Ionic components of charge at the mercury-KCl +KI aqueous solution interphase

Abstract

The ionic components of charge for the mercury aqueous mixtures of KI + KCl interphase have been obtained from capacitance measurements. The experimental results show that the Cl − ion is not specifically adsorbed in the concentration range studied. The specifically adsorbed charge of the iodide ion was obtained by two methods. Grahame's using the Gouy Chapman theory, σ 1 I − (GC) and the method of Parsons—Hurwitz, σ 1 I − (PH). The differences between the two sets is analyzed in terms of the assumptions made in their calculation. The σ 1 I − (GC) shows a crossing point at high σ in the σ 1 I − - vs σ plot. It is explained in terms of an increase in the amount of water at the compact layer and an increase in the amount of iodide ion at the diffuse layer. Other features of the σ 1 I − (GC) vs σ curves are explained in terms of errors of the simple Gouy Chapman model.