Complexation key to a pH locked redox reaction

TitleComplexation key to a pH locked redox reaction
Publication TypeJournal Article
Year of Publication2016
AuthorsRizvi, MAhmad, Dangat, YB, Shams, T, Khan, KZaman
JournalJournal of Chemical Education
Volume93
Issue2
Pagination355-361
Date PublishedFEB
ISSN0021-9584
KeywordsAnalytical Chemistry, Aqueous Solution Chemistry, Coordination Compounds, Oxidation/Reduction, pH, Physical Chemistry, Potentiometry, Second-Year Undergraduate, Thermodynamics, Titration/Volumetric Analysis, Upper-Division Undergraduate
Abstract

An unfavorable pH can block a feasible electron transfer for a pH dependent redox reaction. In this experiment, a series of potentiometric titrations demonstrate the sequential loss in feasibility of iron(II) dichromate redox reaction over a pH range of 0-4. The pH at which this reaction failed to occur was termed as a pH locked reaction. The comparative ability of 10 selected iron binding ligands with varied propensity for the redox potential modification of Fe(III)/Fe(II) redox couple to restore/unlock the pH locked redox reaction is shown using potentiometric titrations. The spectrophotometric speciation analysis of Fe(III) Tiron complexation with pH was carried out to explain the differing ability of EDTA and Tiron to unlock the reaction under different pH Conditions. The experiment illustrates how environmental, biological redox reactions avoid severe laboratory conditions to occur and can be explored in the design of novel redox systems for natural attenuation of environmental toxins to their non- or lesser-toxic forms. The experiment also demonstrates prudent laboratory practice for safe waste disposal.

DOI10.1021/acs.jchemed.5b00499
Type of Journal (Indian or Foreign)

Foreign

Impact Factor (IF)1.225
Divison category: 
Physical and Materials Chemistry