The Mercury/Mercurous Acetate Electrode : Standard Potential in Dioxan-Water Media at 25°C.

Standard potentials of the Hg/Hg₂ (OAc)₂ electrode in dioxan-water media (containing 20, 30, 45 and 70% by weight of dioxan)have been determined at 25°C using a cell of the type.

\(Pt H_2 (1 atmos)\big|\begin{smallmatrix} HOAc(m_1)&NaOAc(m_2) \\ dioxan(W)&H_2O(100.W) \end{smallmatrix} \bigr|Hg_2(OAc)_2,Hg\)

and the values obtained on the molality scale are 0·48035, 0·45980, 0·43170 and 0.31400 abs. V. respectively.

From tho \(E^o_m\) values the standard free energy change (\(\bigtriangleup G_o\)) for tho cell reaction in the media were calculated to be -22·156, -21·208, -19·912 and --14·482 Kcal. respectively in water-dioxan media containing 20, 30, 45 and 70% by weight of dioxan compared to -23·584 Kcal. for the cell reaction in water. The dependance of the standard potential!! on the dielectric constants of the media in the light of the Born equation as well as the volume fraction of water (\(\phi_\omega\)) in the light of Feakins-French relationship has been examined.