Vanadium compounds in reductimetric titrations-II Standardisation of vanadium(II) sulphate with common oxidising agents and determination of binary mixtures.
Methods for the standardisation of vanadium(II) sulphate are described. With weak oxidising agents, e.g., Fe(III)/Fe(II) in phosphoric acid, vanadium(II) undergoes a one-electron change, which is satisfactorily indicated by Neutral Red, Phenosafranine or Safranine T, or by potentiometry. Stronger oxidising agents oxidise vanadium(II) to vanadium(IV); Variamine Blue, Methylene Blue, o-dianisidine, cacotheline, ferroin, bis(alpha,alpha'-bipyridyl)iron(II) and ammonium molybdate are satisfactory indicators. Binary mixtures of oxidising agents can be determined.
Chawla
K L
KL
Department of Chemistry, University of Rajasthan, Jaipur, India.
Tandon
J P
JP