176 



Conductivity of Aqueous Solutions. Part VI. 



It may first be shown that this base, like the neutral salts, conforms 

 fairly closely at all temperatures to the simple cube-root formula of Kohl- 

 rausch (A A = KC h ). Applying it in the form Ac x A C2 = K(C 2 h 

 C x *) we have first calculated the value of the constant K for C 2 =50 (at 

 18 and 100) or 40 (at 156 and 218) and C x = 4, and have then calcu- 

 lated the value of Ad for the intermediate concentration C 2 = 20. The 

 percentage deviations of the so-calculated values from the observed values 

 given in table 59 are as follows: At 18, +0.0; at 100, 0.4; at 

 156, 0.3; and at 218, + 0.3. These deviations are not greater than 

 the possible experimental errors.* 



We have also determined graphically, by plotting against (CA)"' 1 as 



A 



described in section 17, Part II, what value of the exponent n in the func- 

 tion C(A A)=K(CA) n best expresses the results with sodium 

 hydroxide at 18, 100, and 156. f The values of n so determined are 

 given in table 61. It will be seen that they correspond with the values 

 obtained for the neutral salts, all of which lie in the neighborhood of 1.5. 



Table 61. Values of exponent n in the 

 function C(A A) K(C^) n - 



The effect of temperature has interest especially with reference to the 

 values at zero concentration ; for in these the ionic velocities are alone 

 involved. The mean temperature-coefficients (AA /A^) for sodium hydrox- 

 ide and ammonium chloride are given in table 62. 



Table 62. Mean temperature-coefficients of the equiv- 

 alent conductance at zero concentration. 



As in the case of hydrochloric acid (see section 55, Part V) the temper- 

 ature-coefficient of sodium hydroxide decreases rapidly and steadily with 



*The values of the constant K when C is expressed in milli-equivalents per liter 

 are 5.33 at 18, 17.33 at 100, 32.1 at 156, and 61.9 at 218. For purposes of inter- 

 polation they may be used with A values between C = 4 and C = 50, but not with 

 the A values given in the table. 



fThose at 218 are so affected by contamination in the more dilute and by polari- 

 zation in the more concentrated solution as to make a study of the concentration 

 function of little significance. 



