Thermodynamic Studies of Ion Association of s-Acetylthiocholine Halides and Perchlorate in Methanol Solutions


  • Nasr Hussein El-Hammamy Alexandria University
  • Marwa Nasr El-Hammamy Damanhour University
  • Aida Ibrahim Kawana Alexandria University



s-acetylthiocholine salts, ion association, activation energy, thermodynamic functions


Thermodynamic parameters (ΔH0, ΔG0, ΔS0) and the activation energy (ΔEs) were calculated to explain the limiting equivalent conductance (Λ0) and ion association constant (KA) of s-acetylthiocholine halides and perchlorate in methanol solutions at different temperatures by using conductance measurements. It has been evaluated by using Fuoss-Onsager equation. It is evident that the values of (Λ0) increase regularly with increase in temperature. For all salts of s-acetylthiocholine, (Λ0) indicates that higher mobility of the ions in all solvent systems studied. The free energy change ΔG0 values are negative for all salts (Br-, I- and ClO4-) in solvent systems studied. Clearly strengthening the interionic association at higher temperatures is largely caused by a decrease in the permitivity of the solvent. The positive values of (ΔH0) for three salts (Br-, I- and ClO4-) show that the association processes are endothermic in nature. Entropy change (ΔS0) values were positive for all salts because of decrease in solvation of ion-pair compared to that of the free ion. This may be attributed to increase in the degree of freedom upon association, mainly due to the release of solvent molecules.


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Author Biographies

Nasr Hussein El-Hammamy, Alexandria University

Chemistry Department, Faculty of Science

Marwa Nasr El-Hammamy, Damanhour University

Physics Department, Faculty of Science

Aida Ibrahim Kawana, Alexandria University

Chemistry Department, Faculty of Education






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