The use of the Nb-Nb 2O 5 electrode as an indicator electrode in potentiometric acid-base titrations in fused KNO 3

Abstract

An Nb-Nb 2O 5 electrode was prepared by the electrolytic oxidation of niobium in molten KNO 3. This electrode can be used as an indicator electrode in potentiometric acid-base titrations. It behaves reversibly and responds theoretically to the oxide ion concentration in molten KNO 3. Its potential varies linearly with ln[O 2-] and the line has a slope of 68 mV at 350 °C. The standard potential of the Nb-Nb 2O 5, O 2- electrode, i.e. the potential at [O 2-] = 1, is computed as -810 mV with respect to the Ag-Ag + reference electrode.