Page:Text-book of Electrochemistry.djvu/187

 ��THE DISSOCIATION THEORY.

��CHAP.

��point the specific gravities of ammonium chloride solutions, which have the following values : —

Ammonium Chloride.

��CoDoentratlon, n.

�Speclflo gniTlty.

�CuDoentration, II.

�Spedflc gravity,

�

��The following numbers multiplied by 10 * are the moduli for the various ions : —

��NH4 K Na Li iBa iSr iCa JMg JMn

iCd iPb iCu Ag H 01 Br I NOs

CaHsOa OH

��iZn

��The specific gravity of, e.g. a Zn iCaBr2 solution, would be calculated to be —

8= 1-0451 + 3(280 + 373) . 10;* = 1-0431 -f 01959 = 1-2397,

and by experiment 1*2395 has actually been found.

With the aid of these moduli the specific gravities of quite concentrated solutions can be obtained fairly accurately, although, as the example given proves, the salt is not by any means nearly completely dissociated.

Compressibility, Capillarity, and Internal Friction of Solutions. — Other properties of solutions besides the specific gravity show the same regularities. As an example, we may take the compressibility, i.e. the volume change suffered by 1 c.c. when the pressure is raised from 1 atmo. to 2 atmos.

Eontgen and Schneider {2) found the numbers con- tained in the following table for 0'7-normal solutions at the

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