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

Siddharth Pandey , Mary E. R. McHale , Ann-Sofi M. Horton , Sandra A. Padilla , Ashantè L. Trufant , Noé U. De La Sancha , Ernesto Vela and William E. Acree Jr.
University of North Texas, Department of Chemistry, P.O. Box 5068, Denton, TX 76203-5070
J. Chem. Educ., 1998, 75 (4), p 450
DOI: 10.1021/ed075p450
Publication Date (Web): April 1, 1998
History, Education, and Documentation

Abstract

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.

Keywords (Audience):

Second-Year Undergraduate

Keywords (Domain):

Analytical Chemistry

Keywords (Pedagogy):

Hands-On Learning / Manipulatives

Keywords (Subject):

Instrumental Methods
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  • Received: August 03, 2009

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