the diffusion coefficient can be expressed by the equation D = .4 ex&)(- E / H T j
(11)
TABLE VI ENERGY O P
A4CT1V.%'~1(iX AND
where E is the activation energy for diffusion and .I =
el2
(12)
'{e\p(~~ ~ / R I
X being the distance between two successive equilibrium positions. In Table VI, the values of E and X[exp(AS+IR)]"2 for diffusion in the membrane are compared with values of these quantities calculated from literature datal3 on the temperature dependence of diffusion currents a t the dropping mercury electrode. It is apparent that the entropy factor is largely responsible for the difference between the diffusion coefficients of these ions in aqueous solution and in the cellophane membrane. Due to its structure, a (13) V (1929)
S e j e d l y , Collectzoiz Cziclriirloo
Chem
C o ~ i ~ r n u n, s1, 319
COSrRIBUI'ION FROX THE
E N I ' K O P Y ~.4CI'OR FOR L>IP-
:"i'SION
Diffusion s y s t e i n
A
x
103 (cm.g/sec.)
E(kral.)
Xlexp( A S */R)11/1
(A)
T I A -in aqueous solti. 9.4 T1+in cellophane me1ubr;~iie 3.2 Cd'& in aqueous soln. 41
4.2 4.0 5.0
4.9
C d + - in cellophctne xncmhranc
6 5
3.0
6. 6
3.8 1.4
considerable fraction of the iiiembrane is blocked insofar as diffusion is concerned eveii though the diffusion is not restricted to rigorously defined pores. The smaller entropy factor is in accord with this model. Acknowledgment. --The authors are indebted to Professor D. D. DeFord for many valuable suggestions and discussions. EVANSTON, ILLISOIS
RESEARCH INSTITUTE
OF
TEMPLE UNIVERSITY]
The Cyanogen-Oxygen Flame under Pressure BY J. B. CON WAY^ .\SD -4. lT. G~ossr RECEIVED DECEMBER 20, 1957 The cyanogen-oxygen flame yields one of the highest flame temperatures obtainable by chemical means. The experimental flame temperature (4640'K.) a t atmospheric pressure is in good agreement with the calculated flame temperature (4835'K.) providing additional evidence in favor of the high value for the dissociation energy of nitrogen. A technique is described for operating this flame at elevated pressures t o give increased flame temperatures. Flashback velocities at various pressures are reported and are very sensitive t o pressure changes -4 generalized plot is presented for calculating theoretical adiabatic flame temperatures for various CO/N? ratios.
cyanogen-oxygen flame. The inflammability of mixtures of cyanogen and air has been studied by Pannetier and Lafitte.* Doliqueg investigated the represents the simplest possible stoichiometric rela- combustion of cyanogen and reported that i t does tion describing the combustion of cyanogen. The not entirely follow the theoretical chemical equaheat of the reaction a t 298°K. is equal to 126j6802 tion. Reislo made a thorough study of the cyanocal. which when coupled with the fact that the reac- gen-oxygen flame, analyzed the gaseous products tion products are extremely stable suggests the pro- of combustion and also analyzed the flame specduction of very high flame temperatures by this trum. A theoretical flame temperature of 4740" reaction. was reported, but no experimental flame temperaThe reactions of cyanogen with air and oxygen ture was measured. Thomas, Gaydon and Brewer" have been studied for many years. Dixon3 stud- have reported recent work on the cyanogen-oxygen ied the explosion rates of various mixtures of cyano- flame in which the flame temperature was measured gen and oxygen a t several pressures. Smithells by determining the vibrational intensity distribuand Inge14 and Smithells and Dent5 described the tion of the cyanogen bands. The vibrational temstructure of the cyanogen-air flame as obtained perature was found to be 3800 f 200°K. for the with a cone-separating apparatus and also indicated stoichiometric composition. The theoretical flame the gaseous composition of the various cones of the temperature for the stoichiometric composition was flame. The kinetics of the oxidation of cyanogen calculated to be 4SSO"K. using the high value have been studied by Hadow and Hinshelwood'j (AH: = 226,000 cnl. per mole) for the dissociation and Pannetier7 discussed the mechanism by which energy of nitrogen. X temperature of 4325°K. was various additives decrease the luminosity of the obtained when the low value (AH: = 170,240 cal. per mole) was used. From these results the au(1) General Electric C o m p a n y , Aircraft Nuclear Propuliion Department, Evendale, Ohio. thors concluded that the high value is correct. (2) J. W Knomlton and E. J . Prosen, J . Reseavch Tali. B w . SLandAs is the case with all flames the cyanogenu v d s , 46, No. ti (June 1951). oxygen flame temperature is limited by the dis( 3 ) €€, Dixon, J . Chem. Soc., 49, 381 (1886). The equation CZNZk)
+ O ? k ! --+
2CO(g) i S P W
(1)
( 4 ) A. Smithells a n d H. Ingle, ibid., 61, 204 (1892). ( 5 ) A . Smithells a n d F. D e n t , i b i d . . 65, 603 (1894). ihndnn) (fi)H. J. Hadow and C. pi. Hinshelwood, Pvoc. R o y . SCJC
8132, 375 (1931). t7) 0.I'nnnetier, Re?,.I i i c t . F r a n c . Peiit,lt~,4 . ,418 ( l q l l ~ l ~
(8) G. Pannetier and P. Laffitte, Compl. vend., 226, 341 (1918). (9) 12. Dolique, Bzdi. soc. ckim., [ 5 ] 3, 2347 (1936). (10) A. Reis, Z. ,biiy,Tik. Chem., 88, 515 (1914). (11) S.Thnmns. \ C,. f ; , ~ y ~ l al( l ! J l X J .
