EKatremely Dilute Acid and Alkali Solutions. itl 
where p is a constant. Hence, for any given value of the ratio 
E we should have only one value of m, wherever the reaction 
Me 
“occurs. 
_ Now in the illustrative experiments with the ammonium 
carbonate solutions, the form of the curve certainly depended on 
‘this reaction. The value of m, as calculated from Fig. 5 for the 
‘ammonium carbonate solution is found to be the same as that 
calculated from Vig. 4 for tbe distilled water. 
Thus in Fig. 5, if A be the initial conductivity of the solution, 
the straight Tine drawn through A would represent the con- 
ductivity of the acid solution if no combination of ions had taken 
place. Take any vertical line XYZ as shown. XY is the ‘loss of 
conductivity’ at Y. XZ is the total loss of conductivity that 
ultimately takes place, so that YZ is proportional to the number 
of carbonate ions still in solution. 
Ms, XV 
ji, 9 WA? 
since m, and ms are expressed 1 in gram- -equivalents. Also m, 1s 
the quantity of hydrogen ions present, 7.e. the amount added in 
the sulphuric acid (represented by the abscissa of the point Y) 
minus the amount removed as unionised H,CO; (proportional 
‘to XY ). For ionised H,SO,, &/m=0'362. Hence, since the 
velocity numbers of the H, 4SO, and $CO, ions are 320, 73 and 
90 respectively, the value of k/m for ionised H,CO, 
ue 
Hence 
XY 
0340 gram equivalents 
of H,CO, (and therefore of H ions) from the ionised state. 
_ Ms 
We have worked out the case in which —, - = — =], ealcula- 
WA ip 
Hence XY corresponds to the removal of ——— 
ting the values of m, from the Figs. 4 and 5. 
(a) For the distilled water (Fig. 4), 
AY =YVZ=0:44 x 10~ reciprocal ohm, 
which corresponds to 0°44 x 10-* + 0:°340 = 13 x 10~* gr.-equiv. of 
H,CO, (and of the corresponding H ions) per litre. This occurs 
at a point of the curve for which the abscissa is 2:2 x 10° gr.- 
equiv. of H ions added in the H,SO,. Hence the quantity of 
H ions still in the solution is the difference of these, viz. 0°9 x 10-® 
‘gr.-equiv. per litre (=m). 
(b) For the ammonium carbonate solution (Fig. 5), 
AY = YZ=145 x 10% reciprocal ohm, 
