Abstract

Potentiometric And Thermodynamic Studies Of The Protonation Equilibria And Metal Ions Complexation Of Some Zwittrerionic Buffers In NaNO3 Solutions In Water And In Mixtures Of Water And Dioxane

Author(s): Mohamed Taha, Alaa T.Ahmed, Shad A.Saqr, Sawsan A.Mohamed

The protonation equilibria for some selected zwitterionic buffers in solutions have been studied pH-potentiometrically. The second stage dissociation constants(pKa2) of zwitterionic buffers and the thermodynamic quantities(ΔG, ΔH, and ΔS) have been derived at different temperatures in water at ionic strength I=0.1 mol·dm-3 NaNO3 and in the presence of 10%, 30%, and 50%(w/w) dioxine. Titrations were also carried out in water ionic strengths of(0.15, 0.20, and 0.25) mol· dm-3NaNO3. The interactions between the zwitterionic buffers with some metal ions were also studied at different temperatures and in the presence of 10%, 30%, and 50%(w/w) dioxane by using potentiometry. The thermodynamic stability constants were calculated as well as the thermodynamic quantities for the 1:1 binary complexation.