Page:Text-book of Electrochemistry.djvu/207

 192 EQUILIBRIUM BETWEEN ELECTROLYTES, chap.

value 076 for the ratio between nitric acid and dichloracetic acid signifies that on mixing three equal volumes of normal solutions of these two acids and sodium hydroxide, 76 per cent of the alkali is converted into nitrate and 24 per cent, into dichloracetate. The calculated values are given as well as those found by experiment. According to Thomsen's phraseology, nitric acid has an avidity JJ = 317 times greater than that of dichloracetic acid. Except in the case of the ratio between formic acid and glycollic acid, the experimental values agree well with those calculated, and this exception is no doubt due to an error of observation.

The numbers given were obtained by Ostwald, and apply to the ordinary temperature.

��Nitric acid : Dichloracetic acid. . . . Hydrochloric acid ; ,, ,,....

Trichloracetic acid : „ ,

Dichloracetic acid : Lactic acid .... Trichloracetic acid : Monochloracetic acid „ „ : Formic acid. ..

Lactic acid

Acetic acid

Butyric acid

Isobutmc acid ....

Propionic acid

Glycollic acid

Acetic acid : Butyric acid

„ : Isobutyric acid

��Formic acid

��J'

��'»

��«»

��»»

��>•

��Obflerved.

�GalcaUted.

�0-61)

�0-5

��Strength of Acids and Bases.— For a long time it has been customary to determine the strength of acids by measuring their avidities, which, as shown above, are pro- portional to their degrees of dissociation. Now, since the strength of acids varies a good deal, it was assumed, in agree- ment with the conception formulated by Bergman, that the stronger acids replaced the weaker from their salts. Berthelot (6') has given us a large amount of data as to which of two acids is the stronger, or, according to his view, which

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