chem. (London), 2, 399 (1952).
W.F.. Lundell. G. E. F.. Bright. H. .1..and Hoffman, J. I., “Applied Inorganic Analysis,” p. 939, Wiley, Sew York, 1953. (4) Huckabay, W. B., U‘elrh, E. T., and Metler, A. V , A s 4 ~ . (31 Hillebrand.
CHEM.,19, 154 (1947). (5) Ximball, R. H., and Tufts, L. E., Ibid., 19, 150 (194i) (6) Parrish, AT. C., Widmyer, J. H., Brunner, -4.J., and JIathon, F. R., Ibid., 19, 156 (1947). (7) Rafter, T. A., Analyst, 75, 485 (1950). (8) Rowley, R. J., and Churchill, H. V., IND.ENG.CHEM, -4r.4~. ED.,9, 551 (1937). (9) Shell, H. R., and Craig, R. L., ASAL. CHEM.,26, 996 (1054). (10) Steiger, G., J . Am. Chem. Soc., 30, 219 (1908). (11) Willard, H. H., and Winter, 0. B., IND.ENG.CHEX,A N ~ L ED., 5 , 7 (1933).
RECEIVED for review February 17, 1955. Accepted M a y 12, 1955.
Determination of Oxygen in Calciwm Metal A. R. EBERLE, M. W. LERNER,
and
U. S. Atomic Energy Commission, N e w
G. J. PETRETIC
Brunswick Laboratory, N e w Brunswick,
A rapid procedure is presented for the determination of oxygen in calcium metal. The method consists of the reaction of calcium with anhydrous methanol and dissolution of the reahtion products by addition of an anhydrous salicylic acid-pyridine solution. The water formed by the reaction of the oxide with the salicylic acid is easily determined by titration with Karl Fischer reagent. A simple apparatus for the reaction and titration operations is described. Data are presented to show that pyridine effectively inhibits esterification between the salicylic acid and the methanol. Results are given on the determination of anhydrous calcium oxide equivalent to 2.5 to 13 mg. of oxygen with a precision of about 0.1 mg. Calcium metal containing 0.4 to 2% of oxygen was analyzed readily.
L
ITERATURE reviews have disclosed no recorded method for the determination of oxygen in calcium metal. Reccntly, White, Ross, and Rowan ( 7 ) have determined oxygen in sodium by the reaction between sodium and excess n-butyl bromide in hexane solution. The sodium monoxide which does not react with thc reagent was determined by titration, after addition of water. Pepkowitz and Judd (6) developed a method for olygen in sodium which essentially depends upon the extraction of sodium with mercury in an inert atmosphere and the separation of the residual sodium monoxide, which is insoluble in mercury. Williams and Miller (9) have reported a modification of the method of Pepkowitz and Judd. Xone of these methods was found to be adaptable to the determination of oxygen in calcium. The authors have developed a new method which is based upon the fact that methanol reacts with calcium to form calcium methylate, but does not react with calcium oxide. Following this rcaction, dissolution of the calcium methylate and calcium oxide by addition of a salicylic acid-pyridine solution yields soluble calcium snlicvlate, methanol. and water. The water which is liberated stoichiometrically from the oxide present i, determined by the Karl Fischer ( 6 ) method using the dead-stop end point technique of Foulk and Bowden ( I , 4 ) . 4PF4RATUS
The apparatus used for the reaction of calcium with methanol is shown in Figure 1.
N. J.
The borosilicate glass reaction and titrating flask of 250-ml. capacity has a T 24/40 center neck and a T 14/20 side neck which is fitted with a ground-glass stopper. The refluxing condenser is 300 mm. in length and connected to the center neck of the flask through a bushing type ada ter of T 24/40 outer g r o u n i zone and T 14/40 inner ground zone. A straight stopcock is sealed to the to of the condenser and is t i e n connected through a ball-andsocket joint to a Nesbitt absorption bulb containing a layer of Drierite covered with anhydrous magnesium perchlorate. Solutions are stirred with the aid of a magnetic s t i r r e r . T h e glass covered stirring bar is 35 mm. in length and 5 mm. in diameter. A Beckman Model K-F Aquameter is employed for carrying out the Karl Fischer titration. T h e s t a n d a r d 125-ml. titrating flask and duel platinum electrodes supplied with the Aquameter are used in determining the water (blank) content of an aliquot of the methanol drawn from the reaction flask prior to addition of the calcium. The smaller flask is also used for titrating the salicylic acidDvridine solution before addiFigure 1. Reaction and ;
