Journal of Electroanalytical Chemistry

Polarographic behaviour of Cerium (IV)

Introduction

The polarographic study of strong oxidant ionic species, such as Ce (1V), presents serious limitations with the dropping mercury electrode because of the easy oxidability of mercury. We obtain, in fact, polarographic waves which start at the zero of the e.m.f. applied. These waves were utilized by Canneri and Cozzi for analytical purposes. The difficulty of studying the behavior of ceric ion with the dropping mercury electrode justifies the dearth of bibliographic notices upon problems connected with the equilibrium of the red/ox couple Ce (IV)/Ce (III) in the dynamic phase. With the realization of the bubbling platinum electrode which is analogous to the dropping mercury electrode, it is possible to extend polarographic investigations even to strong oxidant ionic species, such as ceric ion. As is known, the ceric ion forms complexes with several reducing ligands but their existence is not compatible with the oxidant powers of ceric ion which reduces itself, in a very short time, to cerous ion. Therefore we have investigated sulphure complexes , which present not only notable stability but , with the non-reducing character of the ligand , are compatible with the strong oxidant character of Ce (1V).

Summary

The Ce (1V) reduction in sulphuric media on the bubbling smooth platinum electrode was widely investigated. The influence on the ceric ion behavior of H₂SO₄ ionic activity, the presence of catalysts, as well as the temperature change was observed. The conditions under which the red/ox Ce (1V)/Ce (III) system becomes reversible in sulphuric media are defined and the influence of acidity, catalysts and temperature are studied. Finally a polarographic direct determination of Ce (1V) is described.

Lesson 7

Part 1

<== попередня сторінка	\|	наступна сторінка ==>
Flocculation	\|	Ammonia

Не знайшли потрібну інформацію? Скористайтесь пошуком google:

Генерація сторінки за: 0.003 сек.