Kinetics-Based Indirect Spectrophotometric Method for Simultaneous Determination of MnO4 (-) and Cr2O7 (2-):: A Modern Instrumental Analysis Laboratory Experiment

• Siddharth Pandey ^[1] ; Mary E. R. McHale ^[1] ; Ann-Sofi M. Horton ^[1] ; Sandra A. Padilla ^[1] ; Ashantè L. Trufant ^[1] ; Noé U. De La Sancha ^[1] ; Ernesto Vela ^[1] ; William E. AcreeJr. ^[1]
  1. [1] University of North Texas

     University of North Texas

     Estados Unidos

     
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 75, Nº 4 (April), 1998, págs. 450-452
• Idioma: inglés
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• Resumen

  • An indirect kinetics-based spectrophotometric method is developed for the simultaneous quantitative determination of permanganate and dichromate ion concentrations in an unknown. The method is based upon differences in reaction times between pyrogallol red and the two analytes. Oxidation of pyrogallol red (PGR) by permanganate ion is rapid, whereas oxidation of PGR by the dichromate ion is much slower. From changes in the measured absorbances after 3-and 8-minute reaction times, the molar concentrations of the permanganate and dichromate ions are determined.