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The Chemical Educator

ISSN: 1430-4171 (electronic version)

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Abstract Volume 16 (2011) pp 72-75

Utilizing 1,10–Phenanthroline Ligand Effect in Estimation of Cobalt (II) and Simultaneous Estimation of Cobalt (II) and Iron (II) with Cerium (IV)

Masood Ahmad Rizvi*, Raashid Maqsood, Roheena Jan, and Ghulam Mustafa Peerzada

Department of Chemistry, University of Kashmir, Hazratbal, Srinagar, 190006, J and K India,
Received May 25, 2010. Accepted September 23, 2010.

Published: 25 February 2011

Abstract. Transition metals have multiple oxidation states separated by a finite potential value. A redox reaction between a transition metal or a mixture of transition metal ions with an oxidant is feasible provided their reduction potential are sufficiently different and lower than the reduction potential of oxidant concerned. Since complexation modifies potential of redox systems involving metal ions, this phenomenon has a potential capacity for the development of new titrimetric methods of analysis .While potentiometric titration of cobalt (II) and simultaneous potentiometric titration of cobalt (II) and iron (II) with cerium (IV) is not spontaneous due to a mismatch of their reduction potentials. Complexation with 1,–10 phenanthroline ligand in the pre step modifies potential of both the ions thereby making an otherwise not spontaneous and interfering reaction feasible.

Key Words: Laboratories and Demonstrations; analytic chemistry; redox potential; coordination compounds; potentiometric titration; electrochemistry; potentiometry; iron (II); 1; 10 phenanthroline; cobalt (II); cerium (IV)

(*) Corresponding author. (E-mail:

Article in PDF format (424 KB) HTML format

Supporting Materials:

Three sets of student data, derivation of equations, instructor notes, experimental observations, calculations, titration assembly description, CAS registry etc are available as supplementary material in Lab Documentation (281 KB).

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