Experimental Evaluation of DSºrxn, DHºrxn, and DGºrxn Using Voltaic Cells: A First-Year College Chemistry Laboratory

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 5 Issue 1 (2000) pp 17-19

Experimental Evaluation of DSº_rxn, DHº_rxn, and DGº_rxn Using Voltaic Cells: A First-Year College Chemistry Laboratory

Donald E. Mencer* and Elaine Anne Elliott

Department of Chemistry, The Pennsylvania State University-Hazleton, Hazleton, PA 18201

Published online: 1 February 2000

Abstract. Six voltaic cells have been evaluated for their suitability in the determination of thermodynamic parameters. The cells were prepared with all species present at conditions that approximate standard-state conditions and cell potentials were measured as a function of temperature. From these measurements graphs of voltage versus temperature were prepared. From these graphs it was possible to determine the standard heats of reaction (DHº_rxn), standard change in entropy or disorder (DSº_rxn), and the Gibbs free energy (DGº_rxn) for the spontaneous oxidation–reduction reactions. The standard cell potential (Eº_cell) values were also calculated. Two cells with opposite temperature dependence of the cell potential were found to produce good agreement with the literature values of DGº_rxn, DHº_rxn, DSº_rxn, and Eº_cell. Criteria for identifying additional cells that may be suitable for potentiometric studies of thermodynamic parameters are also included

Key Words: Laboratories and Demonstrations; electrochemistry; thermodynamics; laboratory instruction; general chemistry; voltaic cells

(*) Corresponding author. (E-mail: dxm53@psu.edu)

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Supporting Materials:

Student handout (32 KB) 10.1007/s00897000352b

Materials list (11 KB) 10.1007/s00897000352c