574 
CHEMISTRY: E. W. WASHBURN 
The method consists simply in plotting values of K^, the mass-action 
expression, against values of the concentration, employing different 
assumed values of Ao and rejecting such values of Ao as cause the curve 
in dilute solutions to exhibit sudden changes in direction. In this way 
it is found that, if too small a value is employed for Ao, the curve will 
eventually shoot upward ; while, if too large a value is employed, it will 
turn downward in the lower concentration ranges. By employing this 
method it is possible to determine the value of Ao with a certainty of 
0.01%, provided the conductance data themselves are as accurate as 
this and extend at least as low as 0.00002 normal. 
48 , 
46 
44 
42 
40 
38 
3-* 
32 
30 
28 
.26 
24 
_22 _5-^^^^^ 
18 V^-^ 
J 4 O 
J 2 
2 4 6 8 10 12 14 16 
1 1 1 ■ ■ ■ ' 1 
8 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 
J. 1 1 1 1 1 1 1 — -J 1 1 1 1 1 1 1 1 1 
CONC. X 10' • 
FIG. 3 
This will become evident from an examination of figure 2, which has 
been constructed from conductance values which are substantially 
those represented by the curve in figure 1. It is also evident from this 
figure that the value of Ao for potassium chloride at 18° is 129.64=^=0.02, 
and that the value of is 0.020 ±0.001. 
Figure 3 illustrates the behavior of potassium chloride with respect 
to the requirements of the Mass-Action Law and shows that this law is 
obeyed within the experimental error in the concentration range 0 to 
0.0006 normal. The different series of points represent independent 
sets of measurements. Those indicated by the dotted circles represent 
