Zur Polarographie von Niob und Tantal

✍ Scribed by R. Gut

• Publisher: John Wiley and Sons
• Year: 1960
• Tongue: German
• Weight: 869 KB
• Volume: 43
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19600430326

✦ Synopsis

Abstract

The polarographic behaviour of Nb^V^ and Ta^V^ in aqueous solvent systems does not allow a simultaneous determination of the two metals in presence of each other, therefore some organic solvents have been investigated. Characteristic waves have been obtained for Nb^V^ in acetonitrile and for Nb^IV^ in dimethylformamide. Melts of the system NaCl‐KCl‐AlCl~3~ proved to be much more favourable however. NbCl~5~ and TaCl~5~ as solutes are present in such melts as monomolecular species and their products of hydrolysis, if any, are converted into the pentachlorides by AlCl~3~, one of the components of the solvent. In this kind of melt Nb^V^ yields a polarographic double wave (Nb^V^ → Nb^IV^ → Nb^III^) and Ta^V^ a single wave (Ta^V^ → Ta^III^). The half wave potentials of the reductions of the two metals differ by 500 millivolts.