THE CONDUCTANCE OF SOLUTIONS VISCOSITIES 115 



Since p is in general less than unity, it follows that the conductance of 

 the ions changes less rapidly than does the viscosity of the solvent for a 

 given increase in temperature. As a rule, the lower the conductance of 

 the ion, the greater the value of the exponent p. For most slowly mov- 

 ing ions the exponent appears to approach the value unity as a limit. 

 This is exemplified in the case of the acetate and the calcium ions. The 

 lower the conductance of an ion, therefore, the more nearly does the 

 conductance change in direct proportion to the fluidity change of the 

 solvent. But while the value of p in Equation 42 h^s thus been evalu- 

 ated, there is no good reason for believing that the exponent p in Equa- 

 tion 41 will have the same value. It obviously is not possible to deter- 

 mine the manner in which correction should be applied for the change 

 in the conductance of solutions due to concentration change, unless we 

 know the manner in which the ionization at these concentrations varies 

 as a function of concentration. In other words, the nature of the cor- 

 rection as found will depend upon the assumed nature of the conductance 

 function. 



We have the equation: 



where /(C) is some function of the concentration of the solution. As we 

 have seen, in solutions at higher concentrations, the function K' follows 

 approximately the relation: 



where n has a value in the neighborhood of 1.5 for aqueous solutions. 

 Assuming this equation to hold at higher concentrations, we may deter- 

 mine the nature of the viscosity correction on the basis of this assump- 

 tion. In order to determine the nature of the correction, therefore, we 

 may determine the value of the constants n and D at lower concentra- 

 tions, where the viscosity change is negligible, and thereafter extrapolate 

 this function to higher concentrations. In other words, by means of 

 Equation 9a we may calculate the value of y at higher concentrations 

 and compare it with the directly measured value and with the fluidity 

 of the solution at that concentration. Or, conversely, the experimentally 

 determined conductance values at higher concentrations may be multi- 

 plied by an assumed correction factor and the corrected values compared 

 with the values calculated by means of the above equation. If the 

 assumptions made are applicable, then the two values should correspond. 



