Review of effect of temperature and thermodynamic quantities upon acidic dissociation of Glycine in 10, 20 and 30% dioxane (m/m) in dioxane-water system at 288.15K, 298.15K, 308.15K and 318.15K by e.m.f. measurement

Abstract

<p>For study of effect of temperature and thermodynamic quantities upon acidic dissociation of Glycine in 10, 20, and 30% dioxane(m/m) content in dioxane-water system at 288.15K, 298.15K, 308.15K, and 318.15K, the following types of cell has been set up:</p> <p>H<sub>2</sub>(Pt) | Glycine, HCl, X% Dioxane, Hg<sub>2</sub>Cl<sub>2 </sub>| Hg</p> <p>m<sub>1 </sub> m<sub>2</sub> (C-1)</p> <p>in 10, 20, and 30% dioxane in dioxane-water system at 288.15K to 318.15K at an interval of 10K, and e.m.f. of the cell was given by:</p> <p>E = E<sup>0</sup> - (2.303RT/F) (log m<sub>H</sub><sup>+</sup> m<sub>Cl</sub><sup>_</sup> + log Ɣ<sub>H</sub><sup>+</sup> Ɣ<sub>Cl</sub><sup>_</sup>) (1)</p> <p>where,</p> <p>log Ɣ<sub>H</sub><sup>+</sup> Ɣ<sub>Cl</sub><sup>_</sup> = - (2A`√μ/(1+√μ) ) + b<sub>1</sub>μ (2) </p> <p>log K<sub>1</sub> - b<sub>1</sub>μ = log K<sub>1</sub>(A) – (2A`√μ/(1+√μ)) (3)</p> <p>The equation (2) is called Modified Davies equation given by B. Prasad<sup>1</sup> for calculating activity coefficient in the system.</p> <p>From equation (3), acidic dissociation constant of glycine was calculated<sup>2-5</sup> by extrapolating the graph at μ=0 in 10, 20, and 30% dioxane (m/m) in dioxane-water system from 288.15K to 318.5K at an interval of 10K, and then standard free energy change, standard enthalpy change, and standard entropy change were calculated by thermodynamic relations:</p> <p> ΔG<sup>0</sup> = -RTlnK<sub>1</sub> (4)</p> <p>and ΔG<sup>0</sup> = ΔH<sup>0 </sup>- TΔS<sup>0 </sup> (5)</p> <p>and by least square method<sup>6</sup>.</p>