Chemical Affinity. 191 



3. Systems consisting of an indefinite Number of Soluble 

 Substances. 



When several chemical reactions proceed simultaneously in 

 the same solution, the velocity of each individual reaction is in- 

 dependent of the other reactions. 



The conditions of equilibrium for such a system are ex- 

 pressed by the formula 



A/ A/1 /tO • • • thy, • 



Putting - =z, it may be shown that 



1+ r z 



k x 



The general equation is deduced 



P±J + Zi±Qi. + .... + P^ = Q +Ql+ .... Qn . (6) 



1+ tt z 1+ T 



fCi K n 



The value of z can be found by aid of this equation, and from 

 that the value of g, <? lr • • g n , and finally the value of p, p lr . . p n . 



Several illustrations are given of the application of this for- 

 mula ; but no experimental data have as yet been accumulated. 



As an example of the method of solving the problem pre- 

 sented by a system consisting of many soluble substances, the 

 question is discussed : — How would one equivalent of soda 

 divide itself between 1 equivalent of hydrochloric acid, 1 equi- 

 valent of sulphuric acid, and 1 equivalent of oxalic acid ? 



Let the original system consist of 1 hydrochloric acid + 1 

 sulphuric acid + 1 sodium sulphate; and let A = hydrochloric 

 acid, Aj = sulphuric acid, A 2 = oxalic acid, B = sodium chloride, 

 B"i = sodium sulphate, and B 2 = sodium oxalate; then 



P = l, P 1= =l, P 2 = 0, 



Q = 0, Q, = 0, Q 8 = l. 

 From Table I. (p. 189) the following values are found: — 



k=l, ^=025, £ 2 = (K>676. 

 Equation (6) then gives 



1 + * + ,i .1. 



1+z 1+4. z ' 1 + 14-8.* 



By repeated trials of various values for Z\ the approximate 

 value of that proportion is found to be 0*62. Hence the 

 following equivalent proportions are determined for the con- 



