x IO-'" for phenylmercuric hydroxide, 1.5 X 10-5 for phenylmercuric acetate, and 3.1 X for phenylmercuric propionate. Each of these values was found to be constant for experimental points taken 01 er a wide range of (Tacld/TPhHgOH) values. The constant for the hydroxide is further substantiated since it was used in calculating both of the other constants. The value for phenylmercuric hydroxide found in the present work that has been agrees with the value of 1.0 X reported.2 Thwe constants may be used in estimations of equilibrium constants for the interaction of phenylmercury compounds with groups such as the sulfhydryl group in biological materials.
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I
SORPTION OF SULFUR HEXAFLUORIDE RY ARTIFICIAL ZEOLITES BY DANIELBERGA N D WILLIAMM. HICKAM V e s t i n g h o u s e Cmtrnl Laboratories, I'ittstiuryh Q 5 , Pmnsylz'ania R e c e i i d .April 86, 1961
The small and uniform size of the intracrystalline pores left, by t,he removal of water from hydrated crystalline zool.ites results in "molecular sieve" act'ion. 31Iolecules of large diameter are excluded from the pores,; smaller diameter molecules may be sorbed in the intracrystalline pores. With mixtures of molecules of diameter smaller than the sieve pore :sizes preferential sorption may take place. Habgood' 'has studied the kinet'ics of Molecular Sieve action for nitrogen-methane mixtures. In this case nitrogen diffuses more rapidly into the small pores and is preferentially taken up in the early stages of sorption but methane has a higher affinity for the sieve and is preferentially sorbed a t equilibrium. In this work we are interested in studying the sorption of a rnolecule of roughly 5 A. diameter, namely, SF,, :is a function of t'emperature and pressure and the selective sorption in mixt'ures of SF6and air. Experimental Procedure A gas circulatclry system wit,h mass spectrometer2 was used in measuring sorption of SF6 by the Molecular Sieve. This system ofler~~ wveral advantages over other equipment used for similar measurements. The calibrated volume and manometer permits accurate determination of the quantity of gas used. The system is attached to the mass spectromtter which providcs analysis of the gas when desired. When mixturw of gases are being used the circulating pump ensures ihiLt the gas abow the sieve is of uniform composition. 'This sondition, eomhined with the mass spectrometric analysis, permits calculation of the quantity of each cornponeizt adsorbed even though there are large teniper3turc gradients in the system due to heating of the sieve. .A weighetl amount of sieve was plxed in the system. T h r sieve vv)~.r ~ \ x t i l t t dand heated to ahout 200" to re. Sulfur hexafluoride wv&sintroduced
r I O it known pressim of i: tn the romvcjir was
SF, :tnd then repeated sev-
: I ) R.W. K>L,goc?, Can. J . Chem., 36, 1384 (1958). (2) L.,;.!
