Section 69. Ionization values. 



177 



rising temperature, owing to a greatly decreased acceleration of the fast- 

 moving ion. On the other hand with ammonium chloride, as with the other 

 neutral salts previously investigated, the temperature-coefficient is greater 

 between 100 and 156 than between 18 and 100. 



It is also of interest to note that with sodium hydroxide as with other 

 substances the velocities of the ions approach equality with rising tem- 

 perature. The ratios of the equivalent conductance at zero concentration 

 to that of sodium chloride and potassium chloride (see section 54, Part 

 V) at each temperature are as follows : 



18 



NaOH:KCl 1.98 



NaOH:NaCl 1.67 



Finally, attention may be called to the fact that ammonium hydroxide 

 like acetic acid at 0.1 to 0.01 normal exhibits a maximum of conductivity 

 between 100 and 156 owing to the increase in migration-velocity being 

 overcompensated by decrease in ionization. 



69. IONIZATION VALUES AND THEIR CHANGE WITH THE 

 CONCENTRATION AND TEMPERATURE. 



The percentage ionization of the various substances is shown in table 

 63. The values were obtained by dividing the equivalent conductance at 

 the different concentrations by that at zero concentration, as given in table 

 59. Those for 10-milli-normal sodium hydroxide were interpolated by 



Table 63. Percentage ionization. 



