106 PROPERTIES OF ELECTRICALLY CONDUCTING SYSTEMS 



relation between the conductance and the concentration. In the case 

 of aqueous solutions, however, sufficient data are available to make it 

 possible to obtain a general notion as to the manner in which the con- 

 ductance varies as a function of concentration. Assuming a reaction of 

 the type 



MX 2 = M- + 2X-, 



and assuming the mass-action law to apply, we obtain the equation: 



In Table XXXV are given values of the function K' calculated 

 according to the above equation at a series of concentrations for calcium 

 chloride dissolved in water at 18. 



TABLE XXXV. 



VALUES OP THE MASS-ACTION FUNCTION FOR CaCl 2 SOLUTION 

 IN H 2 AT 18. 



C .... ID' 3 5X10- 3 2X10- 2 10' 1 5X10- 1 



.954 .910 .849 .764 .686 



1.88X10' 5 1.7X10' 4 1.62X10' 3 1.88X10' 2 2.6X10' 1 



I v:.: 



It will be observed that the mass-action function for this salt increases 

 very greatly with the concentration. On the whole, the increase is much 

 more marked than it is for binary electrolytes. The value of the func- 

 tion, moreover, is much lower throughout than it is for solutions of binary 

 electrolytes. At 5 X 10' 1 normal the value of K' is only 0.26, which is 

 approximately one-half that of potassium chloride, while at 10' 3 normal 

 the value is 1.88 X 10~ 5 . The mass-action function, therefore, falls off 

 very rapidly as the concentration decreases. In the case of copper sul- 

 phate solutions we have the equation: 



Values of the mass-action function for this electrolyte at different con- 

 centrations are given in Table XXXVI. At higher concentrations the 

 value of the function K' for this salt is smaller than that for calcium 

 chloride, but the constant decreases much less rapidly as the concentra- 

 tion decreases and at lower concentration the value of the function is 

 much greater than that of calcium chloride. On the whole, the function 

 appears to undergo a smaller change with the concentration in the case of 

 copper sulphate than in that of uni-univalent electrolytes. However, it 



