NIOBIUM AS A POTENTIOMETRIC SENSOR IN REDOX TITRATIONS WITH AND WITHOUT PASSIVATION BY AMMONIUM MOLYBDATE
Abstract:
<p align="justify"> The Pt indicator electrode has been commonly used for redox potentiometric titrations. In this work the Nb indicator electrode is suggested as an alternative for the Pt indicator electrode for the redox potentiometric titrations of the system Fe(ll)/K<sub>2</sub>Cr<sub>2</sub>O<sub>7</sub>. The utilization of the proposed electrode has been studied with and without passivation. The passivation is made by electrode immersion in oxidising anodic inhibitor of NH<sub>4</sub>MoO<sub>4</sub>. The result was an observed increase of the potentiometric leap from 30 mV to 60 mV, allowing better visualization of the equivalence point. The same equivalence point was observed with the conventional and proposed electrode. With the Nb electrode, an inverse potentiometric leap was also obtained. </p>
<p align="justify"> The Pt indicator electrode has been commonly used for redox potentiometric titrations. In this work the Nb indicator electrode is suggested as an alternative for the Pt indicator electrode for the redox potentiometric titrations of the system Fe(ll)/K<sub>2</sub>Cr<sub>2</sub>O<sub>7</sub>. The utilization of the proposed electrode has been studied with and without passivation. The passivation is made by electrode immersion in oxidising anodic inhibitor of NH<sub>4</sub>MoO<sub>4</sub>. The result was an observed increase of the potentiometric leap from 30 mV to 60 mV, allowing better visualization of the equivalence point. The same equivalence point was observed with the conventional and proposed electrode. With the Nb electrode, an inverse potentiometric leap was also obtained. </p>
DOI: 10.48141/SBJCHEM.v2.n2.1994.57_1994.pdf
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