Page:Text-book of Electrochemistry.djvu/172

 CHAPTER X.

��Degree of Dissociation and Dissociation Constant.

��Strong and Weak Electrolytes. — Before proceediug further it will be advisable to classify the electrolytes into two groups — those highly dissociated and those dissociated only to a slight extent, or, shortly, strong and weak electrolytes. All salts belong to the first class, with a few exceptions which have not yet been thoroughly investigated (copper acetate, mercury salts, potassium antimonyl tartrate, and possibly some compounds closely allied to these) ; and to this class belong also many of the inorganic mono- and di-valent acids and bases. The organic acids and bases (but not exclu- sively these) are weak electrolytes; as examples we may quote the already-mentioned cases of acetic acid and ammonia. These latter substances at moderate dilution are only dissociated to the extent of a few per cents. There are, of course, substances which stand roughly between these two groups, but their number is comparatively small.

Degree of Dissociation of some Typical Electrolytes. — In order to give some idea of the behaviour of various electrolytes, the following table contains the degree of dissociation of some commonly occurring salts : —

��V

��OOOOl

HCl.

�KCl.

�KG9U,02.

�iBaOj.

�iKgSO^.

��iZnSOi.

�� �