REACTION OF ACTIVENITKOGEN WITH
SULFUR
bution of radiation chemical effects to the recoil product distributioii probably does not exceed about 2%.
2501
Acknowledgment. This research was supported in part by the U. S. Atomic Energy Commission.
The Reaction of Active Nitrogen with Sulfur12
by J. A. S. Bett'b and C. A. Winkler Upper Atmosphere Research Group, Department of Ch.emistry, McGill University, Montreal, Canada (Received March 16, 1964)
The amount of nitrogen that reacts with Szvapor to form sulfur nitrides has been measured for three different initial concentrations of N atoms and several sulfur flow rates. A marked induction period preceded formation of any nitrides, and the maximurn concentration of Iz' atoms that appeared in the products was less than the initial 8 atom concentration. These results are explained by a mechanism in which the NS radical is formed in the initial reaction(s) and is rapidly destroyed in the presence of excess Tu' atoms. I n the absence of PI: atoms, the KS intermediate will either disproportionate or form stable sulfur nitrides both in the gas phase and at the surface of the reaction vessel. The infrared spectra of the products showed t h a t IY.S.1and a t least two other sulfur nitrides were present. The blue flame associated with the reaction may be attributed to a transition D ( 2 ) + C(*II) of the NS radical.
Introduction The reaction of active nitrogen with sulfur has been described briefly by Strutt,2 who sublimed sulfur into a stream of active nitrogen and obtained a yellow and a blue product. He suggested that these were NSd and a polynier of SS, respectively. Moldenhauer and Zimmerman3 found, in addition to these, a red compound, S2Se,when solid sulfur was heated to 100' in a nitrogen discharge tube. The present study was made to obtain quantitative information on the react>ionbetween active nitrogen and sulfur vapor, for comparison with the analogous reaction with oxygen, which has been investigated previou~ly.*-~ Experimental The apparatus was essentially a conventional fastflow system with a cylindrical, horizontal reaction tube. One stream of nitrogen, with a flow rate of 140 prnoles/sec., was subjected to an electrical discharge
to produce the active nitrogen, which then passed into the reaction tube. A second nitrogen stream, 50 wmoles/sec., was passed through a furnace at 450' and entered t h e reaction tube through a concentric jet 2 mm. in diameter. The pressure was 3.0 mm. in the discharge tube and 4.5 mm. in the furnace. Sulfur was contained in a vessel that could be niaintained at any desired temperature between 100 and 250". A third stream of nitrogen was passed over the (1) (a) Presented a t the 145th National Meeting of the American Chemical Soriety, New York, N. Y.,September, 1963; (b) postdoctoral Research Fellow. (2) R. J. f3trut.t. Proc. Roy. Sac. (London), A88, 539 (1913). (3) W. Moldenhauer and A. Zinimerman. Ber., 62, 2390 (1929). (4) C. B. Kistiakowsky and G. G.Volpi, .I. Chsm. Phys.. 27, 1141 (1957). (5) C . Mavroyannis and C. A. U'inkler. International Symposium 011 the Cheniistry of the Lower and Upper Atmosphere, San Francisco, Calif., April. 1961. (6) M. A. Clyne and B. A. Thrush. PTOC. Roy. SOC. (London), A261, 259 (1961).
