Section 42. Change of Conductance with Concentration. 705 



It was shown in table 11, section 17, Part II, that the value of n for 

 sodium and potassium chlorides lies between 1.40 and 1.50 at all tempera- 

 tures, and it will be seen from this table that the same is true also for the 

 tri-ionic salts, potassium sulphate and barium nitrate. This striking fact, 

 which is in utter contrast with the requirements of the mass-action law, 

 according to which the exponent should have the very different values 2 

 and 3 for these different types of salts does not seem to have been suffi- 

 ciently considered in the discussion of the possible causes of the devia- 

 tions. It is worthy of note also that the exponent has about the same value 

 for the uni-univalent salt silver nitrate, which is very different chemically 

 from the alkali-element chlorides, and that this is also true even for the 

 bibivalent di-ionic salt magnesium sulphate at 18. For the last salt we 

 have not calculated the exponent at higher temperatures, owing to the 

 large hydrolysis which doubtless exists. 



Attention may also be called to the constancy throughout the whole 

 range of temperature of the exponent n for each individual salt. This 

 seems to indicate that even at the highest temperature the hydrolysis has 

 not in any case become considerable. It should be mentioned, however, 

 that in the case of potassium sulphate it was not possible to determine the 

 value of the exponent nearer than 0.05 unit, owing to the fact that this 

 salt, unlike the others, does not seem to conform completely to any expo- 

 nential function of the type in question. 



43. CHANGE OF THE EQUIVALENT CONDUCTANCE WITH THE 



TEMPERATURE. 



The effect of temperature on the equivalent conductance values at zero 

 concentration (the A values) will be mainly considered in this section. 

 Attention may first be called to the ratios given in table 25 of the A values 

 for silver nitrate, potassium sulphate, and barium nitrate to those for 

 potassium chloride. 



Table 25. Ratio of A values to those for potassium chloride. 



It will be seen that with rising temperature the conductance of silver 

 nitrate, like that of sodium chloride (see section 18, Part II), approaches 

 the conductance of potassium chloride, thus furnishing another exempli- 

 fication of the principle that the ratio of the specific velocities of the vari- 

 ous ions approaches unity with rising temperature. 



