Page:Text-book of Electrochemistry.djvu/232

 is valid, where r is the number of ions contained in a mole- cule of the salt, and - denotes the degree of dissociation. We

c

then obtain —

i = 1 + (r - 1/

c

d(d) _ d( c + ( r - l)g) ^ dc + ( r - l)dg c c c

By differentiating the equation for mass action we obtain- —

r(c - ff)d(/ :=[/dc - (/dg

"i'^ = dc+(r^l)dg

y

d(ci) __ rdf/

from which it follows that —

T^ iJr. 2-3025 ,. ^^^^y\

n. 23,070 Oq

rr BT. 2-3025 .^(jv

Kg = __ -. r. 7;t. log ^- \

n. 23,070 ^ V

where Vi is applicable for concentration elements with unpolarisable electrodes of the first order, and Fa for those with unpolarisable electrodes of the second order (log denotes the ordinary logarithm). Without appreciable error we may

set ~^^^ =r 10"^ These formula?, which are convenient for calculating, agree with those of Nemst. The product of

concentration and degree of dissociation, g, is a measure of the concentration of the ions. For electrolytes consisting of two monovalent ions r = 2 and 71 = 1. Most of the determinations which have been carried out were made with such electrolytes.

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