Volume 68, Number 9 September, 1964
heated sulfur, t a carry sulfur vapor through a jet into the second iiitrogcn strcaiii in thr furtiace a t 450' a i d thenct. into tkic reaction tu1)o. A iiictal-iti-glass plug that rostcd in a ground glass srat prcvcwtrd the flow of sulfur vapor until the sulfur had attaiticd thr>desired tempcraturc. I%w of thc vapor \vas thcii start~t.dby raising t h e plug niagricltically froiii its seat. A stiugly fitting iririer sletvc~\vas insc'rtcd into the rchaction tube to act as a rercivtlr, on the wall of which the solid products of the. reaction wcre drpositcd. After rach expcriinrnt this slctw was rctiiovrd t,hrough a ground glass joint, and t h c \wight of solid products was ohtaincd froni the gaiii in weight duc to their deposition during t h c cxpcrinient. ?'he rcaction titile was adjusted, in t h c range of 5 to 120 min., to yield 50 t o 150 nig. of products. The nitrogcw content of t h e products was dctcrtiiiIied by Kjrldahl analysis, using 2 N NaOII for thc hytlrolysis. Applied t o a known sariiple of tctrasiilfur tctratiitride, A'&, t h e method gave 97% of t h r t)hcorrtical nitrogen content,. Sitice S4Sr is tiiore stable to hydrolysis than any other sulfur tiitride, it was assuiiicd that the iiirthod was satisfactory for any rnixture of nitrides that might be foriiivd. The weight of sulfur deposittd during cach cxprrirneiit was obtained siiiiply as thc difl'twnce t)ctwrcn the w i g h t of the total product arid the w i g h t of t h c iiitrogeti givcm by Kjeldahl analysis. Calilratioii of the sulfur flow rate with the tcbtiipcratnre of the sulfur was thercfort utiricccssary. In practicr, the flow ratcs of sulfur, calculatcd froni analyscs of rcm-tion products, were in good agrcenieiit with thosc ohtaincd whcri the discharge was not in opcratioii (12ig. 1). Siricc the logarithm of t h e flow rtitc of sulfur was linear with 7', rather thaii 1 T,' thr carrier gas was presumably riot saturated with sulfur vapor. Active nitrogen was produced (ither by niicrowave clcctrodclrss or by corideriscd clcctrotle d i s ~ t - i a r g c . ~ ~ ~ The concentration of S atonis in thc active nitrogen was rstitiiated in tn-o ways: (i) from the tiiaxitiiutii prowhich was introduced duction of I l C S frotii etliylcric,~O undcr exactly the satiit c.otiditiotis as tkic sulfur, arid (ii) by thc SO titration t r c l i r i i q ~ cin , ~which ~ NO was siniilarly i titrocluced. 'l'tic wall of t h e rractioti tubr was riot dclibrratrly poisotid, hit sincr tht. systeiii was opct~cd t o t h r atniosphcic M o r r cach rxpc.riiiictit, sotiic wall poison was protlably introduccd. ('otit inuous puiiiping for scwral days was found to reducr gradually the niaxit i i u i i i H C S yic,Id froiii cithyl(wc.,prwuiiiably its tlic walls dcgasscd. llowever, rmsonnbly consistcrit va1uc.s for the iiiaxiiiiiiiii IICS productioti were ohtaiticd by
30-
2.0-
0
/
f
P
a/
allowing t h e systciu to rcniain opeti to the atmosphere for at lcast 30 niiii. prior to rach cxpcriiiicnt. Qublitii(?d sulfur, suppliod by Jlctx!k and e o . , was used wit,liout, furthcr purification. I.irido " l m i i e dry" nitrogen was passctd over coppcr t,tirtiiigs a t 150' txforr entering the imctioti syst,cin.
Results T h e results for diffrtvnt, flow rates of sulfur, at rach of three different initial coiiceiitmtions of N atonis (HCK basis), arc show1 in Fig. 2. T h o amount of iiitrogeri atonis that, reacted wit,li sulfur to forrii stable products varictd in a siiiiilar tiiatiti(?t'i n ( 4 1 set of experimcvits. T h e behavior may bc dcscribrd u.ith rcforeti(:o to three zorics of stoichionictry, reprcsetitd as I, 11, and 111, for rach 9 atjoin concetitrat,ion indicated. In zone I , whrre tht: sulf'ur atotii Aow rat(. was less than the S t t t o i i i flow rate, iio apprcciablc atiioririt of nitrogen was found in the product laid down in the re( i ) IV. Ko\v.:dski, C'lrim. Slosoci~nrm.4 , 517 ( 1 9 N ) .
( 8 ) 1'. A . Gartnpaliix and C . A. Winklcr. Pun. J . Chcm.. 39, 1457 ( 1 961)
~
(9) r,SIawoj,aniiis and ( ' , A . W i n k l e r . i b i d , 39, 1001 (1901). (10) rZ. S. Wright. It. I,. Nclson, arid (". A. M'inklcr, ihut., 40, 1082 (1962). ( 1 1 ) 1'. Kirifrirari a n d J. I
