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  Home > JCE Print > Journal of Chemical Education > Issues > 2003  > January  >
In the Laboratory
Environmental Redox Potential and Redox Capacity Concepts Using a Simple Polarographic Experiment
Alejandro Pidello
Laboratory of Biological Chemistry, FCV, CIUNR, National University of Rosario, 2170 Casilda, Argentina
Cover
January 2003
Vol. 80 No. 1
p. 68
Abstract
The redox status of a system may be analyzed in terms of the redox potential (redox intensity component) and the size of the pool of electrons able to be transferred (redox capacity component). In single chemical systems, both terms are thermodynamically related by means of the Nernst equation, the classical redox equilibrium equation. Consequently, either the redox potential measurement or the redox capacity may be used without distinction to define the redox characteristics of these systems. However, in natural environments, which are a complex mixture of compounds undergoing redox reactions in several stages of nonequilibrium, it is difficult to establish the relationships linking redox potential and redox capacity. In this situation, as suggested by various authors, the complementary use of intensity and capacity measurements improves the characterization of the redox status of these systems. The aim of this laboratory experiment is to enable undergraduate students of applied biology (agronomy, veterinary or environmental sciences) to distinguish clearly between redox potential and redox capacity concepts through concrete results obtained in complex natural system such as soil, and to discuss the ecological significance of both concepts.
Supplement
Notes for the instructor and detailed laboratory documentation for students are available.
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*  Citation
 Pidello, Alejandro. J. Chem. Educ. 2003 80 68.
*  Keywords
 Agricultural Chemistry; Electrochemistry; Environmental Chemistry; Redox Reactions; Laboratory Instruction
*  History
 Created:
Last Updated:		 December 5, 2002
February 28, 2005
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