Part XL 



THE EQUIVALENT CONDUCTANCE OF HYDROGEN-ION DERIVED FROM 

 TRANSFERENCE EXPERIMENTS WITH NITRIC ACID. 



111. OUTLINE OF THE INVESTIGATION. 



In an article published four years ago by A. A. Noyes and G. V. 

 Sammet* there were described some transference determinations made 

 with -jL, B L- and gV normal hydrochloric acid at 10, 20, and 30, which 

 when combined with the equivalent conductance of chloride-ion (using 

 the value of Kohlrausch) yielded for hydrogen-ion a much higher equiva- 

 lent conductance than that which had been derived from the conductivity 

 of acids at high dilutions. Thus the value for hydrogen-ion at 18 derived 

 from the transference experiments was 330, while that of Kohlrausch 

 derived from conductivity was 318. This serious divergence appeared 

 greater than the possible errors in the transference determinations! ; and it 

 seemed as if it must be due either (1) to an error in the extrapolated 

 values of the equivalent conductance of acids at zero concentration, (2) 

 to the formation of complex-ions or some other abnormality of the hydro- 

 chloric acid, or (3) to a marked difference in the relative velocities of the 

 hydrogen-ion and the anion, at moderate and at very low concentrations. 

 To test the first of these possibilities a study of the effect of the impurities 

 in the water upon the conductance of very dilute hydrochloric and nitric 

 acids was made in this laboratory by H. M. Goodwin and R. Haskell4 the 

 results of which showed that, after eliminating the effect of impurities as 

 far as possible, a value for the equivalent conductance of hydrogen-ion 

 at extreme dilution (315 at 18) even lower than that previously derived 

 by Kohlrausch (318) was obtained. 



In view of these results it did not seen possible that the divergence 

 could be due to the first-mentioned cause. The present investigation was 

 therefore undertaken, in order to test the second explanation, or that being 

 excluded, to establish the correctness of the third one. 



For it was thought that independent transference experiments with 

 another acid, if they yielded results concordant with those with hydro- 

 chloric acid, would serve both to exclude any specific error that might 

 arise from complex-ion formation or other individual peculiarity of that 



*J. Am. Chem. Soc, 24, 944-968; 25, 165-168 (1902-3); Ztschr. phys. Chem., 43, 

 49-74 (1903). 



fThe experimental results of Noyes and Sammet have recently been fully con- 

 firmed by those of Jahn, Joachim and Wolff (Z. phys. Chem., 58, 641 (1907). 



$Phys. Rev., 19, 369-396 (1904) ; Proc. Am. Acad.. 40, 399-415 (1904). Reviewed 

 in Z. phys. Chem., 52, 630 (1905). 



313 



