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Thermochemistry of Precipitation of Alkaline Earth Laurates

Vesna Hrust ; Laboratory of Physical Chemistry, Department of Chemistry, Faculty of Science, University of Zagreb, 41001 Zagreb, P. O. Box 163, Croatia, Yugoslavia
Đurđica Težak ; Laboratory of Physical Chemistry, Department of Chemistry, Faculty of Science, University of Zagreb, 41001 Zagreb, P. O. Box 163, Croatia, Yugoslavia

Sažetak

The solubility of alkaline earth laurates was studied in aqueous solutions as a function of temperature. Dissolution enthalpies AdH°, determined directly by calorimetry, were compared with the solubility data. The enthalpy change AdfiT0 showed linear dependence on temperature. The heat capacity change AdCp, calculated from AdH°vs. T plot, was found to be 1.1 kJ mol"1 K"1 for all salts.
The entropy change of dissolution AdS°, as obtained from solubility and calorimetiy, showed linear dependence on In T; AdCp, calculated from these plots, was the same as obtained from temperature dependence of the enthalpy.
Specific behaviour of each alkaline earth cation is characterized by the entropy change A<*S°, which is the lowest for calcium salt, thus explaining the irregular low solubility of calcium carboxylates. The so called compensation effect was explained in terms of the »critical compensation temperature®, which was found to be just an average temperature within the examined temperature region.

Ključne riječi

Hrčak ID:

137300

URI

https://hrcak.srce.hr/137300

Datum izdavanja:

15.10.1991.

Posjeta: 1.062 *