Study of Ion-Solvent Interaction during Acidic Dissociation of Glycine in 10, 20 And 30% Dioxane in Dioxane-Water System At 318.15K by Potentiometric Method

Abstract

Ion solvent interaction was studied by free energy transfer during acidic dissociation of Glycine in 10,20 and 30% dioxane in dioxane-water system at 318.15K and free energy was given by the thermodynamic relation </p> <p>ΔG_t = 2.303RTΔpK₁</p> <p>where ΔG_t = free energy transfer when solvent change from water to dioxane-water.</p> <p>ΔpK₁ = pK_s1-pK_w1</p> <p>where pK_w1 = -log K_w1 negative logarithmic of dissociation constant of glycine in water.</p> <p>pK_s1 = -log K_s1negative logarithmic of acid dissociation constant of glycine in dioxane-water.</p> <p>For this purpose acidic dissociatio constant of glycine was determined potentiometrically by setting up the cell:</p> <p>H₂(Pt) | Glycine, HCl, X% Dioxane, Hg₂Cl₂| Hg …(C-1)</p> <p>m₁m₂ (100-x)% water</p> <p>and e.m.f. of the cell was given by the formula:</p> <p>E = E⁰- 2.303RT/F (log m_H⁺ m_cl^- + log Ɣ_H⁺ Ɣ_Cl^_) …(1)</p> <p>In the equation (1) activity coefficient of the solution has been taken into consideration to understand ion solvent interaction and activity coefficient is given by the relation:</p> <p>log Ɣ_H⁺ Ɣ_Cl^_ = -2A¢√μ/(1+ √μ) +ꞵ₁μ …(2)</p> <p>Equation (2) is modified Davies equation given by B. Prasad and hence acidic dissociation constant of glycine can be calculated by calculating m_H⁺ as: log m_H⁺= (E⁰- E)/K - log m_Cl^_ + (2A¢√μ/(1+ √μ)) - ꞵ₁μ …(3)