REACTION VELOCITY AND SOLUBILITY 47 



The réaction velocitj constants are proportional to tlie equilibriiiin 

 constants and tlie proportionality constant is represented by // in équa- 

 tion (2). Tliis factor A contains the efïect due to viscosity and othei- 

 as yet unclassified causes. Let us now change the solveut, tlie new 

 solvent bj définition to be one in which the first substance is less sohible 

 and the second more soluble. This means that, for the same concen- 

 tration, the chemical potential of the first substance is higher and of 

 the second lower. In otlier words, /•, in équation (3) is to be rephiced 

 by tlie larger value /•', and /,:, m e(iuatiou (4) hy the sniallcr value />■'.,. 

 The equilibriuni will be displaced to th(> side of the second substance 

 for we shall bave equilibriuni when 



//, c, = /•', c,. (5) 



If the change of the solvent introduces no disturbing éléments other 

 than the change of soliibility, the réaction velocity at any moment 

 will be 



We thus see that a decrease in the solubility of one of the reacting 

 substances tends to increase the rate at whicli the other is forined. 



It does not necessarily follow that the actual reaction velocity will be 

 increased in any concrète case, because it is extremely improbable that 

 the change of solubility will be the only change produced by substituting 

 a new solvent. It is quite conceivable that there might be an increase 

 in the factor ^7 which would more than couuterbalance ') the changes 

 in k^ and k.^. This would nierely show what we already know, that the 

 relative solubility is not the only factor in determining reaction velocity 

 coefficients and does not ali'ect the validity of the proof that the réaction 

 velocity coefficient varies in a perfectly deiinite way with the solubility 

 of the reacting substances. 



Silice a monomolecular reaction running one way dillers from the 



') Beuzaldoxinie in lienzene solution would appeav to be an inslance oflliis. 



