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

Abstract

The Ta/Ta 2O 5 electrode was prepared by the electrolytic oxidation of molten KNO 3 on tantalum. This electrode can be used as an indicator electrode in potentiometric acid-base titrations. It behaves reversibily and responds theoretically to the oxide-ion concentration in molten KNO 3. Its potential varies linearly with the logarithm of [O 2−] and the slope of the line amounts to 65 mV at 350°C. The standard potential of Ta/Ta 2O 5,O 2− electrode, i.e. the potential at [ O 2−] = 1, is computed as -985 mV relative to the Ag/Ag(I) reference electrode.