201 



Q^ 



log k = (25 to 35) ——^ — 2 v . l,hlog T — :E r . 1,1 



4,571 7' 



while the following form maj be derived for the temperature coef- 

 ficient of the reaction constant: 



kr, ^ ^ 



From the first of the two equations maj be read that in bi-mole- 

 cular reactions the velocity is greater, as the Q, is smaller, while 

 it follows from the second equation that the temperature coefficient 

 increases on increase of the Qi- When, therefore, the same reaction is 

 brought about without, and one with exceedingly little catalyst under for 

 the rest identical circumstances, the catalysed reaction, which proceeds 

 more quickly, will require a smaller heat of activation for its mole- 

 cules, and possess a smaller coefficient of temperature than the not 

 catalyzed reaction, two conclusions which may be verified experi- 

 mentally. 



Briefly T.'s train of thought comes to this that he assumes that 

 it is required both on formation and decomposition of molecules 

 that they pass into a reactive form (not always atoms) with absorp- 

 tion of energy and that on collision of these active molecules the 

 reaction always takes place. Van 't Hofp's reaction isochore being 

 the starting point in Trautz's theory, it is comprehensible that the 

 stress has been laid on the changes of energy taking place in the 

 reaction, and that the importance of the constant of integration is 

 not sufficiently brought out. And yet it is clear on some consider- 

 ation that the only thing required for a bi-molecular reaction is 

 not a collision, but a collision at the right place (perhaps with the 

 exception of very simple molecules). This favourable constellation 

 which may be expressed in the form of a quantity of entropy, does 

 not occur in the reaction isochore. Accordingly in Tkautz's theory 

 changes of entropy in the reaction have only been considered in 

 so far as the number of collisions are concerned. 



That with by far the majority of the reactions change of the 

 internal energy of the molecules is accompanied with change of the 

 molecular entropy ^), is not sufficiently taken into account in Lewis's 

 theorie either. There, too, it is assumed that before being able to 

 react, every molecule must have a certain excess of energy, called 

 by L increment of energy. This increment would be absorbed in 



1) Tresling, These Proc. Vol. XXIII, p. 143. 



J 3* 



