CONDUCTOMETRIC INVESTIGATION OF MAGNESIUM (II), CALCIUM (II) AND BARIUM (II) COMPLEXES IN AQUEOUS SOLUTION | ||||
| Al-Azhar Bulletin of Science | ||||
| Article 6, Volume 2009, Issue 6, June 2009, Page 61-70 PDF (134.9 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/absb.2009.7544 | ||||
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| Authors | ||||
| WADIE AL–ARIQUI1; ABD ALLAH A. MOHAMED* 2; WADIE S. AL–ARIQUI3; MOUSTAFA F. BAKR2 | ||||
| 1Chemistry Department, Faculty of Science, Sana'a University, Sana'a, Republic of Yemen. | ||||
| 2Chemistry Department, Faculty of Science, Al–Azhar University, Nasr City, Cairo, Egypt | ||||
| 3Chemistry Department, Faculty of Science, Sana'a University, Sana'a, Republic of Yemen. | ||||
| Abstract | ||||
| The ionic association constants, KA, of Mg, Ca and Ba metal ions with succinate, malate and tartrate ligands were conductometrically determined in water at 25–40oC. The conductometric data were analysed by the Shedlovsky extrapolation method. The KA values tend to decrease with the cation size in the order Ca > Ba for all the salts under study with the exception of Mg salts, whereas the KA values for the ligands increase in the order succinate < malate < tartrate. For the salts under study, standard thermodynamic functions, Ho and So for the association were evaluated and discussed. The positive values of both Ho and So in all the systems indicate the ionic association processes are the reactions of unfavorable enthalpy and favorable entropy changes in aqueous solution. The thermodynamic metal gradient, , was evaluated and its significance of ion association of all salts under investigation was discussed. On the other hand, the results of limiting molar conductance, o, are discussed on the light of Walden product. | ||||
| Keywords | ||||
| Conductivity; Association constant; alkaline–earth metal; succinate; malate; tartrate; aqueous solution | ||||
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