Page:Text-book of Electrochemistry.djvu/231

 ��ELECTROMOTIVE FORCE.

��CHAP.

��solutions of potassium chloride, sodium chloride, and hydro- cliloric acid. According to the results obtained by Loomis and Hausrath, we may set i = 1 + a (approximately), where a is the degree of dissociation calculated from the conduc- tivity. In the following table Jahn's experimental values (E, observed) are given along with those calculated (E, calculated). The concentrations (in gram-molecules per litre) of the solutions used are given in the columns headed xi and X2.

��Xleotrolyte.

��KCl

�� ��HCl

��n

��NaCl

��it

1*

��sr,. 0-008aS

��»2.

��»i

��»•

��jj

��J'

��n

��M

��E (obeenred).

�E (calubted)

�•

��IXflference.

��- 2 0^'' -M

��The agreement between the observed and calculated values is very satisfactory. The observed values are always somewhat smaller (on the average about 1 per cent.), which points to a constant experimental error.

The formulae given above for V are perfectly exact, but they are more or less inconvenient, since they cannot be directly integrated. They can, however, be integrated if we assume that they are constant, and that the law of mass action —

��rr.

��= const.

��c ^ g

�� �