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Thermodynamic Study of Complexation Phenomena of Some Alkaline Earth Metal (II) Complexes in Propanol‐1‐Water Mixtures at Various Temperatures
Author(s) -
Bakr Moustafa F.
Publication year - 2003
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.200300051
Subject(s) - chemistry , stoichiometry , conductance , alkaline earth metal , metal , inorganic chemistry , stability constants of complexes , ionic radius , propanol , limiting , conductometry , aqueous solution , ionic bonding , analytical chemistry (journal) , ion , chromatography , methanol , organic chemistry , mechanical engineering , mathematics , combinatorics , engineering
The stability constants of Mg 2+ , Ca 2+ , Sr 2+ and Ba 2+ perchlorates with 2,4‐diamino‐3,5‐dicyanothiophene (DADCT) have been determined at 15, 25, 35, 45 and 55 °C in 10, 20 and 30% (w/w) propanol‐1‐water mixtures using the conductometric technique. The conductometric data were analysed using a model 1:1 stoichiometry by which the stability constants, K s , and the limiting molar conductance were obtained. The plots of specific conductance versus the molar ratio [A] o /[C n+ ] o suggest that the stoichiometry of metal ion complexes is of a 1:1 complex. The stability constants tend to decrease with the atomic number as well as the ionic radii in the order Mg > Ca > Sr > Ba in 10% > 20% > 30% (w/w) propanol‐1‐water solvents. This trend was found to agree exactly with the Irving‐Williams series for all the systems under investigation. The thermodynamic parameters, ΔG o , ΔH o and ΔS o , for the complexation processes of all the complexes were evaluated and their significances were discussed.