CJiemistry. — " N'itroffen Jixation bij tnenns of the cyanide-process 

 and atomic structure." By Dr. L. Hambuhgek. (Commuiiicated 

 by Prof. P. Ehrenfest). 



(Communicated at the meeting of June 30, 1923). 



a. Introduction. It is known tliiil tlie reaction 



MCO, + 4 C + N, = M (CN), + 3 CO 

 forms the foundation for I lie nitrogen fixation by the so called 

 cyanide process. For this conversion tlie temperature at which tlie 

 capture of the nitrogen takes place with practically appreciable 

 velocity appears to be very divergent, according as another M is 

 chosen for the metal. H. Lundén ') has also inclnded rnbidiuin and 

 ceasinm in his researches, and is of opinion that there is a relation 

 between the boiling-points and atomic weights of the metals in 

 question and the "cyanizing-teiTiperalnre". It is, however, not possible 

 to derive a quantitative relation on this foundation. 



b. Stages of the cijanizingreaction. In order to arrive at a clear 

 insight the fact should be considered that according to J. E. Buchek '), 

 two stages before all should be distinguished in the course of the 

 reaction : 



1. MOO, -I- 2 C = M -I- 3 CO 

 II. M + 2 C + N, = M (CN),. 



Of these reactions I bears an exceedingly endothermal character, 

 II on the other hand, is strongly exothermal, IT takes place pract- 

 ically momentarily (either with addition of a catalyst or without). 

 Whether a practically appreciable reaction-velocity will appear, 

 will therefore depend on I. The strongly endothermal character of 

 I '), however, causes the temperature to remain pretty well constant, 

 when the reaction sets in, till the reaction of MCO, has been com- 

 pleted. The quantities of energy required for this are so great, that, 

 especially at comparable conditions, factors like energy-quantifies, 



1) Cf. Th. Thorsell. Zeitschr. f. angew. Ohem. 33, 251 (1920). 

 «) J. E. BucHER. Jl. of Ind. and Eng. Cham. 9, 233 (1917). 

 ') In consequence of which the total reaction I + tl is also still endothermal 

 in a high degree. 



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