228 Dr. Todd and Mr. Owen on the Influence of 



its 2 is the cross-section of the sphere of action, \ 3 is the 

 volume occupied by one molecule, and XI is the average 

 molecular velocity. The value of hjO being small compared 

 with unity we may take the frequency of collision propor- 

 tional to O, i. e. proportional to 6. Hence 



But V=&NflNj, where k is the " velocity constant." 

 Therefore 



*«''^[* + iy [*+**] 





If k 9o and k $l are the velocity constants at the temperatures 

 2 and #j we obtain 



< + 4-p + Q) 



* < + &+<*) 



P, Q, and W being constants having the values 



p 4y°" Q= *!4|' w 4( e « +e >)> 



E being the critical kinetic energy of the molecule. 



In the general case A + B + C + . . . .— > it is obvious that 

 we shall obtain the expression 



where the form of <f> is determined by the number of 

 reactants. 



The Effect of Temperature on the Equilibrium Constant. 

 Let us take for example the homogeneous gas reaction 

 A + B^C. 

 For the forward reaction 



and for the back reaction 



