Page:Text-book of Electrochemistry.djvu/107

 92 GENERAL CONDITIONS OF EQUILIBRIUM, chap.

This connection between the heats under the different conditions was tested by van't HofiF {11), and was found to be experimentally confirmed, as the numbers in the following table show: —

�� �Tenperature.

�SolubUity.

�Heat of eolation.

� �Substance.

�t

�<i

�c

�»i

�obs.

�calc.

�t

� �

�o

� � � � � �Succinic acid

�

� �Benzoic acid

� �Salicylic acid

� �Oxalioacid

�

�Boric acid

�

� �Lime

�Barinm hydroxide. ..

�

�Aniline

�Amyl alcohol

�

�Phenol

�Potaaaiam oxalate (acid).

�

�Potaasinm bichromate. .

�

�Alum

�

�Potaaaium chlorate. ..

�

�Borax

�

�Barinm nitrate ....

�

�Mercuric chloride. ..

��In the first column is given the substance experimented upon ; under t and ti two temperatures at which the solu- bilities s and si were determined (the solubility being expressed in percentage). Strictly, the solubility should be measured in grams per 100 c.c, but the values which would be obtained in this way do not differ much from those contained in the table, especially in those cases where the solubility is Cal. = 1000 cal.); the observed values are mostly those found by Thomsen, and the calculated values are those obtained by van't Hoff according to the above law. Under i is given the value for the various substances at con- centration — ^ and temperature — ^ — ^ . As is evident, the

agreement between the observed and the calculated heats of solution is eminently satisfactory.

�� �